Jesuscookies

iTrader: (1)

People please, think before you speak. If you do not know what you are talking about you should not be posting. Don't drag down this thread, with uninformative, assumptions.

Hamburgler, thats quite the slippery slope you have taken...

Hamburgler

What are you talking about? People are wanting opinions and I added that someone I know broke his motor using toulene. Air fuel was mid 11's all across.

No assumptions here.

Evil Aviator

Hehehe, well that explains the blown motor then. Actually, you bring up a good point that people who don't understand fueling issues should leave the tuning to professionals.

Hamburgler

What explains the blown motor and what do you mean by your last statement?

gnx7

iTrader: (10)

People have been running Xylene/Tuolene for years with no adverse effects. Just don't exceed a 30% mix as the car will start to drive funky.

as stated
Tuolene- 114 octane
Xylene- 117 octane (cost is about same get Xylene)

Open an account at Sherman Williams and you will get an additional discount. I pay $32 for 5 gallons.

7 gallons 92
3 gallons of Xylene
3 tablespoons/ounces Marvel Mystery Oil (lubricant)
yields
100 octane

Allows higher boost/timing in all turbocharged cars with proper tuning.

I'm not sure if it was designed for an internal combustion engine... but guys in TurboBuicks have been running it for years with no problems.

It is a good idea for us turbo guys to add a gallon to every fillup just for added insurance to avoid detonation. It is listed in the table showing what fuel is comprised of. Directly related to octane levels.

Want more fun and not mess up your cat if you run one. Add 3 gallons of Xylene to 7 gallons of 100 octane unleaded . Keep turning up the boost/fuel.....

-GNX7

Evil Aviator

Toulene has a stoich AFR of 11.5:1, and a best power AFR of about 9.8:1, and you would want to run richer than this under boost. That mid-11:1 AFR must have really fried that engine something awful, and your buddy probably thought he was being safe with that AFR, lol.

Hamburgler

No ****? Wouldn't you need a killer ignition system though to run that low of a afr?

Jesuscookies

iTrader: (1)

That may have been an opinion, but it was a useless post. There are many reasons why people pop their motors. However, To say that because your friend used toluene he blew his motor, is an assumption, and a slipperly slope approach to a real problem, which in this case sounds like the tuning.

Please, show the proof that because your friend used Toluene he blew his motor? You have piqued my interest, and I would like to see it.

Evil Aviator

He did show proof - the lean AFR. I think this is a valid point.

I don't know. The RX-7's have a pretty good stock ignition system.

Hamburgler

I didn't say it blew because he was using toulene. Read again. I said it blew while using.

Ni5mo180SX

Great thread, provided a lot of information in areas which were a bit grey to me before.

Although I dont mess with boost too much, I think the chance to use xylene as added protection againist detenation during track events is great.

GNX7- I've seen the statement of 30% concentration being at the upper thresholds of mixing as well but in your example, of 7g fuel & 3g xylene, thats a 42% mixture. Have you done this with no adverse effects?

Effects on the premixing ratio for those of us with no OMP?

Jesuscookies

iTrader: (1)

Proof that the AFR that was set leaner than most are comfortable with on a rotary.

On to more important stuff. What does this statement mean: "Toulene has a stoich AFR of 11.5:1, and a best power AFR of about 9.8:1, and you would want to run richer than this under boost. That mid-11:1 AFR must have really fried that engine something awful, and your buddy probably thought he was being safe with that AFR, "

Evil Aviator

Sorry, sometimes I forget that I need to tone down the techno-babble so that normal people can understand the discussion. Let me try again in English:

AFR = Air/Fuel Ratio by weight. For example, 15:1 AFR = 15 parts air to 1 part fuel. It could be 15 pounds of air to 1 pound of fuel, or 15 ounces of air to 1 ounce of fuel, etc.

Stoich is short for "stoichiometric", which means the chemically-correct air/fuel ratio by weight. Different types of fuels have different chemical compositions. Each composition has a chemically-correct mixing ratio with air. Here are some common ratios (some brands of fuel will vary slightly, especially with complex fuel like pump gas):

14.7:1 Regular Unleaded Pump Gas
14.4:1 Premium Unleaded Pump Gas
11.5:1 Toluene
6.5:1 Methanol Racing Fuel

Reducing air (or increasing fuel) to this ratio will result in what is called a "rich" air/fuel ratio. The extra fuel doesn't have enough air to react with chemically, so it is wasted, which means that gas mileage suffers. However, the extra fuel cools the combustion process, creating more power and reducing the chance of detonation. Therefore, the "best power air/fuel ratio" is more rich than the stoichiometric ratio. Here are the approximate best power air/fuel ratios of the before-mentioned fuels:

12.5:1 Regular Unleaded Pump Gas
12.0:1 Premium Unleaded Pump Gas
9.8:1 Toluene
4.5:1 Methanol Racing Fuel

Of course, each engine system is different, so the best power air-fuel ratio needs to be determined by an experienced engine tuner. Also, richer ratios than those listed above may be desirable to combat detonation if the tuner determines this to be more advantageous than the more power-efficient "best power" ratio.

Adding air (or subtracting fuel) to the stoichiometric ratio will result in what is called a "lean" air/fuel ratio. Usually a lean air/fuel ratio will yield better gas mileage than the stoichiometric ratio because the fuel consumption rate is reduced. However, since there is less fuel to cool the combustion process, heat is increased, which increases the chance of detonation.

