10-04-2017, 08:18 PM
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ABSTRACT
Diesel Performance Products introduces the Powershot propane injection system for turbo diesel owners who are looking for more power for towing increased mileage and throttle responsiveness out of their vehicles.
With its innovative and patented design and method of propane delivery, this system is unique to other systems on the market and has overcome many of the drawbacks encountered with earlier designed injection systems.
The Powershot is an infinitely variable-stage vapor injection system. It is controlled, activated and proportionate to the boost pressure of the engine. The Powershot comes on slow and steady and as the boost increases, so does the flow of propane. More boost=more propane=more power! It is fully adjustable and can be customized for your specific application in minutes for towing, performance or mileage gains.
The easy-to-install Powershot system will safely and substantially increase horsepower (up to 100hp) and torque (up to 250 ft lbs). This unit is a must for towing and all- around performance increases. Modest mileage gains are an extra bonus.
INTRODUCTION
POWERSHOT TURCHARGED PROPANE INJECTION SYSTEM
Diesel Performance Products introduces the Powershot 2000 propane injection system for turbo diesel owners who are looking for more power for towing increased mileage and throttle responsiveness out of their vehicles.
With its innovative and patented design and method of propane delivery, this system is unique to other systems on the market and has overcome many of the drawbacks encountered with earlier designed injection systems.
The Powershot is an infinitely variable-stage vapor injection system. It is controlled, activated and proportionate to the boost pressure of the engine. The Powershot comes on slow and steady and as the boost increases, so does the flow of propane. More boost=more propane=more power! It is fully adjustable and can be customized for your specific application in minutes for towing, performance or mileage gains.
The easy-to-install Powershot system will safely and substantially increase horsepower (up to 100hp) and torque (up to 250 ft lbs). This unit is a must for towing and all- around performance increases. Modest mileage gains are an extra bonus.
The system installs in about two hours and requires no permanent modifications to the vehicle or engine. The quality of the components is obvious: Custom LP regulators /Parker fittings, safety features such as custom auto/off rocker switches located inside the cab, and an automotive LP fuel lock-off solenoid valve located at the tank. All of the regulating is done at the tank eliminating the need for under hood installations and further enhancing safety concerns. The custom regulator maintains a constant tank pressure regardless of outside temperatures and delivers consistent, usable power at all boost levels.
Propane Fumigation
Lately, I've been getting quite a lot of e-mail from folks who are interested in the LPG Fumigation system that I have installed on the Pusher, so it makes some sense to have a page dedicated to that subject, with at least as much as I know about it, and some links to other resources.
What it is..and why:
Simply stated, Propane (LPG) Fumigation is the introduction of gaseous propane into the air intake of a diesel engine for the purposes of attaining more power, economy, or both. The parallel is often made between fumigation and using Nitrous Oxide on gasoline vehicles to achieve a power increase. Basically, this analogy is correct, although the properly implemented use of LPG on a diesel engine will actually result in a better-running engine without the possible damaging effects that N2O has on gas motors.
Exhaust emissions are reduced as a result, with lower quantities of unburned hydrocarbons and fewer particulates (smoke). LPG fumigation will even clean up the odor of diesel fuel in the exhaust, making the smell from the tailpipe of an engine utilizing it much less objectionable.
How it works:
Introducing LPG gas into the combustion air intake of a diesel engine acts as an accelerant, promoting the even burning of the diesel fuel, and more complete combustion, resulting in more power being produced. Propane by itself will not self-ignite inside a diesel-fuel compression-ignition engine. During the compression stroke, the air/LPG mixture is compressed and the temperature is raised to about 400C, not enough to ignite the LPG, which has an ignition temperature of about 500C. When the diesel fuel is atomized into the cylinder under high pressure, it immediately self-ignites (diesel ignites at about 385C.), and causes the LPG to burn as well. Since the LPG is in mixture with the air, the flame front from the diesel spreads more quickly, and more completely, including igniting the air/fuel mixture which is in contact with the cylinder walls, which are cool in comparison to the super-heated air inside the combustion chamber. Much of the cleaner burning of the fuel is attributed to this ignition against the "cooler" components of the engine, and accounts for raising the percentage of combustion from a typical 75% for a well-tuned diesel engine running on pure diesel fuel alone, to 85-90% with the addition of LPG. Obviously, this more complete combustion also gives a nice boost in power, with an accompanying increase in fuel economy and reduction of pollutants.
What to Expect:
OK, here's where we have to draw a distinction between engine types. Normally-aspirated engines require different systems to introduce the gas than do turbocharged engines. The results are different as well.
Normally-aspirated (N/A) engines will realize only a modest gain in power by the use of LPG gas. Displacing 1% of the intake air with LPG will result in a small power increase, perhaps 5-8%. Nearly no increase in power will be noted at full throttle, assuming that your injection pump is correctly adjusted already. Attempting to provide more gas to the engine will not increase performance, and will in fact lead to a condition not unlike pre-ignition in a gasoline engine. This has been attributed to "colliding flame fronts" inside the combustion chamber, and may have a lot to do with the fact that most N/A engines are also IDI (Indirect Injection), which means that the diesel fuel is not injected directly into the combustion cylinder, but instead enters a "swirl chamber" where ignition takes place. The flame front then shoots out of the swirl chamber into the combustion chamber, where it combines with the air (and LPG) to force the piston down in a power stroke. Apparently, these engines have a problem in that the flame front exiting the swirl chamber ignites the LPG/air mixture, which then causes back pressure, preventing the proper expansion of the ignited fuel leaving the swirl chamber.
I have had satisfactory results on my VW 1.6 N/A engine when adding LPG at a rate of 8-10% of the BTU rating of the diesel the engine is using. It may be possible to turn the fuel up, but I do know for sure that too much fuel does not increase power, and causes the engine to make very unhappy noises.
Turbocharged diesel engines are able to realize a significant increase in power by using LPG fumigation. While the usual suggested increase is considered to be approximately 20%, by careful management of the gas introduction, power gains of up to 40% are possible. My understanding is that it is a very fine line between lots of extra power and a dose of LPG that will render an engine scrap metal in a hurry, so consider carefully before you decide to "turn it up".
