TH400, TH350, 4L60E or 200R4 questions
 

I am looking to make 600+rwhp, 700+rwtq pretty soon on the bottle and I want to be able to run all night long.

Which takes the least amount of rwhp to run?

Can a 4L60E be built to handle that power?

I have heard of 200R4's being rather strong? True?

If you had to chose between a TH400 or Th350, which one? I want a transbrake, any strength difference?

On the 4l60e there are people running 10's not me but I haven't had near that kind of luck but i am told with the right guy building it can hold up to alot of abuse. I have seen 9sec. cars with 2004r in them also would be expensive to build one to those specifics and to have somebody build it. My experiences with Th400's and 350 are that the 350 takes less power to turn it and will handle 600hp easily. The Th400 is stronger and will handle more power but also costs a little more power. If you want to stay OD and have a about $3k to spend I would build a Ford AOD which they make cases to fit GM's. They are very strong but very expensive. If you want to go 3sd. and plan on making 700+hp go with a TH400. JMO later Clint

With that kind of hp in car as heavy as a Camaro (unless it's been gutted) you need a TH400. The problem is that there is no OD. If you must have an OD, there are two options, both heavy, bulky and expensive. The Gear Vendors overdrive unit or a 4L80E. If you are swapping trannys anyway, and are prepared to give up OD, I see no reason to bother with a TH350. It will cost very close to a TH400 and is not as strong. The number of people running fast and reliably with a 4L60E are very few and far between.

If you want more info on this, let me know. I just went through a major assesment of the tranny options, so I'm pretty familiar with the pros and cons of the different choices.

Rich Krause

Re: TH400, TH350, 4L60E or 200R4 questions
 

TH400 hands down. The TH400 will survive easier than a TH350 will and it's cheaper to build since you don't need to buy as many aftermarket parts. Not just any TH400 will do. If you're building one from scratch you need to mix and match a bunch of factory parts to have a really strong tranny. Over the years the TH400 had many variations of internal parts. Things like the direct drum changed in the very early 70's. After that, the direct drum used the weaker 9 element roller clutch silimar to the TH350. If you find an older 16 element sprag drum, you can install an aftermarket 34 element sprag. The TH350 never had this option so to make it stronger you need to buy the aftermarket drum and shaft plus the sprag.

Any transmission can be built to take that much abuse. The question is, just how much do you want to spend? You could just use a Powerglide but you will only have 2 gears which sucks on the street. The TH400 is 15 pounds heavier than a TH350. It takes 14-18 less horsepower to turn the TH-350 compared to a TH-400.

I use a TH400 with a transbrake. Transbrake's are not all the same price. From cheapest to expensive

Powerglide
TH400
TH350
700R4/4L60E (if you can even find one)

with what you have I would say a rossler t350 will do you just fine. I run a T 400 and am thining about going to a T350 because I loss 89 rwhp going from a 4l60e to the 400. I would have only lost about 30 going to a 350.

Stephen: I agree but want to point out that there is no way a street or street/strip 4th gen has enough torque (compared to weight) to run a 'glide. Unless someone slipped a blown rat motor in there, that is! Definitely needs three speeds.

Rich Krause

Performance wise it might suck but it would still work. Many 60's cars with PG trannies only had inline 6 engines. It depends if you use the 1.76 or 1.82 first gear.

Yes, the rather high first gear of the PG would need a lot more torque to get a heavy 4th gen moving. The very low 3.06 of the 700R4 is too much. With any sort of power, you can easily overpower the wheels if you have any sort of performance gearing in the diff. The best comprimise is the TH350 or TH400 and first gear ratios can still be changed. The 200-4R has been used successfully to push Buick Grand Nationals into the 9's but that's an expensive tranny to make it that strong.

Interesting information guys.

These leads me to ask if I were to get a TH400 or TH350, is there such a thing as more efficient and less power robbing torque converters?

I don't mind losing power if it will mean having a better car, but I want to keep any power loss to a minimum.

That's sort of a loaded question. A torque converter itself doesn't really rob power. It transmits torque from the engine to the tranny. 2 different converters both with the same rated stall speed can be very different. It depends how loose or tight the converter is plus what it's torque multiplication factor is. A 10" converter that stalls at 3500 rpm isn't the same as a 8" converter that stalls at 3500 rpm.

A higher stall converter will slip more at lower rpms. When operating at lower rpms, this slipping causes a lot of heat which isn't good for the tranny. For racing, slipping is good. My converter will stall at 5700 on the transbrake. I launch at 2500 rpm and the converter flashes to 5200. That lets my engine rev up quickly to it's powerband so the car can use as much power as the engine can produce quickly. If the car has to wait for the engine to build rpms into the powerband, it won't be able to use the power effectively. An efficient converter is only on the street and GM has already produced it. It's called a lockup. When the converter locks up, there is no slippage so 100% of the engines power is transmitted through the converter. Lockup converters are not strong enough for high hp drag cars or the ones that are, are very expensive.

You can always estimate that typical power loss through the drivetrain will be around 30%. There are many ways to reduce powerloss. Synthetic oil in the tranny and diff. Low friction pump in the transmission. Aluminum clutch hubs in the tranny instead of the cast iron ones. Differential choice will even change how much power loss reaches the wheels.

Stephen: your posts make a lot of sense, but I think there must be something missing from your account of losing 89rwhp going from a 4L60E to a TH400. There's no way it takes 89 more hp to turn a TH400. The difference must be the converter. Yes, the TH400 has heavier parts, so it will take a few more horsies to turn. But 89rwhp seems way too high.

What is the difference in converters between the two trannies? Also, how do the track times compare (since you can't race a dyno!)

Rich Krause

I lost 89 hp and I saw it right infront of me with the dyno, I dont know track times because I never raced with the 4l60e, it would have blown up with the power im making.

Where did you get 89 hp through the transmission?
The 30% drivetrain loss is the difference between the hp the engine makes and how much actually gets to the rear wheels. The transmission is only part of the drivetrain.

I meant to say that Stephen's post make a lot of sense but that I don't understand what Scott is talking about "losing 89rwhp". None of these trannys takes anywhere near that hp to turn. A very loose converter can give those kind of dyno results, or even more extreme. But not the tranny.

Rich Krause

thats loss with t400 and convertor

With a T56:

762flywheel - 670rear wheelHP (12.1% loss)

With a TH400:

762flywheel - 600rwHP (21.3% loss)

Net difference with TH400 = 70HP loss. And that is a non-locking convertor with more than 10% slip vs. a T56 in 4th gear. Odd a TH400 would cost 89HP vs. some other automatic.