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Old 06-19-2004, 12:23 AM   #1
Black00GTP
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Default Propane

I put this here for lack of a better forum. im curious if anyone has used propane as a supplemental fuel.

For those that dont know, propane has a rather high octane rating, something on the line of 115. When mixed properly with 93 octane you can have on call 104 octane fuel at your disposal. Propane isnt like nitrous. You can get the cooling effect, if you run a liquid setup, but most of them are just gas setups because of the problem with freezing regulators.

Anyone tried this? Had any experience, good or bad?

BC
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Old 06-19-2004, 02:59 AM   #2
no-coast-punk
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The octane rating of propane is ~130 depending on temperature/pressure of the system.

The boiling point of propane is way below anything you would ever see naturally on this earth, that's why you'll never see a liquid propane system. The fact that it will never be a liquid make it impossible to actually mix with gas. If you tried running propane + pump gas, the lack of mixing would simply cause the gas to detonate where it normally would and the propane probably won't ignite at all in a conventional motor. You don't get any cooling effect from the propane because it doesn't undergo a state change when leaving the lines like nitrous does. Propane is also EXTREMELY hard to ignite, you need an ignition system similar to an MSD setup pushing 80kv through plug gaps ~.020. In order to harness the high octane rating of propane of you really need a static compression ratio of 12:1 at the bare minimum, and even then you would be way down on power (propane only has half the energy as gasoline). You can't really run the compression on a propane engine too high because it has a cetane rating of 0 (meaning that it will absolutely not self combust no matter how hard you compress it).

It's late and I may have confused some of these things with compressed natural gas, but alot of it still holds true. You won't be able to run propane as a secondary fuel thing.
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Old 06-19-2004, 04:41 AM   #3
Black00GTP
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its done already. In fact it is VERY popular on diesels. the boiling point may be obnoxiously low, but liquid propane is used daily through out the world. You must be thinking of oxygen, not propane. Next time you fill up your propane tank at home for the barby shake it when its full you will feel the liquid propane sloshing around. Anytime you see the term LP refering to gasses you are talking about Liquid Propane. Compressing a gas to past 1000lb/sq.in. brings that boiling point up to managable levels. In fact there are a few kits out there that allow you to run liquid propane that gets injected into the system just like nitrous. the issue is that the state chagne happens at the regulator and in the lines heading towards the intake. the regulators regularly freeze to the point that some regulators have been built to have the the engines coolant run through the regulartor too keep it warm enough to flow the propane.

Now im not talking about running on pure propane, which is also regularly used on fork lifts, but as a supplemental gas to raise the octane level of you fuel. Having forced induction gets you that compression level you are looking for. Also, gasses mix well with other gasses. If you spray a gasseous version of propane into your intake the engine will suck it in a burn it just like fuel. In a cylinder the propane MIGHT not ignite directly from the spark, but the resulting flame from the liquid gasoline will ignite it. in the meantime the propane gas is absorbing heat as it nears its ignition point. this, along with propanes high octane rating, allows you to run a lot more boost/timing without the threat of detonation. Propane is NOT a power adder. Like you stated above, it has a low btu rating, BUT as a buffer against detonation it works remarkably well. Even without the state change to cool the intake charge it still makes a huge difference in power potential.

So the question still begs to be asked, has anyone used propane as an octane booster here? Id bet that there is a lot of potential in these engines that just has been utilized because of gas prices and lack of high octane fuel. Im sure we are going to get into a "i dont want a bomb in my trunk" argument, but thats not the issue. (mind you, nitrous, even though not flammable is still a bomb in your trunk. if you had ever seen what happens to a bottle under those presures when they loose their valve you would agree with me.)

google propane injection tomorrow when you wake up for affirmation of my previous statements. You may be surprised to find out that you can run a LOT more boost with it, and basically have 104 on tap at any time.
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Old 06-19-2004, 12:51 PM   #4
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Propane is used on diesels because it acts as a catalyst for diesel fuel when it burns. Alot of people think that the propane itself burning is where guys can pick up all that extra power. The energy added to the system from the propane burning itself is negligible.

