I was wondering how hard people have pushed the t31 4 bolt turbine housings in horsepower terms . I run this housing on my GT30 with the .82 housing . It seems to be choking at 520 whp . I have just gotten the unit back from Forced performance as they massaged it with the billet wheel and bigger compressor housing . This mod seems to be a big waste of $700.00 and im not very pleased about it . So i have to assume that back pressure is getting the best of me here . Any one who knows the answer here please by all means feel free to advise me . Thanks ! Oh and the engine is a b18c 1.9 liter .

 

Those take about 520whp on the stock GT30R. Only about another 40-50 on the HTA GT3076R. Don't know what you were expecting, but about 560whp is about good as you're going to get. Backpressure isn't the issue.. You're maxing out the turbocharger, not the housing. trying to change it to a GT v-band or TiAL v-band will not help your situation.

 

So how far have you seen a standard t31 4 bolt housing go in terms of horsepower ? 600 + whp ?

 

People can fit t4 p-trim wheels in a t31 housing.. So you can make a good bit of power. But mac is right, you're at the limit of your current turbo... The gt30 compressor map ends at 32-33lb/min. And that's what the turbine wheel is sized around. You could try going to a larger turbine housing to squeeze a bit more out with your New billet wheel but don't expect a lot

 

On both journal bearing and steel balll-bearing cartridges have made over 670whp. Even the larger 67mm use those. Again, it's not housing type, it's the limit of your turbocharger

 

Thanks Shodan , that was what i needed to hear a solid answer . I am having trouble holding boost pressure past 6.5 k it simply drops down to 23 psi when im trying to run 26 -27 psi . Im thinking its my apexi avcr boost controller that is giving me the problem . I doubt my Tial 44mm gate is causing these issues . Forced performance told me i should have no trouble maintaining a solid 26 - 27 psi all the way to 9k . This would put me around 560 whp like stated before and i would be happier about it .

 

more than likely a small exhaust leak. I LOVE the AVC-R boost controller. Check your duty cycle settings as well.

 

At the track this past weekend i had the duty cycle at 90% ..... yes thats everything the controller has and it didnt make a difference .

 

Boost solenoid is the way to go! I had boost issues before, some days it ran off the gate at 1bar and other days it would run at 21-22psi. Car was tuned at 22psi but wouldn't hold correctly, guess my MBC malfunctioned. At first we thought it was the positioning of the wastegate, but I wasn't going to pay that much to reposition it. I spoke with Jesse of JDL Designs, formerly of AFI Turbo who made the turbo kit, and he assured me it was the newer designed manifold and should not cause boost issues but I wasn't sure if he was trying to just get me off his back. So I opted to the cheaper route and installed the solenoid, $90 for solenoid + $350 for retune = $430 as oppose to $300 to fix wastegate position + $350 = $650. A new PB, Joker smile, and big head later, my car now holds 30psi without any boost issues at all. I take it back, there is one boost issue and that issue is that I can't stay out of boost! Oh yea I forgot to mention, I too have the t31 housing with a 0.63 A/R and am pretty much maxed out on a 61mm compressor wheel. With a 0.82 A/R hot side I would say it might see a touch over 600hp. And of course, this is all on race gas.

Mac, I'm still saving up so that I can have you upgrade my turbo. I know we've been talking on and off about it over a year span or so, but I do have some more questions for you about the upgrade so you will be receiving a PM from me in the near future.

 

What base spring do you have in your wastegate?

 

Then that means that the spring you're using is too small, if the solenoid is at 90% duty and its starting to drop off. You need a slightly stiffer spring, (higher .bar rate) to compensate for the drop.

Pretty easy solution. Nothing to do with the housing at all.

 

Current spring is a .7 bar or 10 psi . I wonder if a 12 psi spring would be enough . I like to run low boost on the streets 12-13 psi but do run lower boost for 1st and 2nd (boost by gear).

 

You guys and this Boost By Gear..... listen.. You cannot get 26-28psi of boost when you're trying to get 8-12psi on the first couple of gears. That spring on the wastegate can't do both like that. There's a balance with this when it comes to holding steady boost pressure at higher levels, and still using a lower boost pressure to help you in gears that won't matter anyway like 1st & to a lesser extent, 2nd gear. (Just my rant of MHO).

You'll need a 1bar spring (14.7) to maintain your 26psi setups with repeatability and consistency.

 

Well thank you for that backhand .... lol i guess i can get this spring and if it works then great and when the car is on the streets ill just swap out the spring back to the old one .

 

Yup, that's why I have a 1bar spring in mine. My tuner setup my BBG as 1bar ramped to 18psi toward the top of the gear in 1st, 2nd gear is set at 24psi, 3rd, 4th, and 5th is at 30psi.