Intake Manifold Vacuum Hose

[catch22]

I'm in the midst of an M50 swap and I decided try the cut-n-fiberglass the intake manifold way instead of messing around with the brake booster.. Since I never had this engine completely assembled yet I was wondering if someone could tell me where that vacuum hose that is by my thumb goes to. It is rubbing against the brake booster and will have to be relocated..





Thanks!

[Van Westervelt]

Fuel Rail, aka fuel pressure regulator

[surebimmer]

Goes to the fuel pressure regulator, on the rear of the fuel rail.

[catch22]

Cools Thanks!

[BDSax]

wont cutting the plenum effect the air fuel mixture?

[Van Westervelt]

wont cutting the plenum effect the air fuel mixture?

Not to such an extreme that the ECU cant adjust accordingly.
I opted for the modified booster myself.

[Mike B.]

wont cutting the plenum effect the air fuel mixture?

The volume of air passing by the MAF shouldn't change if you contour the plenum. The vacuum remains consistent and the diameter of the MAF doesn't change. It may effect flow into the nearby intake runner, but not enough to cause any issues.

[matt]

The volume of air passing by the MAF shouldn't change if you contour the plenum. The vacuum remains consistent and the diameter of the MAF doesn't change. It may effect flow into the nearby intake runner, but not enough to cause any issues.

Don't count on that.

Intake manifolds are the one thing that should never be fucked with.

[FredK]

Matt. Do you kiss your mom with that filthy mouth?

Sincerely,
Your Conscience

[matt]

No. We don't really get along.

All the best,
:hitler:

[Mike B.]

Don't count on that.

Intake manifolds are the one thing that should never be fucked with.

He's just reducing the size of the plenum a bit to accomodate the booster and not messing with intake runner length. Do you really think reducing the size of the plenum a few square inches with completely screw things up? I doubt it.

[matt]

It will for that cylinder.

That cylinder is going to run rich now, won't get as much air or make as much power. It would be noticable if the OP has EGT or lambda on a cylinder by cylinder basis.

BMW intake manifolds are very well designed, there is not a lot of cylinder to cylinder variance... until you mess with it.

[Garageaholic]

Interesting mod. any more pictures?

[Mike B.]

As long as the contours are smooth and the area is not too great, air flow to that cylinder should be fine. It is not like he is going to significantly reduce the available air to that cylinder. I've re-countoured stock intakes on Porsche 911 engines that I have converted over to EFI and EGT temps for they cylinders remained consistent with what was seen prior to the conversion. Albeit, the intakes are different, but based on my experiences, I guess we're going to have to agree to disagree on this one.

I'd like to cut one open or get some pictures through the throttle opening to see what the inside of the plenum looks like.

[StereoInstaller1]

Reshaping a BMW plenum?


Baliff, whack his PeePee!


Seriously guys, it is only a plenum. He is reducing the total volume, and from what I can see it is only going to change the "tuning" of the plenum by a tiny bit. Smaller plenum means higher tuning, so might lose 2ft/lbs in low RPMs.

Personally, I think it is a great idea, second only to going full manual Tilton pedals/Wilwood brakes with an underseat master cylinder so you have room for the V8 thing that is all in my head.

More pics of the 'glass intake, please!

Luke