Camshaft experts?

[V8mate]

This firm supply high performance camshafts for my BMW E36 M52 motor.

http://www.xlraceparts.com/e36z3-non-m3-camshafts-...

When purchasing, there's an option between extending the dwell on either the intake or exhaust side, though: 252 Intake or 244 Exhaust.

What would make you want to choose between these two? Why would you want an extended dwell on the exhaust rather than the intake?

Can anyone shine any technical know-how type light on this?

[dom9]

V8mate said:

Why would you want an extended dwell on the exhaust rather than the intake?

Can anyone shine any technical know-how type light on this?

Assume you extend the duration on the exhaust cam to keep it open longer when the inlet valve starts to open. The momentum of the exhaust gas leaving effectively sucks more air and fuel through the inlet valve, which fills the cylinder better on the induction stroke, hence you get more power.

However, that is normally at higher rpm and you may lose some bottom end torque. I am no expert, so I wouldn't tell you which one to choose, but why not give them a call and let them know what you are building and what your goal is?

Edited to add the relevant bit of quoting!

Edited by dom9 on Friday 22 October 14:48

[The Black Flash]

Erm...isn't it because your engine has twin cams? So you'd buy an exhaust and an inlet?

On some engines you get most gain from the inlet, so you wouldn't always bother upgrading the exhaust cam.

[V8mate]

And that's why PH is great. Because it's better to be an idiot on the internet than when you're engaged in a transaction with a supplier

[The Black Flash]

Woo-hoo! I was useful!