safe boost levels with GTR tranny

[bogaut]

wondering whats a good amount of boost to run on my awd, with GTR transmission. right now its at 15 psi on a GTR motor/turbo/management and rx7 460s, how much higher could i set the boost without having to worry about blowing things up?

[DuRWooD]

I'm sure you could break it at 15, and I'm sure it can take 20 from what I've read on here.

[jay]

I wouldn't go more than a couple psi beyond that with those injectors no matter what gearbox. You'll melt pistons. I'm using 550's @22-23psi on a Link standalone and prolly a bomb waiting to happen duty cycle. I've blown up one centerdiff so far. The other gearbox failure I've had in this car was due to prior damage when that box was in my rallycar, so it don't count...
Driver has more to do with how much power can go through, and how long it'll last, than anything else. Keep up on synth gearlube and keep it fresh, that's about all you can do maintenence wise, the rest of it is how you drive. I never hard launch, I never speedshift, I match revs, I try and remember that it's made of glass, and I thrash on it anyway, but at least it'll last a bit longer fore it blows up. So far, the current gearbox has been putting up with the abuse for almost 4 years and 2 sets of tires.

[bogaut]

Yeah I never launch it. I guess I'll be on the lookout for some bigger injectors. I'm thinking 20 psi should suffice. This thing already pulls like mad at 15. also not running the gtr knock sensor. should i be concerned ?

[jay]

Mmm... I might worry about it but only a little. I mean if you had knock that the sensor woulda noticed enough for ecu to back off timing, it woulda blown already by now. As long as plugs and piston tops ain't showing damage, I guess I wouldn't worry.
But if you turn up the boost even a tiny bit all that goes out the window. Go find one, they can't be all that expensive.

[atomicEGT]

Grab the knock sensor and controller from an F2T since they're cheap and play nice with the GTR.

I have the same setup with an HY35 and ran 2.5bar with 10:1 AFR... YMMV I guess.

[bogaut]

What size injectors are you running ?

[atomicEGT]

460s, GTR ecu, A-code, EGT harness repinned to work with the ECU and wagon bull****

[bogaut]

dayumm wonder what percent duty cycles those injectors are runnin. i dont think i would be ballsy enough for 2.5 bar. cant find awd trannies at the jy :/

[atomicEGT]

Don't know, don't care. Plugs are golden brown, no signs of detonation, car hauls ass. Theory is that the stock FPR is 1:1 so it adds a pound of pressure per pound of boost. Who knows.

[bogaut]

yea im usin the stock bp fpr also. im prolly gonna hook up my wb02 before i mess with it anymore i think

[nerd racing]

I have heard that you can go with more boost on a larger turbo, the lag helps prevent shocking the driveline.

[jay]

Best way to avoid driveline shock is with a fulldisc sprunghub clutch. That and not giving it too much torque, which a bigger turbo will be only too happy to provide. Once the new ecu is installed in the rallycar and the maps are tuned and happy as can be with the 34mm restrictor in place, I fully intend, in the name of science, to remove said restrictor temporarily and make a map that puts out whatever it can get, to find the safe limits of 550cc injectors when the intake and exhaust have been opened up to reasonable maximums with a gt28r. Cuz I won't be worried about blowing up that gearbox!
I actually doubt if it'll be any faster than my street car which is pretty much right at or slightly beyond the theoretical limits for 550's. Injectors will be the limiting factor, and they're the same size. I'm almost curious enough to throw some 750's at the rallycar and make a map for them...hee hee hee

[nerd racing]

^^ do it, you won't!

I'm planning on running 550's with my T3 60 trim with the .63 exhaust side on a tubular ram horn @10 psi with megasquirt. (engine has high miles and I don't want it to pop on me)
I am still debating on going with 3" exhaust right off the bat. I'm running a GTR intake as well. This is all going through a BG GTX trans in my Festiva.

[atomicEGT]

I've got an un-blowed-up junkyard G-series that disagrees with the bigger turbo driveline shock theory.

besides, how does that account for all the dudes blowing up transmissions with baby VJ20 and VJ11s?