I'm considering putting together a more boost friendly shortblock. I'll either use SCAT or EAGLE parts. So my question is, which bore / stroke combination have people had success with?

I'm looking to make in the 400-450whp range, hopefully that's do-able with some stock sleeves. Other than that, I'll obviously be sending the bare block somewhere to get sleeved? I'll be using something in the neighborhood of a Turbonetics/Garrett 60-1...

I know more cubic inches is usually better, and it would definately help eliminate lag to a certain extent, but is extra stroke necessairly better? How would increased stroke affect the rod/stroke ratio on a GSR engine? Sorry if these sound like dumb questions, but I'm simply trying to do my research.....

Thanks,
-Ant-

 

Well you have 2 options really: you can stick with stock sleeves (81.5mm largest stock bore) or you can have the block sleeved and overbore as far as 85mm; however, staying around 83-84mm is better since you can overbore if anything bad happens.

For your power goals though, stock sleeves will suffice. You and i have about the same power goals in mind and i'm running an 81mm LS/VTEC at 9.8:1 compression. I would say that an 81mm or 81.5mm bore would work out nicely for you. I would also suggest running an LS crank (89mm). This will give you a bit more torque due to the longer stroke. By the way, that means you need to buy LS rods rather than GSR...

A big concern in spool time is obviously going to be the turbo, but you need to consider the manifold you choose as well. The 60-1 isn't a bad choice by any means; however, there are a lot better turbos available. For instance, i'm running a BW S256. Its going to spool similar to a 57trim, but is capable of 550+whp. It would be a great turbo for your goals.

 

I would concur. It's really a matter of what is best for you, there are a lot of combination choices. That being said, sleeving to 84mm just to keep the stock GS-R crank size for 87.2mm doesn't really do much for torque as many people think, without the accompanying stroke.

The rest is in the turbo, and not just a 60-1, but what compressor/exhaust wheel combination is used. If power is the greater concern, you don't really need to go big bore. I'm SLEEVED at 81mm, but I'm also looking at it from a response point of view for the type of driving I do with the car.