8v92 vs 60 series

[Scott & Heather]

I own both a 6v92 and an 8v92 coach. I much prefer the sound of the 8v92. Just sounds so sweet. As for the 60 series, I'd love one, but I can't be led to believe they are smoother. The one I rode in vibrated the whole coach at idle. Loud as heck too. Was in a j4500. My 6 and 8v92's idle smooth as silk and no vibrations in the coach.


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[digesterman]

Scott I have heard this before but can't understand it, we can't hardy hear the 60 running at the front and mid coach and don't have any vibration. I have 2 strokes, and cats and can't say the same for them. The 2 strokes do sound nice tho, I agree on that

[chessie4905]

I wonder if you could feel vibration from ANY engine in an XL.

[Scott & Heather]

Lol....maybe the extra 5 feet helps? I don't know, I just recently though experienced a 60 series in a new j4500 and Heather and I both could not believe the noise and vibration when he started that thing. Maybe it smooths out once it's running beyond idle rpm?


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[Jon]

My 40 foot XL with the 8V92 had both noise and vibration. I knew that because when I got my 45 foot XL with the series 60 I was amazed at how little noise and vibration compared to the previous bus. The XLII is at a whole different level. Unless I am in the garage when I start the engine I cannot hear it, and the only way I know it is running is because I can sense it. I don't know if it is a combination of sound and vibration, but regardless they are so low it is hard to tell it is running. I think it all has to do with insulation on the part of Prevost and the converter as well as vibration isolation on the engine. The noisiest part of the ride when going down the road is the AC fan at the dash.

[digesterman]

Yes Jon exactly, mine is the XL (the best I think 😊). When we're on the road Jr sleeps and watches TV in the rear bedroom and it is not a problem, sure you can hear it since the engine is just a couple of feet under you but it really isn't that bad.

[luvrbus]

LOL the 60 series will shake at idle the lead sheet that runs from the rear to front on a Prevost hide a bunch of it plus the $$$ marine engine mounts they used later.

IMO there was nothing worse than a series 60 in the early Prevost for vibration

[lostagain]

Most of us have 2 strokes in our buses because of their age: 70s and 80s. They are still great engines and we love them ( I do) for the nostalgic factor: nice sound, that is what I used to drive way back then, etc. They require more maintenance and attention than modern engines. You have to be a half a mechanic yourself to keep them going, because most diesel shops now do not work on them anymore.

Us bus nut hobbyists are entering a new era recently, with 4 stroke powered coaches  becoming more affordable on the used market. Now you can get a 1990s and 2000s seated bus for less than 40000 or $50000. And even used factory conversions with 4 strokes are quite affordable for the average bus nut frequenting these forum.

The Detroit S60 is a great engine. Even though it is already obsolete, it is still well supported with parts and service. Any diesel shop is familiar with it and will fix it, because almost every truck and bus on the highway in the 90s and 2000s had a S60 then.

I ran one in the hockey team's 102D3. It was a 1995, pre EGR, with a 7 speed Eaton/Fuller manual. Lots of torque between 1200 and 2000 rpm. Go up most hills in top gear with the cars. But yea, awful sounding engine, especially at idle, and vibrations at idle too. I used to snooze behind the ice rinks before and during the game because I'd have to drive all night to get home. The sound and vibrations at fast idle always made me appreciate the 6V92 in my own bus.

It is a cold engine. It will not get up to operating temperature until you work it hard, like out of town on the highway. That bus came from the factory with a Webasto to bring the engine up to temp and keep it there when idling and driving around town. It is also a great pre-heater.

Also very reliable. Electronic, but never any trouble. All I ever did to it was change the oil every 250 hours, and adjusted the valves once. About 8 to 9 m/Cnd gal, 7ish US.

If your bus has a big enough engine bay, the S60 would be a great re-power.

The DD15 in today's OTR trucks is even better. But it will be a while before you see that in our kind of bus conversions...

JC

[TomC]

If you start with a mechanical 8V-92TA, a mechanical 4 stroke or electronic 2 stroke will get about 1mpg better. The electronic 4 stroke will get about 1 more mpg then the others. The new common rail Diesels will get another MPG better.

