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propane efi?


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12 replies to this topic

#1 offroadsubaruguy

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Posted 28 June 2007 - 05:57 AM

first of all, is it possible? has it been done before? has anyone ever heard of it being done? i just think that propane would work better on an offroad vehicle, not to mention that its cheaper than gas and is effectively a 110 octane from what i hear...... the benefits are many, so i figured id see if i could get the legacy converted.....

#2 Reveeen

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Posted 28 June 2007 - 06:21 AM

is it possible?

Anything can be converted to propane.

its cheaper than gas

It all depends where you live (and how much the propane costs). 1 litre of propane contains roughly 80% the energy of 1 litre of gasoline (providing everything else remains equal). Where I live propane used to be cheaper, it no longer is, so no one in these parts is converting.

effectively a 110 octane

This could be a good thing, or a bad thing, it depends how you are coming at it. The burn rate of propane is slower than gasoline, giving you a big octane number, in reality it just means that you advance the ignition timing 10+/- degrees (trial and error, every application being a bit different).

the benefits are many

Depending where you live, and the operating conditions, there can be about as much "downside", as benefit.

I am not trying to disuade you. CAREFULLY investigate the costs, and the benefits, look at the downsides, and make an informed decision.

#3 Skip

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Posted 28 June 2007 - 06:48 AM

many many tow motors are propane fired.

They have a setup that works with the carb (not EFI)

Bet the setup would work on a Brat


hey come to think about it

I have a tow motor propane set up on the shelf
and
a Brat
with a rusty gas tank -ahhhheemmmm??

BTW
The downunder gang are the ones you want to ask this to.

#4 GeneralDisorder

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Posted 28 June 2007 - 08:18 AM

Since propane is a gas at atmospheric pressure, there is no reason to use FI with it. A propane "carb" is literally just an orifice protruding into a venturi with a throttle butterfly. They already run at any angle (even upside down). So there is nothing to be gained by using an FI system - on top of that it would be difficult to convert any conventional gasoline FI system to propane as there wouldn't be any way to lubricate the injectors, and they would freeze as the liquid propane cools rapidly when expanding from it's liquid state.

GD

#5 Skip

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Posted 28 June 2007 - 08:38 AM

If you are real interested in this
try
http://www.gotpropane.com/

And to add to GD's excellent remarks
here is a quote from their website.

Note: we do not sell kits for late model cars and trucks.(87 and up)Please do not call us about these vehicles as it is not legal or cost effective to do these vehicles.(computer controlled)

#6 nipper

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Posted 28 June 2007 - 10:51 AM

http://www.eng-tips....qs.cfm?fid=1139

more reasons it can't be done.



nipper

#7 cubastreet

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Posted 29 June 2007 - 12:14 AM

It can be done, even on a car with sequential injection, but with a LPG carb as mentioned by GD. Nobody does direct injection to my knowledge but it WOULD be a huge advantage as the cooling of the vapourising gas would cool the charge in the cylinder and result in more power output.
Using the standard vapouriser/carb setup this cooling effect is actually a disadvantage as you need to run your engine cooling fluid through it to stop the vapouriser from freezing up.

Other advantages are:
The blowby gases are not acidic, so your oil lasts much longer
You never need to use choke, and the fuel doesn't condense on the cylinder walls washing away the oil on startup, so your engine lasts much longer
You can run a much higher compression ratio without detonation, and on a well-built LPG only engine can get similar milage as on petrol.
Environmentally it's much better than petrol.

Disadvantages:
If you want to use petrol and LPG you will lose space for the tank, a little power and 20% of your MPG.
weight of the extra tank
cost to install

#8 Scott F

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Posted 29 June 2007 - 09:15 AM

There is a lot of good info here. I have experience with a propane powered off road buggy. Propane loves turbos and high compression. I would only use Propane for an ORV with limited miles per day, like say a hill climber or mountain buggy.

#9 daeron

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Posted 30 June 2007 - 05:30 AM

some more links here http://forums.hybrid...ad.php?t=123035

Google a couple of related search terms. "carburetor" conversion are ALOT easier, and simple enough to do even on an engine designed for MPFI.. the biggest reason to go for the multi port injection concept is high performance applications.. which is something that I (as you will discover if you read the thread I linked to) am EXTREMELY interested in becoming (something of) a pioneer in........

#10 LPGsuperchargedBrumby

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Posted 30 June 2007 - 07:28 PM

first of all, is it possible? has it been done before? has anyone ever heard of it being done? i just think that propane would work better on an offroad vehicle, not to mention that its cheaper than gas and is effectively a 110 octane from what i hear...... the benefits are many, so i figured id see if i could get the legacy converted.....


propane efi has been being done in europe for while now using a piggyback ecu to drive the gas injectors......however i don't see any reason to go gas injection on a subaru as we have alloy intake manifolds and they standup to the odd tuning backfire rather well(unlike the plastic intake manifolds that half the new cars come out with).

the other thing to think about is that due to the cold where you are you'd need to start an warm the motor up on petrol as propane injection needs the gaseous fuel to be 30-40 psi above manifold pressure so the propane tank would need to be at least 10deg C...or you'd need to run a pump to boost pressure back up. (i run a carb'd LPG system an found i needed to run a heater hose back an around my LPG tank because at under -5C it 'just' wouldn't give me enough gas for full noise)

#11 AZTOAK

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Posted 05 July 2007 - 07:56 PM

I often try the math and it never works out. Propane is more expensive and has less btu's. It was more than worth it before the big propane conversion rush in the 70's when the gov't/oil co's raised the price of propane by several times to stop it.:banana:

#12 LPGsuperchargedBrumby

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Posted 05 July 2007 - 09:55 PM

in North QLD, Australia....LPG 69c per Ltr....91 $1.28c per Ltr (91 here = 87 in US of A)

#13 Reveeen

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Posted 05 July 2007 - 10:16 PM

Retail Fuel Prices on 3-Jul-2007 NB Canada:
(as reported here: http://fuelfocus.nrc...cfm?ProvCode=NB )
Reg gasoline $1.07L
Auto Propane $1.02L

Propane is 80% as efficient as gasoline, to be equal in value propane at this time should cost .86L.

As I said earlier, there was a time here that propane was worth converting to, it no longer is. (when I was busy doing conversions propane was .19 a liter)

The real "bonus" of a propane installation is when the propane pump jockey figures, with his minimal training, that the surface rust on your propane container (the propane tanks installed under your vehicle) makes your propane container unsafe and refuses to fill you. (in Canada both the system installers and the re-fuelers have to hold a licence, the installers licence is a 2 week course with gov exam giving you a "gas fitters licence", the re-fuelers licence is a 2 hour course, with an open book test at the end).




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