[Guest]

I understand compression, cooling, intercooling, timing, amount of fuel, octane level, and air temp have allot to do with it but any information that you guys have would be great.

Thanks
98toplesscobra

 

[Steve Jarvis]

There are a lot of factors. We have 93 octane in my area. I will probably tune for about 12.0:1 a/f with it richening up to about 11.5:1 by redline. I would run know more than 20 psi on pump gas. You could probably run more, but thats a lot of compression.

BTW If it's not a Supra you may want to run less. Things such as aluminum vs cast iron heads and combustion chamber design can also effect your engines tedency to knock.

Later, Steve

 

[Guest]

Is a supras engine aluminum or iron?

What HP and TQR level do you see at 20lbs?

Does the supras engine begain to detonate after 20lbs on pump gas?

Thanks for help
98toplesscobra

 

[Guest]

Elude

I understand that race gas higher octane keep the gas from exploding early, and that timing needs to be pulled to prevent pre-detonation.

That is give in boost application, race gas helps none boosted cars as well.

What I am trying to get at is where is the fine line for Supra's.

How much boost are you running on pump gas?

Is a Supra's engine aluminum or iron?

What HP and TQR level do you see at 20lbs?

Does the Supra's engine begin to detonate after 20lbs on pump gas?


Thanks again any information helps
98toplesscobra

 

[David S]

iron block and aluminum heads

 

[Guest]

How much boost are you running on pump gas?

What HP and TQR level do you see at 20lbs?

What HP and TQR level do you see at 20lbs?

Does the Supra's engine begin to detonate after 20lbs on pump gas?


Thanks
98toplesscobra

 

[Guest]

How much boost are you running on pump gas?

What HP and TQR level do you see at 20lbs?

What HP and TQR level do you see at 20lbs?

Does the Supra's engine begin to detonate after 20lbs on pump gas?


Thanks
98toplesscobra

Do you mean on stock turbos?
Each tubo will run a different HP and Tq at the same psi. detonation also depends on turbo choice. Smaller turbos have to spin faster and thus heat up the air more to make the same psi.

 

[Grant]

There isn't a fine line with stock turboed supras. The turbos are so puny that it would take a while of high-boosting to damage the engine. I've seen timing retard as low as 15 psi with the stock IC, even on a cold night.

Horsepower #s vary greatly depending on mods, gas quality, and air temp.

Given how hard detonation is to detect, and how long it takes to damage these engines, I'd imagine most people on this board have no idea if they are knocking or not. Many seem to think that you can always hear detonation, so if they can't hear a ping they aren't detonating

Larger turbos are more effecient in terms of intake charge, and leave less exhaust in the cylinder after the exhaust stroke. In other words, less of a tendancy to knock.

If your wondering how to select the amount of boost to run, here is what I did. I saw that I would reach full timing advance at 5700 rpm with minimum boost. At 18-19 psi I saw full timing advance only 300 rpms later. That seemed acceptable to me, so I left it at 18. Anything over 20 and it pulls timing more.