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Turbo TH350 vs. 4L60E

This is a discussion on Turbo TH350 vs. 4L60E within the Automatic Transmission forums, part of the Drivetrain category; Originally Posted by shiftless Not true. The 400 is much stronger in stock or modified form than the 350 because ...

  1. #21
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    Quote Originally Posted by shiftless View Post
    Not true. The 400 is much stronger in stock or modified form than the 350 because it has a center support.
    You are right. What I meant to say was that the 350, in modified form, will be adequate to handle most any street car.

    This is true. I think you'll find though that when rubber meets drag strip, the 400 really isn't any slower than the 350. Maybe a tenth or two at most. In my opinion (and yours may differ), the extra reliability and peace of mind is WELL worth the small horsepower loss.
    Mine does differ, but simply because I don't get any more peace of mind by throwing a 400 in a car, because I have faith in a good 350. Therefore, in my mind, putting a 400 in a car is just a waste of horsepower.

    600 HP on a small block, sure. It will probably handle it with the right mods. 600 HP behind a big block? No way. A big block will eat a 350 for lunch, whereas the 400 will last just about forever.
    I realize that on a good day I'm half retarded, and thus this doesn't make sense to me. Why would a 600 HP rat motor tear up a 350 while a 600 HP small block won't? We sprayed the 383 with 150 shot on multiple occasions, and the 350 handled it just fine. Do you mind elaborating a little more on this?

    I think if you built a big block race car, or a really powerful (700-800+ horsepower) street car, you might feel differently!
    Fair enough. Though like I said earlier, in a car with that much power, I'm going to use a powerglide. That car that had the 383 in it now has a 445 small block which put out 860 hp on the dyno. It has a powerglide.

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    Quote Originally Posted by EZ2NV View Post
    Why would a 600 HP rat motor tear up a 350 while a 600 HP small block won't? We sprayed the 383 with 150 shot on multiple occasions, and the 350 handled it just fine. Do you mind elaborating a little more on this?
    It's because a 600 HP big block generally turns lower RPMs, and makes more torque, than a 600 HP small block. The small block does not hit the tranny as hard as the big block does. For this reason, a stout big block will tear up a 350 in a hurry, even a pretty well built one. The 400 wins here due to the center support, beefier planetaries, etc.

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    A+ for any 82-02 f-body that has a built 4l60e. I've been running 11's all year with the built tranny and get 23mpg on the highway.
    2000 auto camaro
    13.54 @ 104 2.049 60' stock 2.73

    12.94 @ 109 2.002 60' full exhaust, lid, tune, nitto 555r 2.73

    11.899 @ 114.44 1.686 60' full exhaust, lid, tune, nitto 245/50-16 555r 3.73 moser 12-bolt 2800 fuddle, ls6 intake manifold, slp under drive pully,fiberglass hood, bmr k-member

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    Quote Originally Posted by knappbunch View Post
    I have heard that the 4l60e is basically a turbo 350 with overdrive and the 4l80e is the turbo400 with overdrive is this true???
    Yes and no. There are a few similarities between the 4L60 and the 350,,,but the gear ratio's are completely different.

    4L60 has 3.06, 1.62, 1.0 and .70 overdrive.

    350 has 2.52, 1.52 and 1.0

    But the 4L80 and the 400 are very closely related. The 400 was the basis when the 4L80E was designed,,,therefore the gear spread is identical with the exception of the 4L80 having an overdrive.

    Both have 2.48, 1.48 and 1.0,,,,with the 4L80E having an extra overdrive gear of course. Some parts also interchange between these two transmissions as well.

    I like the 350 turbo, it can be built to handle some HP as has been mentioned. But to be honest here, I am a tried and true 400 turbo guy.

    Been building these transmissions for years,,,with very few modifications and very little cash they are damn near bullet proof.
    It takes quite a bit of cash outlay to get a 350 turbo to this level and in my opinion just doesn't make them cost effective.
    Yes the 400 takes more power to turn, but if you want to throw money at a transmission (as you would a 350 for same durability) this power loss can be more than compensated for with lighter aluminum rotating parts inside. This is done with alot of builds as well as different gear sets for the heavier cars,,,as much as a 2.75 first gear,,,second gear is also changed as a result.

    I have 5 cars in the stable with the 400 turbo. One of them a tow vehicle for a 10,000 lbs. trailer, still sporting the original tranny in a 30 year old truck,,,can't say enough about it.
    Another is a low 11 second car at a buck18that weighs 4,108 lbs. cutting 1.5 60 foot times. This particular 400 turbo that I built has been in the car for over 20 years now and still kicking,,,car has seen 4 different motor combos of various power levels over the years with the same tranny I can't say the same for the 350 turbo I had in the car before that.

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    Quote Originally Posted by shiftless View Post
    It's because a 600 HP big block generally turns lower RPMs, and makes more torque, than a 600 HP small block. The small block does not hit the tranny as hard as the big block does. For this reason, a stout big block will tear up a 350 in a hurry, even a pretty well built one. The 400 wins here due to the center support, beefier planetaries, etc.
    I'm sorry, but I'm going to have to strongly disagree here, too. I personally know of a big block running 9.80's on a 350 turbo with nothing more than a shift kit out at Tulsa Raceway Park. Granted, eventually the basically stock 350 will give out with that much power, but as of right now the guy has like 15 or so passes on it with no problems. I also know of a guy who runs big inch motors (500+) that run in the mid 9's on built 350's with excellent (and more importantly consistent) results. According to my tranny guy, who has been building racing tranny's for over 10 years now, there is no reason to use a 400 for anything other than a boat anchor.

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