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Old 11-23-2019, 11:27 PM   #1
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454 engine replacement options

Hello all,

I have a very mint excella that started smoking heavily and then knocking. Id like to replace the 454 with something different.

Has anyone put in a GM 6.0L or 5.3L?

Displacement wise both are much smaller but either make more power than a boat anchor 1980’s 454.

The 6.0L would have 360hp and 380ft-lbs of torque. Packaging wise it’s a lot smaller. These can be had from a wrecker for $800 with very low miles from a 1 ton GM truck.

Another option is the GM 350 vortec 5.7L which has 255hp and 330ft-lbs of torque. My wrecker has one of these with low miles for $440 from a 3/4 ton GM truck.

I’m looking to repower on a budget but I do not see any information on anyone ditching the 454 for something smaller, newer and more powerful.

Thanks
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Old 11-23-2019, 11:41 PM   #2
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Quote:
Originally Posted by Air streamer View Post
Hello all,

I have a very mint excella that started smoking heavily and then knocking. Id like to replace the 454 with something different.

Has anyone put in a GM 6.0L or 5.3L?

Displacement wise both are much smaller but either make more power than a boat anchor 1980ís 454.

The 6.0L would have 360hp and 380ft-lbs of torque. Packaging wise itís a lot smaller. These can be had from a wrecker for $800 with very low miles from a 1 ton GM truck.

Another option is the GM 350 vortec 5.7L which has 255hp and 330ft-lbs of torque. My wrecker has one of these with low miles for $440 from a 3/4 ton GM truck.

Iím looking to repower on a budget but I do not see any information on anyone ditching the 454 for something smaller, newer and more powerful.

Thanks
The early 20ft motorhomes came with a 350, and the 454 was an optional extra. Several people have swapped for a crate 350HO (which has over 3x the power) but they are still non-electronic/carburetor units. The hassle with using the modern equivalent will not be the engine but the electronics to support it.
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Old 11-24-2019, 05:07 PM   #3
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Hey,
As you probably know, a big block vs a small block motor differ in the performance they give you we need low end torque. You won't nessessarily get any better milage or performance from a small block. If she's starting to smoke, it could be as simple as new seals on the valves. They were known to get hard and crack. Maybe all you need is to freshen up the heads. That shouldn't t cost much more than 800 .oo. Do compression test, that lol tell the tale.
If you should decide to go with a small block , try putting a FiTech fuel injection system in. Super easy to install. Mine works great. Cost me I think 900.00 for the kit. You got to get a differant intake though, it looks like a ford manifold. All four holes are the same size. Or get an adapter plate. 20.00 bucks at any auto store. DJ
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Old 11-24-2019, 06:20 PM   #4
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IMO not enough low end grunt with the 6.0ís. When itís time for me to replace my option would be the HT502 crate motor. Lots of low end torque and peak hp all below 3k. Rpm
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Old 11-24-2019, 06:25 PM   #5
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Quote:
Originally Posted by Air streamer View Post
Hello all,

I have a very mint excella that started smoking heavily and then knocking. Id like to replace the 454 with something different.

Has anyone put in a GM 6.0L or 5.3L?

Displacement wise both are much smaller but either make more power than a boat anchor 1980ís 454.

The 6.0L would have 360hp and 380ft-lbs of torque. Packaging wise itís a lot smaller. These can be had from a wrecker for $800 with very low miles from a 1 ton GM truck.

Another option is the GM 350 vortec 5.7L which has 255hp and 330ft-lbs of torque. My wrecker has one of these with low miles for $440 from a 3/4 ton GM truck.

Iím looking to repower on a budget but I do not see any information on anyone ditching the 454 for something smaller, newer and more powerful.

Thanks


An LS motor would be an upgrade, particularly a 6.0 or 6.2 L.

One could be used without a computer with a crank triggered ignition and a new intake manifold to run a carburetor.

As mentioned above, computer kits to run the EFI are fairly inexpensive these days, and they can work very well.
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Old 11-26-2019, 01:58 PM   #6
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Quote:
Originally Posted by Air streamer View Post
Hello all,

I have a very mint excella that started smoking heavily and then knocking. Id like to replace the 454 with something different.

Has anyone put in a GM 6.0L or 5.3L?

Displacement wise both are much smaller but either make more power than a boat anchor 1980’s 454.

The 6.0L would have 360hp and 380ft-lbs of torque. Packaging wise it’s a lot smaller. These can be had from a wrecker for $800 with very low miles from a 1 ton GM truck.

Another option is the GM 350 vortec 5.7L which has 255hp and 330ft-lbs of torque. My wrecker has one of these with low miles for $440 from a 3/4 ton GM truck.

I’m looking to repower on a budget but I do not see any information on anyone ditching the 454 for something smaller, newer and more powerful.

