well im planning on building a evo 8 2,3 stroker( i found a evo 8 FQ340 engine i want to buy and use)
found a kit on this website Mitsubishi Evo 7-8 4G64 2.3L easy stroker kit (zedperformance.co.uk) not sure if its legit

 

I have not heard of this kit before, but I would probably stick to piecing together your own stroker kit. The kit in the link above could work in theory, but you'll end up with a worse rod ratio just to be able to reuse the stock pistons.

 

what would the ratio be with the stock pistons?

 

The stock rod ratio (Rod length/crank stroke) = 150mm/88mm = 1.7

This kit has a rod ratio of 1.4, meaning the angle that the rod travels in order to achieve a complete crank cycle is more extreme. This leads to greater side wall loading and more stress on the rod and block, especially at higher rpm. It's always best to go with a longer rod and move the piston wrist pin location up to compensate for the added rod length. Most aftermarket Wiseco stroker pistons do this to achieve a better rod ratio.

 

1.4 rod stroke ratio. Ouch.

I would piece together your own kit. More then likely on a refresh you will need to hone or bore up to the next size piston to get a proper PTW and ringseal.

A 100mm crank is nice if you are going to stay under 8300-8500 or so on a 4g63. Or under 750whp. Beyond that a 94mm crank really is the move. It has more material in critical places then the 100mm crank to deal with the added rpm/hp.