I have a tuned IX, with the basic mods. 322whp 331wtq on a mustang. I wonder, though, why my boost tapers back so much? If I'm in a low RPM on 3rd gear, it'll spike like 24 psi, then by the time im at 7k its like 18.5 - 19psi, is that normal?

 

It's spiking rather high. I know the IX's boost can be set a little higher than the VIII's, but still 24 is still rather high. The taper is normal on a stock turbo.

 

I spike 22 ~ 19 redline - 7k.

Hallman MBC and a Custon Tune.

 

It's only at like 24psi for not even a second, then it starts to come back. If it's under a lot of load, though, i.e. 5th gear, it'll run 25 psi until like 5500 then it comes back, at redline in 5th it's like 21 - 22.

 

What kinda dyno? Were those your only mods? I'm thinking about a forge WGA, to hold boost better.

 

Not sure on the dyno, dyno jet i think.. it was on rollers.

yuh, only mods.. well, a buschur filter but that's mostly for sound

Ordered my DP/TP from TTP and still doing research on the cat back... don't want anything too loud.

 

That's a nice 1/4 mile run, for that amount of power, you must've been hustling. Are you at sea level, too?

 

yuh, Portland International Raceway is 50 ft above sea level.

oh yeah, power shifting.. no lift throttle. figured only doing drag once, wanna get the best possible.

 

That's normal boost tapering. Before I installed the boost controller mine would spike in the same area as yours then it would taper down alot.

A MBC will take care of this problem.

 

Buddy, I have a boost controller.

 

I liked my old TurboXS HP manual boost controller because it had a small bleeder valve in addition to the ball & spring valve which let me dial out all the spiking. It actually held boost a lot better than my current EBC. If your MBC is a ball & spring with no bleeder, you will normally have spiking, and it will be more drastic at higher boost levels. I think because it is not only increasing boost, but increasing the rate at which boost is increasing as well. The bleeder smooths out the transition by not letting the turbo spool up so quickly.

 

The WGA isn't the problem (even if there is a problem).

Sustaining 25psi that long in 5th with that much load on 93oct is very dangerous. You said it "only" spikes to 24psi for not even a second in 3rd gear, but you fail to realize that when we refer to our boost level, that's exactly what we're talking about - the max spike in 3rd. It's the same for everyone - we all have an initial spike that settles down.

Anyway, the taper may be a little more than normal, but it has been more common on IXs to see a larger taper due to the MIVEC. The ECU doesn't control boost with the MBC installed, but the huge amount of air being passed through makes it difficult for the stock turbo to sustain high boost at higher rpm.

The main problem is that people get their Evo IXs, get really greedy, pay no attention to the actual power they're making, but spend all their time worrying about their boost taper while not realizing that their IX at 18psi is making 30-50whp more than VIIIs at 20psi in the same gear with the same (or less mods).

 

I have the TurboXS HP Boost Controller. I tried a Forge UNOS, it didn't hold boost as good. It could be my car, too. Who knows. But, if what Warrtalon is saying is true, I will leave it a lone. By the way, this setting was made by John with Jestr, I have not touched the boost controller, as he told me not to, since the tune. Also, another question. If I get the Forge WGA, it won't help me, at all?

 

what boost gauge are you running?

 

There's not really anything for the Forge WGA to help.

The TXS MBCs in no way compare to the Hallman or Forge UNOS. They do not work well at all, so not sure where that sentiment came from. You can read countless threads on people ditching their TXS for a Forge or Hallman BECAUSE of the bleed hole (it's a negative thing, not a positive).