Duallylife
Newbie
Ok so this may be a longer write up but I would like to get to the bottom of some things hopefully, I have done lots of research but the more I do the less conclusive it becomes... Again sorry for a long write up, I just want to make sure almost everything is thought of and bought/ fabbed up before trying to make the two, as to make it go as smoothly as possible. Also no I'm not just dreaming and kicking tires, this is a conversion I am going to do, just a matter of gathering knowledge and parts.
I currently have 2 gmt400's a 93 k3500 350tbi single cab long box drw, and a 96 k3500 6.5 ext cab long box drw. My dad also owned a 99 Yukon 350 vortec, so I am very familiar with these trucks and there platform.
I have always wanted to build a crew cab dually gmt400, just love the obs body style and they are very tough, this would be a lowered highway tow pig. I don't have the truck yet but untill I find a clean obs in my price I'm looking to get started on power plant, keep in mind I will be starting with whatever I find first, 2wd or 4wd (preferably 2wd as it will be lowered) unless one or the other is extremely harder then the other. I know I could build a nice 350, or maybe even a slick 383, or find a 6.5 and build that up. Or go the American muscle way and build that 454, but those have been done, plus I don't see why since they start with about 300ft-lbs of torque, but everybody says it's hard to get a 350 to make around 450 ft-lbs. I know I could also do LS, but those don't tickle my fancy, high RPM engine doesn't make the power down as low as I would like, and they are also over done, everybody does it. Now I know if I'm doing conversions I could do a Cummins, but those too are over done. I want to be the odd guy out. I have always wanted to do either a vortec 8.1 496 BBC, or since this will be a highway tow rig, for better mpg and more torque a Duramax. I know why those? Because I like them, there not done as often.
So, we will go duramax, I know the wiring is one of the biggest issues, I will be starting with a donor truck, so right away I'm going in with the mind set of hopefully using OEM harness and converting it, with possibly giving up and buying a stand alone harness. For price probably I would probably stick with the first 2 generations of Dmax, so LB7 or LLY, I know both engines have issues, but we won't get into that as this is souly about the conversion. Here's where I'm not sure though, some guys say the dmax rad won't fit its too tall, others say it will so does it or not? I suspect it doesn't, the guys who say it wont say they just modify the core support, what way doesn't it fit width or height?
The next thing that is undecided is wether the trans fits, some say the allison hits the trans tunnel so you need a 1" body lift, others say it fits. Which one is it? I have also heard of guys adapting the 4l80e to the dmax, which I would consider as my 4l's have been tough, plus I can keep most of my trucks the same then. Of course guys jump in and say "oh the 4l80e will never hold up" while I have the engine and trans out I will be rebuilding both, that way I know I'm good for a long time with no leaks no worries about rings being worn or bearings... This will be a build once and just drive type thing... With that being said, with the dmax out of course who wouldn't juice it up a bit? From let's say 525ft-lbs to 6-700? Doesn't seem too unreasonable with a diesel? Question is, can you build a 4l80e to hold up to even a stock duramax? Or would I be better off "massaging" the trans tunnel to fit the allison, which means now switching the trans computer, trans harness, and the mounts. I expect all the usual things... Oil lines rad hoses wiring fuel system intercooler piping exhaust etc... I want to know all the little things that I need to prepare for or overcome, you know crossmembers needing to be moved/ modified.. Engine parts hitting the frame etc. I know the frames on these trucks aren't designed for this... And might be a bit weak for the extra weight and twist from torque combined, I can reinforce it thats no big deal.
I currently have 2 gmt400's a 93 k3500 350tbi single cab long box drw, and a 96 k3500 6.5 ext cab long box drw. My dad also owned a 99 Yukon 350 vortec, so I am very familiar with these trucks and there platform.
I have always wanted to build a crew cab dually gmt400, just love the obs body style and they are very tough, this would be a lowered highway tow pig. I don't have the truck yet but untill I find a clean obs in my price I'm looking to get started on power plant, keep in mind I will be starting with whatever I find first, 2wd or 4wd (preferably 2wd as it will be lowered) unless one or the other is extremely harder then the other. I know I could build a nice 350, or maybe even a slick 383, or find a 6.5 and build that up. Or go the American muscle way and build that 454, but those have been done, plus I don't see why since they start with about 300ft-lbs of torque, but everybody says it's hard to get a 350 to make around 450 ft-lbs. I know I could also do LS, but those don't tickle my fancy, high RPM engine doesn't make the power down as low as I would like, and they are also over done, everybody does it. Now I know if I'm doing conversions I could do a Cummins, but those too are over done. I want to be the odd guy out. I have always wanted to do either a vortec 8.1 496 BBC, or since this will be a highway tow rig, for better mpg and more torque a Duramax. I know why those? Because I like them, there not done as often.
So, we will go duramax, I know the wiring is one of the biggest issues, I will be starting with a donor truck, so right away I'm going in with the mind set of hopefully using OEM harness and converting it, with possibly giving up and buying a stand alone harness. For price probably I would probably stick with the first 2 generations of Dmax, so LB7 or LLY, I know both engines have issues, but we won't get into that as this is souly about the conversion. Here's where I'm not sure though, some guys say the dmax rad won't fit its too tall, others say it will so does it or not? I suspect it doesn't, the guys who say it wont say they just modify the core support, what way doesn't it fit width or height?
The next thing that is undecided is wether the trans fits, some say the allison hits the trans tunnel so you need a 1" body lift, others say it fits. Which one is it? I have also heard of guys adapting the 4l80e to the dmax, which I would consider as my 4l's have been tough, plus I can keep most of my trucks the same then. Of course guys jump in and say "oh the 4l80e will never hold up" while I have the engine and trans out I will be rebuilding both, that way I know I'm good for a long time with no leaks no worries about rings being worn or bearings... This will be a build once and just drive type thing... With that being said, with the dmax out of course who wouldn't juice it up a bit? From let's say 525ft-lbs to 6-700? Doesn't seem too unreasonable with a diesel? Question is, can you build a 4l80e to hold up to even a stock duramax? Or would I be better off "massaging" the trans tunnel to fit the allison, which means now switching the trans computer, trans harness, and the mounts. I expect all the usual things... Oil lines rad hoses wiring fuel system intercooler piping exhaust etc... I want to know all the little things that I need to prepare for or overcome, you know crossmembers needing to be moved/ modified.. Engine parts hitting the frame etc. I know the frames on these trucks aren't designed for this... And might be a bit weak for the extra weight and twist from torque combined, I can reinforce it thats no big deal.
