Exhaust Manifold Help

[pier_bruce 0 1 Cars]

Been looking at customising a exhaust manifold and would like to know if anyone knows the best lengths I should make my primary and secondary tubes?

Any help would be greatly appreciated

Thanks

Pete

[DamirGTI 344]

Help us a little bit :

 

1. Which engine ?

2. Any modifications or just making the manifold for std. engine ?

3. Which type of the manifold 4-2-1 or 4-1 ?

 

D

[pier_bruce 0 1 Cars]

Thanks for the reply d

It's the XU9j4 with fast road cams solid followers and a mild tickling with the ports. Bottom end is forged..

On the manifold open to suggestions really 4-2-1.?

Pete

[Vili 18]

You'll get close enough by doing 4-2-1 this way:

4-outer diameter 41,5 mm, length minimum 350 mm (I would propaply do 450 mm)

2-outer diameter 48 mm and choose length so that total length is 950 mm

and the actual exhaust diameter could be between 55-63 mm. The 55 mm is better.

 

Really it all depends what are your camshaft timings and where do you wan't your manifold to work.

[pier_bruce 0 1 Cars]

You'll get close enough by doing 4-2-1 this way:

4-outer diameter 41,5 mm, length minimum 350 mm (I would propaply do 450 mm)

2-outer diameter 48 mm and choose length so that total length is 950 mm

and the actual exhaust diameter could be between 55-63 mm. The 55 mm is better.

 

Really it all depends what are your camshaft timings and where do you wan't your manifold to work.

 

Ideal thanks il see if I can work something out to those dimensions.