mesterious

I need to know if 11.3:1 compression ratio is too much for a 93 octane 406 High Performance Street motor. The Details of the Motor: Cam 249/255dur@.50 624/640 lift, .040 head gasket, and AFR 210 65cc Aluminium Heads which i havnt bought yet till i know i can run that compression ratio so i wont be stuck in a bad situation with them. Also I found a real DCR calculator and it came out to be 8.6:1 where as 8.5:1 is supposedly the limit on pump gas, is that too much?

cody96ss

I'm sure I'll be corrected on this shortly, but to the best of my knowledge, the stock compression ratio for the LT1s is around 10.4... Idk bout your calculator...

94FormulaLT1

Stock is about 10.25 CR if I remember correctly, but what I believe the OP is asking is if his purpose built motor will be ok at the new 11.3 CR. Having your Dynamic that close to what it says is safe with 93 octane is questionable. I do not know enough about it to tell you if it will work for you or not. You may just have to go with it and see what you end up with. You could always back the timing down a couple notches like the computer would if it was too high. I would personally try to stay at around 11.0:1 on 93 for a street use motor. That should be doable.

There are those of use who are stuck running even lower compression just because we can't even get close to that grade of fuel. The highest grade around here is 92 and I havent seen that in almost a year as most of the stations have opted for 91 as the max. We get 87, 89 with 10% ethanol, and 91 as our 3 choices. Pretty well limits what we can do.