[GunMetalGrey]

I’m wondering if octane booster will have a significant cooling effect and how much it will help reduce any timing that might be pulled due to the potentially higher IAT’s that spinning the stock SC faster (9% pulley) could produce while tracking the car.

Also I’m not sure what octane I can/should aim to accomplish this on a full tank of gas before heading out on the track for a day...

[Can'tHave2MuchHP]

It won't having cooling effects per say like a bigger heat exchanger. It will allow for colder ignition when the same timing is used. However, given the opportunity for more timing, tuners are likely to take advantage of that to produce more power and usually nullifying the cooler temps for more power which is understandable and even preferable in most cases. Spinning the blower faster is not a good move for the track.

You'll want to shoot for whatever octane level your car is tuned for. Running 91 or 910 won't matter if it's tuned for something different (Ok it may have some effect though it won't be positive, that I can guarantee).

[GunMetalGrey]

Originally Posted by Can'tHave2MuchHP

It won't having cooling effects per say like a bigger heat exchanger. It will allow for colder ignition when the same timing is used. However, given the opportunity for more timing, tuners are likely to take advantage of that to produce more power and usually nullifying the cooler temps for more power which is understandable and even preferable in most cases. Spinning the blower faster is not a good move for the track.

You'll want to shoot for whatever octane level your car is tuned for. Running 91 or 910 won't matter if it's tuned for something different (Ok it may have some effect though it won't be positive, that I can guarantee).

I should have clarified that the tune would remain stock or at least if tuned in the future for mods like a 9% pulley and headers, it would still be based off 91 octane... so in that sense are you saying that increased octane won’t help prevent any timing that might be pulled when tracking the car? And/or are you also saying that boosting the octane higher when the car is not tuned for it will have negative effects that out weigh the positive ones if there are any positive effects?

I know spinning the stock SC faster makes it less efficient and creates heat, I just can’t get over the idea of such cheap HP increase for the street compared to other mods..

[Stephen12ZL1]

E85 has a cooling effect in the cylinders

[wnta1ss]

Originally Posted by Stephen12ZL1

E85 has a cooling effect in the cylinders

I think he has the right idea here. ZL1 mod talk seems to jump right to wanting a pulley change, which means spinning the blower faster, which means more heat. I would be curious to see what, instead of that, doing ONLY a flex fuel sensor and tune for E85 would do on a ZL1. Making better use of the boost you already have.

[Rlhay2]

Increased octane and E85 will result in cooler cylinder temps.

Both IAT sensors are located upwind of the cylinder thus neither will do much for IAT temps.

[BMWM.D.]

Octane booster will allow more timing, but doesn’t provide any cylinder cooling as far as I know. I run a half bottle of Torco per tank on mine in an attempt to get our 91 octane up to 93 or so. Even stock, you’re going to get some KR on our 91 octane. Then the ECM will learn down to the low octane table (or a percentage of it). Adding octane booster should keep a stock ZL1 on the high octane table (ie full power).

A lot of guys add it at the track only for extra engine protection against potential knock. It may not help if timing has been removed to adjust for your fuel, but it definitely will on a stock tune that is optimized for 93+. My thoughts anyway.

[Can'tHave2MuchHP]

Originally Posted by BMWM.D.

Octane booster will allow more timing, but doesn’t provide any cylinder cooling as far as I know. I run a half bottle of Torco per tank on mine in an attempt to get our 91 octane up to 93 or so. Even stock, you’re going to get some KR on our 91 octane. Then the ECM will learn down to the low octane table (or a percentage of it). Adding octane booster should keep a stock ZL1 on the high octane table (ie full power).

A lot of guys add it at the track only for extra engine protection against potential knock. It may not help if timing has been removed to adjust for your fuel, but it definitely will on a stock tune that is optimized for 93+. My thoughts anyway.

This. It was late when I responded, thanks for making it clearer.

There have been several people who have done E85 and very little else, it's not that beneficial. Not to mention, you cannot run 100% E85 through the stock fuel system, constantly mixing at the pump. Now if you talk to DSX or similar flex fuel proponent, of course they're going to say it's the best first mod.

[Vtor_ZL1]

Only cooling effect is how much lighter you wallet got.

[GunMetalGrey]

Originally Posted by BMWM.D.

