The lower tail pipe exit atmospheric pressure has to impact the exhaust port pressure at least to some extent, but the question is whether that’s practically relevant.CamKing wrote: ↑Sun Sep 12, 2021 10:35 amIf you overdrive the blower to get the same pressure in the intake manifold, the pressure in the exhaust would be the same.
Exhaust Duration, Boost and Elevation
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Re: Exhaust Duration, Boost and Elevation
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU
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Re: Exhaust Duration, Boost and Elevation
These cams work very well in street 383's.
The blower just essentually amplifies whats there.
The slight added advance from cam card enhances the blowers performance overall on a low cr 383 that does not want to go much beyond 6000 rpm.
The valve events (on 104/116 phasing) are street blower friendly on a simple 383. It will GLH.
Last edited by F-BIRD'88 on Sun Sep 12, 2021 10:44 am, edited 1 time in total.
Re: Exhaust Duration, Boost and Elevation
You're talking about the atmosphere, the tail pile dumps the exhaust into, after the collector, and after the mufflers.ptuomov wrote: ↑Sun Sep 12, 2021 10:37 amThe lower tail pipe exit atmospheric pressure has to impact the exhaust port pressure at least to some extent, but the question is whether that’s practically relevant.
The engine will never see any effects from that.
Mike Jones
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Jones Cam Designs
Denver, NC
jonescams@bellsouth.net
http://www.jonescams.com
Jones Cam Designs' HotPass Vendors Forum: viewforum.php?f=44
(704)489-2449
Re: Exhaust Duration, Boost and Elevation
The turbo situation is interesting where my first instinct is that it could be very close to the same pressures in the intake and exhaust ports for a turbo compensated engine at different altitudes. For a belt driven supercharger, I’d guess that tail pipe pressure does alter the exhaust port pressure trace, especially for low pressure periods. The question is whether that’s a practically relevant change in terms of magnitudes.CamKing wrote: ↑Sun Sep 12, 2021 10:43 amYou're talking about the atmosphere, the tail pile dumps the exhaust into, after the collector, and after the mufflers.
The engine will never see any effects from that.
Paradigms often shift without the clutch -- https://www.youtube.com/watch?v=cxn-LxwsrnU
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Re: Exhaust Duration, Boost and Elevation
A vaguely related question here:
Say I had a turbo blow-through carb engine with a turbo that could come on boost before the stall converter, so it's effectively always on boost at full load...
If I set it up so that it ran 5psi at sea level (for 20psi-ish absolute) and at 6000ft I run 8psi (ambient pressure at 6000ft is 3psi lower, so it would be close enough to the same absolute pressure), would the carb calibration be the same? And if I had a MAF sensor somewhere in the piping, could I just raise boost with altitude until the MAF read the same?
Say I had a turbo blow-through carb engine with a turbo that could come on boost before the stall converter, so it's effectively always on boost at full load...
If I set it up so that it ran 5psi at sea level (for 20psi-ish absolute) and at 6000ft I run 8psi (ambient pressure at 6000ft is 3psi lower, so it would be close enough to the same absolute pressure), would the carb calibration be the same? And if I had a MAF sensor somewhere in the piping, could I just raise boost with altitude until the MAF read the same?