Danno

"It's one of the primary ingredients burned in top-fuel dragsters (nitro):"

And also a large component of pump gasoline as well (aromatics):



Please check out the FUEL-FAQ section of my <a href="http://members.rennlist.com/951_racerx" target="_blank">RacerX website</a>

Contains several archived website, including the F1 Rocket Fuel one quoted above (with functional external links) It will answer several points that's been brought up.

"--It is fat soluble, and goes pretty quickly through the skin and blood to the brain. As another pointed out, it's the stuff that the glue sniffers sniffed, with resultant."

But it's not as toxic as the manganese-based organometallics used in the 104+ types of bottles which can cause cancer on contact. As such, the concentrations are extremely low (as well as the benefits).

"--It takes a lot."

Comes down to what benefits you get as well. For the price of one of those little bottles of 104+ stuff (which raises octane 91-&gt;91.2) you can get a gallon of toluene for a much larger increase 91-&gt;92.0. It would end up costing 5x as much to use the 104+ as compared to toluene.

"--Actually reduces performance if your car doesn't need the anti-knock protection."

Why? Knock-sensing ignition retards your spark when it senses knock. Such as in Brendan's case, he feels stumbles and hesitation from the momentary lost of power resulting when ignition is retarded. Having the higher octane from toluene, the ignition can be run at full advance without problems.

Even if you didn't have a knock-sensing ignition system, increased octane would still help. Perhaps even save your engine since the knock and detonation would simply continue on low octane until your pistons melted or your headgasket blew.

Toluene is common knowledge stuff; the F1 teams discovered it way back in the '80s...

Normy

For what it is worth-

Those of you with general aviation experience have probably run across 100LL avgas, which is dyed blue. Before I put my catalytic converters on, I decided that it would be interesting to find out how it ran in a shark.

Procuring a 5 gallon container, I went out to the local GA airport and told them I had a 152 sitting at a private strip and needed to get it airborne, at which point they sold me some blue. $2.00/ gallon.

I probably should have mixed it with Chevron, but I noticed that there was no real increase in power. In fact, the car seemed slightly flat, and started running rough after a few days. Based upon this, I cannot recommend using this stuff...

Normy!

'85 S2

BC

I think, Danno, that the other's point was that if you increase the octane TOO MUCH, then you will have to deal with what normy found - it canont even advance it ENOUGH at the lower rpms because of the "slower* flame speed of the high-octane stuff. There is a good sweet spot for production computers though.
Now, when I get my DTA set up on my 928, THEN I can control the timing, and will take FULL utility of whatever go-fast-crack-gas I will put in there.

I will be boosting as well, so that will change my octane needs.

John:
[quote]You should use overpressure breathing apparatus, face shield, and commercial chemical resistant gloves - not Platex - when using these chemicals. Be real careful with this stuff, it flashes off incredibly fast, like ether, and is not healthy to be around for any length of time.
It is, however, a real go fast juice. <hr></blockquote>

Where could I find these parts? Especially the breather and the gloves? When I got my garage, I was going to just order 55 gallon drums, and keep them contained in a sfae place, but with a sealed pumping contraption so I didn't have to touch or breath it.

Nathan Valles

If you are mixing gas with different octane ratings here is the math.

[(16 gal*91 octane)+(5 gal*114 octane)]/21gal = 96.5 octane

dr bob

GoRideSno posted:

&gt;&gt; Dr Bob,
&gt;&gt;
&gt;&gt; 1) What kind of Dr are you?
&gt;&gt;
&gt;&gt; 2) What will Brakeclean do to the human body?

1) I am not an MD, so no questions about inflamed livers and kidney problems from sniffing 2), especially if it is the chlorinated kind.

Read the labels, read the labels!


Danno wrote:

dr bob&gt;&gt; "--Actually reduces performance
dr bob&gt;&gt; if your car doesn't need the
dr bob&gt;&gt; anti-knock protection."

&gt;&gt;&gt; Why? Knock-sensing ignition retards your
&gt;&gt;&gt; spark when it senses knock. Such as in
&gt;&gt;&gt; Brendan's case, he feels stumbles and
&gt;&gt;&gt; hesitation from the momentary lost of
&gt;&gt;&gt; power resulting when ignition is retarded.
&gt;&gt;&gt; Having the higher octane from toluene,
&gt;&gt;&gt; the ignition can be run at full advance
&gt;&gt;&gt; without problems.

Both statements are correct.

The only time when more performnace is available with toluene is if your car does need the anti-knock protection, and the advance is not limited by the knock sensors.


Toluene has been on the Cali shlt list for a lot of years, due to the low flash point and problems with photochemical smog and the resultant ozone. It's sold for industrial uses, painting, and stuff like that, but is no longer used at all in commercial motor fuel mixtures. Wonder why California gas is only 91, and not 92/93? Wonder no more!

goodspeed

WELL I THINK AFTER ALL AT (TECH) I'LL STAY WITH
94.
Thanks Guys

Greg

Danno

"I think, Danno, that the other's point was that if you increase the octane TOO MUCH, then you will have to deal with what normy found - it canont even advance it ENOUGH at the lower rpms because of the "slower* flame speed of the high-octane stuff. "

Part of the issue with using too much toluene is your air-fuel ratio. Since it's denser than gasoline, your mixture will be too rich, thus the difficult ignition and lazy flame. You've always heard the thing about having to re-jet your carbs or lowering your fuel-pressure to use race gas, well that's the reason...

