In the next fallowing weeks I'll be busy building my evo. I'm staying 2.0l and doing .20mm over bore IMO is better than stroking the motor , Anyways I will be using JE pistons & Manley turbo tuff rods new oil/ water pump ect..........! The real big question is what compression ratio should I go with 10:1 or 9:5 , keep in mind I will be running e85 . if anyone has some information on this please help me I want to build my bottom end once and I want to make sure I do it right thanks .

 

One of our customers runs 9.5 on e-85 with a borgwarner 374 he made close to 900 on the dyno. He does drive the car on the street quite a bit so i am sure you would be safe with either. I know he runs arias pistons and crower rods

 

what turbo is he running,I think im going to use 9:5?

 

Go 10:1, and the poster above that said he just used a borg warner s374.

 

10:1 was what i wanted to go with a first but people tell me different things is hard to make up my mind , havent seen to many people running 10:1 in the other hand I seen plenty of evo's using 9:5 im still undecided .. anyone help?

 

E-85 will like 10/1 minimum. I would do 10.5-11. I just built my 2.0 to 10/1. Didnt even touch the timing. No knock with the compression increase.

 

I agree with 94awdcoupe, I would run 11.1 compression and 10.1 minimum, all alcohol based fuels love compression. You will love compression too, I run 10.1 in my 2.3 and love it! My next engine will be 12.2 but I run E99 under boost and 93 pump during vac and cruise.

 

I would go 11.1. Like everyone is saying. Alky loves comp

 

I have made up my mind im gong to use 10:1 ia the way to go since ill be using e-85 anyone knows how much does the machine shop charge?

 

What is your question - machine shop to do what ???

 

Yes you can run higher compression. I on the other hand like to add more boost and timing cause those are variables i can control. The guy with the S374 runs 42psi and a lot of timing on e85. Not for sure if you are going to drive it in fall/winter but they do change the ethanol content(lower) which will change air/fuels so i would not go to crazy on compression unless this is a drag only car. please tell me you are not planning to mill the head to get you compression. you will be changing head gaskets like underwear .

 

I want to balance and polish and everything that is require when building the bottom end .20mm over bore ?

 

I'm sure he will tune for it.... Me personally I like the idea of a more efficient engine using less boost to make the same power and turbos lasting longer due to not being pushed as hard while other engines and turbos are being stressed while blowing couplers,gaskets and stretching head bolts

Besides English racing has a thread on compression and it seems that with each point of compression you add 40hp... I'm about to add 80

 

In the bay area through darkside performance I believe it was $750 for the bottom end bored, crank polished and balanced within 0 gram