Turbo 400/Duramax?

M

mick

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Aug 15, 2006
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Ive been contemplating for a while to put a Turbo 400 in my truck with an aftermarket O/D. I know they have been building TH400's out here for big hp for years. I paid about 12,000 $US to have a PPE Stage 4 Installed in my truck. I could get 2 supplied and built 400's for that. Fairly sure I will have issues with the ally as power goes up in future. I feel the 3 speed would suit the high tq of the diesel better at the track rather than the 5 speed.. OD would give me higher gearing for cruising back on the road. I know they build some tuff 400's for the gassers but dont know how they would stand up to the big tq. Any ideas anybody - Mike any thoughts on it?
 
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M

mick

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Just been talking to the Transmission Guru in Aust who builds all the top race trans. He says he has TH400's behind 2000hp gas engines - no problems with manual shift.To supply the transmission in that state would cost 3200 $US -
 
sweetdiesel

sweetdiesel

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mick
sorry for my ignorance and i know you will do your reseach on this before doing it
but how much torque is it good for?


I agree, Mike and Pat would be 2 guys worth talking to on this subject and i hope you get the info you need
 
Mike L.

Mike L.

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I will have to think on this a little. The first thing I would worry about with a 400 is a broken case. I have seen quite a few 400 behind big heavy trucks and the case loves to break behind the bellhousing under high tq conditions.
 
MAXLLY

MAXLLY

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Aug 15, 2007
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Mick, great idea!

This is all i know and it isn't much.

I used to have a bunch of 400's and i whipped them like they where free... they are compared to fixing an Ally. You can pick it up as well.... I still have 3-4 sitting in the shop and may use one in February depending on Ally braindamage. In all the reading i thought someone put a dodge trans (47?) into a dmax and gained 6/10ths and lost weight. Maybe i heard it? Dunno, maybe this will help you?

I love my Ally she is stout, but it's to smart for it's own good. If it helps you any i am using an '01 trans tune, whenever it shifts consistantly well i try and TAPS and adjust them into T/H as prefered. She still acts retarded alot, with the same tune i may see a 2-4/10th change in 0-60.

Hope this helps.
 
Bluemax

Bluemax

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Would you be able to use it for daily driving or would it have to be manual valve body? How would the kickdown work, aren't they on a cable on the 400?
 
Mike L.

Mike L.

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Kickdown is electric so no problem. The 400 is vacum operated and would need meachanical modulator for automatic shifting or manual valvebody for racing.
 
duratothemax

duratothemax

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Aug 28, 2006
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Mike L. said:
Redrilled Caddy case.
Click to expand...

interesting...



I always thought the electronic kickdown on the 400's was kind of wierd/cool, no TV cable or anything like the 350's.

I rebuilt one a few weeks ago to swap outputs from a chevy 4wd to the BorgWarner long 10 spline output (I know, wierd) and I couldnt beleive how simple it was..

another thing Mike, on the bellhousing...IIRC campbell makes a replacement strong SFI-cert bell housing...cut the stock one off and the SFI one bolts to the pump...would that work?
 
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Mike L.

Mike L.

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Ben
The wierd 10 spline shaft was very common in the '70s and '80s on the Jeep Wagoneers. They had a special round bell housing with AMC bolt pattern. The 400TH is so widely used that there are a multitude of case options out there. I don't do many of them anymore and am not in the know of what's out there.
 
duratothemax

duratothemax

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Mike L. said:
Ben
The wierd 10 spline shaft was very common in the '70s and '80s on the Jeep Wagoneers. They had a special round bell housing with AMC bolt pattern. The 400TH is so widely used that there are a multitude of case options out there. I don't do many of them anymore and am not in the know of what's out there.
Click to expand...

yep...im building a custom offroad buggy...its built on a narrow track 1976 CJ7 drive train. Im putting a VW beetle body on it...so it will be like a huge 4wd beetle. BUT I fabbed up new custom cross members and motor mounts so the engine will still be in the rear, and the VW rear hood will be able to close, so it looks stock...it will certainly be unique when I get it done. :D

the CJ had an AMC 258 mated to a TH400, mated to a borgwarner xfer case. I didnt want to run a 258 because its longggg, weighs 600 pounds, and has 110hp or something like that. So I bought a TBI chevy 4.3 with harness for less than 300 bucks at a junk yard...I went to bolt it up and SURPRISE, AMC TH400's arent the same!! :mad: So as you said mike, I found a GM TH400 (with the 90* pattern bell housing), and swapped all the guts (including the goofy 10 spline output) into the chevy case...just to get the 90* pattern. :rolleyes:

but ok sorry back on topic.

Im sure you could rig up a simple voltage divider circuit that measures the TPS reference voltage so when it goes above 4.8 volts (effectively WOT) it would trigger a relay that would close the kickdown circuit... vacuum modulator I have no idea?
 
M

mick

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If I was sure the TH400 could handle the abuse and high tq better than the Ally, Im good to try it. What do you think Mike - really? The other plusses (for me and my truck, Im talking about) are weight loss after removing Ally with Transfer Case, 3 speed I like for racing, Love that Hurst sticking through the floor, and price and availabiliy of parts etc. Out of interest a new Allison in Australia is in excess of US$17,000. I shouldnt say that Mike when my next question would be what would be app price for you to supply a 400 in such trim with a manual valve body and as you suggested a Redrilled Caddy BHousing. How about Converter, Shaft Length, Splines etc are they all going to work or will it be a cut, weld, machine etc etc - I know this project wont interest alot of folk here, especially as most use them as work trucks etc, but for me my long term goal is going to be a one off play truck that will do well at the track and have number plates on it
 
JoshH

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What about a 4L80? I asked about that a couple of weeks ago at TDP, after I heard about the 47 swap, but no one really wanted to discuss it. The only problem I would see with the 400 is the lack of overdrive, and most aftermarket overdrives aren't known to be that strong.
 
M

mick

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