454 to Cummins

[92landyacht]

Originally Posted by Punch

...... and a vacuum pump, if you have the vacuum operated HVAC controls, which I think you would.

Yep, lots of vacuum needed and none from a diesel.

[bkahler]

Originally Posted by carl2591

my '03 7.3L is quieter since doing the fuel lines and some other mods.. even the wife noticed when we were driving around and I had not said a word.

I've got a 2000 F250 SD with the 7.3L.

Care to share what mods you made?!

[choctawmel]

Originally Posted by Punch

There are some knock-on effects. Mainly rear axle ratio. 4.56:1 as opposed to usually something like 3.5 or 3.73:1 for most diesel trucks. You are removing an engine that likes to run at 2800 to 3500 rpm and inserting one that really prefers to be around the 2000 to 2500 rpm mark.

Then there is that gasoline-powered generator.......

Well maybe, maybe not. I run about 2600 rpm at 70 in overdrive w/torque converter locked. 2600's not too bad to run a cummins at. 4.10/1 would be a better match, but not needed.

[choctawmel]

Originally Posted by Punch

...... and a vacuum pump, if you have the vacuum operated HVAC controls, which I think you would.

Get it from a Dodge and it will have a vacuum pump on it. My 2001 Dodge diesel does.

Maybe I need to start looking at craigslist for something '96-97.:<)

Now that's Crazy Mel talking.... But what is on craigslist????? Drat :<( Nothing. Maybe next time.

I've got the fever now!

[blkmagikca]

I doubt whether your tranny would be able to handle the torque of the Cummins engine. As well, gas engines typically red line at 5K. The '94 LY I used to have red lined at 2.5K.

[J. Morgan]

It will work, but there are a lot of details that will have to be worked out, a lot of them.

Sometimes a fix in one place will lead to a new issue, but for a person who is dedicated to seeing it through, and willing to buy the parts that will make the swap reliable, it can be made rock solid.


Brevi tempore!

[Kota]

Originally Posted by Punch

...... and a vacuum pump, if you have the vacuum operated HVAC controls, which I think you would.

Mine doesnt have a vacuum pump on the engine. They use a little electric pump and a baseball sized reservoir to run the HVAC controls. I does have an air compresser for the airbags and brakes.

[Kota]

Id find an engine/transmission combination. The Allison MD3060 is a real nice option. 4th gear is 1:1 fifth is 0.75:1 and sixth is 0.65:1. I believe the rear end is 4.10.

The Cummins ECM is built into the engine and very easy to interface with vs the computers they typically use gas cars and trucks which are integrated into the vehicle. They can be like doing a brain transplant. The Allison controller is also pretty easy to transplant. I can be done.

[choctawmel]

Yeah, it can be done.... BUT.
My problem now is the 454 has run like crap every sense it was rebuilt in Las Cruses this last January. Now it's got all the evidence of another inlet valve failure. AGAIN!!!
I just the other day pulled the 454.... AGAIN. Got to get to tearing it down. Maybe it's some thing simple. I'm thinking I'll put the bigger angle valves and valve spring locks because the springs are heavier with the roller cam. Something I should of used when I first rebuilt it
I'm actively looking for a 12 valve Cummings. if I can find one before the end of the month, I'll look at the 454 next year.
Need to get going on this think one way or the other in time to get out of Oklahoma before winter.
If all else fails, I know where a 1954 Spartan trail is that would be a fun project.

[J. Morgan]

A swap is always complicated.

A 454 in stock form is a good engine, but as I recall the motor that blew in Las Cruces was a stroker. Was the replacement a stroker too?

If I were you I would consider buying a NEW engine from GM or building a strong stock displacement 454 with pre 78 heads on it. (A Mark IV not a Mark V). No "hot rod" stuff, just the early oval port heads, such an engine can easily make 400 hp dependably.


Brevi tempore!

[choctawmel]

Originally Posted by J. Morgan

A swap is always complicated.

A 454 in stock form is a good engine, but as I recall the motor that blew in Las Cruces was a stroker. Was the replacement a stroker too?

If I were you I would consider buying a NEW engine from GM or building a strong stock displacement 454 with pre 78 heads on it. (A Mark IV not a Mark V). No "hot rod" stuff, just the early oval port heads, such an engine can easily make 400 hp dependably.


Brevi tempore!

