Upgrade to M30 intake manifold

[cdevine]

I'm going to be putting in a schrick cam and was wondering if anybody knew what is a good upgrade to the stock intake manifold. Any ideas or thoughts would be greatly appreciated.

thanks

[Mike in Seattle]

A B35 intake manifold is the only upgraded manifold that I know about for our cars. It does require port matching the head to the manifold to run them on a B34 car though.

Mike

[Shawn D.]

Mike's correct on the port matching. However, you'll still have the same runners in the head and the same valves, so it'll probably provide little to no gain.

[Mike W.]

Even port matching a B35 would be a little iffy, while B35 ports are larger, they are also a different shape, wider but shorter.

[LA]

A reduction in pressure drop is a reduction in pressure drop, no matter how you come by it. No need to port match...the trip, or step will just keep the flow well mixed. I have run one that way and it definately does not hurt, with a hotter cam I would certainly go with the b35 intake.

Hey - everything else equal, it looks cooler than the B34 version!

[Shawn D.]

No need to port match...the trip, or step will just keep the flow well mixed.

BS. Dyno tests have repeatedly shown that intake port matching is beneficial to power production. A step up in size in the exhaust can help with reversion, but a step down in size in the intake is detrimental. You never want to have an abrupt step down like you will if you install a B35 intake on a B34 without matching the port.

[Jeremy]

A reduction in pressure drop is a reduction in pressure drop, no matter how you come by it. No need to port match...the trip, or step will just keep the flow well mixed. I have run one that way and it definately does not hurt, with a hotter cam I would certainly go with the b35 intake.

Hey - everything else equal, it looks cooler than the B34 version!

But it's not a smooth transition to the smaller intake port. The abrupt step will create a high pressure area at that point, right where the air and fuel are mixing. Turbulence might be good for the mixing, but it'll hurt overall flow.

If you've got the head off anyway, may as well smooth out the transition. It'd be kinda silly not to.

Jeremy

[turbodan]

BMW bothered to cast a new intake manifold for the '88 528e just to match the intake ports on the 2.5i head. If it werent worth doing I'm sure they would have just bolted on the 82-87 eta intake manifold, which was identical except for vacuum ports and the way the runners open up right before the head.

It probably wouldnt make a real difference anyway. I'd say you would probably be better off with the stock intake and a cam anyway. The cam and intake have a big effect on the volumetric efficiency of the engine. If you change that too much without retuning the fuel injection to suit the engine's new personality, you're not going to make much more power, and you'll probably notice that it runs a little worse where the old cam and intake used to work.

[louielouie]

This why the B35 exhaust manifolds (left) seem better:

[Jeremy]

Um, the question was about intake manifolds.

[louielouie]

Um, the question was about intake manifolds.

ummm.... yes - that darn night school just isn't helping my remedial reading at all!

But it does illustrate that the b34 exhaust manifold will limit the impact of a cam and larger intake. If I'm not mistaken the Schrick profile is actually 284/280 in./ex. so efficiency in the exhaust is paramount ( <-- that was extra credit for my class )

[LA]

No need to port match...the trip, or step will just keep the flow well mixed.

BS. Dyno tests have repeatedly shown that intake port matching is beneficial to power production.

Of course, that's why I winked with the comment about mixing. I really think you break even with the 15% or so improvement in flow (because of larger area) until you come to the step, then lose what you gained because of the increased pressure drop at the step. Run the numbers & see what you find...

So as I said...with all else equal, go with the better looking one!

Also, as I mentioned, I have tried this and it did not make a noticeable difference. My set up was experimental and temporary (while my b35 head was in the shop.) For long term I agree that the couple of hours with a Dremel would be time well spent. But even better would be a b35 head and pistons.

[ElGuappo]

So who has used b35 exhaust manifolds with a b35 head?
Any pics? That looks to be a totally different exhaust mating arrangement. I am really curious to see what people have done to accomodate that.

Jay3

[turbodan]

This why the B35 exhaust manifolds (left) seem better:

What happened to the picture? That was good info.

[turbodan]

Hey look at that, it seems to be working again.