Bob Holton

Has anyone done any work with LPgas in an RX7,? this 2,20 /gal has to go.

RotaryRyan

i dont know about propane but i hear you about those prices. I go broke because i have to get gas

nevarmore

http://www.google.com/search?hl=en&l...ar&btnG=Search

Its been done and is incredibly easy on any carbureted vehicle. The hard part is finding a local LPG dealer. Usually located around RV parks since a few of them run on it and most of them cook with it.

Bob Holton

Info on how and mileage expected?? Please

Static

u could probably run lpg and gas like the deisels do but that is just my suggestion

QuagmireMan

it gets about 5% less miles to the gallon and you loose about 10% HP. Acceleration is lagged, but you can count on you engine running for ever. The LP requires less Oxygen than gasoline so you might need to restrict Oxygen flow slightly. The best setup is dual fuel where the car can switch between gas/LP but you need fuel injection / electronic controlled ignition.

nevarmore

Ya gotta do a little of your own work man.


Best summary of LPG in a car

It gets high enough miles per gallon and has a low enough cost per mile for big fleets to adopt it. Warehouse's have been using propane forklifts for years too.

The conversions are still early commercial kits or DIY homebrew so its hard to get solid efficiency numbers.

The rough overview is that you install an LPG tank in place of your gas tank or in the trunk. A trunk install would be a bit unsafe in an RX-7 and replacement gas tanks are more expensive than the standard tanks. From there its no more complicated than installing a new carb. The system is a bit different than a gasoline one because you're dealing with a high pressure gas that will burn uncompressed not a liquid fuel that has to get packed into a combustion chamber to blow.

I belive it was 4-Wheel Magazine that did a conversion of an old truck (K5 Blazer??). They seemed to like it. Check thier website and back issues for a review of one companys kit. There are a few other kit makers too.

grantmac

Hmmm, says that it has like a 110 octane rating; can you say super/turbocharged? That would certainly recoup the loss of power. I do know there is a high-compression early 80s corvette with like 400RWHP that goes to local autocross and does very well.
Grant

GavinJuice

LP is a great addition to Diesels because it's a very compressable substance. Also burns easier because it's essentially already vaporized, no need to swirl the air and propane.

Bob Holton

Thanks to all of you, sounds like I will pay2.22/gal to keep on driveing cause I dont have a turbo . Thanks again. Bob

Nick-7

I am going to research this more and I might think of doing it for a future project. Since the LPG must convert to gas, and in doing so it absorbs heat, it just seems to me to be perfect for forced induction. When the turbocharger compresses the air and heats it up the LPG will use the heat to convert from a liquid to a gas and in doing so it should super cool the air charge. Right? It would work similar to nitrous, but without all the extra heat.

The "Do-It-Yourself Automotive LPG Conversion" site said that the LPG causes engines to last longer. If this is true to rotaries a N/A motor could last 300-400k or even longer.

I was reading a site a while back where a guy in Britian, I think, converted his rotary to propane. I will search for it sometime.

QuagmireMan

buddy of mine had 568k miles on his 4.0 lp run jeep.

Feds

Propane gets worse mileage, but because it is stored as a liquid and burns as a gas, you will get amazing range out of similar sized tanks.

And yes, propane, and CNG for that matter, have very high octane (well, technically, they have no octane, only methane and propane, but they are VERY resistant to knock).

Anywho, my 2c. A forced induction lpg conversion would earn mad props from me, yo!

QuagmireMan

but the 4.0 run forever anyways

QuagmireMan

hydrogen is the way to go

Feds

Don't get me started about hydrogen.

Tonnes of mass-specific power, but it is mucho difficult to flow the neccessary volume to make good power in an ICE. Also, very prone to knocking. Also, not very dense. Range @ 5000 psi storage pressure will be < 100 miles.

Hydrogen is the wave of the future, but do not expect to see a hydrogen economy in less than 50 years.

zyounker

I am currently working on a true liquid propane injection for my turbo 1st gen.


Propane is 118 octane.. running 89 octane gas i should get ~105 on boost..


It uses a hobbs switch to turn on at 7 psi.


Most out there i have seen are a vapor system, which is cool cause you still get the octane but i want the pressure drop too for cooling the intake charge.

Nick-7

That's is why I think propane would be so good. Because of the cooling effect on the intake charge. I would like to use full propane power, but I need to do much research to see if it is worth. This is not going to be done in my daily driver. The propane injection is a great idea to raise octan and cool the intake charge.

I even thought of the idea of a propane burning drag RX-7 that would also serve auto-x duties. I went to Kentucky Kingdom a few years back and they had a propane powered dragster ride. You could stage and take off down the strip, they were very fast, but they were own a rail that forced them to go straight. The rider had the power to make it go and shift from first to second gear. Man, I wish I would have ridden it.

zyounker

The big problem with using compressed liquid/gas is the pressure variations.


Some try cooling the tank.. Seems lame to me.. I am working on something better. But until i know it works i rather not tell people.

nevarmore

Looks like you're using propane in a similar method to nitrous oxide. Have you seen any similarities between that system and using propane as the sole fuel source??

zyounker

Yeah i am kinda using it as nitrous and a fuel.. OR that is my idea.. I have not run it yet.. just have theorys and concepts down..


I worked around some of the known problems and just need to test it in the real world..


My car should be running this week. So testing shoudl start soon.



I will not be using propane as a sole fuel though as i think normal fuel is good for that..

The fact i should be able to run 89 octane fuel which on a rotary works better and will create more exhaust to spool the turbo will also give it a better powerband. then kick the propane on and get the benifit of added octane and a cooler intake charge when in boost.


I know they use it this way on deisel applications. I am just using that with some other parts to make it a more predictable system.


With a normal vapor system they say a 5 gallon tank typically last ~500 miles.