Sorry for the newb question but I cant seem to find it by seraching the site.

I read that a standard tranny wont hold up to a TII motor hp. Yet there is only a 40hp +/- and 43+/- Ftlbs of torque.

I just want to know how far I can push a NA tranny before I need to think about stepping it up.

Is there a number that people use as a "Dont go over "XXX HP" ...

Thanks
2988008

 

Generally 200whp is considered to be the outside limit for a NA transmission.

It will hold more than that without breaking, but you have to be gentle on it. If you're rough with it, even around 200hp, you can break it.

There are people who have run 250hp or so through a NA transmission (I think Kevin was pushing something around there), and they'll last for a while (year or two) if you're gentle, but eventually they break. IIRC the common failure mode is the teeth sheering off the countershaft input gear.

Another factor is that a turbo engine puts a lot more torque through the transmission. A 200hp NA is generally making that kind of power at 7000+ RPM, whereas a turbo engine can be making 200hp at 4000-5000 RPM - a lot more torque on the input side.

-=Russ=-

 

^ +1 Torque breaks things, not HP. Moreso, shock breaks things too. If you're gentle, when you shift and come on power, the tranny won't break until there is enough torque to twist the casing enough to seperate the gears enough to shear the teeth. That's a LOT of load. But who drives like little girls?

 

Kinda what i figured but even the torque numbers had me wondering.
Can a NA tranny be beefed up during a rebuild to handle more torque?

Thanks
2988008

 

Sure but a TII trans is way cheaper.

 

Im not sure if it will work, but flying miata has a beefed up gear set for the Miata tranny. IIRC the FC na tranny and the miata 5 speed are very similar.

http://www.flyinmiata.com/index.php?...0500%20%20WIDE

For $2500 though, you are better getting a TII tranny.

BC

 

im running about 250 whp through an na trans. so far so good but its only been going for 1k miles.. im gentle on it but i have a couple drift events this month so ill let you know. i have a turbo train waiting for when this snaps though so im not too worried

 

I use to run 280 Rwhp through mine.
First lasted about 6 months then blew 2 more in about 1 month.
Have now got a Turbo one and its fine on 340Rwhp.

dont waist your time with them, change to a Turbo one.

 

Not easily. There's a difference in the metals used in casting the gears. I haven't torn apart transmissions, but if I recall pictures I've seen, the NA and turbo transmissions are basically identical, it's just the turbo transmission gears are cast from a stronger (but more expensive) alloy.


If I were a betting man, I'd place good money on the NA trans not surviving the chain of drift events.

I assume you have a way to get the car home when the tranny explodes mid-drift?

Actually, depending on the distance/driving, *most* of the failures involve the input gear to the countershaft failing, which leaves 4th gear. If you're careful, you can start from a stop in 4th, but it's hard on the clutch, and not suited to stop and go driving at ALL.

-=Russ=-

 

Great info guys. Thanks.
Will look for a deal on a Tii tranny.

 

i know someone that was running abuot 250 whp on the n/a tranny

 

Syonyk im not trying to call you out or anything, but ive read on past threads that the t2 and n/a tranny gears (not gearing) are pretty much identicle, but the housing is just beefed up on the t2?? ive kinda been looking for a straight answer on this same subject.

lmao this sounds brutal.

 

TII tranny and N/A tranny are not even close to the same internally, externally, or otherwise.

 

They're not even close to being the same on the inside. You think the extra 30+ lbs comes from more meat in an aluminum casing?

 

well your talking to someone who hasnt seen a t2 tranny up close, i said i wasnt sure about it its just what ive read, im not trying to fill this thread with misinformation just looking for clarification, and thank for it.

 

I blew my NA tranny and diff from drag racing with a 4 puck clutch. Stay away from puck clutches, they are hell on the car.

 

Ive driven 6 puck clutches on my n/a before and I am currently driving a 4 puck, without any issues. This probably only applies at the track when you make great traction.