Only issue I would see with the LS 8.1 is that the engine wasn't around long. Does that impact parts availability at all? Otherwise, awesome choice of powertrain combo
from what I've read, the 8.1 swap w/allison.....you'll have the power, but not any gas mileage. That along with it not being that popular in the after-market community, sorry but good luck. Please prove me wrong, I've got access to both in my price range.
While short lived in trucks the 8.1 had lots of industrial and marine applications so parts are available.
Howell makes a direct stand alone harness for the 8.1/Allison not listed on their site (I called in and asked) for $750-$850 which is the easiest route. It’s 4 wire with the option Cruise Control which is why I want it
Adavance adapters makes a kit for the Allison 1000 to NP 205 $800
For cam options BBC GEN 6 swap in but require a reprogramming of the ECU/firing order. There are 8.1 specific cams available also.
Raylar Engineering makes performance stuff for this engine like aluminum heads and intakes. Although expensive it’s available.
While not a popular option for sure it’s not impossible to fit it in this truck. I could swap a 4l80 behind it and not cut the floor.
I wanted a power train that wouldn’t be near its limit with the truck empty. If it was a 2 door 1 ton or 3/4 ton 2wd 6.0 or even 5.3 would be fine.
This truck with the 454/th400 and 4.56 gears had GCVW of 17,000 so the chassis is stout and though I don’t see towing 10k all day long the 8.1/A1000 had a GCWR of 21,000. So I won’t lose the utility of the truck.
I wanted GM EFI for reliability and usability, the 8.1 had 340hp and 460 Ft lbs stock. Family trips with my 2 young boys and wife would be a lot more pleasant with a vehicle capable of 75 mph at 2300 rpm. I am building a truck I can use instead of buying one for $60k +.
As far as fuel economy, crew cab, long bed duallies with 4wd, suck. I’ve owned lots of trucks in diesel and gas. At 75mph 11-12 mpg diesel and 9-10mpg gas, going from Albuquerque to Denver/Cheyenne/Billings is all I’ve ever got. Slowing to 65mph improves mpg but I’m not interested.
I’d have loved a Cummins swap but noise was partly why I didn’t. I have a 7.3 powerstroke cclb drw 4x4 cost of fuel and maintenance is another.
Over all my engines were the vortec 7400 (gen 6 454), the vortec 8100 (“gen 7” 496) and the L8T. I really thought about the 6.0 L96/6l90 and if I was going for just cruising I woulda tried it. But I was just worried that 380 pounds of torque at 4200 RPMs would have been too high in the powerband (stock 454 was 380 lbs at 1500 rpm).
This is not ”THE POWERTRAIN” for everyone but it’s what I think will work best for me. Well see how it goes but I’m pretty confident it’ll be in there a while.
This is my dream truck so I’m taking my time with it. Progress will be slow but be made. Thanks for reading, happy holidays