Is it possible to run 91 on a b20 with wiseco pistons that are 13:1 or a gsr with 12:1 supertech pistons? Thanks

 

Yes, just have to take timing out and prevent detonation. Im running 12:1 on an 89x81.5 on 93 daily. All in the tune.

 

Cool. I am getting it tunned right away.

 

Cool. Yeah Im Getting it tunned right away.

 

Idk if I'd chance it on a b20 block, slightest detonation & you got a cracked sleeve just be super careful have you looked into e85? I thought about running my 13.1 on pump, but why have such high compression and not able to utilize it %100

 

12.1 will work I'm %98 sure what I was told is cut of is 12.5:1 people say they've done 13.1 but that sounds scary lol

 

Realistically, you can runany C/R you want with any fuel you want, its all about the tune.

I COULD run 15:1 on 87 octane, but it would have so much timing pulled that it wouldnt make any power.

Boosted guys have an effective C/R of beyond 15:1 in boost, and they run on 91 octane. But with boost, you dont need timing to make power, the turbo takes care of making power.

On an NA motor, you need timing to make power, so the higher the C/R and the lower the quality the fuel is, you have to pull more timing out to avoid detonation, thus, making less power.

You could potentially make more power on a 11.5:1 motor on 91 oct. than on a 13:1 motor on 91 oct. simply because of the tune, the lower compression motor gets more timing and is more aggressivley tuned, so it make more power, make sense?

 

I'm building a d16y5 and I no I'm goin with 10.5:1 CR bt the engine has 256000 on it and I was wondering if I should order a slightly bigger bore.

 

what about having big cams that need higher compression with 91 octane what you do then?

 

Tuning on these fuels is essential in determining whether or not it makes sense to add big cams in the first place. It doesn't make any sense to try and run 12.5:1 if timing has to be adjusted as though it were only 11.0:1. Even with "big cams". If the cams require a certain effective compression (notice I didn't say static), and you haven't reached it with that tune, there's no point in running the big camshaft.

This is why it is important understand the limits of the fuel you plan to use in your area (depending upon use of the car) when planning your build.