I am about to start building a whole new exhaust system for my car - but I'm a bit undecided as to what diameter pipes to use .
The manifold plates have been made to fit 1 5/8 , I was planning on dropping to 1 1/2 for the primaries , mainly due to lack of space , and allso I cant find 1 5/8 bends on fleabay at the mo'...........
But..........what size should I make the rest of the system ? It's a 2.5 V6 , making something close to 200 BHP , and revving to 8000 .
I currently have the cast iron `log' manifolds going into 1 7/8 , with a link pipe under the engine (which I will repeat on the new system )
I am torn between 2 or 2 1/4 ? ?

There is a pretty good calculator here: www.headerdesign.com (you need to create a login which is free). It should tell you primary and secondary lengths and diameters.

I would guess at 1.5" primaries and 2" secondaries would be what it suggests.

There are a few other calculators around on the net too.

Cheers,
Dan

Hi Claire, I know mine is a bit larger, 2.9 against your 2.5, but I found that 15/8"x 20" long primaries and 2" secondaries worked really well, (238 BHP, 250 Lbs torque), and I only rev to 6100, (grenades over that, :-) ). Unfortunately being a se7en type car couldn't run a ballance pipe. HTH Ray
Edit to add
DanP your link doesn't generate a web page

[Edited on 20-3-10 by Chippy]

hmmm, i posted an answer linking to the excel spreadsheet Dave Ashurst made. If you do a search on locostbuilders in google with words like dave, excel, spreadsheet, exhaust etc you'll find it eventually.

quote:

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DanP your link doesn't generate a web page

[Edited on 20-3-10 by Chippy]

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hmm yeah the website appears to be down, google cached version of it in february so hopefully it is just down over the weekend rather than permanently.

Cheers,
Dan

quote:

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That's 'cos it ain't a link.

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I get all my exhaust parts from OJZ engineering:

Link

Ed.