Forced Induction gains and 7AT
 

I've posted this in the "development" threads, and it doesn't get answered, so, here it is.

I and a few others on here have the 7AT...how much power can those handle before they pop?

I'm thinking of going with the GTM Twin Turbo setup, or, potentially a supercharger when one comes out.

But, if the tranny can't hang, then it'll be headers/HFC's/catback and call it a day (or maybe trade it in for a 6MT and lose my ***...)

Good question! I wonder, too. I'm at that point now.....bolted myself to the max on my Z.....only FI left...if I decide to go there. I will consider the Cobb AccessPORT when they finally have it available and an ECU flash.

According to my last DynoDynamics numbers I was sitting at 307 whp....not bad....but I'd like to squeeze a lil more out, if possible.

The 350Z's AT was only good to about 400 to 420 RWH before mods were needed. I'd hope that the new 7AT handles more power. Another problem with the 350 AT was that when you went FI, the slower shift speed of the tranny would allow the RPMs to jump and hit the rev limiter when shifting under full acceleration. The fix was a throttle body upgrade on the tranny and/or a software change to the rev limiter level.

That shouldn't be an issue with the 7AT as the shift times are pretty quick.

Pardon if this a dumb question.

Wouldn't the extra gear also be a factor to the amount of power the tranny can handle from a turbo??

Hopfully so. From what I've read, the full shift time has dropped about 500 milliseconds between the two trannys. That's an incredible improvement. I think the same 7AT is used in the FX45 (390 HP stock). If so, I'd imagine it's power handling has gone though the roof as well.

Look on myg37.com you will find a pretty good answer there. But you can expect slightly more gains due to less power throuhg the drive train on the Z compared to the G.

Kinda hard to squeeze more out when you have to drive on a cushion :rofl2:

:shakes head:


:roflpuke2:

no one knows is why your not finding the answer. When one pops then youll have your answer. You could do the community a favor and TT your 7AT, push that boost way up until the tranny goes splat then we can all answer this question:bowrofl:

Sure, if everyone on the forum donates a couple bucks to the cause for a replacement transmission, and can wait until the end of next year when I'll have the free money to buy a TT kit ;)


:tiphat:

I know this is an old thread and I dont even own a 370z but this info may be relevant: Stock 2009 Infiniti FX50 S AWD Dyno Sheet Details - DragTimes.com

I believe your 7at is the same as in the fx 50 which appears to dyno at 329hp and 299lb-ft on a dynojet according to the above dyno chart. Torque tends to be more important then HP in transmission longevity so it stands to reason that if it can handle a stock 5.0l fx50 with 299lb-ft it probably has some engineered in cushion for more torque. Granted that was a dyno jet and not a mustang dyno..... hope this helps

EDIT: off to my regularly scheduled lurking... see you all in 6 months.

Well, given the torque of a stock Z is 269ft-lb, that leaves only about 10% gain before hitting that 299ft-lb transmission spec.

I assume there is some margin of "over-engineering" built in, but, how much?

I mean, we're only talking a fwe percentage points of increase before something could go pop.

10% seems "safe" in terms of torque gain. Will a supercharger do more than that - probably...it's only a gain of about 30ft-lbs.

I'm sure with bolt-ons people are seeing that much.

I posted that same question and never got a clear answer. I suspect that someone will offer a package to build the tranny to sustain higher HP numbers.

I would think the 7AT could handle 450whp easily, But thats just me



DAN

Well, the difference between think and uh-oh is only about 15K...assuming a new transmission and a FI system that you can't use without blowing another tranny ;)

Im going based off of the old tranny and its power handling capabilities, also this is the trans out of the FX50 is it not?


DAN

I am going to mostly agree with Lug I would bet that the trans can handle somewhere between 420-430 HP. Now the real question is how much torque can it handle. reason I say this is because most trans are rated by how much torque they can handle, the Z's don't put out an incredible amount of torque stock but adding F.I. will drastically increase the torque that the drive train has to handle therefore adding much more stress.

We can speculate all we want but until we start seeing high hp/tq or F.I. cars dropping trans and looking at what numbers they are killing them will we truly know the answer. Add to that driving style will have a lot to do with how well the drive train handles the power as well. if you are a street light racer every light and push your car regularly you may see a failure at a lower hp/tq level than someone who is a less aggressive driver.

So really who knows do some research as Lug has and we can add lets say 20-30% over engineering to what they are handling stock and that is probably a safe number to stay around for starters at least.

the factory engine torque is 270lbft but the rear wheel torque (as was measured by the fx50 dyno or a 370z dyno) would be less in a Z ~230 ish.... remember a stock engine torque rating for the fx50 is 369lbft.... or about 100lbft more at the engine then a Z.... Even if this translates to only 70lbft at rear wheels (as evident by the dyno) that is a substantial built in margin. Thats why I posted an actual dyno sheet of the rw torque rather then the official values, but even so the engineerd cussion would be above the fx50's value...380-390lbft at the engine would be a very conservative guess ie about 320rwtq... ok last post for a very long time.

EDIT: Interestingly that Greddy turbo kit looked to be about 330-340rwtq at about 450rwhp and 6.4psi.... so just dial back to 4.5 to 5 psi and you theoreticly should have a 400rwhp/310rwtq car. Still would be very very quick at 3200-3300lbs.