Turbo engines are by design blessed with a lean air-to-fuel ratio, and can be fed concentrations of LPG up to about 6-8% of the intake air volume. TDI (Turbo Direct Injection) engines have shown dramatic power increases when properly fumigated with LPG, combined with an "Upsolute" chip, or computer engine management upgrade. (Of course, these modifications will void any manufacturers warranties..)
Types of systems:
I am aware of two basic fumigation systems.
The first, I call the "dump" system, which means that you pick a value of propane to feed to the engine, either by calculation, or by trial-and-error, and you simply "dump" it into the air intake. Little provision is possible for correcting gas flow depending on engine load, so the system is probably only optimized for one type of load demand. The advantage is that this type of system can be cobbled to together by backyard experimenters like myself at a low cost. The disadvantages are that you will probably need to error on the side of caution to make sure that you aren't overloading your engine with too much gas, and that the system doesn't compensate for variations in engine speed, load, etc.
The second system is much more sophisticated, and uses a variety of sensors and controls to monitor engine performance and load, and adjust the gas flow to suit the need at the moment. Most commercially available systems will be of this type.
In order to determine the load on the engine in a N/A system, a venturi must be placed in the air intake, as diesel engines have no natural intake manifold vacuum. A sample of the vacuum produced by the venturi is fed to a metering system, either electronic or mechanical, which adjusts the gas flow to suit the circumstances.
Turbo engines have a great indicator of load built in. It's a fairly simple process to take a sample of the boost pressure developed by the turbocharger and use that to control the metering system. Most commercially made systems are designed for turbo engines, both for this reason, and because of the greater power gain that the turbo realizes from fumigation. Since boost is such a reliable indicator of engine load, higher values of fumigation can be realized, with tighter control over the results.
Construction of My System:
(But first, a message from the Shark Central Legal Department
BIG WARNING..!!
LP gas, like any combustible fuel can be dangerous. If you are going to attempt to construct your own fumigation system, be aware of the hazards present when you use this fuel. Use proper fittings and fixtures, and be aware of the high pressure present at the output of an LPG storage tank. Gaseous propane is heavier than air, and can collect in enclosed places. Any containment of a tank must be properly vented. Never check for gas leaks using a flame. ETC, ETC, ETC. This is not intended to be a complete tutorial on good engineering practice for flammable gas systems. You should be familiar with the tools and techniques of gas plumbing systems before attempting construction of such a system.
Additionally, while adding fumigation equipment to a diesel engine is becoming a commonly accepted practice, keep in mind that doing so may void your warranty, negate any emissions certifications your engine has and/or violate local or state vehicle codes. It is not impossible that done incorrectly, adding LPG to your diesel engine will cause damage to it's operation or construction.
The information contained here is believed to be accurate, but like anything else, is not necessarily 100% infallible. Use your own judgement, applied to your own circumstances.
All of this is meant to say: "YOU are ultimately responsible for any and all actions that YOU may take after reading this web page. In no event, will I be responsible for any damage to your property or person, or that of any others as a result of anything you do with the information contained here".
OK, now that that's out of the way (can't be too careful these days), we can get down to business.
The Tank and Regulator:
What type of tank you use may depend a lot of what type of vehicle you intend to use it on. If you are adding a system to a large truck or a motor home, you will probably have plenty of room for a frame-mounted horizontal tank. If it's a motor home, you may not need to add a tank at all, just use the existing one, although an additional regulator may be necessary, depending on the type of system you install. The smaller the vehicle, the more difficult the job of finding a suitable location to mount the tank, and the more difficult it will be to find a tank the right size and shape.
Should you be tempted to mount the tank in the enclosed trunk of your car, remember that DOT (Department of Transportation) rules forbid such installations unless the enclosure (your trunk) is well ventilated to allow any seepage or leakage of gas to readily escape. If you want to know how well ventilated it needs to be, go visit a motor home or travel trailer dealership and see how propane cylinders on recreational vehicles are mounted. Unless you plan on wearing a racing fire suit while driving, forget mounting the gas cylinder inside the passenger compartment.
The size of the tank will also depend on your usage. If this is a long-haul truck or RV tow rig, you will probably want the gas on full-time, in which case you will need a sizeable cylinder. For occasional hill climbing or passing on the road, you might be able to get by with a capacity of only a few gallons. Installations in cars meant for racing or speed exhibition will need only a small reservoir of fuel, perhaps with several tanks that can be interchanged when emptied.
During my initial trials, I used a Coleman camping fuel bottle as a source for gas. This picture is posted elsewhere on the site, and has been picked up by several discussion forums as an example of how not to do it (like I always drive around with a propane cylinder balanced on the drive train hump..). The small cylinder was good for about 60 miles of continuous use, but has been replaced by a 1 gallon cylinder with a proper shut-off valve. This image also shows the BBQ regulator and 12 volt solenoid valve that I used to test the system. These components will be discussed in greater detail later in this page.
This does bring up an important point. Any containment vessel you choose for your system should be properly and securely mounted to avoid damage to the equipment during driving. Any wiring or plumbing from the tank or associated components should likewise be properly secured out of harm's way.
The regulator you use will depend on how much pressure and flow is needed. The BBQ regulator shown above was perfectly adequate for my purposes on the VW N/A engine, operating at 25,000 BTU per hour. It cost me $2.00 at a salvage yard, and produces 11 inches of water on a manometer (.397 PSI). If your fumigation system will be for a turbocharged engine, or if your engine is of a high displacement, you may want to purchase a regulator that has an adjustable output pressure. Turbo'd engines generally require pressures of 4-6 PSI, at greater flow rates than a household low-pressure regulator can provide.
The 1 gallon LPG cylinder is securely mounted via a steel ring encircling the base and a wing nut through the protective top collar mounts it to a custom bracket. In this photo, I'm trying out a acetylene regulator. Note the proximity of a fire extinguisher!
A regulator of the type use on oxy-acetylene welding equipment is one type suitable for an LPG system. Just make sure that any regulator you use is rated for the pressure of a propane cylinder (approximately 250 PSI) and is rated for flammable gas duty. Two-stage regulators will be less affected by changes in altitude, barometric pressure and temperature.
Note that systems which demand a lot of vapor will need a regulator which can supply the specified flow without freezing up. At some point, large gas flows will require you to install an evaporator system like those used on LPG fueled spark-ignition engines, and the tank will need to feed liquid LPG to the evaporator/regulator.
