RallyBob said:
Basically, I need to be sure it fits any GT chassis, whether it's with a manual or automatic tranny, and I will need to mock it up with a stock downdraft intake, an EFI intake, and various sidedraft intakes. It pretty much has to be a 'catch-all' design, but it will be for warmed-over engines or nearly stock engines.
Bob
Yep, that sounds almost impossible!
Why not 2 designs?
1) Stock/nearly stock. 2,000rpm to 5,500rpm.
2) Performance engines with a set "minimum" of modifications. 3,000rpm to 6,500rpm.
Nearly stock/warmed over = smaller primary tubes.(1-3/8")?
Higher compression, big valves, big bores, bigger carb or carbs = 1-1/2" tubes?
The little bit I know and have read about exhaust design is it will only produce max power at a narrow RPM range. Tuning the length and back pressure only moves the power band up or down the RPM scale. Also the pipe size behind the header and muffler back pressure is critical!
On 2-cycle "stock" GoKart racing motors, the expansion chamber must be a fixed length, we adjust the header pipe length by an 1/8" to get the power band to match gearing, track layout and weather conditions. But, some classes allow slippy pipes! These pipes allow the inner cone in the expansion chamber to be moved while racing! This allows the peak power band to be moved up or down the RPM range at different parts of a track, amazing power over a very wide RPM range. Illegal in most classes!
Hey, how about an adjustable 4-cycle header design!:banana:
Bob, I don't see how you can make an exhaust system to do everything!
Lyle