I was haveing a little discussion with my engine builder the other day, and was woundering what people thing about compression ratio.

I want to go for about 8.3 or 8.5 :1
The easier option would be to go for 8.6 or 8.7 :1

The engine is a 2.5 (OD) with V4 heads, forged build.

The ideal power for the engine will be 360 to say 380ish for rast road use so I am after fast spool.

Any thoughts

 

9.1:1 will do nicely

 

We have 8.5:1

 

Built quite a few 2.5's with 8.6:1, works very well on the road, with good response & spool, using SC46's.

 

Anywhere from 8.4:1 static upwards depending on the total engine spec/package/etc.
Good results to be had from a higher CR with off-boost performance and the transition into boost,so long as its not det limited in terms of mapping.

Mick

 

I must admit I have had a few engines , and in the back of my mind I like the hard hit and now i can drive , going from a gtr to a subaru, cant say how much I miss the throttle control due to the lack off power the subaru at the rear wheels . i think the final solution will be a 370 to 380 BHP / 380Tq, engine and adjustable differential.

 

WMS, ideal I think, 8.5 I think is what I need !!

 

What fuel and boost from which turbo will determine how high you can safely go.
High comp isnt always best though dispite the current trend.

 

TD 05-20g will be my choice.