The Solenoid Valve:
This piece of gear seems to be the sticking point in many of the LPG systems that I hear about. Essentially a solenoid valve is an electrically actuated valve that is used to control the flow of gas into the engine. It needs to be rated for the pressure that it is being asked to control, and be safe for flammable gases. The electrical rating needs to be 12 volts DC, continuous duty. The valve I am using was purchased from C and H Sales, a company which specializes in surplus equipment sales. It is stock number #SV9903, and the price was $5.00. See the "Links" section at the end of this page for more information on C & H. Other solenoid valves are available from suppliers of fumigation equipment, so also check the links to those sites as well.
Orifice Action:
Metering systems for gas pressure devices generally include an orifice, or jet to control flow. The size of the orifice can be fixed, or adjustable. Fixed orifices must be drilled out to increase the flow for a given pressure, while adjustable units can be manipulated with a wrench or similar tool to change the quantity of gas that passes. Note that adjusting the gas pressure will also effect flow rates. Since my "dump" system utilizes low pressure and salvaged components, I opted to simply reuse the orifices that came with the second-hand gas BBQ grille, and drill the hole for best results.
Here you see two additional jets that I drilled to try out high rates of fumigation. The installed orifice (left) has a #53 drill hole, while the two others have 1/16" and 3/32", respectively (They supplied way too much gas for my engine!).
Supplying Gas to the Intake:
While it is possible to connect the orifice(s) directly to the intake of the engine, I chose instead to locate the jet at the solenoid and supply the metered gas to the engine via a length of LPG-rated rubber hose. The hose is terminated at the intake manifold end by three "T" fittings which distribute the gas evenly to four ports drilled into the air box after the engine's air filter. These ports are nothing more than 1/8" male pipe thread to " hose barb 90 fittings. The intake manifold was drilled and tapped to accept the pipe thread ends of the fittings. The aperture of each port is directly above each of the runners in the intake manifold that supplies air to the cylinders. The ports are visible as the brass fittings at the top of the aluminum manifold air box. Also visible is the 3" air duct which supplies intake air from a cowl scoop mounted on the hood. We will discuss the importance of free-breathing a bit later in this page.
Here's a very simple way to get gas into your engine, but it suffers from the drawback that eventually, your air filter will become coated with an oily film from the LPG.
Note that the stock air horn is of a small diameter, and is picking up warm air from behind the car's radiator. See lower on this page for advice about modifying this intake.
Fumigation introduction on a turbocharged engine usually takes place before the air intake to the turbine, allowing the turbo to help mix the propane with the intake air. Please note, however, that this will mean that your turbo, intake piping, and intercooler (if you have one) will contain a flammable and potentially explosive mixture of LPG gas and air under pressure. Adding the gas after the turbine output is possible, but you will need to account for the boost pressure, raising the LPG regulator to a value greater than the turbo's output, typically by 3-6 PSI.
Control Systems:
For any installed LPG system, you will need at least a basic electrical control system to activate the solenoid valve, as well as protection and interlocking circuits to make sure that the propane is turned off when the engine is not running. Here's a description of how my system is wired:
1) First and most important, the 12 volt power to run the solenoid valve is supplied from the switched side of the ignition system. This insures that the gas is always off when the ignition switch is off. The supply wiring to the rest of the circuit is protected by a fuse.
2) On/Off switch on the dashboard. On my system, I use the gas for a boost during passing and hill climbing mostly, so I need to be able to control the LPG "on the fly". It's a good idea to have one on any system, so that you can defeat the gas when the engine is cold, or in case a problem requires shutting down the gas.
In this photo, the LPG switch is mounted in a plastic box along with the other Pusher controls, but you could just as easily put in in a hole drilled into the dash.
3) A throttle-mounted switch to prevent gas from entering the engine during idle conditions. You don't need additional power while sitting stopped at a signal, and from experience, I can tell you that you probably won't remember to shut it off manually. Adding gas during idle will also result in a fast idle, which isn't necessary either.
I lucked out and the injection pump for the Pusher already had a switch mounted, although I did easily fabricate one for my other BioDiesel Rabbit.
4) An interlock that prevents gas from entering the engine when it isn't running. "Oh, isn't that the ignition switch" you ask. No, it's not. What happens if the engine dies, or you turn on the ignition to listen to the radio, or you're having trouble getting it started and are holding the throttle open while your crank it, or any of 19 other "impossible" scenarios that can dump gas into the motor while it's not running and consuming the fuel Forget it, install an interlock tied to the engine oil pressure and you're done. No oil pressure means that the engine isn't running (or won't be for very long) and the gas should stay off.
There are two ways to sense oil pressure. One way is to install a "Hobbs switch", which is a normally-open contact device that closes the circuit and supplies power to the gas solenoid when it senses oil pressure in the engine. This type of switch must be installed on the engine oil gallery, either by using a "T" fitting, or by attaching it to a spare oil port on the engine, if one exists.
The other method, which I used, is to use the existing oil pressure "idiot light" switch to supply logic to the interlock circuit. Unfortunately, oil pressure indicator lights are the exact opposite logic from what is needed, so an interface circuit is needed to turn the normally-closed oil pressure switch into a normally-open one. This simple circuit monitors the indicator logic and simply reverses it for the interlock without affecting the operation of the oil pressure indicator on the instrument panel of the car:
The Darlington transistor should be a power type and be properly heat-sunk. If you use a Hobbs switch, put it in place of the Darlington transistor, on the negative side of the LPG solenoid, and ignore the connection to the oil pressure indicator light.
Calculating the amount of gas to apply
For the simple dump system on the Pusher, I calculated gas flow in BTU's, since this was about the only way that I could understand how to correlate diesel-vs.-LPG. Here's what I started with:
The Pusher, using a 1.6 liter diesel engine gets around 30 MPG of diesel fuel. A gallon of diesel contains 128,000 BTU's of thermal power. Assuming 60 MPH, the consumption would be 2 gallons per hour, or 256,000 BTU/hr. I was aiming at 10% LPG for a start, so I simply divided 256,000 by 10 = 25,000 BTU of LPG.
Consulting the chart at in the appendix of this page (down towards the bottom), we see that in order to get 25,000 BTU/hr from the regulator that I planned on using (11" WC), I'd need an orifice of 1.5mm diameter, or a # 53 number drill bit.
