Using this boosted compression calculator ( http://www.rbracing-rsr.com/compression.htm ) my boosted compression is 19.31:1 and without altitude correction its 19.41:1. Is this to high? What is a target compression to aim for when going with FI? I really want the motor to last, so any info is appreciated, thanks.

 

The calculator is useless because it uses static CR.

Rich

 

Then what is the correct way to figure your boosted compression? Sorry about this, im a noobie to FI

 

Well, you could substitute DCR for SCR in the calculator, but I am still not exactly what the result would mean.

Rich

 

Use this calculator. Based on DCR and accounting for atmospheric conditions (natural and unnatural ).

-Mindgame

 

The reason I am doing this is because I am building a FI 383 over the winter. I wanted to drop the compression down to around 8:1 or so and was told that it wasnt needed. I want to run at LEAST 17#s of boost with room to run more if I desired. I was told that 9:1 was plenty low enough for 17 pounds with room to spare. Any inputs on this?

 

If you plan to run pump unleaded, 9:1 would be too high unless you have a huge cam with a very late intake closing point.

Rich