I live in Cali and need to pass smog. I've been doing a lot of research and figured I'd go straight to this board for some answers.

My plan was a 383 to get around 500 RWHP. 8.4:1 - 8.8:1 CR, moderate cam, 12#s of boost, and ported stock heads or AFR 210s.

Some say to raise CR and lower the boost to pass emissions.

Some say that the stock heads are fine, other sources are telling me that AFR 210s are recommended. If I go with AFRs then I will need an LT4 intake right?

This will make runs to Vegas and through canyons. But, it will also be driven in the California Freeway Parking Lot to work.

Sorry about the newby questions...

Greg

 

come on someone answer him because even though i am not from cali i was thinking the same thing. about 383 low compression and still able to pass emission.

 

It is posable it just takes some good tuning.Ok i will start off by saying that CA smog test is allways changing. I think there doing the dyno test now. I got my car to pass in vegas by driving up to the smog check shop, changing to a smog only tune with LT1 edit then back to normal after the test. This is with 9 to1 compresion, 42 lb injectors,LT4 hot cam, 355 and D1sc 12# boost. troy

 

So far, here's what I got from more research. While it is true that the compression ratio does affect combustion temps, a blower cam that has the proper overlap combined with the positive pressure from the blower will increase the dynamic compression which will raise the temps (maintaining HC output instead of increasing it).

Also, ported stock heads should be fine for the street up to 10#s of boost... I'd like to get 12#s to reach the 500RWHP mark.

It is mostly the cam which will effect emissions, not necessarily the CR in a blower application. Plus proper programming...

 

With a 383 and stock heads you might have some trouble lowering your CR to below 9, which will thus limit the amount of boost you want to run. The biggest dish piston I can find that off the shelf is a JE 31cc dish. With 54cc heads and a zero deck, you are looking at about 9.5:1 with a .039" head gasket. My engine builder is contacting JE to see if they can make a custom piston with a bigger dish. The other option is to have the stock head's combustion chambers opened up. I have seen a set that were opened up 10cc to 64cc. If I could do it all over again I would get AFR heads with at least 64cc chambers (they are available with chambers ranging from 52 - 76cc).