Calculating for an ordinary VW Rabbit, which gets 50 MPG, we see that fuel consumption is 1.2 gallons per hour at 60 MPH = 153,600 BTU. 10% would be 15,400 BTU, or about 1.2mm/#56 bit. Using the larger orifice from the Pusher would yield about 16% LPG.
Determining gas rates for turbocharged engines is a bit more troublesome, as there is a lot more air available to add fuel and gas to. What I have been told is that gas pressures can run in the 6 PSI range, with orifices of to 3/8 of one inch. This is a *lot* of gas, and will require a regulator capable of the increased flow, as well as a much larger storage tank for the gas. See the gas flow calculator in the appendix of this page.
Tuning it up
Adjusting the orifice and/or gas flow for optimum performance could be tricky. Basically, increase the LPG flow incrementally until you see/hear detrimental effects. The first, and most noticeable is hard knocking, or pinging from the engine. If it sounds like someone threw a handful of ball bearings inside your motor when your turn on the gas, by all means TURN IT DOWN!! The rattling you are hearing is the "colliding flame fronts", and is also the sound of your pistons being turned into molten aluminum. If anything, adding LPG to a diesel engine's intake air should make the engine quieter.
Another thing to watch for if your engine has a pyrometer (exhaust gas temperature gauge), is EGT's dropping. LPG promotes more complete combustion, so some of the heat that used to escape through the exhaust pipe is now being converted into mechanical power and transferred to the wheels.
Diesel engines do not react well to LPG fumigation when they are cold. Turning on the gas before the engine has warmed properly will result in rough idle and bogging, or lack of pulling power. Let the engine come up to something near operating temperature before turning on the gas. Another reason to have a dash-mounted control switch.
What to Expect
If my experiences using LPG fumigation on a normally-aspirated VW diesel engine are any indication, don't expect a lot, and you won't be disappointed. I don't get any huge surge in power, in fact, it's unnoticeable for the most part. If I'm holding a steady speed and turn on the gas at, say, 60 MPH, I see a gradual increase in speed of about 4 MPH. Someone with better math skills than me could probably figure out how much increase in power that is, but I'm guessing about 10% (remember, wind resistance goes up with the square of the speed, so 4% more speed is really greater than 4% power increase). Since my EV and Pusher are heavy (4,500 pounds, together), and the diesel engine puts out a paltry 52 horsepower, even a 10% increase in power is welcome for passing and climbing mountain passes.
Turbocharged engines will realize a dramatic increase in power when fed an adequate quantity of gas. I've heard stories of long-haul trucks using fumigation burning up transmissions and melting tires after storming up a long steep grade, the rest of the truck's drive train wasn't adequate to handle the power boost the LPG provided. Of course, tweaking the boost pressure, installing a modified engine control management computer chip, and providing intake and exhaust flow enhancements are all a part of race-prep for diesel engines. If you have a turbocharged vehicle, you are probably going to want to look into a commercially manufactured fumigation system to make sure that you get the most from your engine, with the least likelihood of engine damage.
Notes about air flow
Probably the single most important thing you can do for a diesel is to improve the air flow into and out of the engine. This is particularly important in a N/A engine.
Intakeair:
First and foremost, remove any and all possible flow restrictions. Several low-restriction air filters are available, such as the K&N brand filters. Increasing the diameter of the intake ducting is also important. On the VW diesel engines, the "snorkel" which leads into the air filter box is designed to minimize intake noise not maximize flow. Converting to a larger pipe will mean that the engine has less pulling loss, resulting in more air per piston intake stroke, which means you can stuff more fuel (and/or LPG) into the engine, resulting in more power. Check out the 3" ducting on my engine in the photo above in the "Supplying gas to the Intake" paragraph above. This ducting is fed by a cowl scoop at the back of the hood. I like to think that I get at least a little boost pressure out of it.
Temperature of the air is also important. Cooler is better. Cool air is more dense, more oxygen to aid in combustion. The intake end of the pipe leading into the air filter should be supplied with the coolest air possible. Usually, this means from either the grille, a hood scoop or under the front bumper of the car. What you don't want is air that has been warmed after coming through the radiator, in other words, engine compartment temperature air.
Turbo engines benefit from installation of an intercooler, which is essentially an air-to-air heat exchanger that removes the heat produced when the intake air is compressed by the turbine. Cooler boost air will allow greater gains in power through increased fueling, either through adjustment of the injection pump, by fumigation, or both.
Exhaust gases:
Getting rid of exhaust gases quickly is also very important. Diesel engines do not benefit from controlled back pressure like gasoline engine do. In all cases, larger diameter exhaust pipes are better. Low restriction exhaust manifolds, down pipes and mufflers all add to power and performance, in dramatic ways.
If you are trying for ultimate power, a good old fashioned cylinder head port-n-polish of the intake and exhaust ports works wonders, as do exhaust headers.
Simplicity is the key to getting the performance you want out of your truck.
Our patented design means: No mixers, sensors, evaporators, or switches to hassle with or adjust.
Easy installation and maintenance.
Cleaner burning fuel.
Better fuel economy.
Increased torque and horsepower for towing.
The Powershot 2000 Propane Injection Kit is the perfect addition for your turbo diesel engine to gain horsepower at an affordable price.
The Powershot 2000 is boost pressure activated, injecting propane into the engine as the boost pressure of the engine increases producing a throttle control, that you will definitely feel behind the wheel.
Safety features such as: Power switch inside the cab so driver has full control of turning the system on and off. Fuel lock off valve, stops the flow of propane unless the vehicle ignition and system is on.
Fits all FORD, DODGE AND GM TURBO DIESELS.
An adjustable orifice allows you to change flow rates from towing to performance effortlessly in minutes.
Variable flow rate delivers smooth, steadily increasing power, proportionate to the boost pressure.
CONCLUSION
The easy-to-install Powershot system will safely and substantially increase horsepower (up to 100hp) and torque (up to 250 ft lbs). This unit is a must for towing and all- around performance increases. Modest mileage gains are an extra bonus.
The system installs in about two hours and requires no permanent modifications to the vehicle or engine. The quality of the components is obvious: Custom LP regulators /Parker fittings, safety features such as custom auto/off rocker switches located inside the cab, and an automotive LP fuel lock-off solenoid valve located at the tank. All of the regulating is done at the tank eliminating the need for under hood installations and further enhancing safety concerns. The custom regulator maintains a constant tank pressure regardless of outside temperatures and delivers consistent, usable power at all boost levels.
