chriscar

iTrader: (24)

You need an EBC. Wastegate pressure when it's off, plus low and high settings give you 3 boost level options, all from the convenience of your driver seat. And if you get the Greddy remote switch, your low/high control is at your fingertips.

Get a B or an S, stay away from the SpecII, it's a pain in the ***.

C

AbeFM

iTrader: (3)

*if* swapping the spring is easy, you could still do that. In fact, hitting the same numbers with an MBC, for me on the street, isn't trivial. I have to drive it, tweak it, drive it, tweak it. If you can pull 6 screws, swap a spring, and be back on the road, why not? Just keep a collection of 3 or 4 springs for big steps, and shims for fine tuning (to add 3 psi, new spring, to add 1/2 psi, add a shim) you could cover a range of 15 psi with no trouble.

The only downside I see is the heat making it hard to change on the road.

Anyway, my MBC and internal wastegate work awesome, so, if you want to trade just let me know. :-) But if you want to run under 14 psi you're kinda fucked. :-P

hustler

iTrader: (6)

I'll probably just leave it where it is for now. :(

I really enjoyed the 16psi overboost, I'd love to put 20psi through this pig on the dyno just to see what it does (bends time).

Laur3ns

Reduce bleeder hole indeed.

AbeFM

iTrader: (3)

I've heard the same. MegaSquirt II's closed loop EBC is supposed to be much improved. I'm still very, very skeptical (especially since they use the same code on idle and that's abysmal) but I'm going to be testing it soon, this 16 psi at night and 13 in the daytime is getting old.

How are you on boost spiking with the EBC?

chriscar

iTrader: (24)

I just got the Miata running last week, no boost controller yet, but I plan on using the Profec at least initially instead of the MS because it's simpler.

C

hustler

iTrader: (6)

I just had a thought:
I wonder if the ball is not sealing? This will let air pressurize on both sides of the WG diaphragm. This could also be the reason I have the strange wastegate noise when cruising with the boost controller hooked up. I need to plug in a friend's controller and see if it works better.

AbeFM

iTrader: (3)

Huh? The ball in the MBC? If it's not sealing, you'll get lower boost, that's for sure. I've seen dirt get in them, though it's rare. I took mine out and cleaned it once and saw marginal improvement.

What do you mean pressure on both sides of the diaphram? If you did, you'd get higher boost. I pumped mine with a mighty vac to see when and how much it leaked, btw.

hustler

iTrader: (6)

Yes, pressure goes to both sides. Its the differential between the two sides of the diaphram which makes the glory.

I've tried just running the boost controller on one port and it overboosts too.

Cpt_Slow

iTrader: (2)

How is the MBC setup? You have lines running to both sides of the EWG? As I understand things you leave the back port untouched on the EWG when using a MBC and just run the MBC inline to the bottom port of the EWG. Is this not the case?

Edit: Now I see how you have it setup - I'm not familiar running like that.

Braineack

iTrader: (62)

sounds like once you have the MBC on it, the wastegate cant bleed off exhaust well enough. You've tried just the MBC on the lower port? it takes about 2 seconds to put a piece of duct tape over the bleeder hole on the MBC to test too.

wayne_curr

iTrader: (8)

In for the solution. My hardware store MBC wont work with my 3" exhaust. If I romp on the throttle it'll overboost instantly. Runs great sans the MBC.

hustler

iTrader: (6)

I've tried the lower port, it does the same thing.

I have not plugged up the bleeder yet. I should not that this boost controller worked fine on the old internal set-up.

hustler

iTrader: (6)

Jake at TiAL told me to run it like this, or die of aids.

AbeFM

iTrader: (3)

That's what I thought, but didn't want to make any assumptions. There's basically no sense to that. Pressure on the spring side of the diaphram will hold the wastegate shut, building more boost. At boost increases, it'll be more likely to hold shut (depending on the ratio of the cross sectional area of the diaphram to the dump tube valve, and the efficiency of the turbo)

Turbine pressure on the non-spring side of the diaphram will tend to open the wastegate - which is how you control boost.

In short, if you have the compressor attached only to the lower, non-spring side of the diaphram, you will never be able to run high boost.

You could use a set up like that to run LOWER pressure than spring, though, which is slick.

AbeFM

iTrader: (3)

Take your manifold pressure (actually, IC lines just ahead of the throttle body) with or without the MBC in it, and put that into the "compressor Reference Port (as you have it labeled). The the "boost controller port" (as you have it labeled) should be open to atmosphere, or welded/soldered shut if you want to have an absolute pressure instead of a gauge pressure.

That should work.

(If you swap them from how you have them labeled, you should also be ok. It should make it control faster than leaving it hooked to atmosphere as I was saying)

sixshooter

iTrader: (12)

And more reliable, and adjustable on the fly, and allows for three set boost levels, and...(ahem)...always works.

Braineack

iTrader: (62)

so normally when you try it, full boost goes to the lower port, and the mbc is teed off and goes to the upper port correct?

Zaphod

Wanne see, Abe?



Screenshot from today - still needs a small bit more P and maybe a little tweaking I and D but apart from that - for me it seems to work great.

Greets

Sven

hustler

iTrader: (6)

This is correct. Jake at TiAL was very specific that it must be done like this (not just to the bottom port) or the gate will not close quick enough to do part-throttle correctly. "Follow the directions or you might as well have an internal gate."