Compression and emissions

[johnnyvista]

How much will raising the compression in my engine affect CA emissions? If I run an 11:1 compression ratio with a stage 1 cam, will i be able to pass a sniffer?

 

[Beau]

isn't 11:1 pretty high compression?

i think with stage 1 cams you'll be fine. i am planning on doing VT Engines stage 1 cams this summer and i think i'll pass emissions without any problem.

 

[johnnyvista]

on the stroker kit i'm going with, i have the option of running 9.5:1, which is basically stock, or 11:1. i'll get a lot more HP out of the higher compression but i want to make sure my car'll pass next year first.

 

[mrvax]

The increased compression should help emissions if anything. Cams that have a lot of duration would tend to hurt, and lift wouldn't bother emissions at all.

 

[KJ Hoppus]

i would agree with mrvax...subscribing

 

[trinity_gt]

Increased compression may lead to higher NOx emissions levels due to higher peak combustion temps. Check the overlap on the cams...too much may increase HC emissions. If your idle is lumpy due to the cams it's possible the overlap might cause an HC fail. Alot depends on the tune and the condition and temp of the cats during the test.