Another BBC combo

[BBchevelle]

I'm probably going to sound like a broken record with my combo but, I want the best out of what I'm building so. I have a 4.350 bore X 4.250 stroke (505ci), 13.5:1 comp, howards roller cam 765 in. 737 ex. lift and 282 in. 286 ex. duration at .050" with 4-7 swap firing order, Super Victor intake with a 1150 dominator, all MSD ignition (digital 6) and will have up to 400hp of N2O. Currently I have a set of GM bowtie heads 861 casting that have a huge intake runner volume of 380 cc. They also have been ported and flow 376 @ .700" intake and 269@ .700" exh. This set up is in a stock type suspension 10.5 tire chevelle with a th400 trans. that is at about 3350#'s with me in it. The engine is sluggish in lower RPM (I'm thinkin the 380cc runners) and am looking at the Dart 355 CNC Pro 1's. Please guide me in the right direction of what the best head would be for maxium horsepower. Let me know if any one needs additional info. All help would be greatly appreciated. Thank you, Chris

[Dart331stroker]

You are correct, your thought of the engine being lazy due to the excessively large runner is correct. Your engine would wake up tremendously with a smaller more efficient runner. A heavier car also will benefit from a smaller runner. With your engine combination, the Pro 1 325 would be the better choice. The chambers on the 335 and 355 CNC Pro 1 heads are machined for the larger 4.500 bore size. The 325 heads flow as well as your ported 380 runner heads, and will move fuel better, and make better power and torque. Nitrous will still work very very well with that port volume and again the engine will be more efficient making it faster with less nitrous.

Good Luck

John

[BBchevelle]

Thank you, thats what I was looking for. If anyone else has ANY comments please speek up. Also I'm looking to buy a set, so anyone who is a dealer for Dart let me know what kind of deal you can make me for the right cylinder heads. Thanks again, Chri

[Awesome Bill]

what do you mean sluggish? Is this happening while on the spray or off the spray. Because, the very large headed engine even one with a larger head would just go wild with that amount of spray. Who cares what it runs off the spray, or do you care. You can't have 2 engines with 1 combination set up for NOS. Either build it for HP off the spray or build it for HP on the spray. We use heads larger than that. Ofcourse, they won't fall out of a tree if they were pushed off the spary. But wakes up a roaring lion while on the spray. Would need more information to accurately suggest whats up. e.t. and mph and rpm crossing the finish line in particular.