How much power can the automatic transmission handle with just a valve body upgrade?
Would a torque converter be recommended?


I already have a twin turbo kit and the Transgo kit waiting to go on. I'm highly considering building the block. If I spend the extra money on forged internals then I'm going to want more out of the car except now the tranny is the weak point. Not looking to spend $4,500 on GTM's built tranny. And yes I know I should have got a manual but its too late for that now.

 

SFR also has a built trans for about $3000.From what ive read and from my own car i would think 450rwhp but its not the rwhp its the amount of torque and the limit is probably 400rwt.The big thing i have noticed after all these years of boosting is that you dont want the trans to be shocked by a sudden rush of torque.
I have always made sure i was in the right gear when getting on it hard and luckily my trans has held up with the v/b mod and a trans cooler.

 

I have a built auto with sgp valve body upgrade I'll be selling soon. If you'd be interested just shoot me a PM.

 

^PM sent
I've been researching SFR's for a while now too. I probably wouldn't mind paying $3K, but theirs doesn't come with a torque converter (if I even need one) and my car is going to GTM here in a few days to start the process. Maybe I'll just have the VB kit installed and get a mild tune then visit SFR once GTM is done. Thanks

 

I had just the VB upgrade and I could hold just around 420rwhp and then I could just start to feel it slip so I had mine sent to GTM and had their tranny upgrade done, they gave me a break on the price as they did my engine build also.

I have 139k on the car and had the tranny and engine put in around 70k....pushing 520rwhp and no complaints so far

 

^Quick question about the annual smog checks, if I temporarily toss my stock cats on will the car still pass? Will shops care if the mods are illegal if it passes the breather test?

Thanks for the help, looks like I'll eventually be getting a built tranny. I'll wait till I'm used to 370whp first.

 

We have smog checks every 2 years, I have heard it may pass the sniffer with the cats on but visual may be a different story.....especially in CA.

 

I have a GTM Stage 3 Transmission. I got it about a year and a half ago. I think the trans is good to 625whp.

I have a 3k Stall Torque Converter.


I kinda wish I had a manual at times too but since my knee is blown out I cant really work a clutch for more than 10-15 mins before I am a lot of pain.

I look at it this way, not to many people have TT Autos so it just makes your car more unique.

 

Update and change of topic:
Car has been boosted for 7 months and so far haven't had any issues with the tranny. Transmission is still stock with the Transgo VB. Car has been dragged several times and pushed hard on the weekends. Decided to build the short block after all and is currently at 467whp/465wtq @ 14psi. A 2.75"/3" dual exhaust will be going on shortly.
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I was wondering what the possibility was of snapping an axle with 285/295 street tires. On my350z, so far everyone I've read about breaking an axle has done so with DR while at the track. I've always dragged with street tires and won't be considering DR unless I have a built tranny and DSS level 5 axles.

 

Both my broken axles were with DRs on, alot of it also has to do with shocking the drivetrain. So without the dumping of the the clutch the auto maybe easier on axles than the MT. I would wait untill you break one until I got the DSS ones anyway.

 

I know the AT shifts softer, I don't have the wheel hop issue besause of it. My overall goal is 550-600whp which has me questioning the axles. But I'll keep the stock ones on for now. Thanks

 

auto are just fine on drag radials. Its the manual cars that break stuff on DRs

 

^good to know

 

The torque convertor absorbs a lot of shock from the drive line so we dont have the same problem as the 6mt's do.

 

Bump...
I'm having a hard time deciding on an exhaust setup.

I currently have the HKS dual (2.25") which is restricting the turbos. I know a 3" would be ideal but I'm trying to keep the noise level as low as possible. I'm planning on going with a dual 2.75" resinated exhaust with either 3" or 3.5" down pipes. As of now, I'm leaning towards the Greddy Turbo Ti-C. Any suggestions? Will 2.75" piping allow me to support 570+whp?