Best torque-increasing exhast system

So I was changing my fuel filter on base the other day in the auto shop and happened to bump into a guy I went wheeling with a long time ago. We talked for a while and got to talking about my car and what would be a cheap build for torque. For exhausts, he said a 2" would be the best for torque, ( I have a DOHC 2.0L NA Foci). Is there truth to this? I had thought a 3" exhaust would be best. Any input?

Ben

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Ben Hetland
1973 Volvo 142 project car (with some cone-smashing on dirt in it's future, however)

"No. Rally Racing is a back alley sport filled with jackals, headhunters and thugs!"
-Pops Racer (Speed Racer movie)

www.utahrallygroup.com

3" is much too large for a NA engine. I would think 2.25"

dtompsett Wrote:
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> 3" is much too large for a NA engine. I would
> think 2.25"
3" is much too large for a weenie sub 135 bhp wheeeeeezie little stock NA engine.
I would think that a smart guy would be looking ahead to a modest power increase and size the exhaust so that it woulkd be ready for that and spend money once.

Thus, a far sighted person might choose 2 1/2" as a foundation.

I have used 2" on all the Saab V4s I built with 1700cc V4s and mild 100 to 128 bhp, but the upper end cars did benifit from larger diameter.


Build a 230bhp NA motor, go 3".

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

john vanlandingham Wrote:
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> Build a 230bhp NA motor, go 3".

A 230hp NA motor would be schweet. If it's under 200, though, I still think I'd stick with the 2.5" ID. As important as torque is, I wouldn't concern myself with how efficient the exhaust system was below, say, 3000rpm. After all, "top end" has little to do with the actual speed of the vehicle.

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Brian Driggs | KG7KCA | PHX, AZ | 89 Pajero
alterius non sit qui suus esse potest

DR1665 Wrote:
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> john vanlandingham Wrote:
> --------------------------------------------------
> -----
> > Build a 230bhp NA motor, go 3".
>
> A 230hp NA motor would be schweet. If it's under
> 200, though, I still think I'd stick with the 2.5"
> ID. As important as torque is, I wouldn't concern
> myself with how efficient the exhaust system was
> below, say, 3000rpm. After all, "top end" has
> little to do with the actual speed of the vehicle.

in a way, while we want broad spread of torque, we also should recall that "what da motor don't giveth, the final drive can", and if the spread is narrower, cause we got crazy and did make a real 4000-8500 rpm motor, there's still the ratios in the box to help us keep the power boiling.
>
>
>
> Brian DR1665 | Phoenix, AZ
> Have a lucky day.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

On our 1.9 L weber carbed, NA, Opel engines, we used 2.25" for years.

Mark B.