Prevost engine swap possible?

hanko wrote:
Id take that old Jimmy any day,compared to those smog choked def cumaparts

Aint that the truth?

I spent my career running 871s in commercial fishing boats.
They will spit out most of the rings and keep running.

No one wanted a Cummins, too temperamental, kinda hard
to pull a boat off to the side of the road and wait for a mechanic!

Id take that old Jimmy any day,compared to those smog choked def cumaparts

That's the company in MO I was referring to. Excellent folks who do excellent work.

Thanks Mark,

I've emailed him...

Don

DonHutchins wrote:
I'm looking at a used Prevost that's a beautiful unit in nice condition, but it's got the old DD 8v92 motor, which I'm really leery of. It's got a rep as a dripper and fuel guzzler. What are the chances it could be swapped for the newer DD Series 60 motor? I know this is off-the-wall, but I really do like this unit and might go for it if this is do-able...

Don Hutchins
Kingston WA

Mr. Don,

Brian was at one of our 'know your Prevost' seminars. Nice fella and the company he works for would know what is best.

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Brian Stanton 417-865-4420
2441 E. Jean St. Springfield , MO 65803

bstanton.americanfleetinc@gmail.com
http://www.americanfleetinc.com

American Fleet Inc. specializes in Detroit Diesel Engines and repairs for the motorhomes, entertainer coaches and any bus application. We offer Allison Transmissions for the same applications. Most engines and transmissions are available to ship within 3-5 days. Feel free to call or email with any questions.
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MM.

It can be done but everything has to change. Engine, transmission and electronics. I was quoted north of $60,000 to make the change. You will be better off buying a newer coach. My current 1988 has the 8v92 and gets 5.5 MPG. Changing to a series 60 can up that to 7-8 MPG so that's not going to pay for the change. The 8V also has more torque and can often out run the newer 60 series up a hill. Yes, the slobber tubes drip some oil and I burn about a gallon every 1000 miles but that's OK, too. There are even ways to catch the oil from those tubes if you just want to keep the underside of the coach cleaner.
There certainly is no reason to swap engines if you are concerned about reliability as the 8V92 is a long haul work horse that will last nearly forever. Even if you needed to swap one out, there is a company in MO that can do it in 2 days for about $15,000 compared to an in-bus full rebuild for about $30,000.
My only caveat would be to ensure that the bus does not have the DDEC 1 electronics (1988 and earlier). I would recommend that it have at least the DDEC 3. If that's the case, buy it, drive it, love it!

Wow! That's a LOT of great input in almost real-time. I think I'm gonna like this forum!
Plenty of good suggestions here - including the vote to go with the DD as is, because it is a very reliable rig. I've heard of them running happily with a holed piston, though I certainly would hope never to be in that position! Believe I'll talk to Country Coach (it's their conversion) about the motor swap, as they've done all the maintenance on the rig since new.
Thanks again for all the good poop. I'll keep the forum updated on how we do with this search. We're moving up to a tag-axle pusher so I can mount my big BMW moto on the rear, and move up from the 5'er we've pulled it around in for several years.
Best regards to all.
Don Hutchins

Yeah, my 8V71 has fighter jet-style switch that close big flapper on intake in case of run away. Never had to use it, but tried out of curiosity.
It also had 2 fire sensors in engine compartment and loud bell under driver floor. It worked fine as I tested it.
Funny all-metal coach had fire alarm, while wood and fiberglass newer coaches don't

Greyhound ran the 8V71 and 8V 92 in many applications from coast to coast, for many years, until enviromental regulations made a cleaner engine a requirement.

The 8V92 is 92 cubic inches per cylinder and there are 8 of them! IT is also supercharged and two stroke, so it makes power on each stroke. It is a little more fuel costly than a 4 stroke, but if you get a quote of $25,000 to install a rebuilt inline 6 and adapt to your transaxle, you will be lucky.

The inline 6 will be about 8 feet long, while the V8 is a compact 5 feet long. You might not have enough space. You will never save $25,000 on fuel. You might get 7-8 MPG with the most fuel efficient engine and transaxle, while this one has a lot more slippage than a modern transmission, but still was built with fuel efficiency in mind.

The 8V92 can be turned up to about 500HP. The 8V71 mentioned above is much smaller - giving up 168 cubic inches with smaller cylinders. They also came in 6V71, 6V92 and inline versions. I worked on a 16V92 generator, rated at 1500 HP and 750KW power output! It turned 1800 RPM and roared! The most that many road engines are allowed to run at is 1700 or 1800 RPM, before the governor kicks in.

The advantages of a 2 stroke engine over the 4 stroke is more compact size, lighter weight per HP, and less internal friction per HP rating. The disadvantage is a little more fuel consumption. It will use about 20% more fuel than a 4 stroke engine. But they are fun to drive! My buddy has one, and he said he took it in for a check up - they hooked it up to the computer. Said it was rated at 450 HP and they could turn it up to 500, but he said no, it is fast enough. They stated the maximum road speed was 87 MPH. I suggested that his poor little Honda was hanging on for dear life to the back of the RV!

Good luck with your decision! I think you will end up liking the 8V92. Drive it hard, the engine can stand to be wound up to it's max RPM rating. At slow engine speeds, it will not put out the HP that you will need for getting over a mountain, but it will cruise along with no problems.

Another friend had a 8V71 in a 18 wheel tractor. He ran coast to coast with it but had poor performance in the mountains. He ended up turbocharging it, and installing fuel injectors from a 92 cubic inch engine. Then it would make lots of power, got 10 mpg empty and 6 full. Just check the fuel and fill it with oil. Because it is two stroke, the air is blown into the engine, then into the slots in the cylinders. IT can take in oil and burn it with the diesel fuel. So it can burn a lot of oil at higher RPM range.

The generator that I took care of had a specific over RPM shut off, that closed off air to the supercharger in the event that the engine started to burn it's oil, and not slow down. In come cases, they would shut off the diesel fuel, but if overfilled with oil, and over the rated RPM, it would splash enough oil into the cylinders to keep running at the higher RPM. It was a sort of panic switch to close off air to the engine on the generators.

Good luck, happy camping!

Fred.

The old DD silver 8V92 was dry. At 500+ HP it should get you down the road well.
How about a 1998 45' Blue Bird with a Detroit 60 at 55,000 miles?
One of my FMCA chapter members has it for sale.

Richard