Octane/Compression/Boost/Knock???

[GSEclipse620]

I am currently in the prossess of building my n/t 4g63 for a turbo kit. (just started pulling sensors/intake ect. getting it ready to pull and send to the machine shop )But anyways I was just curious on what everybody thought my max boost leval could be for octane rating. My bottem end is going to consist of the SBR stroker kit which comes with 8.8:1 compression, EvoIII 16g turbo and I am going to be tuning with either a Maf-T or a Maf-T Pro and fine tune with an S-Afc. How much boost is it possible to run on say 93 octane before knock problems? 89 octane? I plan on getting a data loggor to moniter my engine and tune w/. Thanks for the Input

 

[jaredgsx]

I am currently in the prossess of building my n/t 4g63 for a turbo kit. (just started pulling sensors/intake ect. getting it ready to pull and send to the machine shop )But anyways I was just curious on what everybody thought my max boost leval could be for octane rating. My bottem end is going to consist of the SBR stroker kit which comes with 8.8:1 compression, EvoIII 16g turbo and I am going to be tuning with either a Maf-T or a Maf-T Pro and fine tune with an S-Afc. How much boost is it possible to run on say 93 octane before knock problems? 89 octane? I plan on getting a data loggor to moniter my engine and tune w/. Thanks for the Input

89 octane is never a good idea. Its not really that much more to get 93
Lets say that 89 octane is 2.00 a gallon, and 93 is 2.20 (its 20 cents more)
You have a 12 gallon tank
2.00 x 12 = 24 bucks to get it full on 89.
2.20 x 12 = 26.40 to get if full on 93

that is a 2 dollar and 40 cent difference, its worth the little extra.

I have heard people running 18-20 psi on pump gas, so long as you have a proper tune and a good fuel pump.

 

[GSEclipse620]

Are there any fuel additives around that increase octane? Or any type of injection systems that can do this?

 

[jaredgsx]

Well you can buy octane boost, but it usual runs about 5-17 bucks a bottle. I would just really run 93. If I had to run 89 like gun to my head had to, then i would just disconnect the actuator arm on the wastegate so that way i could build 0lbs of boost. Its just not a good idea for the health of your motor.

 

[GSEclipse620]

How much does this boost the octane? I was just wondering if I would be able to get an additive incase i wanted to up the boost on a particular occasion to 25-30, but maby run like 15-20 dd on pump.

 

[jaredgsx]

A few points, nothing to get a chubby about. Well 25-30, i dont know about most people, but i would want some race gas for that. Personally I would only go to 20 on pump 93. 30psi on a 16g is going to be out of its efficiency range. You will still make a little bit of power but you will be pushing so much hot air it will he hard to stop the knock.

 

[keymaster]

On a built motor with a GOOD tune, you should be able to push 25 psi out of an evo3 and still be efficient. This is, of course, dependent on whether or not you have a good FMIC. If you're putting all this money into your car, why even consider running 89 octane? 93 is 10-20 cents more a gallon. Plenty of people have run over 20lbs on pump, you have to have enough fuel and a good FMIC.

 

[GSEclipse620]

I was just kind of curious on what would be possible. I've never really looked into this and this is going to be my first time with a turbocharged high performance car once the project talon is done so I was just trying to get an idea on figures i could run. Thanks everybody!