Thanks
The 6.0 was a purpose built truck motor that would have more low end torque than the others that you have listed and would do a better job. The actual replacement for the 454 was the 8.1 L or 496 ci that is, in my opinion, one of the best motors GM ever made. The 8.2 L 502 ci is a spinoff of that motor and used throughout the boat and hotrod industries. GM sells them as crate motors.
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Old 11-26-2019, 04:06 PM   #7
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A 8.1 with an allison sounds good.
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Old 11-26-2019, 07:13 PM   #8
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If you're going to go to the trouble to install a new engine then the extra effort for fuel injection will be well worth the while. Apart from increased gas mileage, you no longer have a carburettor washing down the cylinder walls everytime you drive down the road.
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Old 05-04-2020, 06:26 PM   #9
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need a new motor in my 85 345 also smokin and clunking
did you replace or have it rebuilt
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Old 05-04-2020, 07:51 PM   #10
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Quote:
Originally Posted by Air streamer View Post
Hello all,

I have a very mint excella that started smoking heavily and then knocking. Id like to replace the 454 with something different.

Has anyone put in a GM 6.0L or 5.3L?

Displacement wise both are much smaller but either make more power than a boat anchor 1980ís 454.

The 6.0L would have 360hp and 380ft-lbs of torque. Packaging wise itís a lot smaller. These can be had from a wrecker for $800 with very low miles from a 1 ton GM truck.

Another option is the GM 350 vortec 5.7L which has 255hp and 330ft-lbs of torque. My wrecker has one of these with low miles for $440 from a 3/4 ton GM truck.

Iím looking to repower on a budget but I do not see any information on anyone ditching the 454 for something smaller, newer and more powerful.

Thanks
The 454 has more power than the 5.7...5.3...if you went with the 6 liter..you need all the computers and ecm.....stick with the 454...or go to a Chrysler 440...
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Old 05-04-2020, 07:52 PM   #11
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A 8.1 with an allison sounds good.
That would be a good engine in a motorhome if you co7ld find one
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Old 05-04-2020, 09:05 PM   #12
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454 engine replacement options

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Old 05-04-2020, 09:10 PM   #13
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Old 05-04-2020, 09:31 PM   #14
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Quote:
Originally Posted by Paul J Mauro View Post
need a new motor in my 85 345 also smokin and clunking
did you replace or have it rebuilt


If you're mechanically inclined and have the tools rebuilding the engine yourself would be the cheapest way out....

If not, buying a rebuilt engine is the cheapest and probably the best way out....
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Old 05-05-2020, 05:12 AM   #15
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If you're mechanically inclined and have the tools rebuilding the engine yourself would be the cheapest way out....

If not, buying a rebuilt engine is the cheapest and probably the best way out....
i agree leaning toward a rebuild .dont need to hassle with the new electronics
she ran great new about 150,000 miles ago
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Old 05-05-2020, 06:41 AM   #16
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If you're going to go to the trouble to install a new engine then the extra effort for fuel injection will be well worth the while. Apart from increased gas mileage, you no longer have a carburettor washing down the cylinder walls everytime you drive down the road.
X2

Re-manufacture or Crate engine w/ factory warrantee. 👍

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Old 06-12-2020, 05:55 AM   #17
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+1 ht502

Quote:
Originally Posted by cliffcharb View Post
IMO not enough low end grunt with the 6.0ís. When itís time for me to replace my option would be the HT502 crate motor. Lots of low end torque and peak hp all below 3k. Rpm
This is what we did. Itís an expensive experience, and proper support is imperative, either in your own shop or someone elseís. End result for us is a solid power plant that gives us confidence in a rig we plan to keep another 30 years.

The folks on this forum will be your biggest asset, either way.

Kevin
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Old 06-12-2020, 06:48 AM   #18
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About 7 years ago a customer with a 345 bought a totaled GMC pickup with a 6.0 and 6peed transmission. They took the engine transmission unit and all the electronics out of the truck and put it in the MH. He had the skills to do it. I drove it when he was done and it worked great, far more performance than the 454 and it was about half the noise level.

He was going to do a GM engine and transmission combination that came with all the electronics but the totaled truck was cheaper and gave him everything.

Andy
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Old 06-19-2020, 12:29 PM   #19
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I believe the Vortec 7400 L29 was the last 454 which married up to the standard P32 chassis. I might be wrong though. http://67-72chevytrucks.com/vboard/s...d.php?t=266963
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Old 08-10-2020, 04:25 PM   #20
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We recently dropped a NEW Chevy 454 into our Magic Bus and its been FANTASTIC... (1985 345)

Now... in addition, we also put in a 4L80E (4 speed trans with locking hub). When installing a new transmission... be sure the folks doing it install a transmission cooler... (sounds basic, but the first shop we went to didn't and its a LONG sad tale. My Personal believe is you need more then the 3 speed transmission for long drives at 65 or 70 mph or so.

We went with the carburetor config because I DIDN'T want to deal with all the computers etc... The 4L80E hooks right up to the 454, and while it DOES have a computer... its not a big deal.

With this configuration, we finished a 2 week trip through Colorado where we topped out at over 11,000 feet of elevation. Engine temps at 200, and Trans temps a 205. NO ISSUES at all.

My advice, TAKE YOUR TIME and ENSURE you have a SHOP that can handle the work... Our experience to get to where we are now took a few years and $5k more then it should have because we started in the wrong shop.

GOOD LUCK !

Todd
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