Honda D Series Forum banner

1 - 20 of 20 Posts

·
Boost Gets You Laid
Joined
·
4,402 Posts
Discussion Starter #1
So I built myself a MBC following the thread in the DIY section. Have a hose off the cold side housing that goes to the internal WG on my greddy kit, that's where I put the MBC in.

Hose from compressor housing to the bottom of the MBC, nipple on the side goes to the WG.

Went for a spin, everything functions as it should. Pull over, screwed the adjustment bolt in some, no change. Figured I'd adjust it in more, still no effect.

Pulled the MBC off, put a stiffer spring in, and repeated as above... you guessed it, no effect.

This go-around I changed the spring and went to a slightly larger "bearing"(shift rod lock ball out of an old subaru trans). Head up the road to see where it's at, tweak the adjustment knob. It now boosts to 10psi but then drops back down to 7psi. Tried turning the adjuster in more and same thing: 10psi drop back to 7psi.

Any ideas?
 

·
Registered
Joined
·
2,022 Posts
so you are using a line form the turbos compressor cover? ive never used that one with any luck i always just used a good manifold vac signal. we can play with that some this weekend too if you want homie.
 

·
Boost Gets You Laid
Joined
·
4,402 Posts
Discussion Starter #3
Yea, the only "signal" through that hose pushes the diaphram down to open the WG flapper. No sence in running more hoses if I don't need to.
 

·
Registered
Joined
·
1,467 Posts
I believe I read somewhere that the best way to do it is from the IM because your compressor housing might be seeing a constant PSI while your IM is seeing a lower amount.... Or something along those lines.

But it sounds like your problem is unrelated to that. Sounds like you need a real MBC.
 

·
Registered
Joined
·
6,365 Posts
drop off around red line? or spiking?
It kinda sounds like you didnt build it right. There are to kinds, which did you build?
There is the bleeder which bleeds off air. Then there is the spring kind which doesnt open till the ball is moved from psi.

Also fyi you can buy an air compressor reg and it will do the same that pretty much.
 

·
Boost Gets You Laid
Joined
·
4,402 Posts
Discussion Starter #7
Neptune, map is out to 30psi... It'll never see that much. Using spring type, bleeder seems to be suggested for apps over 15psi. I'm shooting for 13ish.

Kinda hard to screw up build wise. T fitting, 1/4" npt barbs on the side and on the bottom. Spring and ball inside. I'll post a pic tomorrow
 

·
one grumpy old man
Joined
·
786 Posts
what did you use for the ball inside? a metal ball bearing?
 

·
Registered
Joined
·
3,720 Posts
Try getting the boost signal from after the intercooler, or from the intake manifold.

That will fix the boost sag.
 

·
Boost Gets You Laid
Joined
·
4,402 Posts
Discussion Starter #10
what did you use for the ball inside? a metal ball bearing?
1/4" steel ball that's a shift rod retainer out of a old subaru transmission

Try getting the boost signal from after the intercooler, or from the intake manifold.

That will fix the boost sag.
Guess I'll have to give that a try when the snow quits flyin
 

·
Registered
Joined
·
6,365 Posts
I read the first post and the diy. Maybe you got the port mixed up? The ball should be on the intake/boost side. while the - should be to wastegate bottom port.

Once the intake manifold hits boost it will push the ball in and the pressure will go out the t to the wastegate bottom port. where it will then push the diaphragm and open it.

Is that how yours is hooked up? if so maybe the spring is to tight?
 

·
Boost Gets You Laid
Joined
·
4,402 Posts
Discussion Starter #15
Yup, vac log is hooked to the bottom where the ball is. That way when it boosts it will push the ball up. Heading to punkbombs tomorrow, gonna try the mbc he has in his box.

Last thing I can think of is make my bleeder port slightly larger than 1/62
 

·
Registered
Joined
·
2,340 Posts
so you are using a line form the turbos compressor cover? ive never used that one with any luck i always just used a good manifold vac signal. we can play with that some this weekend too if you want homie.
this^^^^^
on my setup. i HAD to run manifold pressure. i plugged the nipple on the compressor housing. I too use an mbc, and my setup is this: manifold - mbc - wastegate.
 

·
Boost Gets You Laid
Joined
·
4,402 Posts
Discussion Starter #18
Must be the spring I'm using is too stiff. Switched to the other, known working, DIY MBC and worked better.

Going from the vac log, it would spike to 20psi then drop to 10psi. Switched over to the compressor housing port and the nasty spike went away:) It'll hit 13.5 and drop to 13psi now.

Just need to go have the timing tweaked a little now: Needs a slight advance
 

·
Registered
Joined
·
1 Posts
A vacuum/pressure tester is gold for this type of thing, you can have it (mbc) set up for what you want before even fitting it to the car, rules out problems with the part. Ive always run from the comp. housing without issue on previous cars with no problem, the only problems Ive ever had were when mbcs sit up the ball corrodes and it no worky any more....
just my 2p
 
1 - 20 of 20 Posts
Top