454 Dually....5.3 Swap....Pros and Cons.

[Ford Assassin]

Hey guys, I have a mild 454 mated to a NV4500 in my 88 R30 dually. I get 14 mpg now highway, but under 10 in town.

I am considering swapping in a spare/fresh Gen IV 5.3 into it and retaining the NV4500. I tow about 6 times a year, but it it only weighs 3500 lbs. I have done no less than 20 LS swaps, mostly with a turbo, but nothing in something this heavy.

I am after better MPG without losing a bunch of towing ability.

Thanks!!

[mongocanfly]

14mpgs from your setup sound pretty good to me...
I swapped my 350 for a 6.0 in my C30...went from 8-9mpgs to 15-16.....I also swapped the sm465 for a nv4500 at the same time and have 4.10s in the rear....I wouldnt think a LS would get enough better mpgs to justify the swap..
Mine tows great...regularly pull a 9500lb loaded trailer...gas mileage is terrible while towing
Hanging a NV behind a LS isn't cheap if you have to go with AA like I did

[Ford Assassin]

Originally Posted by mongocanfly

Hanging a NV behind a LS isn't cheap if you have to go with AA like I did

I don't think it will be bad at all since the bellhousing is the same pattern. I just need a 2000's 6.0/NV4500 clutch setup and crank spacer.

Unless you know something I don't.

[mongocanfly]

Yeah I realize you've got the bellhousing...but I couldn't find the OEM parts to do the swap...
I used all advance adapters...the flywheel,clutch ,pressure plate was the big expense..
It cost me roughly 1k to connect a LS to a NV....I've done 2
I'm betting you wont see much if any jump in mpgs though

[Ford Assassin]

https://www.rockauto.com/en/catalog/...mission-manual

[kipps]

Originally Posted by Ford Assassin

I don't think it will be bad at all since the bellhousing is the same pattern. I just need a 2000's 6.0/NV4500 clutch setup and crank spacer.

Unless you know something I don't.

No crank spacer needed. Just a 6.0 flywheel from the mid 2000's. nfw1050 is the classic example. It will fit a LS clutch, which will be the better option because it has more friction area. It will also fit an old-school 454 or 350 clutch, which will be the cheaper option. Just price out the parts, and decide if the extra friction surface is worth it. You will need to ream three of the bolt holes in the gen 1 pressure plate if you go that route.

I "think" all the chevy nv4500's were 10 spline by 1-1/8 diameter, but keep that in mind.

That 6.0 flywheel will still leave you with a 1/8" misplaced clutch surface. Use an adjustable fork pivot ball to make up the difference. Note that the fork pivot ball that I referenced in the link below will probably not fit your transmission.

Keep in mind that the commonly recommended manifolds for LS swaps are not assuming manual transmissions. Your passenger side external slave might be a challenge to get around. A driver's side slave can be cleared with a LS1 F-body manifold, but I think the passenger side manifold for these cars dumps further back.

Link to some of my measurements. Scroll down to post #11. Some day I'll get around to finalizing that list and neatening it up a bit.

https://ls1tech.com/forums/conversio...lhousings.html

[Captainfab]

Subscribing for later reference

[cdub2010]

14mpg is damn good for yours right now, id be thirilled with that. I cant imagine why the 5.3 wouldnt meet your towing needs.

If I remember right I was getting 10-12 mpg from my 2007 2500HD 4x4. I couldnt get any better than 18 mpg from my '16 gmc 1500 4x4 with a 5.3. My '88 dually with a gutless tbi 454 gets maybe 10mpg so Im swapping in a supercharged 6.0 next summer. I figure If I can t have mpg Im gonna have fun.

[Clyde65]

I think the NV4500 is your biggest mpg draw, that thing is huge!

[Ford Assassin]

Change of plans, still moving forward with the 5.3 swap, but going with a GT45 turbo either in the engine bay or under the truck in a mid mount configuration.

[mongocanfly]

That sounds interesting...

[Ford Assassin]

Found a low mile reasonable priced 6.0 and grabbed it last Friday. Heads are at the machine shop getting checked out and getting bigger valve springs. Bought and installed a new 8719 Summit truck cam, smallest aftermarket cam I have ever bought too, lol.

Going with my typical boost prep, including LS9 head gaskets. Oil pan is already drilled and tapped for a 1/2" NPT to -10AN for the turbo oil drain.

[mongocanfly]

Sweet..!!

[Ford Assassin]

Build thread....

http://67-72chevytrucks.com/vboard/s...d.php?t=803608