BC

Yes, I didn't think to add in the "denser" idea on the toluene. Hmmm. Well, I have always thought that the car was a bit lean anyway, so this may help on the track - when it gets there.

Brendan

Mike Schmidt

The toluene is denser than the gasoline, but the ideal air/fuel ratio for maximum power with toluene is different than it is with gasoline too. The best air/fuel ratio for power with toulene is around 9.8:1. At full throttle the LH computer doesn't use any feedback from the O2 sensor to make mixture adjustments. It just delivers fuel based on the amount of air flowing into the engine as determined by the MAF sensor, and delivers the amount of fuel for that amount of air based on the maps stored in the LH computer. At full throttle the LH computer doesn't know what the air/fuel mixture is. It just adds the programmed amount of fuel. It assumes that this fuel is gasoline, because the maps where programmed with that assumption. With the toulene being denser, the mass of it getting through the injectors, at the pulse width that they're being opened by the LH computer, would be more than if it was gasoline going through the injectors. Since the ideal air/fuel ratio for toulene is richer than for gasoline, you'd need more of the toulene for maximum power anyway. Now the question is whether the addition mass of toulene is enough to compensate for the greater required mass of toulene for that maximum power. Toulene is about 17.5% denser than the gasoline, but the required air/fuel ratio for it is about 18.3% richer. In other words, you're probably running leaner with the toulene than you would be with gasoline. With stock fuel pressure, the full throttle mapping in the LH computer is programmed too rich for maximum power at the high end, probably for engine safety reasons. I think that any power increase you might be seeing from using the toulene is coming from it leaning out the air/fuel mixture, and not from any octane increase that it's providing.

You really don't need any more octane than what is required to run the engine without knocking. If the engine does knock, the engine management system will retard the ignition timing until the knocking stops. The ignition timing is programmed into the maps stored in the engine management computers. You will not get any more timing advance than what's programmed in there. The system will retard the timing from those programmed values if knocking is detected, but it will not advance it any further, no matter how high the octane of the fuel you're using.

John Veninger

Brendan,

Hopefully you will have an A/F meter hooked up during the dyno runs. I have looked at several properly running GT's and S4's dyno sheets. They all go very rich at the top end. Might be Porsches way of saving motors during warrany period.
Also have seen some run to lean, usually indicates injector or MAF problem.

Normy

Interesting, Mike-

My theory as to why my car didn't actually run as well with very high octane fuel has nothing to do with spark advance- indeed, I am driving a 1985 928 S2, Euro version with 10.4/1 compression and plain EZK ignition- no knock sensors. An thus no advance based upon lack of detonation.

From my days of teaching aviation, I know that any otto-cycle engine, as it completes its cycles, will occasionally "knock" or detonate. Every once in a while, a power stroke will not proceed as planned and the mixture will burn excessively quickly [explode, for lack of a better term]. Increasing the octane rating of the fuel minimizes the percentage of the time that this takes place. However, there is always the notion of diminishing returns and this was one case. Basically, the lack of occasional detonation allowed the average cylinder temperatures to be low enough that the lack of detergent additives in the avgas caused fouling to begin on my spark plugs. Voila- loss of power from the cooler temps [these are heat engines, afterall....] and lower driveability from slightly fouled plugs. At least that is my theory...

-One thing that I was taught was that an excessively lean mixture causes higher cylinder temperatures because it actually takes longer for the charge to burn. This longer burn subjects the cylinder head and block to a greater thermal load while not heating the gases in the cylinder as quickly, resulting in lower power [exhaust valve opens and the still burning mixture rushes out = no more work done] and higher temps. The opposite- a rich mixture, tends to burn far cooler and quicker, as some of the fuel is not burned- the very quick burn leaves some fuel vapors unburned, which in turn absorb some of the heat and carry it out the exhaust port. Loss of power and fuel.

Obviously, in our otto cycle engines, mixture is important!

Normy!

BC

Once again Mike S comes through with a well-thought-out set of scientific facts and observations.
I appreicate your ideas Mike, and have a few comments, questions.

With your Toluene observations, and the advance/retard ideas, would you say it is possible, that because of California's known gas formulations and iffy 91 octane claims, the S4 is running at a retard somewhat, to curb detonation?

My point here is that the gas door says 91 minumum. It doesn't say that it will run great on it, nor does it say what its perfect octane will be. It just says it needs 91 AT LEAST to run.

My assumtion then was base don my prior experiences with 93 octane from Chicago and 91 here.
I have felt, since I moved here, that there is a slight "hunting" between 3k-4k. I do not mean the flappy opening, as that, I blieve will be on off. I am describing something in the way of "throbbing" or "pulsating" between 3 and 4k. This happens on part and full throttle applications. When I increase the amount of T in the gas tank (such as my current 16+5), I do not feel this throbbing in the rev range, and I also feel that the car will rev from 2k in higher gears more smoothly. No scientific data, just my feelings.

