pushrods

That's a bummer to hear that I was given bad advice. Like I said, my original intent was an 11:1 engine....

So what final dynamic compression ratio should I be shooting for? I want to operate under 7500rpm and hadn't intended to spin the blower more than 20% on the 525ci - about 16-17lbs of boost on this engine. I know the chart says closer to 20lbs, but I always ran a few lbs short of the chart spec spec on the 462ci gas engine.

Any advice appreciated. I can change heads or repiston - I'll likely up the chamber cc with an upgraded cylinder head. Somebody give me some good advice I can trust so I don't build it wrong again next spring.

 

Chris, I dont necessarily think it is wrong, rather very different, most of us guys run bigger blowers eg. 14/71's with lower engine compressions at higher overdrives like say 36% over making 40+lbs of boost.

As I said just different, so more investigation will be the key.

 

Thanks Ray. Time will tell I imagine. I'm not intending to make the 2000+hp many are making, 12-1400 will be more than I can put through the car that I have and want to keep since I've run it going on 18yrs now - sentimental hobby value and only certifiable to 8.50... On the blown/gas motor I picked up 3mph bumping the static a half point so I bought into the logic that it would be worth power with alcohol too especially given the bigger ci/smaller blower I'm running. Having a small budget, comparatively, I don't want to get into the higher od's on the blower and deal with the maintenance that would go along with that. I doubt I'll get off the 10% over tune up Gene gave me for quite awhile and the motor will not likely see the high side of 7000rpm until I do.

If I ever intended to go to a bigger blower, or even start to approach was this 8-71 is capable of, I'd knock the cr down a point or two for certain. I'd likely have to ditch the 290cfm factory iron heads too....

This board and members have been very helpful on the couple posts I've made, and the archives are full of information that a person doesn't just 'know' out of the gate. The hard part is determining what info applies best to blown Pro Mods and what might be more applicable to an entry level alcohol motor in a 10.5" tire 3700lb door car - not to mention a real Pontiac, not a Big Chief motor