Author Topic: Chevy LS conversion anyone?  (Read 245 times)

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Offline David.lgtwks

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  • Make: Winnebago
  • Model: M-400 brave
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  • Engine: 440-3
Chevy LS conversion anyone?
« on: May 11, 2021, 02:13 PM »
I'm looking to convert my  one-ton Dodge 440 to a Chevy LS type engine. Using A  LMZ 5.3l H.O. engine with the 6l90 6 speed transmission (from a wrecked 2018 2500HD truck). Complete modern  electronics with variable valve timing (VVT) and active fuel management. ( displacement on demand) These neat tricks gives the engine torque when called for, and disables engine cylinders when not needed, reducing fuel consumption under low load conditions. These trucks are supposed get 18-19 mpg, but real life is much lower. My daily driver has these options,  and averages 13.1. I can guess 17 highway. (Maybe). Anyway, I think diesel conversions are not always the answer. I know someone who did one, and really wasn't that impressive. Diesel smell in the cab, and no real top end speed. Sure, mileage is good; but with all these LS conversions, with anything with 4 wheels, why not our motor homes?

Offline eXodus

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Re: Chevy LS conversion anyone?
« Reply #1 on: May 14, 2021, 12:47 PM »
The question as an Vortec Guy - why the 5.3?  You get it for next to nothing?   6.0?

The 6.0 has a proven record of being reliable, while every nice feature you are mentioning on the new LMZ makes me cringe and thinking about breaking and being expensive to fixe. Further the aftermarket support is amazing.

You can probably get a 6.0 from your local junkyard with a 6l90 transmission for less then $2000  if you DIY pull it probably less then $1500

So you got my vote - YES for LS swap - and a WHY for the 5.3?

Most of the fuel economy comes these days from Aerodynamic - A Box like a classic Winnebago will never get fuel economy. So don't do it for that reason :P

Offline tmsnyder

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Re: Chevy LS conversion anyone?
« Reply #2 on: May 18, 2021, 01:43 PM »
AFM?, why would you want that problem waiting to happen in your motorhome??

There are literally dozens of videos on YouTube and parts houses dedicated to AFM delete. 

Here's one:   https://www.youtube.com/watch?v=3GKF2ic5iRQ

If you got the 5.3 and HD Tranny already, I'd say heck yeah, put it in!  I'm sure there will be moments when you'd rather have the 6.0l but you'll just be going slower up that hill at that point.   At least it will be easier on the tranny with the 5.3.

But before you install the 5.3, consider deleting the AFM

Or just look around and get a 6.0 or 6.2L and sell the 5.3L


Offline eXodus

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Re: Chevy LS conversion anyone?
« Reply #3 on: May 18, 2021, 04:42 PM »
"If you got the 5.3 and HD Tranny already, I'd say heck yeah, put it in!  I'm sure there will be moments when you'd rather have the 6.0l but you'll just be going slower up that hill at that point."

I mean that 5.3 will be still a lot faster and has more power then anything what comes out of that RV.

The former owner swapped a 5.7 Vortec in my RV - it's decently more powerful then the 454 it replaced. But I wished that they would have put in a 6.0 LS :P


Offline tmsnyder

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Re: Chevy LS conversion anyone?
« Reply #4 on: May 19, 2021, 11:08 AM »
If you're going to go through all that, how about a Duramax with Allison transmission?


Offline eXodus

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Re: Chevy LS conversion anyone?
« Reply #5 on: May 20, 2021, 07:59 AM »

The Allison alone costs more then then whole LS + transmission setup :P  with all the computer setup you need to get the Duramax running - it's about 3-4x to an LS swap. 

Further the Duramax is one heavy hunk of iron.  like 900lbs and the Allison is another 300lbs. 
Not as heavy as a Cummins, but heavy.

The 6.0 with tranny is less then 700lbs. Full dressed - all accessories.

Not impossible, but something to consider.

Offline tmsnyder

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Re: Chevy LS conversion anyone?
« Reply #6 on: May 25, 2021, 09:41 PM »
You RWD motorhome guys are lucky to have engine and transmission swap options!

Does your 5.7L Vortec class A go down the road reasonably well, acceleration and climbing hills ok?

Offline eXodus

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Re: Chevy LS conversion anyone?
« Reply #7 on: May 26, 2021, 04:47 AM »


I don't know if the engine was built with some upgrades, but it's surprisingly quick of the line (4.56 gears) and drives along nicely at 65mph on the interstate.
The only hills I got around here in Florida are interstate bridges, and it doesn't even downshift.  Where my 454 definitely had to shift.

The stock 5.7 Vortec has around 260 horsepower and 330 foot-pounds of torque.
It has the cold-air intake of the 8.1L Vortec attached, so it definitely can breath.  Maybe the former owner put in some computer tuning, who knows  Hm?

While the stock TBI 454 makes 230hp and 380tq

Just compare this with a Stock 6.0L   LS   360hp  and 380tq