BIBLIOGRAPHY
dieselperformanceproducts.com
pushertdipropaneinjection.html
A book on modern injection system by H.Humes
CONTENTS
1. INTRODUCTION 1
2. PROPANE FUMIGATION 2
3. TYPES OF SYSTEMS 4
4. CONSTRUCTION OF THE SYSTEM 5
5. CONTROL SYSTEMS 10
6. CALCULATIONS 12
7. TUNING 13
8. NOTES ABOUT AIR FLOW 14
9. FEATURES AND BENEFITS 15
10. APPLICATIONS 15
11. CONCLUSION 16
12. BIBLIOGRAPHY 17
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ABSTRACT
Diesel Performance Products introduces the Powershot propane injection system for turbo diesel owners who are looking for more power for towing increased mileage and throttle responsiveness out of their vehicles.
With its innovative and patented design and method of propane delivery, this system is unique to other systems on the market and has overcome many of the drawbacks encountered with earlier designed injection systems.
The Powershot is an infinitely variable-stage vapor injection system. It is controlled, activated and proportionate to the boost pressure of the engine. The Powershot comes on slow and steady and as the boost increases, so does the flow of propane. More boost=more propane=more power! It is fully adjustable and can be customized for your specific application in minutes for towing, performance or mileage gains.
The easy-to-install Powershot system will safely and substantially increase horsepower (up to 100hp) and torque (up to 250 ft lbs). This unit is a must for towing and all- around performance increases. Modest mileage gains are an extra bonus.
INTRODUCTION
POWERSHOT TURCHARGED PROPANE INJECTION SYSTEM
Diesel Performance Products introduces the Powershot 2000 propane injection system for turbo diesel owners who are looking for more power for towing increased mileage and throttle responsiveness out of their vehicles.
With its innovative and patented design and method of propane delivery, this system is unique to other systems on the market and has overcome many of the drawbacks encountered with earlier designed injection systems.
The Powershot is an infinitely variable-stage vapor injection system. It is controlled, activated and proportionate to the boost pressure of the engine. The Powershot comes on slow and steady and as the boost increases, so does the flow of propane. More boost=more propane=more power! It is fully adjustable and can be customized for your specific application in minutes for towing, performance or mileage gains.
The easy-to-install Powershot system will safely and substantially increase horsepower (up to 100hp) and torque (up to 250 ft lbs). This unit is a must for towing and all- around performance increases. Modest mileage gains are an extra bonus.
The system installs in about two hours and requires no permanent modifications to the vehicle or engine. The quality of the components is obvious: Custom LP regulators /Parker fittings, safety features such as custom auto/off rocker switches located inside the cab, and an automotive LP fuel lock-off solenoid valve located at the tank. All of the regulating is done at the tank eliminating the need for under hood installations and further enhancing safety concerns. The custom regulator maintains a constant tank pressure regardless of outside temperatures and delivers consistent, usable power at all boost levels.
Propane Fumigation
Lately, I've been getting quite a lot of e-mail from folks who are interested in the LPG Fumigation system that I have installed on the Pusher, so it makes some sense to have a page dedicated to that subject, with at least as much as I know about it, and some links to other resources.
What it is..and why:
Simply stated, Propane (LPG) Fumigation is the introduction of gaseous propane into the air intake of a diesel engine for the purposes of attaining more power, economy, or both. The parallel is often made between fumigation and using Nitrous Oxide on gasoline vehicles to achieve a power increase. Basically, this analogy is correct, although the properly implemented use of LPG on a diesel engine will actually result in a better-running engine without the possible damaging effects that N2O has on gas motors.
Exhaust emissions are reduced as a result, with lower quantities of unburned hydrocarbons and fewer particulates (smoke). LPG fumigation will even clean up the odor of diesel fuel in the exhaust, making the smell from the tailpipe of an engine utilizing it much less objectionable.
How it works:
Introducing LPG gas into the combustion air intake of a diesel engine acts as an accelerant, promoting the even burning of the diesel fuel, and more complete combustion, resulting in more power being produced. Propane by itself will not self-ignite inside a diesel-fuel compression-ignition engine. During the compression stroke, the air/LPG mixture is compressed and the temperature is raised to about 400C, not enough to ignite the LPG, which has an ignition temperature of about 500C. When the diesel fuel is atomized into the cylinder under high pressure, it immediately self-ignites (diesel ignites at about 385C.), and causes the LPG to burn as well. Since the LPG is in mixture with the air, the flame front from the diesel spreads more quickly, and more completely, including igniting the air/fuel mixture which is in contact with the cylinder walls, which are cool in comparison to the super-heated air inside the combustion chamber. Much of the cleaner burning of the fuel is attributed to this ignition against the "cooler" components of the engine, and accounts for raising the percentage of combustion from a typical 75% for a well-tuned diesel engine running on pure diesel fuel alone, to 85-90% with the addition of LPG. Obviously, this more complete combustion also gives a nice boost in power, with an accompanying increase in fuel economy and reduction of pollutants.
What to Expect:
OK, here's where we have to draw a distinction between engine types. Normally-aspirated engines require different systems to introduce the gas than do turbocharged engines. The results are different as well.
Normally-aspirated (N/A) engines will realize only a modest gain in power by the use of LPG gas. Displacing 1% of the intake air with LPG will result in a small power increase, perhaps 5-8%. Nearly no increase in power will be noted at full throttle, assuming that your injection pump is correctly adjusted already. Attempting to provide more gas to the engine will not increase performance, and will in fact lead to a condition not unlike pre-ignition in a gasoline engine. This has been attributed to "colliding flame fronts" inside the combustion chamber, and may have a lot to do with the fact that most N/A engines are also IDI (Indirect Injection), which means that the diesel fuel is not injected directly into the combustion cylinder, but instead enters a "swirl chamber" where ignition takes place. The flame front then shoots out of the swirl chamber into the combustion chamber, where it combines with the air (and LPG) to force the piston down in a power stroke. Apparently, these engines have a problem in that the flame front exiting the swirl chamber ignites the LPG/air mixture, which then causes back pressure, preventing the proper expansion of the ignited fuel leaving the swirl chamber.
