Well, my engine is getting close to its last leg I think. Compression is down and it is eating a little oil. I really want to start a build and eventually add a turbo. Problem is, I won't be able to afford a full system right away. Not for at least 6 months or so after the engine is done. How bad will it be to run on a lower CR? How much power am I looking at losing, and how crappy will it run? I really want to get a new engine in my car ASAP, but I don't want to wait longer just so I can afford a turbo system. Any help is greatly appreciated.

Thanks
Sean

 

Not bad at all. Don't worry about it.

Rich

 

I agree with Rich, as long as the plan is to have some form of FI eventually, it's not a big deal. The accepted calculation is that you will lose or gain approx. 4 to 7% for every full point of compression. eg. going from 10.0 to 1 down to 9.0 to 1 would net somewhere around a 4 to 7% power loss in a naturally aspirated application.

 

The change in hp with change in compression varies with where you start. Which maes sense: going from 8:1 to 9:1 is a ~12% change in the CR. going from 11:1 to 12:1 is only ~9% sifference in CR, and so on. Going from stock CR to ~8:1 will cause ~5-7% hp loss if everything else stayed the same.

Rich

 

I think I will lose about as much n/a power with my -36cc pistons as I will gain with my 3.75" crankshaft.