Swap to an 8.1 Vortec?????

[OkieFishMan]

I'm seriously considering locating a good used 8.1 Vortec and dropping it in my '84 GMC C2500 Crew. Seems to be a pretty straightforward swap. From what I know it will mate up to an SM465, of course I imagine I would have to come up with a flywheel. From what I understand I'd have to notch the frame a bit to clear the factory 8.1 exhaust manifolds. Use van brackets to relocate the a/c compressor to the top of the engine. I'm sure there is much more, but it seems the best thing for modern towing power and fuel injection.

I won't be starting on this until next spring, but I want to have this well thought out and have time to save up some cash and amass the various parts I will need, like an ecm that does away with the torque control.

Anyone done this swap? Any input is appreciated. Hell, there may be a link to a thread with answers to what I am asking. If so, please share it. Thanks fellas!!

 

[CSFJ]

Had a coworker that had one. With the O/D trans he was in the single digits (6-8mpg)with gas mileage. Not sure I'd want to see what it would get behind a 465.

 

[Honky Kong jr]

I'm seriously considering locating a good used 8.1 Vortec and dropping it in my '84 GMC C2500 Crew. Seems to be a pretty straightforward swap. From what I know it will mate up to an SM465, of course I imagine I would have to come up with a flywheel. From what I understand I'd have to notch the frame a bit to clear the factory 8.1 exhaust manifolds. Use van brackets to relocate the a/c compressor to the top of the engine. I'm sure there is much more, but it seems the best thing for modern towing power and fuel injection.

I won't be starting on this until next spring, but I want to have this well thought out and have time to save up some cash and amass the various parts I will need, like an ecm that does away with the torque control.

Anyone done this swap? Any input is appreciated. Hell, there may be a link to a thread with answers to what I am asking. If so, please share it. Thanks fellas!!

Might be able to ring a whole vehicle with one in the. You'd have everything in one neat package. Alltho a 6.0 would probably be a more fuel friendly option. My one work truck 2500 6.0 and 6L80 and I towed way more The I was supposed to and it did fine. Can't believe I just said that ......I'm a big block guy not an LS guy. Lol just makes more sense for a DD/ tow rig i guess.

 

[yevgenievich]

I had a very good experience with the 7.4 version. Best mpg for a 1 ton truck I had. 15-16mpg with the nv4500.

 

[OkieFishMan]

The SM465 will have a Gear Vender Overdrive behind it, which I now will help mileage, but I am also doing it to effectively have a 7 speed. I just want it to have plenty of tow power. Pulling my 10k fifth wheel, I have never got very good mileage, no matter what I tow it with. This truck is basically going to be my dedicated tow wagon. I'm tired of making payments on new crap that I can't hardly work on, and still gets 5-6mpg towing my camper. So I'm building this to pull with, and my daily can be something cheaper, if I want it. I like driving this thing enough that I'm leaning towards it being my daily. I only drive about 3 miles a day to work, so gas mileage is really a non issue. Power is the issue.

 

[CSFJ]

Fair enough. I don't recall what the guy I worked with said about it power wise, but he'd had it since new, and it was only about a year and a half ago that he was talking about the mileage.

 

[Craig 85]

When you mentioned the swap, I immediately thought of this truck.
http://67-72chevytrucks.com/vboard/showthread.php?t=298696

I had a 2001 GMC 2500 HD crew cab with a 5 sp. Allision and 4.10 gears. I still regret getting rid of it. I got as high as 14 MPG with it unloaded. The worst I every got was 7 MPG towing my 30 foot travel trailer to Lake Tahoe (7300' elevation). There were 5 of us in the truck with the A/C on. The best part about this combination was I could still pass people on uphill grades and be going almost 70 at the end of the passing lane. Only mods I had was exhaust, CAI and a chip.

 

[Honky Kong jr]

I have an adapter to put an Allison to a Chevy V8......

