Will the 317 heads raice the C.R on my 5.3 08 NNBS

and If they are milled will they rasie it?

 

if there milled, they will raise it!! but stock no i dont think they will

 

Will I feel a Difference if I have a stock cam?

And is the texas speed cam 228R good for my truck witht the 317 heads and some 918springs and retainers.

Mods will be Cat back , S&b Intake , ASP pulley , And maybe i'll order pacesetters and try to do some mods on them to make them fit , And a Custom Tune ofcourse.

 

Your probably going to need to mill those heads so much to get any compression out of them you will run into shrouding issues.

If you don't mill them I'd imagine you'll loose a full point in compression at least.

 

no good for a 5.3....I dont think you could mill them enough to use on an NA setup.

 

I did a bit of research on this. I see that GM rates the factory compression ratio at 9.9:1 for '08 model. (See link) '08 factory Silverado engine specs

Your current heads have a 65cc chamber volume and the 317's have a 71cc chamber size. Putting this data into my compression calculator it appears that your new cr with the unmilled 317's will be 9.25:1. You would need to mill them .035" to get the chambers to the same cc your current heads are at. None of this is going to add performance because the ports on the 243 heads and the 317 heads are the same as cast. The only difference is with the combustion chamber sizes and shapes.

In short, stick with the heads that are currently on your engine. They have the best potential for making max power. Instead of replacing the heads look into an aftermarket cam and long tube headers.

Good luck,

Richard

 

Good info Richard. I didn't know the '08's were alumium blocks too!

 

I'm ordering the TSP 228R cam tommorrow with springs and other stuff Will I get power out of this cam or I move to something abit smaller?

 

You'll definitely need some stall in the converter with that cam.

Richard