[ta man]

Originally Posted by Nicks67GTO

After talking back and forth with Dave from SD performance, i decided to build a 400 over a 455 for my 5 speed GTO. I was told by SD that I can make 500-525 hp and around 500 ft lbs, idle nice at 750 RPM, run power accessories and pull to 6,000 in a snap. The basic combo we talked over was a 10.5:1 400, their 290cfm heads and their stump puller hydro roller. That's plenty of power for a street car. It will probably be a little better on gas and I might just be able to keep my 5 speed together if I hook it!

You are working with the right guy..which heads the KRE's?.

[Nicks67GTO]

Originally Posted by ta man

You are working with the right guy..which heads the KRE's?.

Yes, the SD ported 290cfm KRE's.

[Half-Inch Stud]

Originally Posted by Nicks67GTO

Yes, the SD ported 290cfm KRE's.

Geez, that is going to be a SWEET "400"

Ah, just one more ting: What does SD say about 9.3:1 so you can press WOT on 87-to-89 Octane?

[Nicks67GTO]

Originally Posted by Half-Inch Stud

Geez, that is going to be a SWEET "400"

Ah, just one more ting: What does SD say about 9.3:1 so you can press WOT on 87-to-89 Octane?

I could ask them about that. I'm not sure what a 10.5:1 poncho would need for fuel requirements with a modern chamber, cool temps, and that stump puller. Its on a 112 l/s so it should technically be a little more forgiving and the good modern chambers don't usually require as much timing if i'm not mistaken, like maybe 32 degrees is all so that may play a factor too? I wonder if i could get away with some 89 or 90? Thats a good question to ask them regardless.

[ta man]

Originally Posted by Nicks67GTO

I could ask them about that. I'm not sure what a 10.5:1 poncho would need for fuel requirements with a modern chamber, cool temps, and that stump puller. Its on a 112 l/s so it should technically be a little more forgiving and the good modern chambers don't usually require as much timing if i'm not mistaken, like maybe 32 degrees is all so that may play a factor too? I wonder if i could get away with some 89 or 90? Thats a good question to ask them regardless.

I'm running 85 cc chambers on a 462 with KRE heads and can run on 87 octane...Last friday I ran on a mix of 60%87 octane and 40% 91 octane .I'm at about 10.25 :1.