Much of the conversation depends on what you really want from your "High Compression NA Street Combo".

For instance, some people want to drive it hard on the street, and race it at the track with out ever adding race gas at all.
Others, don't mind having an engine that runs good on the street with pump gas, but when they get to the track, and tune for best ET, they add race gas.

Still others have "Street engines" that have to be de-tuned and driven like an eggshell is under the pedal to avoid detonation on pump gas! I've had one of those and after awhile it just sucks the soul right out of you and makes the street experience unbearable! In combos where we've missed just a little, I will add race gas to every tank on the street because I refuse to not be able to enjoy the drive. My brothers, however, are cheap, so even many of their bracket cars were pump gas combinations because they refused to buy race gas.

The 428 small block in my Valiant is 11.0 to 1. 4.125 stroke by 4.07 bore. The flat tappet cam is 269/275 @ .050 , .600 lift, on a 111 c/l, installed at 107. Made 615hp @6700 on dyno.
We don't have access to 93 most of the time, but I've ran it hard on 91, several times on Drag Week I've resorted to 89, and occasionally 87 with nary a whimper. Love this engine on the street!

The 580 Mega Block in Dale's Gremlin is 10.8 to 1. Nitrous spec cam is huge, 282/296 @ .050, 750/730 lift, 114 c/l. 352 cc Indy -1s, Tunnel Ram with twin Dominators. Runs around on pump gas with no issues, has been 9.47-144 NA with Nitrous gearing and bad converter.

One of the problems we've ran into is converting filled block race engines to street use, oil temperature control is tough, and as such they tend to be detonation prone in street use, even though the compression and cam seems like it should work.


"Livin' in a powder keg and givin' off sparks" 4 Street cars, 5 Race engines