The V8 Owners Forum -

Posted: **Thu Jun 09, 2011 7:38 pm**

I was planning on using a single 3 inch system but have been told I would be better off with 4 inch

Hoping for around 340 to 360 flywheel BHP from a 5.4 SBF

Any views or formulas I could use to be sure I'm not strangling the engine ?

Collectors are 2.5 inch and primaries 1 5/8 inch.

Thanks for any help

Mark

Posted: **Fri Jun 10, 2011 9:22 am**

Hi
If you can find straight silencers for 4" exhaust pipe and fit them under the car (which I think will be the biggest issue) then they would be better than a single 3". Provided that is that having a quiet car is not high on your priority list

. But I am pretty sure a single 3" system with straight through silencers will flow more than enough for the power output you are looking at.
Best regards
Mike

Posted: **Fri Jun 10, 2011 10:26 am**

3" is more than big enough

Posted: **Fri Jun 10, 2011 11:06 am**

That's handy as I already have a 2 box 3 inch cosworth system that was going to get butchered to fit..

thanks

Mark

Posted: **Sat Jun 11, 2011 10:04 pm**

Would also agree that 3" will be fine.

The V8 Owners Forum -

Optimum exhaust diameter ?

Optimum exhaust diameter ?