Adjustable cam gear gains?

[jules325i]

Are there good gains to be had if i fit one to my stroker next time i do my timing belt.

[bmwman91]

Depends. Are you going to get a custom chip that takes advantage of the cam phase shift? If not, then leave it alone. You really do need to get the fuel and spark tables tuned to really see an advantage.

Generally, adjusting the cam's advance/retardation will shift the shape of the power curve, but not really add more area under the curve. You can advance the cam to get a bump in higher RPM power and lose in the low/mid-range.

To really increase air flow, you want a cam with higher lift and longer duration, to a point. Even that will still change the power curve's shape and too aggressive of a cam will kill your low-end. And of course, if the head and intake are relatively restrictive, changes to the cam will not provide much benefit. To really reap the benefits of cam changes, you nee to take note of the engine as a whole and decide what sort of power curve you want, and what is actually attainable.

Cliffs:
There is no simple answer with cams. Generally speaking with regard to your question, no, leave it alone unless you plan to hit the dyno for some tuning.

[nando]

Advancing gains low end torque, retarding gains top end power.

If your motor is stock, look elsewhere. If its built and tuned, its a nice way to adjust your torque curve.

[digger]

it depends alot on what cam you have in relation to the CR, how good the head works and exhaust work. certainly no harm in trying other than a little on the wallet. in my experience you don't need to redo timing and fuel to see gains on the dyno but you will want to get it tuned correctly at some point particularly at low rpm and throttle as this can change massively.

[jules325i]

My setup is 2.9l 10:5.1 comp, 272 cam, port polish and multi angle valve cut, 19lb injectors + miller PSIK and W.A.R chip, i have a full exhaust extractors back through high flow cats.

i feel my car really runs out of legs from 5500 rpm onwards, yet power band comes on quite early, earlier than my stock 325i engine.

[nando]

Then a cam gear is a great idea, retard it a few degrees to shift the power band to the right. :)

[digger]

play around on the dyno retarding might help a bit but it can hurt somewhere else in the powerband which you might not like. sometimes advancing it will make the engine perform better below peak hp and even improve the peak but it will fall off the cliff faster by advancing it which doesn't sound like something you want. its going to be a compromise i always go for most area under the curve int he powerband i use most often.

strokers with relative small duration cams do run out of steam about that rpm changing the adv/ret is not going to perform miracles.

[jules325i]

Thanks for the info, I'm still kicking myself about fitting the 272 over the 284/272