If I am going to be running Nitrous, should I raise or lower the compression or does it matter? I want to raise my compression so I have more power all through the RPM's but I don't want blow another engine. Any suggestions?
Flame Red SRT-4 GT40,8.5:1 Built Shortblock, Brian Crower Stage 2 Cams, etc etc etc...
#44260, "RE: NOS and Comp Ratio????" In response to Reply # 0
Well my head is milled .040" and 9.8C pistons for an appox 10.6:1 compression ratio maybe a bit more. I haven't had to take any additional precautions with a 70hp shot but colder plugs and narrower gapping would probably be wise (I still use 6 range NGK or equivalent and .035" gapping). An aftermarket ignition with retard capabilities might be wise also (although I dont have one I'll get one if/when the need arises). I haven't noted any detonation ever. NOS isn't too specific but all they say is " High or low compression ratios can work quite suitably with nitrous oxide provided the proper balance of nitrous and fuel enrichment is maintained. NOS kits are used in applications from relatively low compression stock type motors to Pro-Modifieds, which often exceed 15:1. Generally, the higher the compression ratio, the more ignition retard, as well as higher octane fuel, is required." That said I'd probably stay a bit on the conservative side (unless you think like I do which is "if it blows it blows"). I wouldn't go crazy milling the head because its only worth a 3-4% gain per point increase. On a 140hp engine going from 9.6 (stock) to 10.6 is only (relatively speaking) good for about 4-5hp. 11.6 would be good for 10hp which is quite good but a bit ballsy trying to run with nitrous. With 10.4 compression and a 50hp shot I dont think you'll need to do anything. Beyond that is a lets see what happens approach. So far with what I've got nothings happened (on a side note I have forged pistons so something could be happening that might hurt stock pistons but aren't apparent with mine, I doubt it though).
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