- #1
Mark Tamblyn
- 12
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Hi there,
prob a simple question for you physics gurus, but this application is for a race car, and question relates to air flow velocity through a pipe, in particular exhaust and intake.
Now, my thinking for the exhaust (push) is that by going from a small diameter to a large diameter will create a vacuum/vortex, i.e. going from a high pressure to a low pressure, therefore sucking the exhaust gases out. was thinking of having the mid section of the exhaust 2.5", and the tail section 3".
Same principle with the intake, but in reverse, as I need air velocity to increase, hence going from large diameter to small diameter, remembering though this is a suck.
Its the exhaust scavenging affect.
I did some quick calcs
Engine capacity - 5948cc @ 7,000rpm = 116.7 rps
Exhaust is every 2nd revolution therefore = 58.35 rps
5948 x 58.35/sec = 347L/sec of gas vol/velocity
the 2.5" pipe has 12672cc (12.7L) of volume per 1 m
the 3" pipe has 18249cc (18.2L) of volume per 1m
I guesstimated length of pipes to be 3.5m x 2 (dual pipes).
The variables are the header design, mufflers and catalytic converters.
This may or may not help with my question about the theory of going from small pipe to big pipe (vice versa) to increase gas scavenging
Any theories?
Thanks, Mark
prob a simple question for you physics gurus, but this application is for a race car, and question relates to air flow velocity through a pipe, in particular exhaust and intake.
Now, my thinking for the exhaust (push) is that by going from a small diameter to a large diameter will create a vacuum/vortex, i.e. going from a high pressure to a low pressure, therefore sucking the exhaust gases out. was thinking of having the mid section of the exhaust 2.5", and the tail section 3".
Same principle with the intake, but in reverse, as I need air velocity to increase, hence going from large diameter to small diameter, remembering though this is a suck.
Its the exhaust scavenging affect.
I did some quick calcs
Engine capacity - 5948cc @ 7,000rpm = 116.7 rps
Exhaust is every 2nd revolution therefore = 58.35 rps
5948 x 58.35/sec = 347L/sec of gas vol/velocity
the 2.5" pipe has 12672cc (12.7L) of volume per 1 m
the 3" pipe has 18249cc (18.2L) of volume per 1m
I guesstimated length of pipes to be 3.5m x 2 (dual pipes).
The variables are the header design, mufflers and catalytic converters.
This may or may not help with my question about the theory of going from small pipe to big pipe (vice versa) to increase gas scavenging
Any theories?
Thanks, Mark
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