Which Tranny Should I get?

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Tongan310

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So looks like I might have to find another trans. I don't wanna be a baby driving it. Wanna have fun and not worry about. ( I mean anyone that looked up this swap even with a cheap engine still expensive af)
 

RDF1

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You can make a 80E hold a good bit of TQ, but you have to get the pressure higher at low rpms. Boost Valve in the pump and some pump mods along with valvebody mods and such

It depends on what transmission controller you use also.

For the LS1 generation 4L80E's the PCM tells the transmission how much pressure to make by Throttle Input (Desired Torque).
So if your cruising at 10% throttle its not going to have much pressure (say 40psi), But when you press the throttle down to 75% it will turn the pressure up ( say 200psi). In reverse its max pressure at 100% throttle (~300PSI)
These are rough numbers not actual, just a representation of how the controllers work.

So if you went with a gasoline style tune, then yea the low end torque of half throttle is going to be rough on the clutches since they don't have the fluid pressure behind them to hold together.

I know of a diesel company that is switching some of their higher HP Dmax over to the 4L80E just so they can get away from time wasted on so many shifts and defuels during shifts. They said it did help their times a good bit and let the diesel use its torque over the longer gear ratios.
 

RDF1

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Sorry that was a typo!
It was suposed to say " I knew"
my buddy fried 2 Allison 5 speeds and was looking at all the options.

I think it was Duraburb that i was talking to that told me about it.

https://www.youtube.com/user/DuraBurbinc

Its been quite a few years ago and a bunch of sleepless nights. I wish i could remember who it was.
I just remember thinking what all they would do to get the pressures up at low rpms and how awesome it would be to have something like that.

If i come across it again ill post it.
 

L31MaxExpress

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So looks like I might have to find another trans. I don't wanna be a baby driving it. Wanna have fun and not worry about. ( I mean anyone that looked up this swap even with a cheap engine still expensive af)

I don't know why..GM put the 4L85E behind the Duramax from the factory. The controllers exist with the factory calibrations to do it. Start with the factory tunes and turn it up.
 

L31MaxExpress

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Chevy express vans with a duramax came factory with the 4l85e. You should be good with the 85.
Thats what I have been saying all along. I tuned one up to over 800 ft/lbs with an 85E that was stock save for a shift kit, deep pan and tuning.
 

Tongan310

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Thats what I have been saying all along. I tuned one up to over 800 ft/lbs with an 85E that was stock save for a shift kit, deep pan and tuning.

Which brings me to the next question. Since I did some digging and saw that yes the vans did have them. Is there a size difference? That also brought me into the 6l90e but I have a feeling that trans is big too so probably stick to the 85e.
 
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