liquid propane fuel system, not vapor.
liquid propane fuel system, not vapor.
(OP)
I have a h/p SB chev eng that i'm thinking of changing to propane power. The most common systems change the liquid to a vapor before it enters the eng. I have heard of systems that inject liquid into the eng. does anyone know of such a system? Does it need some type of direct injector, or mybe some kind of carb-mixer that would spray liquid into the intake? The problem I have with direct injection would be high cost.The possible high performance gains of a system like this could be huge. Thankyou for any help.





RE: liquid propane fuel system, not vapor.
Franz Hoffman is the resident expert on this subject and I believe another member here was actually directly involved in design and development of one liquid LPG injection system.
As far as I know, none are direct injection, but are EFI and can be used in place of OEM EFI injectors on modern cars so long as you have a method to tune to adjust the injector pulse width to correct for different injector flow rates and different fuel flow rates required.
It also helps if you can remap the ignition timing.
It also helps power if you can adjust the compression to around 11:1, the exact optimum number depending on you inlet valve closing point among several other things.
Don't expect real gains in power over high octane petrol.
You can get real gains in power and economy over old gas phase carbies or mixers.
You might get small gains by replacing low to mid 90s octane pump petrol and carbies if you go to liquid injection propane and raise the CR a few points.
Remember, although gains can be had from the higher octane, there will also be losses from the lower energy content per unit weight of the fuel vs petrol.
I deliberately use the British terminology of petrol instead of gasoline so as to avoid confusion between gas (gasoline) and gas (LPG or propane).
If you can source reasonably pure propane you get a somewhat higher octane than if you only get a commercial grade LPG fuel which often contains quite a lot of butane in many parts of the world. Butane lowers the octane considerably.
Regards
Pat
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RE: liquid propane fuel system, not vapor.
The other member is Turbo Cohen, his expertise is invaluable.
Franz
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RE: liquid propane fuel system, not vapor.
Actuation of the injector is by peak-and-hold solenoid; we'd be controlling this with a Opal-RT HiL controller and the "ECU" realised in Simulink.
RE: liquid propane fuel system, not vapor.
Part of your post states in-cylinder injection, but the last portion describes an in-manifold injection (very close to the intake valve in a composite runner/holder). Different strategies, different technologies.
Franz
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RE: liquid propane fuel system, not vapor.
RE: liquid propane fuel system, not vapor.
They must use a pump because the radiant heat of th engine will cause the propane to flash to vapor at the rail. The pump raises the relative saturation pressure. No one has worked out a means of keeping propane liquid at lower pressures or higher temperatures at the given saturation pressure.
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RE: liquid propane fuel system, not vapor.
in the late 90's a student in Canada adapted a modified CNG injector I made out of a DI prototype and I think it was on a Chrysler 2.4.. Ran damn good and smogged well within ulev II. Heat was the issue as it so often is.