m30+turbo questions

[CorvallisBMW]

Cross-posting this from the m30 section:

I'm in the process of working out my FMIC setup and ran in to a few Qs that I'm hoping some of you turbo folks can help with.

-IC core size. I've found a bar & plate design that I like, core size is 21 x 5.5 x 2.5. Seem big enough?

-Would 2" IC piping be too small? The m106 turbo outlet is 2", as is the intake tube. Plus I have a lot of 2" pipe and couplers already. I'd like to reuse what I can, but am I shooting myself in the foot with small-ish pipes?

-BOV size. Is a 25mm port BOV large enough for an engine/pipe setup like this?

- Manifold vacuum source(s). I need at least 3 "signals" for the MAP sensor, boost controller, and boost gauge. m20s have that nice little plate on the manifold, but no such luck on m30s. Where did you guys go for your vacuum signal? Drill+tap the manifold, or use one of the existing ports for the FPR or brake booster and tee off?

- IAT sensor needs to be placed after the IC but before the TB, correct?

[TheTacoMan]

My IAT sensor is placed roughly 5 inches away from the TB after the intercooler on my m20, I have no idea where kamotors tapped into vaccuum but Im sure he will chime in.

[jim325]

On my m30b34 intake manifold there were a couple little ports on the bottom of the manifold. I used 1 for my fpr the other for the map sensor. I swapped my tb to the other side so I just drilled and tapped a couple holes on the block off plate I made for my BOV and wastegate. Drilled and tapped the manifold for a signal to the brake booster.

I think that's all of them.


I also did my IAT sensor about 10 inches(prolly a little less) before the throttle body after the intercooler. If I have any suggestions about IAT placement it would be to try and put it away from sources of heat. It will help with hot restarts. Sometimes my car doesn't like it and I have heard of others having the same problem.

I think my ic is about the same size but 4" thick. 4" is too thick, id like to get a skinnier one, maybe like 2.5 inches or so. I also used 2.5" piping. Im not real sure if 2" would be too small. Im not an engineer so I can't speak too the technical aspects of why 2.5" piping would be better than 2" or 3" but 3" is just big and harder to fit than 2" or 2.5". Plus Unless your doing like 25lbs of boost I don't think the air would need 3" of room to move around.

I thought I read something about too small and it could choke the engine and or slow down the velocity of air and too big could slow it down because of to much area to fill to get it moving. True? No clue, but it sounds smart.

[CorvallisBMW]

I'm tempted to buy a vacuum attachment for my drill and just drill+tap three spots on the manifold. The MAP sensor is large (3/8 NPT I think) and so won't work with a small 1/8" barbed hose tee.

Actually now that I think about it, I need a vacuum source for the BOV as well. I guess that's 3 small vacuum ports and 1 larger one needed.

[kamotors]

-IC core size. I've found a bar & plate design that I like, core size is 21 x 5.5 x 2.5. Seem big enough?-it'll work, I use 27x12x2.5 and its plenty to keep cool, pull after pull. you can upgrade this later if your IAT reads too high

-Would 2" IC piping be too small? The m106 turbo outlet is 2", as is the intake tube. Plus I have a lot of 2" pipe and couplers already. I'd like to reuse what I can, but am I shooting myself in the foot with small-ish pipes?
This shouldnt be an issue and you will be able to upgrade later.

-BOV size. Is a 25mm port BOV large enough for an engine/pipe setup like this? this a bypass valve? I'd consider this to be the last concern here.

- Manifold vacuum source(s). I need at least 3 "signals" for the MAP sensor, boost controller, and boost gauge. m20s have that nice little plate on the manifold, but no such luck on m30s. Where did you guys go for your vacuum signal? Drill+tap the manifold, or use one of the existing ports for the FPR or brake booster and tee off?
I'd give map its own dedicated signal for sure, there were several ports on my M30's manifold that I used to run my lines. I did not have to drill and tap any lines for my build. Does your turbo's comp housing have a vac port?
- IAT sensor needs to be placed after the IC but before the TB, correct?
anywhere after the intercooler will work to give an accurate reading

[CorvallisBMW]

Actually now that you mention it, my turbo does have a port on the compressor outlet. It's large, like M12x1.5 or something. But maybe I can find an adapter. Though that wouldn't be a good place to put the MAP sensor as it's very far away from the manifold and pre-intercooler, which affects density.

Is there anything wrong with tapping for a vacuum signal before the throttle body? There are two 10mm round ports on the m106 intake tube, I'm sure I could use those in some way. Just not sure if a pre-TB signal will be accurate enough. It seems as though pre- and post-TB vacuum would be the same in all situations except idle, yes? In that case I could probably run the boost controller from there, but what about the BOV?