I have had satisfactory results on my VW 1.6 N/A engine when adding LPG at a rate of 8-10% of the BTU rating of the diesel the engine is using. It may be possible to turn the fuel up, but I do know for sure that too much fuel does not increase power, and causes the engine to make very unhappy noises.
Turbocharged diesel engines are able to realize a significant increase in power by using LPG fumigation. While the usual suggested increase is considered to be approximately 20%, by careful management of the gas introduction, power gains of up to 40% are possible. My understanding is that it is a very fine line between lots of extra power and a dose of LPG that will render an engine scrap metal in a hurry, so consider carefully before you decide to "turn it up".
Turbo engines are by design blessed with a lean air-to-fuel ratio, and can be fed concentrations of LPG up to about 6-8% of the intake air volume. TDI (Turbo Direct Injection) engines have shown dramatic power increases when properly fumigated with LPG, combined with an "Upsolute" chip, or computer engine management upgrade. (Of course, these modifications will void any manufacturers warranties..)
Types of systems:
I am aware of two basic fumigation systems.
The first, I call the "dump" system, which means that you pick a value of propane to feed to the engine, either by calculation, or by trial-and-error, and you simply "dump" it into the air intake. Little provision is possible for correcting gas flow depending on engine load, so the system is probably only optimized for one type of load demand. The advantage is that this type of system can be cobbled to together by backyard experimenters like myself at a low cost. The disadvantages are that you will probably need to error on the side of caution to make sure that you aren't overloading your engine with too much gas, and that the system doesn't compensate for variations in engine speed, load, etc.
The second system is much more sophisticated, and uses a variety of sensors and controls to monitor engine performance and load, and adjust the gas flow to suit the need at the moment. Most commercially available systems will be of this type.
In order to determine the load on the engine in a N/A system, a venturi must be placed in the air intake, as diesel engines have no natural intake manifold vacuum. A sample of the vacuum produced by the venturi is fed to a metering system, either electronic or mechanical, which adjusts the gas flow to suit the circumstances.
Turbo engines have a great indicator of load built in. It's a fairly simple process to take a sample of the boost pressure developed by the turbocharger and use that to control the metering system. Most commercially made systems are designed for turbo engines, both for this reason, and because of the greater power gain that the turbo realizes from fumigation. Since boost is such a reliable indicator of engine load, higher values of fumigation can be realized, with tighter control over the results.
Construction of My System:
(But first, a message from the Shark Central Legal Department
BIG WARNING..!!
LP gas, like any combustible fuel can be dangerous. If you are going to attempt to construct your own fumigation system, be aware of the hazards present when you use this fuel. Use proper fittings and fixtures, and be aware of the high pressure present at the output of an LPG storage tank. Gaseous propane is heavier than air, and can collect in enclosed places. Any containment of a tank must be properly vented. Never check for gas leaks using a flame. ETC, ETC, ETC. This is not intended to be a complete tutorial on good engineering practice for flammable gas systems. You should be familiar with the tools and techniques of gas plumbing systems before attempting construction of such a system.
Additionally, while adding fumigation equipment to a diesel engine is becoming a commonly accepted practice, keep in mind that doing so may void your warranty, negate any emissions certifications your engine has and/or violate local or state vehicle codes. It is not impossible that done incorrectly, adding LPG to your diesel engine will cause damage to it's operation or construction.
The information contained here is believed to be accurate, but like anything else, is not necessarily 100% infallible. Use your own judgement, applied to your own circumstances.
All of this is meant to say: "YOU are ultimately responsible for any and all actions that YOU may take after reading this web page. In no event, will I be responsible for any damage to your property or person, or that of any others as a result of anything you do with the information contained here".
OK, now that that's out of the way (can't be too careful these days), we can get down to business.
The Tank and Regulator:
What type of tank you use may depend a lot of what type of vehicle you intend to use it on. If you are adding a system to a large truck or a motor home, you will probably have plenty of room for a frame-mounted horizontal tank. If it's a motor home, you may not need to add a tank at all, just use the existing one, although an additional regulator may be necessary, depending on the type of system you install. The smaller the vehicle, the more difficult the job of finding a suitable location to mount the tank, and the more difficult it will be to find a tank the right size and shape.
Should you be tempted to mount the tank in the enclosed trunk of your car, remember that DOT (Department of Transportation) rules forbid such installations unless the enclosure (your trunk) is well ventilated to allow any seepage or leakage of gas to readily escape. If you want to know how well ventilated it needs to be, go visit a motor home or travel trailer dealership and see how propane cylinders on recreational vehicles are mounted. Unless you plan on wearing a racing fire suit while driving, forget mounting the gas cylinder inside the passenger compartment.
The size of the tank will also depend on your usage. If this is a long-haul truck or RV tow rig, you will probably want the gas on full-time, in which case you will need a sizeable cylinder. For occasional hill climbing or passing on the road, you might be able to get by with a capacity of only a few gallons. Installations in cars meant for racing or speed exhibition will need only a small reservoir of fuel, perhaps with several tanks that can be interchanged when emptied.
During my initial trials, I used a Coleman camping fuel bottle as a source for gas. This picture is posted elsewhere on the site, and has been picked up by several discussion forums as an example of how not to do it (like I always drive around with a propane cylinder balanced on the drive train hump..). The small cylinder was good for about 60 miles of continuous use, but has been replaced by a 1 gallon cylinder with a proper shut-off valve. This image also shows the BBQ regulator and 12 volt solenoid valve that I used to test the system. These components will be discussed in greater detail later in this page.
This does bring up an important point. Any containment vessel you choose for your system should be properly and securely mounted to avoid damage to the equipment during driving. Any wiring or plumbing from the tank or associated components should likewise be properly secured out of harm's way.
The regulator you use will depend on how much pressure and flow is needed. The BBQ regulator shown above was perfectly adequate for my purposes on the VW N/A engine, operating at 25,000 BTU per hour. It cost me $2.00 at a salvage yard, and produces 11 inches of water on a manometer (.397 PSI). If your fumigation system will be for a turbocharged engine, or if your engine is of a high displacement, you may want to purchase a regulator that has an adjustable output pressure. Turbo'd engines generally require pressures of 4-6 PSI, at greater flow rates than a household low-pressure regulator can provide.