Now, if you look at the numbers posted, you will see that 11.5:1 would correspond to a slightly rich air/fuel ratio for best power when using premium unleaded pump gas (11.5:1 is more rich than 12.0:1). However, when it comes to toluene, 11.5:1 is its stoichiometric ratio, which would be similar to running premium unleaded pump gas at a 14.4:1 ratio. This is usually too lean to run an engine under boost in a safe manner.

So given that, do you think you know why Hamburgler's friend fried his engine running a mid-11 AFR under boost with toluene? I agree that the lean mixture is not necessarily the reason the engine blew, but it is a strong suspect.

Also, given that, do you know why that jerk, Evil Aviator, keeps telling people not to tune their engine by chasing some magical AFR that somebody on the internet said was good?

Jesuscookies

iTrader: (1)

Damn, mister I had too much coffee this evening. Okay, That is what I thought you meant. However, I did not understand that different fuels, have a different "Ideal AFR". You learn something new everyday.

That would also mean that Hamburgler's friend was running pure toluene in his tank, or at best a very high concentration of toluene right?

Also according to the numbers you gave up top, if I am running 10Gals of 91 and 1 gal of Toluene, my ideal AFR as a average of these 2 gases is 11.8, correct? anything above that may be pushing it?

Finally, if Toluene is supposed to be so good as a anti dentonation fuel, does this stoich level of 9.8 negate that? even in small quantities as many use?

Evil Aviator

No, Hamburgler just said that his friend was using toluene and had the engine tuned to mid-11 AFR's. It could have been anything from pure toluene to any given percentage. The more toluene that was in the mix, the less that mid-11 AFR would have been appropriate for the engine. I was just quoting pure toluene numbers for lack of more information on the blown engine, to simplify my post, and to make a point about how Hamburgler's post related to this thread.

You would need to average the AFR's by weight, not by volume. The stoich AFR is only suitable for low-load conditions like cruise, so even a stoich AFR is pushing it when the engine is under high load. Something around the best power AFR would be more suitable under high load.

1) Toluene is already in most pump gas.
2) Toluene is a good anti-detonation fuel because it has a high octane rating of 118 R+M/2.
3) The stoich AFR for toluene is 11.5, not 9.8. Don't confuse "stoich" with "best power" or "best economy" AFR's.

Spank

iTrader: (1)

So Evil Moderator, since I run full race fuel K & S Extreme Unleded at 103-107, does that mean that if I started to do the mixing of fuel the car should be retuned.

I had the car tuned by Koji at XS to run 17-18 lbs of boost and put out lots of power. I like the idea of saving a bunch of money on race fuel (over $1,000) spent last year. However I do not want to pop my motor. I was thinking this was the way to go to save me a boat load of money but now it sounds that if I do this I should have the car retuned with the mixed fuel.

Any response would be appreciated.

Allan

07 SM2

RETed

Boy, this is worse than the drifting threads...

Evil Aviator is right - different "chemicals" should change your target AFR's, period.

Try and talk to the guys who run methanol and argue your 10.0:1 AFR was still too rich - they will all laugh in your face.


-Ted

Evil Aviator

If you are asking a question like that, I think you are better off paying $1,000/year for racing fuel rather than messing with things that you don't understand, especially when those things go "boom" if you screw up. I don't mean that in a bad way, as we all have our own strenghts and weaknesses, but I think it's important that we have at least a basic idea of what we should and should not attempt. For example, I do not weld aluminum or stainless steel, or mess with my transmission. This is not because I am stupid, but because I am smart enough to know that I am not good at these things. Sure, it costs me money, but not as much as if I botch the job in an attempt to save money.

andericus mack

Evil, what is the stoich for xylene?

rotaspec

It might be timely to ask a question here:
Will it actually be dangerous to the engine for a person with a stock ECU setup to run an additive like toluene? If in fact the additive mix requires a much richer a/f ratio, will the stock ECU actually be able to produce this mixture, or will the advantage of higher detonation resistance that the additive provides be offset (or worse) by the fact that you will end up running too lean?

I know that aftermarket ecu's can be retuned to take advantage of the additive by richening the mixture, but what will the stock ecu do, by itself?

D-town R2

Anybody have a resopnse to Rotaspec? Can the stock ECU compensate for the A/F ratio when running tolulene or xylene. I would think it would try to keep it stock and you end up lean with the mix. What would you gain. I might have to test this idea.

RETed

back from the dead...

Remember, these chemicals are "aromatics", and that in itself implies "not very clean burning".

This is why recommended ratios are like 20% or less.

It's basically an "octane enhancer", and used in recommended doses, it will stave off detonation...to a point.


-Ted

SPOautos

I've basically stayed away from this topic for one reason, I dont understand why people care about spending $40 on 5 gallons, thats $8 a gallon.

I can buy 116 cheaper than that. I dont understand why anyone cares about this stuff. Is it just cause its easier to find than race gas???

Guess its just cool to live in Alabama where I can pick up 112 and 116 out of a pump 3 minutes from my house haha

STEPHEN

j9fd3s

iTrader: (3)

i live in california and theres 100pump 15minutes away....

mikey D

I live in CA to and race gas just just a few miles away...

I can buy race gas for less and have properly formulated fuel that i dont hve to worry about.

there was a big post on this a while back and it has been discussed several places over the years.

I posted the prices for differnt types of race gas that could be aquired by anyone and shipped to your front door cheeper than putting other things in your gas tank.