Disadvantages of a turbo 400

**Lawnman** · 03-05-2008, 04:28 AM

What are the disadvantages of a turbo 400 transmission over the standard a4 in a 2000 t/a ? The only reason I ask is I found a 2000 ws6 but it has a turbo 400 in it. I am thinking I am going to pass on it as of right now.

**mghawk57** · 03-05-2008, 04:32 AM

I thought for a long time about putting a Turbo 400 in my 2002 Firehawk with a 402 stoker with a Procharger,but did not want to lose my 4L60E overdrive.I know it is way stronger than the 4L60E.So it comes down to less mpg and less friendly on the highway.

**Lawnman** · 03-05-2008, 04:43 AM

I was told it tachs at 3k at 70 mph.

**ntimid8r** · 03-05-2008, 05:22 AM

Turbo 400's are stronger than the 4L60E for drag racing. The serious racers install TH400's but the street/strip guys just upgrade or purchase a built 4L60E.

**stoney2677** · 03-05-2008, 05:43 AM

Originally Posted by Lawnman

I was told it tachs at 3k at 70 mph.

have one in my 71 camaro its more like 60. normal driving youll be in 3rd by like 40mph with 373's

**Lawnman** · 03-05-2008, 05:46 AM

I had one in my 72 Vette and I would get around 12 mpg's . I hope the t/a gets more than that.

**Jays00ss** · 03-05-2008, 07:16 AM

My 71 SS elcamino has a th-400 behind a 540HP big block. They are bullit proof transmissions but if you do a lot of highway driving your rpm's will be up there, and your gas milage will suffer.

I say if you drag race A LOT or it's just a weekend warrior, they are one of the best besides running a powerglide, but if it's a daily driver, it's better to have a tranny with an overdrive.

**Lawnman** · 03-05-2008, 09:31 AM

That's what I am thinking. It is a pretty good deal on the car though, he is even throwing in the old 460le .

**Jays00ss** · 03-05-2008, 10:28 AM

Originally Posted by Lawnman

That's what I am thinking. It is a pretty good deal on the car though, he is even throwing in the old 460le .

Well hell, If he is throwing that in, I would jump on it. Best of both worlds there. Not talking down about the TH-400 (I would Love to have one in my car) But if you do not race, and daily drive like an old lady, The 460le is a better choice. What rear end gears are in the car?

**Lawnman** · 03-05-2008, 10:32 AM

3.27

**Jays00ss** · 03-05-2008, 11:01 AM

Originally Posted by Lawnman

3.27

Thats not too Bad, I would drive the car and see where the RPM's are at. My elcy, I am at 3300 Rpm At around 65 mph on the highway with 3.73's. That gear sounds pretty good with a th-400, + its a much better tranny than the 460le.

**mghawk57** · 03-05-2008, 11:38 AM

Maybe 3.23 ?

**Lawnman** · 03-05-2008, 01:18 PM

Yes 3.23 . I do not know what I was thinking.

**LS1 Hawk** · 03-05-2008, 01:29 PM

Having NO overdrive stinks. Not good for any long term highway driving.

**bamaz28** · 03-05-2008, 01:36 PM

i thought th400 was a overdrive?

**LS1 Hawk** · 03-05-2008, 01:47 PM

My older TH400 has only three gears and I hit 3k rpm at about 60mph. Maybe newer ones have overdrive.

**bamaz28** · 03-05-2008, 01:49 PM

well alright then, A TH350 is a 3 speed i thought the th400 was four!

**Jays00ss** · 03-05-2008, 02:20 PM

No a TH-400 is a 3 speed. I have had many of them over the years.

**bamaz28** · 03-06-2008, 05:04 AM

Originally Posted by Jays00ss

No a TH-400 is a 3 speed. I have had many of them over the years.

Turbo 350 is also a 3 speed built many of them, i wasnt sure about a Th400 never messed with one.

**408WS6** · 03-06-2008, 06:19 AM

I have a TH400 in mine. I really like it. The only thing I don't like is no overdrive for highway driving. But my car doesn't see much highway driving, and very little street duty so I'm not worried about it. If you want a bullet proof transmission and overdrive (have your cake and eat it too) you should go with a 4L80E. Its basically as strong as a TH400 but with over drive (and alittle heavier). There are drawbacks to the 4L80E though. Main one being cost. Look at spending about 4k for 4L80E and converter. You might be able to pick one up on ebay for alot less from a reputable seller, but buyer beware (and you get what you pay for). Also, if you have a '98, the PCM will not support the 4L80E and you will either have to shift it manually or buy a stand-alone PCM (I think TCI makes one), but these are very pricey, $900 I think. Can you tell I've given this some thought?

But there are other advantages to having a 4L80E: being able to lock up the converter on the dyno, and being able to electronically control your shift points. I can't tell you how many times I wanted to lock up my converter for various reasons. But at the end of the day, the TH400 is an excellent value and performs very well at the track (but expect painfully low dyno numbers).