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140 exhaust size choice

vwbusman66

Stößelstange über alles
Joined
Oct 12, 2016
Location
SE MI
Need to build an exhaust system for the 142
I have 10' of 3" pipe and clamps as well as a muffler already. Will this be OK? I know its wicked overkill and will probably hurt performance due to the total absence of backpressure.
 
It's too big. But there is no performance advantage to a smaller exhaust system.

There are tuning effects of the exhaust manifold/header/merge styles and distances and tubing diameters. But after all that, all the rest of the exhaust system needs to do is stay out of the way.

Since you have it, might as well? 2.25 or 2.5 is probably about all a heated up B20 would ever need.
 
why does he need 10 feet when routing it up through the hood only takes maybe 1.5

Why even pipe, just flip the header, use some spacers to clear the carbs. theyre almost symmetrical anyway.
 
A good first step is a 142E exhaust, but building is more fun. I say 2.5" straight off the joining from the manifold into a 2 chamber, Flowmaster. No restriction. Lots of noise. Terrible at low RPM with a cam with a lot of overlap.

It also confused a cop hearing the car coming, seeing a yellow 145 with white (fiberglass fenders and cage) slide through a left at the end of an off ramp. He just shook his head and pretended not to see anything.
 
I used 2" system on my 123gt. Bought a 142E front pipe. Then had a local shop make up the rest with only one muffler. Had a nice bark to it and was in the affordable zone. I think it was a couple hundred?
 
Simons Sport system, 2" is fine if you don't mind quiet performance at a reasonable price. Otherwise, 2.25" is fine. If you are doing head work, bigger camshaft, more compression, more fuel, you might benefit from 2.5". The larger you go, the louder it'll be with no help to anything else but more weight.
 
For a mild B20 2.25 is about the ideal size. For a well worked B20 then you will likely want 2.5 inch

Going too bit will loose you low and mid range power
 
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