Turbo 350 or 400?
 

Which is better, a turbo 350 of 400? I have a 355 ans I have a chance to by either one.

Re: Turbo 350 or 400?
 

The 400 is just Heavy duty...

Honestly I'd look into a 700r! That overdrive sure would be nice....In my 85 3/4 ton I'm running 3000 rpm at 65 with a 350 engine/400 trans and 4.10's!

Re: Turbo 350 or 400?
 

400 is the better tranny , depends what is in there now and if your willing to change things to install a different tranny . If it has a 350 now there is nothing wrong with them either ,not as strong but still ok

Re: Turbo 350 or 400?
 

The Turbo 400 is definitely the beefier transmission. I suggest it if it's at a reasonable price.

Re: Turbo 350 or 400?
 

Depends on how much horsepower you are making ?

I have a T350 behind a 550Hp 408 and it works great.

the t400 takes more HP to turn, and is heavier, but if you have a high HP engine then the T400 is definitely the way to go

So if you are under 500 HP go for the T350, its lighter, and uses less HP

Put a Shift Kit in it while its out, and put a Deep Finned Pan with a Drain plug and a good Trans cooler in it... also put a Converter that matches your Hp / Torque curve.

Its a pain to do those things after you put it in

Re: Turbo 350 or 400?
 

Id love to see a vid of your truck. I LOVE 408 motors. PM me if you have any.

Sorry for OT.

Re: Turbo 350 or 400?
 

put new seals in it while its out as well.

Re: Turbo 350 or 400?
 

Either way you can say your truck has a Turbo ;) :lol:

Re: Turbo 350 or 400?
 

Yes.
IMO depends on the usage and what the truck is equipped with now. My 4wd it didn't make financial sense to swap to a tbh400. Trying to find the correct adapters and whatnot, it was much simpler to just have the tbh 350 rebuilt.

In hindsight, the OD would have been nice....

Re: Turbo 350 or 400?
 

Re: Turbo 350 or 400?
 

I have a TH350C (with lock up unhooked) in my 82 K10 It has a 454 bolted to it and hasn't giving me any fits since I fixed the front seal leaking. I think the TH350 is a great transmission and like jrcaprai stated if your not making huge horspower the TH400 is not needed.
But if you want to swap go to a 700R4 your going to have to shorten the driveshaft and move the trans crossmembers anyways. Let us know what you do.

Re: Turbo 350 or 400?
 

I think in stock form the 350 has a lower first gear than the nearly bullet proof 400. Both are great transmissions, if not doing heavy towing and your under 400 HP i would do the 350.

Re: Turbo 350 or 400?
 

I have a th400 in my sisters 71 nova and with 4.11 gears... it'll spin the tires all day.

Re: Turbo 350 or 400?
 

350's are fairly tough and light. 400's are the toughest, and heavy. 700r4 can be built tough and have overdrive, and have a wicked low 1st gear. Depends what you want it for I guess, you can build them all to last. Whatever you end up with, put an aftermarket tranny cooler on it and it will last longer....

Re: Turbo 350 or 400?
 

each trans has their advantages and it really depends on how you use your truck.

like mentioned above the turbo 400 uses up more power to make it work than the th350.

th400 is better if you are hauling heavy stuff and or pumping out alot of torque and horspower.

th350 is best if you are running a healthy motor and driving around town, haulin lighter loads and wanna save on gas mileage.

i would run a th350 anytime unless i was haulin heavy stuff up hills all day long.

Re: Turbo 350 or 400?
 

The TH350 is one of the best tranny's ever made. It will hold up to insane use and abuse. The TH400 is just as good and will handle more power and abuse, but as stated, that doesn't make it the best choice. It does have more parasitic loss. It comes down to what you expect out of the truck.

Re: Turbo 350 or 400?
 

i see only a few discuss the work involve in swapping a T400 from a T350. the cross member is an obvious one you can catch just by looking under the truck and making a few initial measurements.

what about shift linkage/cables, tranny cooler lines, will i have to change anything about the exhaust, especially if i have headers? i want to have the electric downshift of the T400 functional. i understand the shift solenoid on the tranny is hooked to a switch on the firewall. what kind of wiring do i need to do?

nothing is ever just a straight-forward swap. i picked up this 74 3/4 ton 4X4 with a big block. somebody had a T350 in it and i want to put a T400 back in. i would like to know what to look forward to.

sorry, don't mean to threadjack, but i thought this applied to this one.

Re: Turbo 350 or 400?
 

The problem I had with the swap is the different spline count on the transmissions. Iirc the tbh 350 is 27 spline and the tbh 400 is 32 spline, the transfer-cases weren't interchangeable without a lot of work. I would have also needed a new adapter for the trans/transfer case and drive shafts. As usual ymmv, this is what I ran into

If you have a complete tbh 400 setup for your 4x4 then go for it.

I didn't bother to check linkages or other connections. Measurements were comparing my K-20 to a K-30 in a grocery store parking lot. lol

Re: Turbo 350 or 400?
 

I think you have to consider the whole drive train - engine, trans, rear axle ratio. For gas mileage an overdrive transmission or stick is best, unless you only do city driving. For hauling and performance I liked my 454/400/4:11 combo - one of the fastest vehicles I have ever owned.

Re: Turbo 350 or 400?
 

Go Built th350! i went from a 700r4 with a 2500 stall to a crappy th350 with a 3500 stall and it still outran the 700, i finally got a nice built th350 with a b&m shift kit with my 3500 stall and wow what a difference, i cant wait to eat my buddys gt muskrat. Th350's have a lower first gear that the 400's and they take like 25 less horsepower to turn them, the way i see it the less power it takes to turn the trans the more power i can put to the wheels.

Re: Turbo 350 or 400?
 

Yo!
Ya wanna pull trailers and stumps,...install the TH400.
Squeeling about on the asphalt,...it's TH350 time!
Believe me.
FRANKENTRUCK needs the 400

Attachment 705508

,...my Camaro does not.
Todd.