My street car is tuned on pump gas what you guys would call 93octane it supposedly doesn't knock on the dyno but I think it does on the street on high boost. Its fine at 17psi but at 22psi I seem to have problems.

I have had it back on the dyno many times tuner says it should be good blah blah.

Its tuned with a Power FC that has a built in knock detector.

But I am still seeing very high knock levels after 2nd gear on the road, I'm wanting to take it to the drag strip this summer and am wondering if putting in a 50/50 mix of AV gas 100LL and 93octane would be beneficial or just screw up the tune further?

My reasoning being if its just the slightly greater load on the street causing the knock maybe slightly higher octance levels may prevent it?

 

Sounds like that would be a smart move in your situation.

 

You don't see it making it run overly rich or anything particulary bad?

Cheers

 

Overly rich is better than detonation anyday, but you could also retard some timing and play it safe on pump gas and be fine.

 

Thing is the timing is retarded to the max every time I went back he would set the timing super conservative. Was tuned on a Dynapack aka hub dyno.

I think I will go for a test on a roller dyno except I will run the 50/50 mix if tony says its a decent idea then I can't see why not.

Power FC doesn't allow you to run two separate tunes which is lame.

 

i would not say that its better to run rich over detonation anyday, because to much fuel will cause your cylinder walls to dry up due to, to much gas wiping all oil off cylinder walls, which can be a start of piston damage due to friction. no bueno' . i say try to race fuel man.

 

id say it isnt a terrible idea, the tune will be off.... if yur just going to try and stop knock i wouldnt mix as much as 50/50 more likejust add a gallon of it or something to slightly bump up the octane

 

Is the knock sensor calibrated for that engine? If you truly are knocking then throw in the higher octane fuel and retune.

 

what are the numbers its making? i dont have any problems running 22 psi on my car with 93 and im using a gt35r , i also ran 22 on my crx with a bastard 20g turbo with no issues. if hetruly had timing retarded to the max it would run like **** , sounds like your knock sensor is either garbage or you need a new tuner. 93 octane can support well over 500 hp.

 

Its a Nissan S14 sr20det only makes 350whp at 22psi with a gt2871r .64 turbo, timing its not retarded as far as you can go I was meaning the timing is very conservative.

The knock sensor is just the OEM factory sensor, the Power FC is able to get a reading from it.

Car runs very well and shows no worrying knock readings on 17psi with it being a street car I like to have it primarily tuned for 93 and unfortunately the Power FC only allows you to run one MAP.

Thanks for the feedback.

 

ok sorry i know nothing about nissans . try tossing in a gallon or 2 of race gas to a half tank of 93 and see if the knock count changes. if so its probably a accurate reading and you should lower teh boost a psi or 2 try 19 psi instead , what goods a 350 hp motor that can pop , a 330 hp one that can be beat all day is better

 

Yeah but I only want to run the higher boost at the drag strip.

I will report back with how I go.

Cheers all.