Hey guys!
Pretty new G35 owner compared to the rest of the community, my current ride is a '03 5AT with intake and exhaust (HFCs and catback). When researching future power adders (forced induction) I realized that my biggest limiting factor will ultimately be the transmission, long before the crappy connecting rods. The general consensus seems to be that the 5AT in the V6 vehicles is rated for 333 ft-lbs of torque from the factory. Now, if one was able to keep this moderately low torque all the way up until redline, then you're looking at nearly 420hp at the crank, but we all know torque falls off hard in the high rpms, especially with the stock cams, and with drivetrain losses from the 5AT, this 420hp becomes barely 350 put to the ground.
My question is, what limitations have people who boosted 5AT vehicles found? I know the transgo shift kit gives you a little more headroom for torque, but its annoyingly hard to find old discussions about actual data and numbers. I also want to know, how much reliable power have people ended up pushing with just a shift kit installed? There's so many factors that feed into the weakness of the 5AT, and I really just want to see what has been done and what is possible.

 

Get a plenum spacer, transgo shift kit, and Uprev tune (I can help with this part), then see how you like the car. FI on this platform is already really expensive, and with a 5AT it can get really really really expensive really fast.

 

well i mean i wasn't intending to go FI super soon, i just want to future proof my plans. I've been toying with the idea of a PD style blower using the universal plenum that SWS motorsports is developing. It has crazy potential and with their intercooler opens up a ton of possibilities.
I was planning to get maybe a shift kit and some intake upgrades this summer, but full FI, is too risky for now.
I am very aware of the costs of this platform, but I'm trying to find examples of 5AT builds because people rarely write on them. One of the sticky threads in the FI category does actually mention a lot of 5AT builds hitting like 400whp stock, but considering the factory spec I just cant take that to be real. It's hard to find well documented cases of 5AT builds with just a shift kit proving the true limitations, thats really what I want to know.
Shift kit honestly sounds like one of the best future proofing mods I can get right now though. It prevents slippage through increased line pressure and allows for a more engaging driving experience than the stock 5AT, I just need to figure out what local shops will charge for an install...

 

They don't last... Pretty much every 5AT build either ends up with a fully built trans or in the scrap heap

 

fair enough, If i want to dump heaps of money into this car and still keep it daily driveable, i either deal with not having an unfathomable amount of power, or manual swap, because any auto trans from other cars costs just about as much as buying a new car lol.