Exhaust Pipe Size

[pontiacgp]

I've been kind of tip toeing around the issue for years......but thank you.....I think?

meetings are every second Wednesday...

 

[pagrunt]

What would of been perfect for you would of been the discontinued Edelbrock TES shorty header/Y pipe set up. Has anyone seen either the standard cat or SS cat versions anywhere? With a set of those you could keep a single set up & be ready for the next engine.

 

[88ss408]

Your idea of a good y pipe in a single 3inch would be alrigh for a mild motor

 

[marcar1993]

Primary tube diameter:

2.5" vs 3" pipes:

Now, that being said, this is for all out peak hp. There is a trade off to some extent on the lower end of the hp spectrum on an motor that will never see over 4k rpm. My thought is, if you plan to change to a bigger motor later, go as big as you want. The hp loss will be significantly less than the cost to replace the exhaust again in a few years.

Also, if you want a 3" exhaust, just do it. It won't hurt power enough to make a difference if you are looking for sound.

Finally, temperature has less to do with velocity in a larger pipe than volume and surface area. Adding surface area over a larger diameter pipe increases surface for friction for the air to contact. Further, with the same displacement of air being pushed into a larger volume area, there is less need for the air to move, as it can fill this larger void before it needs to be expelled out the other side. The temperature decreases as a result of this expansion. Decompression of gasses both slows AND cools the gas. (Think of how your a/c system works, the measured oriface allows high pressure gas to decompress, thereby cooling it.)

 

[SupremeSpeed]

Primary tube diameter:

2.5" vs 3" pipes:

Now, that being said, this is for all out peak hp. There is a trade off to some extent on the lower end of the hp spectrum on an motor that will never see over 4k rpm. My thought is, if you plan to change to a bigger motor later, go as big as you want. The hp loss will be significantly less than the cost to replace the exhaust again in a few years.

Also, if you want a 3" exhaust, just do it. It won't hurt power enough to make a difference if you are looking for sound.

Finally, temperature has less to do with velocity in a larger pipe than volume and surface area. Adding surface area over a larger diameter pipe increases surface for friction for the air to contact. Further, with the same displacement of air being pushed into a larger volume area, there is less need for the air to move, as it can fill this larger void before it needs to be expelled out the other side. The temperature decreases as a result of this expansion. Decompression of gasses both slows AND cools the gas. (Think of how your a/c system works, the measured oriface allows high pressure gas to decompress, thereby cooling it.)

Thanks for sharing, that was very informative.