Transmission Stock Capacity
 

Hey guys,

(search has been done)

After seeing the "FA20 stock capacity" thread tumble into transmission breakage talk, it got me really concerned on my plans to go the forced induction route. Though these fears are mainly sparked through only one source @Reaper.

As far as I understand it, the engine coupled with a really good tune seems to hold power really well (300 whp pump gas / 400 whp e85 or so on street driving). In my 2 years on the forums, most issues in general were tune/install related.

The diff hasn't seen breakage either and is a Toyota unit (apparently good for 500 whp, don't quote me on that though).

Unfortunately transmissions are the least upgradable part in the drive line and I think it would be really interesting to try spark discussion on what it is capable of. My personal targets are around 250-300 ft.lb, I understand any increase in power will technically lead to a reduced life and there are many variables to pin point an exact number but it would be interesting to know what you guys think about what torque level is considered "reliable" or "bulletproof"

:thanks:

i think 300whp is limits of gearbox for both manual and automatic for long safety.
this means max boost with E85 should be under 9psi.
i think 7.5psi is good like avo kit for stock engine

Torque is what breaks gearboxes. At 300whp you're at around 220-240 ft/lbs torque.

I'd bet that 400 whp and 300 torque are prett safe numbers, depending on how you drive. These numbers as a drift car with lots of clutch kicking, maybe not. Same thing for a big, sticky tired road race car, where the box would get super hot.

For street and AX and general hooning, I bet 400whp and 300torque are pretty safe IMO.

Stock cars are getting transmissions warrantied for excessive syncro wear.

400wtq will shear 4th with street tires everytime. I did it with 460whp 393wtq in just a few thousand miles on hankook ventus v12s. Not a grippy tire.
@Synack sheared 4th with only 350whp I'm not sure his torque. He has stock suspension and 19 inch wheels. So he can't have too much grip.

My first transmission the syncros died. Not power related at all. A faulty part.

My second transmission had bad syncros as well and I sheared 4th while in boost.

My 3rd transmission that's in the car now is a used one with 19,000 miles and shifts smoother than all the others. I've put 1000 hard miles on it and it hasn't broken yet. With stock fluid in it.

The box is very very weak.

Element tuning blew one up at around 400 hp and started running a cooler. I'm running a similar setup now and it's thermostatic but I haven't gotten it hit enough to turn on. It's been in the 30 and 40s here with cold slippery pavement. I don't think it's going to do much good honestly.

I'm well educated in every available transmission swap for this car.

How do you drive the car?

Why not do a permanent fix instead of band-aids every time?

Hard but generally I'm easy on the box. I also don't have grippy tires at all. Im on 245 hankook ventus v12s for crying out loud. I figured an axle would have broken first. I also haven't tracked it and I run a sprung clutch. I've used flat foot shifting once and that's when I stripped 4th.

8 - 10k for a v160 swap. 5.5k for a tremec swap and there's no guarantee it will shift past 7k rpm. Holinger quoted me 20k, so did quaife. I've only spent 500$ so far on transmissions. So I could buy 12 transmissions for the price of just a v160 box without the adapter kit.

You want to give me the other 15k $?

I'm also working with a few companies to build gearset for the stock box and waiting for that to pan out.

So is Quality control just shit for these syncros or what?

Yes.

We need a cryo-treatment option.

If you read the 4 other transmission threads you'll see its been done. Doesn't work. Factory gears are as hard and as strong as the space available allows them to be.

Sooooo....QED iconel gear set anybody? :bonk:

Inconel is not stronger. I've used Inconel in other applications before.

Nah bro, MP35N gear set.

What is the strength of the gears being used? Inconel is fairly strong, we use 718 fairly often with a strength around 120 ksi yield for some of our oil equipment. Of course these materials have to meet NACE, so the strength is artificially limited for those applications.

It's tensile strength is only superior over 700*F otherwise it's a waste and the manufacturing cost difference is huge.