The 1 gallon LPG cylinder is securely mounted via a steel ring encircling the base and a wing nut through the protective top collar mounts it to a custom bracket. In this photo, I'm trying out a acetylene regulator. Note the proximity of a fire extinguisher!
A regulator of the type use on oxy-acetylene welding equipment is one type suitable for an LPG system. Just make sure that any regulator you use is rated for the pressure of a propane cylinder (approximately 250 PSI) and is rated for flammable gas duty. Two-stage regulators will be less affected by changes in altitude, barometric pressure and temperature.
Note that systems which demand a lot of vapor will need a regulator which can supply the specified flow without freezing up. At some point, large gas flows will require you to install an evaporator system like those used on LPG fueled spark-ignition engines, and the tank will need to feed liquid LPG to the evaporator/regulator.
The Solenoid Valve:
This piece of gear seems to be the sticking point in many of the LPG systems that I hear about. Essentially a solenoid valve is an electrically actuated valve that is used to control the flow of gas into the engine. It needs to be rated for the pressure that it is being asked to control, and be safe for flammable gases. The electrical rating needs to be 12 volts DC, continuous duty. The valve I am using was purchased from C and H Sales, a company which specializes in surplus equipment sales. It is stock number #SV9903, and the price was $5.00. See the "Links" section at the end of this page for more information on C & H. Other solenoid valves are available from suppliers of fumigation equipment, so also check the links to those sites as well.
Orifice Action:
Metering systems for gas pressure devices generally include an orifice, or jet to control flow. The size of the orifice can be fixed, or adjustable. Fixed orifices must be drilled out to increase the flow for a given pressure, while adjustable units can be manipulated with a wrench or similar tool to change the quantity of gas that passes. Note that adjusting the gas pressure will also effect flow rates. Since my "dump" system utilizes low pressure and salvaged components, I opted to simply reuse the orifices that came with the second-hand gas BBQ grille, and drill the hole for best results.
Here you see two additional jets that I drilled to try out high rates of fumigation. The installed orifice (left) has a #53 drill hole, while the two others have 1/16" and 3/32", respectively (They supplied way too much gas for my engine!).
Supplying Gas to the Intake:
While it is possible to connect the orifice(s) directly to the intake of the engine, I chose instead to locate the jet at the solenoid and supply the metered gas to the engine via a length of LPG-rated rubber hose. The hose is terminated at the intake manifold end by three "T" fittings which distribute the gas evenly to four ports drilled into the air box after the engine's air filter. These ports are nothing more than 1/8" male pipe thread to " hose barb 90 fittings. The intake manifold was drilled and tapped to accept the pipe thread ends of the fittings. The aperture of each port is directly above each of the runners in the intake manifold that supplies air to the cylinders. The ports are visible as the brass fittings at the top of the aluminum manifold air box. Also visible is the 3" air duct which supplies intake air from a cowl scoop mounted on the hood. We will discuss the importance of free-breathing a bit later in this page.
Here's a very simple way to get gas into your engine, but it suffers from the drawback that eventually, your air filter will become coated with an oily film from the LPG.
Note that the stock air horn is of a small diameter, and is picking up warm air from behind the car's radiator. See lower on this page for advice about modifying this intake.
Fumigation introduction on a turbocharged engine usually takes place before the air intake to the turbine, allowing the turbo to help mix the propane with the intake air. Please note, however, that this will mean that your turbo, intake piping, and intercooler (if you have one) will contain a flammable and potentially explosive mixture of LPG gas and air under pressure. Adding the gas after the turbine output is possible, but you will need to account for the boost pressure, raising the LPG regulator to a value greater than the turbo's output, typically by 3-6 PSI.
Control Systems:
For any installed LPG system, you will need at least a basic electrical control system to activate the solenoid valve, as well as protection and interlocking circuits to make sure that the propane is turned off when the engine is not running. Here's a description of how my system is wired:
1) First and most important, the 12 volt power to run the solenoid valve is supplied from the switched side of the ignition system. This insures that the gas is always off when the ignition switch is off. The supply wiring to the rest of the circuit is protected by a fuse.
2) On/Off switch on the dashboard. On my system, I use the gas for a boost during passing and hill climbing mostly, so I need to be able to control the LPG "on the fly". It's a good idea to have one on any system, so that you can defeat the gas when the engine is cold, or in case a problem requires shutting down the gas.
In this photo, the LPG switch is mounted in a plastic box along with the other Pusher controls, but you could just as easily put in in a hole drilled into the dash.
3) A throttle-mounted switch to prevent gas from entering the engine during idle conditions. You don't need additional power while sitting stopped at a signal, and from experience, I can tell you that you probably won't remember to shut it off manually. Adding gas during idle will also result in a fast idle, which isn't necessary either.
I lucked out and the injection pump for the Pusher already had a switch mounted, although I did easily fabricate one for my other BioDiesel Rabbit.
4) An interlock that prevents gas from entering the engine when it isn't running. "Oh, isn't that the ignition switch" you ask. No, it's not. What happens if the engine dies, or you turn on the ignition to listen to the radio, or you're having trouble getting it started and are holding the throttle open while your crank it, or any of 19 other "impossible" scenarios that can dump gas into the motor while it's not running and consuming the fuel Forget it, install an interlock tied to the engine oil pressure and you're done. No oil pressure means that the engine isn't running (or won't be for very long) and the gas should stay off.
There are two ways to sense oil pressure. One way is to install a "Hobbs switch", which is a normally-open contact device that closes the circuit and supplies power to the gas solenoid when it senses oil pressure in the engine. This type of switch must be installed on the engine oil gallery, either by using a "T" fitting, or by attaching it to a spare oil port on the engine, if one exists.
The other method, which I used, is to use the existing oil pressure "idiot light" switch to supply logic to the interlock circuit. Unfortunately, oil pressure indicator lights are the exact opposite logic from what is needed, so an interface circuit is needed to turn the normally-closed oil pressure switch into a normally-open one. This simple circuit monitors the indicator logic and simply reverses it for the interlock without affecting the operation of the oil pressure indicator on the instrument panel of the car:
The Darlington transistor should be a power type and be properly heat-sunk. If you use a Hobbs switch, put it in place of the Darlington transistor, on the negative side of the LPG solenoid, and ignore the connection to the oil pressure indicator light.