I did screw up and confuse propane with CNG in a few spots, and for that I'm sorry for the mis-information (never post when you're drunk and tired). The state change will cool your intake charge quite a bit, however the propane gas will still not mix with the fuel vapor in the way that you're thinking. The pump gasoline will still self ignite close to where it normally would (although the massive temp. drop will help) while the propane won't ever ignite until the spark plug fires. You will still need to run a plug gap that is way too small to be very effective for the gasoline burn and you will still need much higher ignition voltages.

If you're still convinced that you can run boost levels appropriate to 104 octane... go for it, you'll be suprised to see you're running timing curves similar to guys with water injection only your EGT's will be massively higher because the propane will still be at full burn through the exhaust.
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Old 06-19-2004, 01:09 PM   #5
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Speaking of propane. I remember seeing a Justy that was running completely on propane.
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Old 06-19-2004, 03:41 PM   #6
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any way to get ahold of the justy owner? Once I'm out of this crap town in March and have a place for projects I'd like to get a suby running on CNG.
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Old 06-20-2004, 02:54 PM   #7
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actually in europe(from my vacation last year) at some gas stations, people were filling up there propane tanks in there trunks and were running w/o fuel gas. ive seen all kinds of cars getting it, from merc, to fiat, to honda, etc. from what i found out is that since gas is $$$...$$$..$$$.$$$ there that people convert all the time. all it is they say is just a kit they install.
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Old 06-25-2004, 04:09 AM   #8
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here is some info.

http://www.onlygoodstuff.com/

http://www.importpoweronline.com/propanecontent.html

http://www.sccoa.com/forums/showthr...opane+injection
http://us.f802.mail.yahoo.com/ym/Co...&.redir=ymmapi2


http://www.turbobuick.com/forums/sh...opane+injection
http://www.turbobuick.com/forums/sh...opane+injection


No coast, i dont want to be a prick, but you are off on your thought process. I wont argue it. there are PLENTY of people out there running propane injection and added boost without the detonation problems. here are a few links to the products. Hopefully i can post these here without violating any sponsor rules. Long story short, propane has a higher octane rating, and acts as a heat buffer until the point of ignition. So having the propane in there DOES prevent your fuel mixture from lighting off before the spark is added. Ive spoken with a few performance shops in my area, and with a few mechanics i know. two of which are diesel, one of which is a regular old gas mechanic. the three of them agree with me and the decades of proven results. check it out, yuo might be impressed what it can do. But in the end it does make a difference. Besides helping to spread the liquid fuel better (dont quite understand how, but two shops brought it up) the propane helps to absorb more heat out of the cylinder. much like adding more fuel to a cylinder will help prevent predetonation from the cooling effect of the added fuel, so does propane. Even in gaseous form the propane helps to take up some of the heat left in the cylinders.

BC
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Old 06-25-2004, 04:26 AM   #9
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propane, like CNG has a problem, storing equivalent amounts to fuel without adding an arse load of weight to a vehicle, that and the fact that to get more then 75% fill in a tank takes approx 8 hours
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Old 06-25-2004, 06:31 AM   #10
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more then 75% fill in a tank takes approx 8 hours

ru talking straight liquid?
and ru sure thats correct?
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Old 06-25-2004, 12:49 PM   #11
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Quote:
Originally posted by White 2.5rs
more then 75% fill in a tank takes approx 8 hours

ru talking straight liquid?
and ru sure thats correct?
yes i am sure that is correct, that is why CNG cars have no taken off, you must fill them all night long

<---certfied to work on CNG cars

don't forget Propane and CNG are liquid until they are combusted, tehy are not gas
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Old 06-25-2004, 09:07 PM   #12
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i know ubvt i figured there was some sort of a liquid flush to push out the vapor
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Old 07-01-2004, 05:39 AM   #13
Black00GTP
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im not talking about switching over to propane though. and a 20lb propane tank wont take 8hr. Im talking about running a seperate system that only adds the propane when its needed. Usually using a window switch for a nitrous system.

As for it being a liquid. thats assuming you bought a tank designed to move it as a liquid. A dot approved, or even bbq approved tank will not move the propane as a liquid, but allows the change to happen in the tank. In the case of liquid it becomes a problem with the regulators freezing. In the case of gas you dont get the intercooling effect, but still the octane and detonation buffer.

so im taking it no one has tried this on their car huh? too bad. someone should give it a shot.

BC
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