Octane booster will allow more timing, but doesn’t provide any cylinder cooling as far as I know. I run a half bottle of Torco per tank on mine in an attempt to get our 91 octane up to 93 or so. Even stock, you’re going to get some KR on our 91 octane. Then the ECM will learn down to the low octane table (or a percentage of it). Adding octane booster should keep a stock ZL1 on the high octane table (ie full power).

A lot of guys add it at the track only for extra engine protection against potential knock. It may not help if timing has been removed to adjust for your fuel, but it definitely will on a stock tune that is optimized for 93+. My thoughts anyway.

Thanks for the response regarding cooling!

I probably havent been very clear with my communication, I was already planning on adding octane booster to hit 93 octane (I have a stock tune), however what I’m not clear on, is there any benifet to aim for an octane above 93 (even though the stock tune is set for 93) if you have higher IATs (whether due to long tracking session or a SC with a pulley change or both) that causes your engine pull more timing?
or am I confusing the octanes ability to prevent knock with the car pulling timing due to high IATs, which is what it does to prevent knock in the first place?

I don’t think Ethanol, like racing gas, is much of an option where I am located...

[GunMetalGrey]

Originally Posted by Rlhay2

Increased octane and E85 will result in cooler cylinder temps.

Both IAT sensors are located upwind of the cylinder thus neither will do much for IAT temps.

So if I am understanding you correctly, any timing the car will pull based on higher IATs will happen regardless of what octane fuel I’m using because that is determined before the car even takes the octane into account because the IAT temp sensor is upwind?

[onelfastlride]

Originally Posted by GunMetalGrey

So if I am understanding you correctly, any timing the car will pull based on higher IATs will happen regardless of what octane fuel I’m using because that is determined before the car even takes the octane into account because the IAT temp sensor is upwind?

Possibly true and not true. I am not aware of the tuning for the ZL1, but the newer mustangs and gt500 will add or remove timing based on knock detection. Therefore you will see more timing with higher octane and no knock detection.

E85 has lower energy content when it burns, therefore it burns at a lower temperature then gas, thus the cooling effect. But it takes more of it because of the lower energy content, and that equals less miles per gallon. It has a higher octane (~105 octane). Octane is the resistance to burn, which helps prevent pre-ignition(detention) before the spark plug fires.

[Gunkk]

Alcohols are highly polar solvents and have much higher enthalpies of vaporization than largely non-polar gasoline. Translation: they absorb more heat when they evaporate, thus have a great cooling effect when sprayed into an intake air charge, lowering IATs. So in our cars, particularly when boosted, there can be a huge benefit from methanol injection in the intake.

Alcohols also can produce more gaseous volume when burned, so can produce more cylinder pressure and thus more power per unit of air. But this is offset by the need for more fuel volume per unit of air. So while E85 can give more power, our cars quickly hit the limit of the fuel system, which is comparatively expensive to upgrade vs. other mods.

[BMWM.D.]

Originally Posted by GunMetalGrey

Thanks for the response regarding cooling!

I probably havent been very clear with my communication, I was already planning on adding octane booster to hit 93 octane (I have a stock tune), however what I’m not clear on, is there any benifet to aim for an octane above 93 (even though the stock tune is set for 93) if you have higher IATs (whether due to long tracking session or a SC with a pulley change or both) that causes your engine pull more timing?
or am I confusing the octanes ability to prevent knock with the car pulling timing due to high IATs, which is what it does to prevent knock in the first place?

I don’t think Ethanol, like racing gas, is much of an option where I am located...

Timing that gets removed due to IATs has nothing to do with fuel. To simplify it, the ECU adds or removes timing based on the temperature of the air after the intercooler bricks. It does this to prevent Knock from occurring, as hotter air is more likely to cause knock. To reduce this, upgraded heat exchangers, lowering overall engine temps, or chemical intercooling (ie methanol) are what you want.

You’re probably getting confused when people refer to ‘cooling’, as there is cooling that occurs in the combustion chamber (E85, etc) that greatly reduces knock, while there is also cooling of the intake charge (meth injection, etc) that reduce timing being pulled due to manifold air temp calculation.

As far as I know, manifold air temp (what these engines use to control IAT timing) is a calculation based on IAT1, IAT2, and coolant temp. It’s not read from any one sensor, but an algorithm based on those things and probably more. I feel that keeping coolant temp down goes a long way to keeping things in check.

But no, there probably isn’t much benefit to going above 93 octane on a stock engine/tune. Add more boost, and there will likely be a benefit.