7.4L to 8.1 Swap?

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SmittySS

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So, I just thought I would through this out there...
Has anyone done a 7.4L to 8.1L Swap?

I have a 1996 K2500 Suburban with a 7.4L and I was curious what might be involved in swapping it out with an 8.1L. What might be some of the hurdles I might come across?

Let me know your thoughts, or maybe share links on here that I've missed of others who have already addressed the question.

Smitty
 

someotherguy

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2001-2002 3500HD donor truck get the engine, harness, PCM, misc. other underhood items...and then figure out what you're gonna do about how your 1996 model does not have Passlock antitheft but the 1998-up trucks do. Maybe have custom tuning done to remove it from the PCM. Or, you're looking at changing out the steering column and the dash harness too so you can include the BCM/TDM that Passlock uses. IMO eff that...

Richard
 

SmittySS

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Thanks for the response Richard. It sounds like there could be a lot things to the swap.

I wonder if the short block would be something that can be swapped?
Will the 7.4 heads bolt on... and is there a provision for the distributor, and anything else that might need to crossover?
...and would there any advantage to the swap?
It would be an easy stroker kit...

Along the lines of the ckmllete swap...
I have an associate who deals with "retired" fleet vehicles often. He told me runs across 01 and newer trucks from a specific company that are the same body style as my Suburban, but have the 8.1 vortec. He said he could get me one of these trucks complete (minus the work bed) for around $1100.00
If these trucks exist, that would have everything for the swap...

Smitty
 

thz71

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Thanks for the response Richard. It sounds like there could be a lot things to the swap.

I wonder if the short block would be something that can be swapped?
Will the 7.4 heads bolt on... and is there a provision for the distributor, and anything else that might need to crossover?
...and would there any advantage to the swap?
It would be an easy stroker kit...

Along the lines of the ckmllete swap...
I have an associate who deals with "retired" fleet vehicles often. He told me runs across 01 and newer trucks from a specific company that are the same body style as my Suburban, but have the 8.1 vortec. He said he could get me one of these trucks complete (minus the work bed) for around $1100.00
If these trucks exist, that would have everything for the swap...

Smitty

The heads will not bolt on there is no provision for a dist. In an 8.1. If your gona do it swap the whole engine everything is impoverished over the previous gen big block. Everything. Pass lock is easy to tune out that's not a big deal.
 

SmittySS

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Awesome!
Thanks for the comments and information ...
I've got my guy looking for one (or two) of those trucks now.
Smitty
 

thz71

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I'd buy everyone of them I could at that price. They're awesome trucks. The 8.1 is a monster.
 

Sampuppy1

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The only real issue after swap that you run into is that repairs and parts for that engine are harder to find and are expensive. If you ever want to have more power the aftermarket is limited and even more expensive since these engines were not produced for very long. Also keep in mind these things make a very respectable amount of hp/tq and that can really put undue stress on your driveline. I toyed with this idea in my truck at one point but the cost of what I wanted was far beyond what I needed to spend to achieve similar performance from a smaller and equally unique setup.

I'm not saying don't go for it. I think it would be cool to see the whole shebang (Allison trans included) swapped into a 400. I just don't have the funds or connections to be the guy to do it.

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TylerZ281500

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harness and engine take out, 411 swap

full 01-02 3500hd parts truck

they don make intakes and cams to run dizzys on an 8.1 but waste of money to revert back into technology.

theres probably a handful of other ways to do it if desired.
 
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