Quote:
Originally Posted by XfireZ51
Pete used a Hogan sheetmetal plenum on Kevin's 441 several years ago. I believe it really didn't offer much improvement.
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I can offer an opinion on that sheetmetal intake. I did have it flow tested, and it was 2 to 6 cfm better than my (highly) modified plenum and housings. That was with the TB and Airhorn attached, and the other ports taped.
From what I remember, Pete and Kevin said it lost a ton of torque almost all the way through the rev range, only crossing over >7000 rpm. I could be wrong on that--its been awhile.
Why? My belief is two factors. 1) the runner cross section area was pretty big. I didn't measure it, but visually, most of the runner was oval with no divider. Only like maybe an inch at the head was two separate holes. 2) the runners were exceptionally short, as they have to be for hood clearance in that style of manifold. We need runner length to catch the stronger harmonic waves for best cylinder filling. That's why I didn't go to a sheetmetal manifold on the 427. The stock runner length is pretty good for the rev range we need. Downside is that the runners have to contort to get that length without too much height, if that makes sense.
Anybody got $10k to develop a cross-over style IR manifold?
Seriously, Lee is on the right path by enlarging the plenum. We need more volume for the big motors. Especially because the TB is undersize when you get to that level. I saw over 1" of manifold vacuum @ 7000 rpm. A large plenum box would crutch that a little. Of course, a big billet oval throttle body will help too