I had an 8V-92TA mechanical in my truck. The suggested maintenance was, 10,000mi oil change. At every 100,000mi adjust valves and run rack. At every 200,000mi roll in new crank and connecting rod bearings. At every 300,000mi, rebuild the turbo and blower. At 500,000mi, typically was time for an in frame overhaul.

The suggested maintenance on a Series 60 is, oil change at 25,000mi, adjust the valves at 50,000mi, then every 200,000mi after that. Perhaps bearings at 500,000mi. Overhaul at 1 million miles. See a difference?

The new DD engines have 50,000mi oil change, same adjust valves at 50,000mi, then every 200,000mi. No bearing changes. Overhaul at 1.3 million miles.

It is very hard and getting harder to find a decent 2 stroke mechanic. Series 60's were installed in every truck manufacturer before Freightliner bought Detroit in 2002. Series 60's are still being made for industrial and marine. I would pay extra for a bus with a Series 60-especially a pre-'98 EGR engine. Good Luck, TomC

[wg4t50]

If you want SMOOTH, get the 12V-71, vibrates just lie an electric motor or ZERO vibes.
Dave M

[CrabbyMilton]

The drawback of the old 71 and 92 DETROIT DIESEL's in buses is that unless one wanted to make much work for themselves, you pretty much had to stick with those engines due to the fact that most builders designed the engine compartment and wheelbase around the shorter 71 and 92 engines. So repowering with a S-60 may cause many to conclude the heck with it that's more trouble than it's worth. But many used the S-50 which fit much easier than the longer S-60 but talk about vibration of the 4 banger...wow.
But buses that were designed with the S-60 as standard or optional equipment could easily fit one of my CUMMINS(ISM, ISL, ISX) engines.
As stated, those old 2 strokes could be ID'd just on sound alone. Although, that 12V-71 sounds alot like the 6-71. Still nice though.

[Lin]

My 5a has a 8v71 and Allison.  The Allison was the best thing I ever did for the bus.  I can not see doing anything about the engine.  However, if I were buying something else, I would want the S-60 for the serviceability and extra power.  I would accept the electronics that goes with it.

The point has been made that everyone is driving electronic cars, but the is a different story.  Every little mechanic shop is equipped to deal with them at a reasonable price.  However, unless you are going to learn to diagnose and repair your coaches systems, it will require a specialized shop to deal with it; such a shop might not be local or reasonable.  Simplicity is certainly the ally of an amateur like me.

[belfert]

Lol....maybe the extra 5 feet helps? I don't know, I just recently though experienced a 60 series in a new j4500 and Heather and I both could not believe the noise and vibration when he started that thing. Maybe it smooths out once it's running beyond idle rpm?

The J4500 must not have been too new as the Series 60 was discontinued in 2010 I believe.  My series 60 does idle rough, but it seems smooth once up to speed.

[bigred]

Guy's; I have a '93 Prevost XL with the 8v92 and it is very quite inside the coach even in the bedroom.As a matter of fact ,one can carry on a fairly  normal conversation standing at the rear of the bus with the engine compartment closed off ,but when you open the rear doors ,better have the ear plug's handy.              I saw somewhere on here where the XL Prevost had some delam issues.Where does this happen? I swear there is a rivet every six inches on this thing!!

[Hard Headed Ken]

XL's don't have the delam problem, it started with XLII's they didn't have rivets from the factory although that is part of the fix for the delam problem.

My DDEC II 8V92 got 5.5 MPG. It was smooth that's about the only good I have to say about it. I've never thought it sounded good, it seemed like it was turning about twice the RPM it was. My Series 60 is getting 9 MPG towing my 1/2 ton GMC truck. I don't have to worry about the oil level, it never moves, the oil stays cleaner loner, no air box drains with oil dripping out and it starts great when it's cold outside. I could go on with the good. Not much bad. It does vibrate some at idle but most of that is my fault because I used 8V92 engine mounts, I hope to correct that this winter. For me I couldn't go to sleep with a 2 stroke under the bed.

Ken