Discussion and technical advice the SW20 MR2. 3S-GTE, 3S-GE, 3S-FE etc
Anything and everything to do with maintenance, modifications and electrical is in here for the Mk2.
Odin_S wrote:They said that's the standard rebuild size...
There isn't a "standard" rebuild size. Use the smallest size of piston the bores will allow. If they meausre up perfectly, then use STD pistons.
There might be a "standard" piston size they buy...
Difficult unless your block isn't in a working car. Makes sense to stay stock if it allows. So are the cp pistons that exact or is there some give? At Honda each piston was matched to each cylinder as far as I know.
Odin_S wrote:They said that's the standard rebuild size...
There isn't a "standard" rebuild size. Use the smallest size of piston the bores will allow. If they meausre up perfectly, then use STD pistons.
There might be a "standard" piston size they buy...
Maybe I should be more pacific, it's for my 400bhp build. Doubt you would still use STD pistons
I've bought Wiseco 86.50mm, I'll have a chat with Luke once I get chance. I'd like to stay as close to oem compression ratios because in my limited knowledge it would lessen chances of detonation?
Odin_S wrote:
Maybe I should be more pacific, it's for my 400bhp build. Doubt you would still use STD pistons
I've bought Wiseco 86.50mm, I'll have a chat with Luke once I get chance. I'd like to stay as close to oem compression ratios because in my limited knowledge it would lessen chances of detonation?
Piston size (86.0 vs 86.5mm) will have no real world effect on the power you make.
You would absolutely use standard size(86.0mm) pistons for 400bhp if you can, but they wouldn't be standard pistons because you would used forged replacements.
If you have already bought Wiseco pistons and you want to keep an OEM compression ratio then you already have a problem, the Wiseco's are 9:1 out of the box from memory.
Sounds like you need to talk to an engine builder before you go any further, and don't buy any more pistons until you have the engine apart and have inspected and measured the cylinders
Odin_S wrote: I'd like to stay as close to oem compression ratios because in my limited knowledge it would lessen chances of detonation?
Yes it will if running stock boost.
If the boost it going up then the compriession ratio has to come down.
You need to design your engine, once you have that all in place the last thing you work out is the compression ratio you need, so the last parts to buy are the pistons.
Designer for turbo set ups on F1 cars, and Nitrous Oxide Systems of the USA in the 80s
wossner do low comp (8:1) aswell as high comp (9:1) pistons so check them if you want to change compression ratio. you dont need to go bigger than standard bore size to make 400bhp. only rebore if your block needs it. I dont think it matters as much on a turbo than it does n/a cars. yeah you may gain a small bit power but nothing more.
So are any of the forged piston better than others? JE's, CP's or wossners ?
More specifically can one take higher intake temperatures than another?
Ta
As a general rule what boost pressure would you switch to a lower crompression over standard?
Would running 1.3 bar on a hybrid CT20 require a lower compression?
Adam86 wrote:As a general rule what boost pressure would you switch to a lower crompression over standard?
Would running 1.3 bar on a hybrid CT20 require a lower compression?
The stock JDM engines when running stock boost on our best fuel use the knock sensor quite a lot.
The problems with blown head gaskets, broken ring lands damaged big end bearings all come from detonation.
You would be surprised how much better a stock engine runs with 8.0:1 compression pistons.
So yes if you want the best from the engine please fit lower compression pistons.
Designer for turbo set ups on F1 cars, and Nitrous Oxide Systems of the USA in the 80s
Does compression directly relate to power? I.e if you have the exact same spec engine one with 8:1 forged pistons and one with 9:1 would there be a power difference?