Calculating the amount of gas to apply
For the simple dump system on the Pusher, I calculated gas flow in BTU's, since this was about the only way that I could understand how to correlate diesel-vs.-LPG. Here's what I started with:
The Pusher, using a 1.6 liter diesel engine gets around 30 MPG of diesel fuel. A gallon of diesel contains 128,000 BTU's of thermal power. Assuming 60 MPH, the consumption would be 2 gallons per hour, or 256,000 BTU/hr. I was aiming at 10% LPG for a start, so I simply divided 256,000 by 10 = 25,000 BTU of LPG.
Consulting the chart at in the appendix of this page (down towards the bottom), we see that in order to get 25,000 BTU/hr from the regulator that I planned on using (11" WC), I'd need an orifice of 1.5mm diameter, or a # 53 number drill bit.
Calculating for an ordinary VW Rabbit, which gets 50 MPG, we see that fuel consumption is 1.2 gallons per hour at 60 MPH = 153,600 BTU. 10% would be 15,400 BTU, or about 1.2mm/#56 bit. Using the larger orifice from the Pusher would yield about 16% LPG.
Determining gas rates for turbocharged engines is a bit more troublesome, as there is a lot more air available to add fuel and gas to. What I have been told is that gas pressures can run in the 6 PSI range, with orifices of to 3/8 of one inch. This is a *lot* of gas, and will require a regulator capable of the increased flow, as well as a much larger storage tank for the gas. See the gas flow calculator in the appendix of this page.
Tuning it up
Adjusting the orifice and/or gas flow for optimum performance could be tricky. Basically, increase the LPG flow incrementally until you see/hear detrimental effects. The first, and most noticeable is hard knocking, or pinging from the engine. If it sounds like someone threw a handful of ball bearings inside your motor when your turn on the gas, by all means TURN IT DOWN!! The rattling you are hearing is the "colliding flame fronts", and is also the sound of your pistons being turned into molten aluminum. If anything, adding LPG to a diesel engine's intake air should make the engine quieter.
Another thing to watch for if your engine has a pyrometer (exhaust gas temperature gauge), is EGT's dropping. LPG promotes more complete combustion, so some of the heat that used to escape through the exhaust pipe is now being converted into mechanical power and transferred to the wheels.
Diesel engines do not react well to LPG fumigation when they are cold. Turning on the gas before the engine has warmed properly will result in rough idle and bogging, or lack of pulling power. Let the engine come up to something near operating temperature before turning on the gas. Another reason to have a dash-mounted control switch.
What to Expect
If my experiences using LPG fumigation on a normally-aspirated VW diesel engine are any indication, don't expect a lot, and you won't be disappointed. I don't get any huge surge in power, in fact, it's unnoticeable for the most part. If I'm holding a steady speed and turn on the gas at, say, 60 MPH, I see a gradual increase in speed of about 4 MPH. Someone with better math skills than me could probably figure out how much increase in power that is, but I'm guessing about 10% (remember, wind resistance goes up with the square of the speed, so 4% more speed is really greater than 4% power increase). Since my EV and Pusher are heavy (4,500 pounds, together), and the diesel engine puts out a paltry 52 horsepower, even a 10% increase in power is welcome for passing and climbing mountain passes.
Turbocharged engines will realize a dramatic increase in power when fed an adequate quantity of gas. I've heard stories of long-haul trucks using fumigation burning up transmissions and melting tires after storming up a long steep grade, the rest of the truck's drive train wasn't adequate to handle the power boost the LPG provided. Of course, tweaking the boost pressure, installing a modified engine control management computer chip, and providing intake and exhaust flow enhancements are all a part of race-prep for diesel engines. If you have a turbocharged vehicle, you are probably going to want to look into a commercially manufactured fumigation system to make sure that you get the most from your engine, with the least likelihood of engine damage.
Notes about air flow
Probably the single most important thing you can do for a diesel is to improve the air flow into and out of the engine. This is particularly important in a N/A engine.
Intakeair:
First and foremost, remove any and all possible flow restrictions. Several low-restriction air filters are available, such as the K&N brand filters. Increasing the diameter of the intake ducting is also important. On the VW diesel engines, the "snorkel" which leads into the air filter box is designed to minimize intake noise not maximize flow. Converting to a larger pipe will mean that the engine has less pulling loss, resulting in more air per piston intake stroke, which means you can stuff more fuel (and/or LPG) into the engine, resulting in more power. Check out the 3" ducting on my engine in the photo above in the "Supplying gas to the Intake" paragraph above. This ducting is fed by a cowl scoop at the back of the hood. I like to think that I get at least a little boost pressure out of it.
Temperature of the air is also important. Cooler is better. Cool air is more dense, more oxygen to aid in combustion. The intake end of the pipe leading into the air filter should be supplied with the coolest air possible. Usually, this means from either the grille, a hood scoop or under the front bumper of the car. What you don't want is air that has been warmed after coming through the radiator, in other words, engine compartment temperature air.
Turbo engines benefit from installation of an intercooler, which is essentially an air-to-air heat exchanger that removes the heat produced when the intake air is compressed by the turbine. Cooler boost air will allow greater gains in power through increased fueling, either through adjustment of the injection pump, by fumigation, or both.
Exhaust gases:
Getting rid of exhaust gases quickly is also very important. Diesel engines do not benefit from controlled back pressure like gasoline engine do. In all cases, larger diameter exhaust pipes are better. Low restriction exhaust manifolds, down pipes and mufflers all add to power and performance, in dramatic ways.
If you are trying for ultimate power, a good old fashioned cylinder head port-n-polish of the intake and exhaust ports works wonders, as do exhaust headers.
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BIBLIOGRAPHY
dieselperformanceproducts.com
pushertdipropaneinjection.html
A book on modern injection system by H.Humes
CONTENTS
1. INTRODUCTION 1
2. PROPANE FUMIGATION 2
3. TYPES OF SYSTEMS 4
4. CONSTRUCTION OF THE SYSTEM 5
5. CONTROL SYSTEMS 10
6. CALCULATIONS 12
7. TUNING 13
8. NOTES ABOUT AIR FLOW 14
9. FEATURES AND BENEFITS 15
10. APPLICATIONS 15
11. CONCLUSION 16
12. BIBLIOGRAPHY 17