Hello again. I have a 1998 5.9... Jeep... But you guys have 1000 times more experience with the 360/46RE combo, so I come to you for wisdom. I use 93 octane, ethanol free gas. Bolt on engine stuff, for now. Now that's out of the way...

Anybody running toluene or xylene in their gas with advanced timing? I know at least one of you has talked about it, but I haven't seen any threads with people actually doing it. Is it even worth doing NA?

Here's some mix (toluene:92 octane) vs octane numbers to think about.

10%...94.2 Octane
20%...96.4 Octane
30%...98.6 Octane
50%...105 Octane

Now, there was a fellow who said his SCT tune was running 40° of timing advance on E10 92 octane, and was getting pinging. Any reason I can't crank it up that high with a higher octane fuel?

 

It is quite some time ago (~30yrs), but from when I raced outboards, we mixed toluene with our gas to up the octane rating, and to allow the use of a typically uncompilable oil.

From memory, the benefits of adding toluene max out at ~10%.
The reason being; gas has more BTU/lb than the other items being mixed in... so diluting the gas with other things of lesser BTU's lessens the amount of energy to be extracted from what is being burnt.
This is why we wanted to use a different oil, so we could use less of it, and hence have more gas in the mix.

We used 115/145 avgas with 10% toluene and 6% synthetic vegetable oil... oh, and a splash of mentholated spirits (to break the surface tension on any water in the system so it would pass and not clog jets).

 

Toluene is the main ingredient in gasoline that raises octane. I've poured 6-8 ounces per 10 gallons of gas in my Neon and that car felt like it had nitrous when "the mix" hit the fuel rail 10 minutes after filling up lol. If you can get it cheap its fine, if you end up paying a lot of money for it at an Ace Hardware or equal you may just be better off buying 110 gasoline & mixing that with your regular gas like an additive.

Nothing is free and the price of toluene probably equals out to just buying that octane of gas you're trying to reach. Almost like E85 being so cheap, its cheaper because it doesn't go as far as pure gasoline, the price difference is the efficiency difference.

When I had the turbo on my Neon (running 17psi on a stock motor) I used Lacquer thinner & denatured alcohol to eliminate ping with lots of success, but toluene was the only additive I ever added where I actually felt a noticeable difference in power, and even after selling the turbo, I still noticed better performance in every vehicle I ever put it in. The only problems I ever had with that motor was the boost breaking through the old intake valve seals & leaking into the engine like a massive plenum gasket leak lol.

 

Unless you are running a higher compression engine, advancing the timing will only result in a over worked rod bearings and mains.
I love using toluene, use to buy it by the barrel. cause you got to use a lot of it to get the octane right. I raced 4 banger engines that turned over 9k for 30 minutes at a time.
Compression was about 12-14.1 to 1.. So I needed the extra SLOW burn of the higher octane. SLOW burn prevents detonation in a engine. Extra octane will not give your regular engine super powers, if anything it will decrease HP. As more fuel than, octane ratio the quicker the burn. People get it backwards..... high compression engines need that fuel to not ignite till the spark pops. Low octane fuel wants to pop easy in a high compression state.

on your ratio list, a 10 gallon tank of 92 gas will need 1 gallon of toluene just to raise the octane 2.2 points..

 

Interesting thread. There was a lot of discussion on the net a few years back when gas prices started to skyrocket about drivers adding toluene to their gas in an attempt at better mileage. I read table after table of results without ever coming to conclusion about it. The results seemed to depend on which engine they had and how much they were adding to there gas. Some reported better mileage, some worse mileage and some no change. Still don't know for sure.

 

I both agree and disagree with your post...

I agree with you on your overall post & that People think higher octane is more explosive and It defies logic that a slower burn would provide more power, but its the fact with higher octange fuels that the fuel ignites when its supposed to with the timing of the engine that gives you your power. The slow burn ensures the fuel will ignite when its supposed to on or near top dead center (depending on your timing). Low octane will ignite sooner and depending on the compression & heat of the engine that ignition could happen anywhere in the stroke where conditions are right for preignition and NOT ideal for proper running of an engine, diesels for instance have an octane rating near 39-40!, which is why they don't need spark plugs, the compression itself ignites the fuel.

The fact the engine is not hiccuping & fighting itself is the reason it gives you MORE power. I disagree with you on the fact that I don't see a senario in which higher octange would "if anything lower your power", with it being used properly in an application its needed in, it will always increase power because the engine is no longer fighting itself with pre detonation. I think standard 87 gas autoignites at around 519-536 F degrees if my memory is correct...

The other work around for fighting pinging is throwing more fuel at the problem. Also people think nitrous is a big hot firey explosive bang, in reality it actually cools & slows down your fuel charges explosion lol.

My Neon has 9.8:1 compression, and while that may not be very high, any small hill in summer or after a long time of running anytime of year you can hear it ping away, when adding toluene the ping disapears and the motor absolutely roars with authority up to 7,000 rpm!. I've yet to put toluene in my truck yet due to me not having any pinging and just plain not having money to buy toluene, but last year I passed the toluene can around members of my family & friends and nearly all of them had positives things to say about their car after using it. Octane boosts in the store don't even compare, I've tried a few and toluene works tons better and you actually feel a difference in power.

But to answer the original posters question, if you're running under 11.5:1 compression adding toluene or mixing even 110 racing fuel into your regular 87-93 gasoline will increase octane with good results and definitely help you out. Advanced timing will help your low end power out as retarded timing will help top end out, finding the happy medium or comprimise you like best is up to you and a tuner.

 

Thanks for all the input, fellas. I don't know why I bother with jeep forum(s). The only good input I got from there was "Try a different forum."

Here's the deal: I'm running 8.7:1 compression (stock) and naturally aspirated. I'm saving and researching (mostly just researching) for when I finally build my 360 the way I want. I'm not looking for cheap HP, or mileage gains , or anything stupid like that. I just want a strong, healthy engine that's as free breathing and as powerful I can manage.

I'm seriously considering building a 408 stroker. That'd put me at 12:1 compression I wan't to play with the different gas mixes, maybe WMI or MEI, different intake manifolds, etc to see what I'm comfortable with.

I think I'm going to try some of the toluene, just to see what happens--the scientific method!

I'm going to bump this with a couple of pictures because, well, who doesn't like pictures?