I successfully sprayed an 80 hp nitrous shot last night with propane as the enrichment fuel. The O2's went from .900 naturally aspirated to .945 on the dope. Looks like I'm pig rich which is far better than searching the boards for a shortblock. I'll continue to lean it out. It feels good, and I feel safe enough to leave the fire extinguisher in the garage from now on. Anyone else have experience with spraying propane?

Hey CRC dude where's the book with the rocket fuel concoction. hehehe

 

That sounds awesome. I like the idea of using propane as nitrous enrichment. I also like to see people try new things (not that this is completely new, but it isn't that popular in these cars).

The only problem I see is trying to watch the o2 readings to tune. I'm sure you have heard it before, but the o2's are not accurate to tune from (you can read about why in numerous other threads). I know some people argue that while "they might not be accurate, at least they are consistent" but, when you use a different fuel (propane) it has a different H/C ratio than gasoline and it will throw the o2's off by some unknown amount. You could be running far richer or leaner than you think.

This variable H/C ratio will even cause problems on a wideband o2 reading. To get a true lambda reading you need the H/C ratio of the fuel. If you are using two different fuels (propane and gasoline) there is no way to tell exacly how much of each you are getting so you can't compute a true H/C ratio. There are also questions as to what effect N2O will have on a lambda reading. I don't know the answer to these but it is feasible that between the air, nitrous, gasoline, and propane, your reading will have some error.

I think the best way you could tune the setup is by EGT and reading plugs. As long as the EGT's don't get too high you probably aren't going to hurt anything. I think you can get EGT setups fairly cheap if you are willing to put bungs in your headers.

Good luck with your setup, and have fun with it. Just be careful to not burn anything up.

Dustin

 

What size jets are you useing for the propane?
With useing a fuel other than gas you will want to use a EGT and read plugs that is the only way to see if you have to much fuel.
I say you should stay with it. Don't let any one tell you not to.
I asked about running Nitrous and Methanol a while ago, I was told not to by a lot of people on the forum. Then I got some emails and privet messages from people giving me tips on different setups and other stuff.

 

Usually I tune with the stock O2's (inaccuracy's included) while reading the plugs all along. I'll admit that night I didn't check the plugs. I've developed a level confidence from the O2 readings. Additionally, I have the stock KR program active. I didn't think any engine damage would occur.

Thanks for pointing out the O2 readings vary with fuel H/C. I didn't think about that. I'll check my plugs. I rejetted for over 100 hp this weekend, I'll try tonight.

No headers here, just stock manifolds.

I'm not aware of any other LT1's running propane enrichment. Anyone?

A 30 jet on the propane.

 

Sprayed over 100hp. Everything looks good. O2s dropped to .923. That's as far as I'm going on pump gas and stock plugs.

 

Neat experiment. How much did you spend on the propane set up for this 100-shot?

I'd wager a 150-shot of Nitrous would be a lot cheaper, less complicated, and more reliable (fewer parts to go bad).

Objections here had little to do with "if it's possible" becasue it clearly is, people have been doing this for several years now... but the cost/benfit ratio is just too ugly IMO. Propane isn't exactly a "cheap" alternative to gasoline, and the extra weight from a compressed flamable liquid tank doesn't get me all that excited either.

Just be safe and go slow. Documenting everything as you go will definitely keep you on the safe end. Let us know where you end up on jet sizings.

 

The problem I was trying to overcome was the expense involved in an enrichment fuel as it appeared the stock pump could not hold fuel pressure/volume at the big end on the 11.52 pass. I was spraying a home made 150 hp dry kit. I use the stock injectors for enrichment. The O2s were dropping into the .500-.600 range and the plugs showed signs of slight detonation. Injectors are $200-300. The beefy pump is $130? or so. That blows my budget. So, I turned to an auxillary fuel supply.

When you think about an auxillary fuel supply for a nitrous kit there is a fuel cell $100, pump (Holley Blue, as an example) $100. Still a couple hundred at the least. Ah, enter propane, the self contained tank and pump.

I have less than $40 in the propane side of the kit and it's very light.

By the way one still needs nitrous bud, propane merely mimicks gasoline (enrichment fuel) in this case.

 

A propane setup is probably more reliable than a stand alone fuel system (or at least as reliable) as far as parts failing. The only moving part to fail is the solenoid.

Also, propane has a high octane rating ( I don't know it off the top of my head), so it helps with detonation more than pump gas.

The only problem is getting it tuned in. All that takes is some experimenting and it looks like we have someone to do that ). I still would suggest an egt gage, but it sounds like you are doing good. Thanks for the updates, I will keep watching this.

Good luck
Dustin

 

Another suggestion:

Do you run a pressure regulator on th epropane tank? If you did you could (theoretically) build pressure higher than you need in the bottle and then regulate it so it is always constant.

 

Propane is supposed to be 105 octane. Your're right only one moving part.

Traditional regulators are to expensive.

 

just curious - what are the NHRA rules regarding Propane setups, such as this? I would be fairly concerned about running around with a bottle of Propane in my car - but Im just paranoid like that

Did they give you any flack during the tech inspection at your track?

 

Alcohol/methanol actually mixes very with nitrous, but you still need a seperate pump, tank and different jetting. Years ago I did a setup on a guys 671 blown BBC.. he had a 150 shot and it wouldn't hook with his 10" slicks.

Propane would be a need alternative, but I don't imagine the track would be too keen on having that tank in the car.

The good side of all this is being able to barbeque in the pits... already got the tank!

 

It looks like some of the setups are inside the car, mine is not. I opted for the protection of the firewall.

Now that I've tested though, I'm thinking of moving the bottle inside the car, there really shouldn't be any significant danger. I even shut off the nitrous and sprayed pure propane, no blowback/backfire. I suppose an accident could pierece the bottle, but then the nitrous bottle was going to get it any way.

I haven't taken the car to the track, at this point I'd remove the bottle for tech. Maybe someone else knows what NHRA has to say, no doubt it already has come up.

Alcohol is an excellent deal with the 130 octane and all, but I just didn't want to add the expense of the tank and pump.

You're right I should look into one of those folding wing grills "as seen on tv" nothing beats a grilled deer burger, mmmm makes me hungry.

 

Continued spraying the 100+ shot. After continued use I'd get a surge while spraying. I thought nothing of it and was not loging data at the time.

I installed cold plugs and switched to the 150hp (.063 nitrous jet). The surging was there from the get go. O2 readings went from .9xx to .07x over and over. Plugs showed massive detonation.

I installed a vaporizer in the propane line. I've logged over 30 seconds total spray time. No more surge and she pulls like a team of Siberian Husky's on Mr Os off season roid stacking program. O2s are at .875. I forgot how much fun spray can be.

Jury's still out on detonation.

 

Sunday by noon the Jury will have spoken.

Guys remember this is the guy who's gone 11.52 @ 115.98 with $1300 worth of add on's. Untouched 115 K mile LT-1...even stock manifolds and Y pipe. Car still has a single muffler and single ex.