Grumpy.... Need your help on what you think about this compr

[Guest Night_rider_383]

Well i'm sure i'm gonna run the AFR 190 74 cc heads on my 327. I think i'm gonna use a better piston than the TRW. Like the SRP 12 cc dome piston

 

Useing the dynamic compression ratio program you gave me the link to my combo will have 10.639:1 static and 7.9427:1 dynamic. I want to run on the streets some but not much and for that i wanna be able to use 92/93 octane fuel. I'm pretty sure with a dynamic ratio of 7.9427:1 i'll be able too, but will this feel soft down low? On the track i'll use race fuel 110 or 115 octane to make sure i dont knock with N20 on. I don't want to go into milling the heads alot, but i can have them milled down 4 cc or less. What would be the best? I don't want it to fall on its face down low. Should i get the dynamic up alittle by milling the heads? If i milled them down to 70 cc the dynamic would be 8.3605 and static of 11.220. I think that's pushing pump fuel, but maybe mill them to 71 or 72 cc and come up about right?

 

The car set up will will have 4.10 gears, around 3200-3300 lbs with me, 3400 stall, 28'' M/T sportsman pro's

 

Sorry for the long post, but i know your the man to talk too. BTW would the angle plug heads give any better power/torque with the SRP dome pistons?

 

Thank's for any insight, info, and help you can throw my way

John

[grumpyvette]

I think your spending a little too much time worrying about what sounds like a nice combo if it was a race only engine the 70 cc dynamic 8.3605 setup would be the way to go but if theres any street driveing with the average crap gas we sometimes see that milder 7.9 dynamic ratio sounds like it will prevent some problems and the slightly larger area in the combustion chamber while on the nitrous may prove to be to your advantage in that youll most likely get a better burn with less chance of detonation as long as the quench area in the chamber is kept in the .035-.040 area to promote good quench/squish this is fairly important so try to use the correct head gasket thickness to get that. as to the angle plug heads, yeah at least in theory they work better but truthfully the differance in hp is not huge and makeing sure the headers fit and you have access to the plugs might be the more important factor in which cylinder head you pick to use

[Guest Night_rider_383]

A big thanks to you grumpy.

 

Yeah I am spending too much time worring about this combo. I spent 6 hours just polishing and weight matching my rods the other day. lol About 4 or 5 hours total playing with desktop dyno with my combo. I'm a young (21 years old)budget racer so once I bought a part its there to stay, and i'm trying to get everything just right for that perfect strip/strip car that can turn low 10's and drive to and from the track. Yeah my quench will be .040'' (.025'' deck height with .015'' gaskets). Being this will go into a 78 trans am theres many headers out there to work with straight and angle plug heads. So with that and the price of the heads being the same for straight or angled i'll go with the angle plug heads and a set of hooker super comp. headers.

 

Thank's again for the help grumpy and sorry to bug you the last few days lol