Exhaust Theory Question
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From: Tucson USA
Exhaust Theory Question
Alright, I have a question regarding back pressure and velocity....
My friend drives a Chebby with a 400 small block bored 30 over, headers, cam, etc... As well, he runs dual 3 inch pipes to the back through single chamber mufflers. Given the huge pipes, do you think he is losing performance, or does he have enough engine to need such large pipes?
On a side note, despite the fact that it's a Chebby, it's got a mean, mean sound. I like. : )
-Patrick
My friend drives a Chebby with a 400 small block bored 30 over, headers, cam, etc... As well, he runs dual 3 inch pipes to the back through single chamber mufflers. Given the huge pipes, do you think he is losing performance, or does he have enough engine to need such large pipes?
On a side note, despite the fact that it's a Chebby, it's got a mean, mean sound. I like. : )
-Patrick
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Joined: Dec 2001
Posts: 378
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Exhaust Theory Question
Hi patrick
exhaust tubing and gas velocity are closely related. I think that the 3'' tubing is way too much for the street. On the street, you need good velocity to help the engine breathe and to properly scavenge. If your friend is racing his 400 at max rpms, then yes, the 3'' will suffice. HOWEVER, if it is street driven, he is losing low end torque. To illustrate my point, think about blowing through a a straw and then a 3 inch pipe. If you feel the end of the straw, you will feel how aggressive the air moves out. On the pipe, its kinda stagnant. NOW, if you were spinning that motor at max rpms, that 3 inch would be of use to rid all that gas. Conversely, on a street engine, (low to moderate RPM), velocity of gas would suffer. So, with this all in mind, Yes, yr friend is losing some performance despite the mean sound. Heck run 2.25 duals with a cross over and low restriction mufflers with huge tips and I guarantee it would sound even better!
this is just my .02!
I hope i helped
regards
Ben
exhaust tubing and gas velocity are closely related. I think that the 3'' tubing is way too much for the street. On the street, you need good velocity to help the engine breathe and to properly scavenge. If your friend is racing his 400 at max rpms, then yes, the 3'' will suffice. HOWEVER, if it is street driven, he is losing low end torque. To illustrate my point, think about blowing through a a straw and then a 3 inch pipe. If you feel the end of the straw, you will feel how aggressive the air moves out. On the pipe, its kinda stagnant. NOW, if you were spinning that motor at max rpms, that 3 inch would be of use to rid all that gas. Conversely, on a street engine, (low to moderate RPM), velocity of gas would suffer. So, with this all in mind, Yes, yr friend is losing some performance despite the mean sound. Heck run 2.25 duals with a cross over and low restriction mufflers with huge tips and I guarantee it would sound even better!
this is just my .02!
I hope i helped
regards
Ben
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