 

[Camar068]

When you mentioned the swap, I immediately thought of this truck.
http://67-72chevytrucks.com/vboard/showthread.php?t=298696

I had a 2001 GMC 2500 HD crew cab with a 5 sp. Allision and 4.10 gears. I still regret getting rid of it. I got as high as 14 MPG with it unloaded. The worst I every got was 7 MPG towing my 30 foot travel trailer to Lake Tahoe (7300' elevation). There were 5 of us in the truck with the A/C on. The best part about this combination was I could still pass people on uphill grades and be going almost 70 at the end of the passing lane. Only mods I had was exhaust, CAI and a chip.

Thanks for the link. Look at those power and torque curves!

 

[OkieFishMan]

When you mentioned the swap, I immediately thought of this truck.
http://67-72chevytrucks.com/vboard/showthread.php?t=298696

I had a 2001 GMC 2500 HD crew cab with a 5 sp. Allision and 4.10 gears. I still regret getting rid of it. I got as high as 14 MPG with it unloaded. The worst I every got was 7 MPG towing my 30 foot travel trailer to Lake Tahoe (7300' elevation). There were 5 of us in the truck with the A/C on. The best part about this combination was I could still pass people on uphill grades and be going almost 70 at the end of the passing lane. Only mods I had was exhaust, CAI and a chip.

I found that thread earlier, its a good one! Lots of good info there. I've spent some time digging on this swap. I will also have to swap the sm465 to hydraulic clutch. Decisions, decisions.

 

[HotRodPC]

I think I'd go ahead with the swap to a hydro clutch in anticipation for an upgrade later on to an NV4500 or NV6500 transmission. You'll like having an OD someday if you keep the truck for long.

 

[Green79Scottsdale]

I gotta admit I was not for this swap at first, but after reading that thread, it could be a nice swap. I didn't realize mounts and accessories we're a direct fit.

The biggest question to me would be how much you can get a good 8.1 for? I would think if they end up being much more than $1500, I would look at a EFI system like the Holley Sniper or FITech. Toss in a new cam and you can transform your current big block into a nice rig.

 

[OkieFishMan]

I gotta admit I was not for this swap at first, but after reading that thread, it could be a nice swap. I didn't realize mounts and accessories we're a direct fit.

The biggest question to me would be how much you can get a good 8.1 for? I would think if they end up being much more than $1500, I would look at a EFI system like the Holley Sniper or FITech. Toss in a new cam and you can transform your current big block into a nice rig.

You read my mind. That is the other option. I really would like to ultimately end up with fuel injection. My current 454 runs good, but it is leaking pretty bad out of the rear main. That keeps me from wanting to do much to it in its current state. I have no idea on the history of this motor.

I already have a one piece rear main 454 sitting in the shop. Maybe I just build it with a roller cam and put aftermarket EFI on it?

Do the one piece rear main 454s keep the oil in a little better than the 2 piece? My experience has been with all 2 piece rear mains and they seem to want to leak more often than not.

 

[HotRodPC]

What's wrong with the current Vortec 454 fuel rail injection system? I hear it's upgradable with Furd Injectors and such. It's not like the 350 Vortec with a spider assembly under the intake. It's my understanding it has fuel rails that the injectors can be changed and such? And then chip it, blah blah blah? Or am I missing something? Will it not bolt onto an 8.1?

You must be registered for see images attach

You must be registered for see images attach

 

[4WDKC]

What's wrong with the current Vortec 454 fuel rail injection system? I hear it's upgradable with Furd Injectors and such. It's not like the 350 Vortec with a spider assembly under the intake. It's my understanding it has fuel rails that the injectors can be changed and such? And then chip it, blah blah blah? Or am I missing something? Will it not bolt onto an 8.1?

You must be registered for see images attach

You must be registered for see images attach

This is my plan, only I also swapped to the 0411 ECM from a vortec 5.7 as it is easier to tune and allows for electric fans and tow/haul mode.