Miata Turbo Forum - Boost cars, acquire cats. - Does the pipe size really matter?

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- - Does the pipe size really matter? (https://www.miataturbo.net/diy-turbo-discussion-14/does-pipe-size-really-matter-7017/)

heh i just asked this in another thread.

some thoughts (no science to them):
changes in flow area are a restriction. you want smooth transitions (not steps)

the flow after the IC is probably very turbulent so larger tubing might help flow.

stock throttle body is 2.5... for flow? people run larger throttle bodies for some reason.

the IC is the limiting factor anyway.

hmm.

well there has to be a step somewhere even if the IC is limiting

but really I doubt there is much, if any, difference

Quote:

Originally Posted by samnavy (Post 76091)

I think if you'll do a search over at m.net, or through Corky's posts there, you'll find that he's researched this at length.

If I remember correctly, he did back to back runs on pipe size ranging from about 1.75-3.00 inches and found virtually no difference in spool/power/response/etc... In the power and psi ranges we typically deal with on this forum, anywhere from 2.0-3.0 will be identical.

The benefit of smaller pipes is (as said earlier) that they are much easier to route... and they're cheaper (both for pipe and couplers). However, almost all of the eBay intercoolers out there are 2.5" in/out and the intake manifold inlet for 1.6 and 1.8 motors is also 2.5".

Depending on your turbo, the compressor outlet can be anywhere from 1.75 to 2.5". Most of the smaller T25's I've seen have been 2", which means a 2"-2.5" enlarger coupler and then 2.5" all the way to the manifold. Somebody with a T3, what do your compressor outlets run?

I run 2" all the way to the manifold, and use a 90* 2"-2.5" enlarging coupler there.

I did some searching and found similar stuff...I'll just try to copy your I/C setup :)

Quote:

Originally Posted by Fritch (Post 76144)

well there has to be a step somewhere even if the IC is limiting

but really I doubt there is much, if any, difference

that was.... step as opposed to smoooooooooooove transition. like changing the diameter by a half inch over a half inch or over 4 inches.

2-inch is fine for your goals.:cool:

2 inches end to end here and I'm running a T3/T04B (soon E).

i'm running the same

Quote:

Originally Posted by Ben (Post 76125)

i don't think she's gonna care if your pipe is 2" or 3" :gay:

Yeah shell still ask where the other half is :gay: :rofl:

Quote:

Originally Posted by samnavy (Post 76091)

... he did back to back runs on pipe size ranging from about 1.75-3.00 inches and found virtually no difference in spool/power/response/etc...

well shit, since mine is situated well, Im going to leave well enough alone.
thanks

Ive stopped searching at m.net about things like this that might be a grey area because of the smug cloud around that forum

FWIW, the rear-mount camaro guys run huge pipes up and down the entire length of the car and they have zero problems with lag or making power. The turbo and the engine both flow such an enormous amount of air that the volume of the pipes are completely immaterial.

I think you will get bigger gains just from avoiding lots of unnecessary turns and unnecessary pipe diameter changes. That is more of a flow-related argument than a volume related argument. My thinking is that if the outlet on my T04E compressor is 2", how much gain am I going to get from running bigger pipes?

Quote:

Originally Posted by beerslurpy (Post 76655)

The turbo and the engine both flow such an enormous amount of air that the volume of the pipes are completely immaterial.

There it is. :cool:

+1