[Farmer2323]

Talking with some local guys about doing a 4.00 or a 4.125 bore. They say do the 4.125 to unshrouding valves. Being that air is forced in does it really help on a boosted application? I dont see a lot of difference in cars with a 347 to a 363 performance wise. Thanks Matt

 

[para pay]

Yes. In na, the motor sees 14.x psi. In a turbo motor, it sees 14.x psi + boost pressure. Same physics, just at a higher pressure.

 

[Farmer2323]

Anybody else? Has anybody seen test done?

 

[tomato]

4.06 / it leaves room for bore clean up if the bad happens and it will relieve the valve.

 

[Farmer2323]

Thats was my agrument. Leave it smaller to keep from sleeveing it for as long as possible. But is there any real power gains either way?

 

[cobrasnake95]

big bore as you can go.

dont put a 4.060 head on a 4.125 bore

many do this and don't realize it.

 

[LilJohn]

Its nothing 1 psi of boost cant make up for.

When it comes to a turbo motor... matching the N/A hp of the motor to the compressors is much more critical. 90% of the time... all those little tricks to pick up N/A hp is pointless.

 

[Farmer2323]

I have the 77189 vic jrs. What bore is better for them? Im only building 1 motor for a while and all the pieces need to work together.