Manual Boost Controller Recommendations?
 

So I'm currently pushing close to 6.5 PSI with the 91 octane tune with the GTM Stage 2 TT. That's about 400 whp so far, and it's so easy to daily drive (probably boost every once in awhile haha since it's pretty conservative). I'm hungry for more so I'd like to kick it up to 8 PSI. Is anyone pushing ~8 PSI with the 91 octane tune?

I'm going to try to resolve the clutch issues first before kicking it up. [sigh]

I knew you would. :happydance:

Boost is like crack, except the first shot is usually not free. Haha.

I've never had great results with a MBC. I've run 3-4 different set ups on my turbo mazda, all had a little boost creep and boost spikes.

I decided to go electronic and went with this:
HDi

it's a dual stage EBC that runs about $100 more than a good quality MBC. I think I got mine for like $150-200. Pretty easy to install. Unit is pretty small and will fit in most discreet locations. It allows you to switch between two different boost settings with just a push of a button.

Adjusting the boost for each setting is a simple as turning a knob, then pushing the knob back in to lock it in place. It can be done on the fly - makes it much easier to adjust as weather temps change - here in Dallas we've had a 25 degree temp shift this week.

There are individual knobs for the two different settings. The low boost knob allows for a lot of turning without much adjustment. The high boost knob is exactly the opposite, little turns make a big difference.

On the low boost setting I'm seeing about a quick 1-2lb boost spike on initial full throttle. Spikes at about 11psi and settles in at 9-10lbs. Boost creep is pretty minimal. Seems to hold the set psi no matter which gear I'm in.

On the high boost setting I'm seeing a 2-4lb boost spike on initial full throttle. Spikes at about 14-15lbs and settles in at 10-12lbs. Creep is a little more on this setting. 2nd gear seems to hold at about 9si while 4th gear will be the desired 11-12lbs.

All in all I'm pretty happy with it. I run the low boost setting most of the time, and just push the button when I need to make a statement.

If it were me though I would probably opt for a better EBC for the Z and stay away from a MBC all together. A 4psi spike isn't so bad on a T25 turbo in a car making maybe 250 WPH. A 4 psi spike on a car making closer to 500 WHP might be a bit too much to handle. For me the Z is worth the added security.

You could also think about changing out your waste gates. If you only want to run 1 set level of boost all the time this is probably the best way to ensure you don't ever overboost.

Personally, running a NA car with aftermarket FI, I would opt for a nice electronic boost controller, like the HKS. I am vary wary of not having very fine control of the boost on such a setup.

I just want to set it and leave it at ~8 PSI. Original plan was the EVC 6 set for low and high boost, but I never imagined the car being this easy to drive. After driving the car with 6 PSI I don't mind more for daily driving simply because I'm hardly in boost. Even if I am in boost, it's hardly at full throttle or even long enough.

So in part, I don't feel the need for EVC and want to drive it as if came boosted from the factory, but at ~8 PSI. :)

Methods?
Tightening the wastegate spring -> MBC -> EVC

If you just want one setting then a boost controller of any sort isn't really needed.

Are you running external waste gates? If so you just need to change the spring.

I have the Turbosmart external waste gates and I'm using a 7lb spring. That is giving me a nice and steady 8psi.

:yum: It's the wastegates that came with the supplied turbos, so I'm assuming this is internal? Sam even suggested adjusting the wastegate spring, but the biggest drawback is accessibility.

The local shop is going to install GTM Stage II on a 370Z soon. I'm told they've done installs for 350Zs, so I'll get with them in a few months or even in the Spring to see if they're comfortable working with the wastegates.

The last resort is MBC. I just wonder if anyone used one with our cars and are running 91 octane map.

If you only want to run 8 psi, just swap the springs, Or get a greddy profec b and be done with it.

what's wrong with your clutch?

Every once in awhile I get stuck getting in or out of gear. If I get stuck getting out of first, I let the car roll back or forward and it'll be fine afterwards. It gets notchy once in awhile, but it is still drivable.

Have you checked your tranny or motor mounts?

When in neutral does your shift knob remains dead center or is it leaning towards one side (fwd, backwards, left or right)? Do you feel "shorter or longer" travel when engaging any gear or do they all feel about the same?

..Or does the pedal get stuck at any position?

The shifter feels fine to me, but the rubber boot from underneath the car somehow caught something and ripped off. A new part is in, and my car is due for service this Friday to get it replaced.

I also told them about my issues, and they'll look into it as well.

As for the shifter, it looks and feels fine. There are no issues with pedal pressure. To check to see if the clutch got stuck to the flywheel, I pressed the pedal down in gear and revved it a few times. No movement, and the RPMs are fine.

Here's a stupid question... if I want to get an MBC, then I would need one for each turbo? If so, then I should be better off with an EBC?

I've used TurboXS MBC's in the past with good results. I always prefer a lower spring in the w/g and controlling boost via MBC or EBC instead (like most others).

I'm going with an EBC on this car, for the first time. I like the options and in-car control in spite of the higher price.

EDIT: No, you only need one boost controller for TT. The output just needs to tee off to connect to each w/g.