The Les Cruces rebuild was about the same engine only 0.010" (0.040 over) more bore w/new pistons, rings, bearing, one valve and valve lock.
Have old racing buddy that built the same motor for his truck (only carb not TBI) has driven for years pulling BIG race car trailer. Was very happy with it(I thought). Was out in his neck of the woods and stopped by to talked to him about my gas engine. Well he has a 12 valve Cummins in that truck now.
Rebuild what I have? (third time be a charm?) Crate motor? Pre-1978 build? 12 valve Cummins?
Think I'll load up my ICE trike (my other RV)and go for a week long bicycle tour

[GCinSC2]

Mel,

You've put a heck of a lot of blood, sweat, cash and maybe some sleepless nights into this project. This swap is way beyond anything I have first hand knowledge of, other than enjoying owning a 12V for about 8 years.

It was wrapped in a Dodge of course but that engine has magic poured right in to the castings. And it sings that 12V song like nothing else.

Its born to pull, has no clue what high RPM's are. Keep clean fuel in it, don't overheat it and it should serve you well. Didn't I say I have never done a swap like this?

This is a front engine setup right? Ever consider dropping in a 12V and its best friend the 5 speed NV4500 handshaker?

Good luck.

Gary

[J. Morgan]

My only real point is a 454, same engine otherwise, with pre 78 big port oval port engine makes about 400 HP, where a post 78 "peanut port" engine makes about 200 HP.

The easiest way to power with these engines is early model heads. A stroker with late heads is like a world class athlete forced to breath through a straw.

Cummins is a great engine, I will be doing a swap on something because I fell into one cheap a couple of weeks ago. I have done lots of engine swaps, what I can tell you is that a swap will ALWAYS have a lot of details to iron out. They are NEVER as simple as they seem on paper. Never.

Your RV will benefit greatly from your proposed swap, just be prepared to iron out a lot of details to achieve a nicely finished product.

My other point is that a nicely done 454 not too far from stock makes a great tow engine too. I have built a lot of them.


Brevi tempore!

[GCinSC2]

Not an engine builder at all but seems like Mel's issues have been keeping something running not having to push it from behind going up a hill.

Buy an old 12V complete with the truck, take what you need and get creative. Just feed it lots of air, 12vdc and #2 in the tank.

Good luck Mel.

[Punch]

On another thread there's a discussion of Classics running hot. Now we're talking about how you can get so much power out of a 454.... power = heat, people, if the stock 454 (which has puh-lenty power for even the 345) overheats, what do people imagine will happen to an engine that, however it is done, develops more bhp? Common sense needs to have a voice please, not just testosterone.

A 5.9 Cummins is a great engine, but your Cummins will only cruise comfortably at 60 (which is fine if you don't like 70, which I do) and will be verrrrry noiiiiiiisy doing it, and if you thrash your Cummins to get more mph, your mpg will start to disappoint you and you'll be switching the hearing aid OFF.

I am sure nobody will disagree with either of my comments......

[GCinSC2]

Punch,

Yup they rattle. It's their music. But isn't cruising RPM the real issue not MPH and that question requires knowing final drive ratio etc.

I don't even have a clue if you cold shove one in there.

Mel has a lot of pondering ahead.

[J. Morgan]

The final drive ratio is one of those "details" that cost as I mentioned above....

Transmission adaptation or computer control of a Dodge unit is another one of those details that cost money, time, and aggravation.

Swapping was easier before the era of "computer everything".

I was considering swapping a Cummins in the place of a blown Duramax in an 05 Chevy I own, but it is too cumbersome, it will be going into a 67 GMC instead.

There will be issues to overcome, but not near as many.



Brevi tempore!

[GCinSC2]

No facts again, sorry. But I bet the old 12 valve engines didn't need a computer.

[J. Morgan]

No they don't need a computer, but any reliable automatic transmission that will bolt straight on the engine does need a computer.

Count on dishing out a grand for the aftermarket computer and wiring harness or a grand for a transmission adapter to make the Turbo 400 work.

Then we have to deal with the fact that the Turbo 400 is vacuum modulated....

Brevi tempore!

[Kota]

The12 valve has no computer. Purely mechanical injection. The Allison MD3060 that a lot of them were coupled to has a transmission controller. It pretty easy to deal with. The only interface to the engine is the throttle position sensor. Shifting is done through a keypad. No cables or shift linkage.