Toluene and ignition advance- how much

[chaz_r33_gtr]

Have been messing around with toluene (safley!) and using about 10% mix. Have mannaged to put 2° extra ignition timing in on my apexi with knock of only around 25.

With normal optimax doing this knock can get to 40-60.

I also retarded my ignition 8 deg to see what knock i get and that still gives me a knock of about 15 (so that most likely engine bay noises and OS Giken pistons).

Question is how much can i trust the apexi knock value dare i try 3 or 4 deg igntion advance over Rod Bells map for Vpower?. (engine is rebuilt with nismo shells, balanced crank forged pistons, tomei head gaseket, ARP bolts etc). Is there a rule of thumb for toluene % and igniton advance? Should i do anything else at same time like richen mixture.. at 1.6bar boost Rod told me mixture is about 10.5:1?

[anthonymcgrath]

depends how Rod mapped it really.. When he did my old un he err'd on the side of caution with it, so I was able to advance ignition a couple of degrees safely if I added some kind of octane boost! Even then tho the knock count rarely hopped above 11 and the drive and torque curve was ace (gtst btw)

I think if yer fiddling at home the power gains just don't justify pushing a car to the final degree of ignition really - all the time your getting closer to getting larger det spikes. Also I've seen ppl do that and they start accepting higher and higher knock values each time. The lower the better imo esp. if everyday driver.. no-one wants to see a skyline at the roadside

retarding it 8 degrees seems alot i think but if knock values aren't going crazy who am I to say lol!

in answer to your question tho I wouldn't push it above 3 degrees personally - the knock sensor isn't brilliant at filtering out other engine noise - lots of info on this site and opinions about it elsewhere. Whether you've got rebuilt goodies or not I'd avoid pushing too hard - is it not fast enough at 1.6bar hehehe

My personal fave trick - fill the car with yer mates for the day... drive about.. then kick em out later on and take it for a spin ...wooooot!!

[kismetcapitan]

det cans. the noise of combustion is lower with toluene. You'll need to map completely differently based on what blend you're running.

In my experience, I didn't advance ignition so much as I raised boost. Toluene is wonderful, wonderful stuff, but it isn't invincible~I've run 100% toluene and it is possible to advance ignition too far. But with brilliant mapping, Honda pulled off 5 bars of boost with the stuff with their F1 engine.

Run more than 30%, and you will need to think about mixing in some lubricant, as toluene as zero lubricative properties. Run over 50% toluene, and you won't get clean firing in cold weather, and every hose in your fuel system must be toluene-proof, or it will eat through it.

I would say that, with turbos that do not run high boost pressures, 30% toluene is as good as it gets. I ran 100% as toluene is about 30~35% cheaper per liter than pump gas in Korea.

[chaz_r33_gtr]

Antony/toby

Thanks for the replies. I only RETARDED the ignition timing by 8° to eliminate the chance of 'proper' knock and so see what the apexi picked up at that point which i am assuming is engine noises totally unrealted to knock.

I think ill just stick to the 2° and not play anymore. 10% toluene is about the most cost effective for me really (as it still standard fuel system pipes etc) and I dont want to run any more boost (have garret GT2580-5s) and looking at their compressor maps anything above 1.6 bar is pretty inefficient.

The extra 2° makes it a bit more lively especially off boost as ihave a trust power evo 2 4 inch system with no baffles and there is no back pressure off boost at all. As an aside have order and Apexi Active Tail Silencer which should help create some back pressure at off boost / v.low boost to make the car pick up a little faster..

Ta
Chaz

[kismetcapitan]

what's the difference between a Garrett 2580-5 and a 2860-5?

And...will temporary back pressure at low RPM really help spooling?

[chaz_r33_gtr]

oops getting confused i meant 2860-5s..

As for temporary back pressure helping spooling, not sure but it certainly makes the engine more responsive off boost. Noticed it when putting in the standard exhaust bung, car much more responsive to throttle input but the standard bung reduced peak boost by 0.4bar! at the same duty cycle!

[kismetcapitan]

I can't read compressor maps, but I can say that there is a HUGE difference between 1.6 and 1.9 bars on these turbos in acceleration. I just wish I knew for sure where my turbos are at efficiency-wise at that boost pressure (factoring in all the various components of my car).