Inlet Manifold

[rik1985austin 0]

On my 9A, how can i tell which inlet manifold i have on my car? Just wondering, so i could get a 50mm one if i have the smaller one fitted.

Thanks For Looking,

Rik

[boost monkey 0]

50mm:

 

notice how the runners get narrow so they can pass the spark plug holes.

 

42mm (polished, not standard):

 

A 50mm will rob you of a little low down torque which will make the car accelerate slower, so the general opinion is to leave the smaller manifold on

[Dec 1]

42mm mani as standard will have a raised circular numbered "stamp" about the size of a 2 pound coin on the left most runner. (It's not present in that pic of the polished 42mm manifold above)

[rik1985austin 0]

just had a look, ive got the 50mm inlet on my car :( . but will be looking into buying a 42mm inlet soon.

Rik

[bananawhip 0]

It all depends on driving style so I wouldn't take it off too soon.

 

The 50mm gives more high end power over 4000rpm which is why it's such a popular Rado upgrade, it made mine drive better when I had a valver as I never expected anything below 4000, if you fancy a bit of 'spirited' driving you need to keep it in the power band anyway to get the most out of that engine.

 

If you want low down torque then buy a VR :)

[boost monkey 0]

^^^ that's a fair point.

 

If you're not just pootling around / shopping in it, then get a 50mm I guess although can anyone actually feel the ~3hp difference between them?

[flusted 0]

theres a very cheap 42mm in forsale section

[davidwort 0]

my vote goes to the 42mm, if possible internally polished and port matched to the head, it's not just the runners that are a different diameter, the chamber after the throttle is a different size too so there's a bit more redesign than is first apparent.

At least one valver I've seen has only gained 1bhp top end for the loss of a lot more torque swapping manifolds over back-to-back, and mine has no breathing difficulties at all with a flowed KR head and cams.