To Dmax, to to not Dmax?

[Kmehr]

Don't try to justify it........just do it if that's what you want. You will enjoy it more.

I share this opinion. If you're not a business so constantly worried about the bottom line and can afford it, do it. You're on this site because you like modding vehicles, so feed what you like. If you only cared about the bottom line, you'd drive a smart car or take public transport. 8.1s are cool, but the Duramax would be majorly bad *****.

 

[NitroExpress]

Doesn't your 8.1 have an Allison? I don't have experience with the Suburban platform, but I know the Chevy HD trucks that had the 8.1 had an Allison Tranny. Just curious since you said the swap requires a suspension modification.

 

[plainjaneFJC]

If it's a lb7 your looking at 300hp and 520 torque. I would build a mild 8.1
It would have the same torque but an extra 125hp more than the duramax. Just as reliable and cheaper to fix.

 

[Dratwagon]

Don't know what year suburban you have but I would go with a Dmax from a classic model. I've had both 8.1 and Dmax, won't do the 8.1 again.

 

[plainjaneFJC]

Really you can pick your poison. The lb7 had injectors issues. I had to replace all mine. The lly from the classic years had overheating issues. I think the lbz was ok. I had an lgh in a cab chassis.. avoid those they are derated.

 

[legendaryandrew]

The suburban 8.1s only came with the 4l85e, not the Allison

 

[Larry]

Yep, same with Avalanche, 2001/2002 G-van and the 2001/2002 GMT400 3500-HD chassis cabs. The 3500-HD was the only old body style truck to sport an 8.1L. Allisons behind 8.1Ls were only a pickup, medium duty and Workhorse Custom Chassis thing. In fact, the Allisons in Workhorse were 2200's…not 1000's although our light RV chassis had 4L85's in the early days of the 8.1L. The G-vans with Duramax's also ran 4L85's and now 6L90's.

 

[legendaryandrew]

Larry, what about swapping an Allison behind my 8.1? Is it any more efficient or geared better, or more reliable in any way than the 4l85? I've found Allisons for around 1k locally.

 

[Larry]

Larry, what about swapping an Allison behind my 8.1? Is it any more efficient or geared better, or more reliable in any way than the 4l85? I've found Allisons for around 1k locally.

The Allison is obviously a much more robust transmission. It does have an extra gear or two more than the 4L85E depending on the year of Allison 1000 but that doesn’t equate to better fuel economy, etc. The Allison consumes more power to spin but you wouldn’t realize it as the 8.1L in front of the 4L85E is more aggressively detuned to prevent drivetrain damage. Fitment is the big issue for swapping in Allison’s. They are huge and require a body lift or floorboard/firewall modifications. Neither are ideal. Wiring is the next hurtle as I don’t believe any of the aftermarket wiring suppliers like Howell are building harnesses to support the Allison but a harness from a period correct Silverado/Sierra with the L18/Allison would probably work. You would need an Allison TCM too. In the end, I doubt it would be worth it just to swap in just for the sake of swapping it in. If you were building a rig from the ground up it may make more sense.

 

[NevadaLover]

Gotta agree with Larry, it seems crazy to swap a perfectly great gas engine for a diesel, never been much of a diesel man in my offroad rigs as I enjoy driving in peace and with the windows down!! That being said, if I was to do a swap like that I would go with a DMAX over a 12V rattlin bangin smokin stinkin cummins!! Highly overrated IMO!!!

 

[legendaryandrew]

The answer to my question is to NOT Dmax. I agree it'd be cool, but not necessary nor practical. I'll just maximize what I have. Thanks guys!