I was incorrect in my assumtption that the computer will advance the timing if it has room to. But your info that says it will retard it if it needs to plays into my point. Thats is to say with the correct level of octane, it will not NEED to retard the timing in anyway and therefore you will get MORE potential from each power stroke than you would have from 91 octane, as I believe the computer DOES sometimes have to retard on that octane. Do you disagree?

In response to your point about A/F ratios, I will say this. In part throttle, bwteen 304k, where i usually feel almost a "pull back" in power, I do not feel it when the T is on in large quantities (16+5). If I could, I would run out right now and install a Adjustable Fuel pressure regulator, as if what you say can be used in this car, then the denser T, with the leaner mixture would then be made richer with higher pressures, and the result MAY be more power. But I have always been lead to believe more pressure doesnot equal more power - unless you rpoint in this case is that if you have T, you need more fuel.


Finally, and thanks for reading this far - you say that the T needs a 9.8/1 ratio. Others have said that the S4 runs way rich at the upper revs. If you put those two points together, and add them to your point that T NEEDS to be richer to make power, then it seems to me that those three points put together equals Toluene making a bit more power in the upper revs than straight gas.
Am I way off here?

I can feel when the car gets flat. It gets flat with heat soak, and it gets flat if you run crappy gas. I can feel differences (though slight) in the intake temp with reference to power. Here in San Diego, it gets nice and chilly/Dense at night. Best power output is after 9pm. ('Course, thats past my bedtime)

All this discussion will be mute when I install the DTA computer this summer. Then I will be able to maximize whatever gas I use, even 91 octane.
And after that, with my SC and Sleeved and stroke plans, it will all change again.

Again, thanks alot Mike S for your comments. I always look forward to your insites. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

BC

John V. - I am currently unsure if I will be able to run on the dyno this weekend. As I noted earlier, this was the plan, but currently, my business is making invest much of my freetime in it. (and the need for required funds for the litte person on the way) I wanted to test my airbox mod (ha! mod - its a big long hole), and my Toluene experiments, but I may simply go and watch for a short time. I have a base run that I have from Chicago, but I did want a base run here as well before I make changes (headers, exhaust, computer, SC, Stroker/BORE). These are long range plans, but if I make them all at once I may get bored with the power. AND I need to invest in track equipment as well, as SoCal is a bonanza for the track junkie.

Mike Schmidt

It is possible that the ignition timing is being retarded if the gas out there in California is quirky. When I've seen S4s on the dyno retard the timing due to detonation it was at higher RPMs than what you seem to be experiencing. When this happens the power fluctuations on the dyno chart can be pretty dramatic looking. It looks like an earthquake hit during the run. Knocking can usually be heard when it occurs too.

Between 3K-4K RPM there is the transition from closed to open intake flap, and more than likely some quirky flow patterns during the transition. At that same point the ignition timing is also increased a good bit by the engine management system. I suppose it's possible that the slower burning toulene helps to smooth out some stuff during the transitions that are occuring in that RPM area.

If the computer is actually retarding the ignition timing ocassionally, then the higher octane would help at those times. Remember that higher octane fuel doesn't knock as easily because it burns slower though. That would mean that if no knocking was occuring a larger amount of the air/fuel mixture would be burning later when it didn't need to be. It would be burning as the piston was already on it's way lower and compression in the cylinder was already decreasing. I've also heard and read that using fuel of excessively higher octane than required by the engine will increase carbon deposits from the slower burning. Carbon deposits in the combustion chamber will raise compression ratio and can lead to hot spots that promote detonation. So in kind of a catch22 situation, using octane higher than you really need over time can cause you to need the higher octane that you wouldn't have needed if you didn't use it in the first place. You can end up with a situation like what Normy mentioned above where the excessive octane fuel burns slower and causes the carbon buildup and fouling.

Yes, if you have toulene you will need more of it to get an ideal power mixture than if you were using just gasoline. The toulene is denser, but not by as much as you'd need to be at the optimum power mixture ratio. You are also right in that because of the stock mapping being too rich at the high end the leaning caused by the toulene should increase power there. The problem is that it's also leaning the mixture lower in the RPM range, where the stock mapping isn't that rich. You might be gaining power at the very top end because of the leaning occuring there with the toulene, but loosing power lower in the RPM range because it's leaning the mixture there too. That's what's nice about being able to program the engine management system electronicly. You can go either richer or leaner at different points in the RPM range independently of what's happening at other points in the range.

John Veninger

A little <img src="graemlins/offtopic.gif" border="0" alt="[offtopic]" />
Mike wrote:
[quote]That's what's nice about being able to program the engine management system electronicly. You can go either richer or leaner at different points in the RPM range independently of what's happening at other points in the range <hr></blockquote>

That's why Mike's A/F ratio is nice and flat on his dyno runs
My GT looks like someone empties a gas can into the intake above 5700 rpms! Dastek one of these days.
On the other hand the Euro w/ CIS has a nice flat line. Got to love older technology.