I want to educate myself on diesel engines and would like to know a good web site I can use. Just want to be conversant on what's good and what's not so good. As an example, I was talking with a guy today who has a D671 with an Allison 4-speed and I really didn't know if that was a good engine or not.
Jim

Jim,

This site won't accomplish what you're looking for specifically, but based on the principle that Bigger-is-Better, I think any gear-head will find it interesting.....

http://www.bath.ac.uk/~ccsshb/12cyl/

Assuming you're interested in theory: http://auto.howstuffworks.com/diesel.htm

As to comparisons among various builders and models, that's going to be tougher - forums like this one will provide some actual experience. Every diesel builder has built models less desireable than other.

Anyway, the "D671" is a Detroit Diesel (GM) 6 cylinder inline 2-stroke cycle. DD designated its engines based on the number of cylinders and the displacement of each, so it's about 426 cu in (7.2L). A 6V53 would have six 53 cu in cylinders in vee config. BTW, DD 2 cycle engines don't require mixing of lube oil with the fuel like gaso engines.

IIRC, GM now calls its 8.2L and 6.5L diesels "Detroit Diesel" - they're four-stroke cycle.

If that 671's not rated at over 300 HP, it's decent, although its fuel consumption tends to be higher than same-sized Cummins or Cats. It's essentially a 100,000 mile engine...where the Cats and Cummins should go 200K +.

[This message has been edited by Rusty (edited January 26, 2006).]

quote:

Originally posted by humbojb:
I was talking with a guy today who has a D671 with an Allison 4-speed and I really didn't know if that was a good engine or not.

More likely then not he was referring to a 6v71. You might have misheard him. D671 or V671 sound alike. The 6 stands for a 6 cylinder the v stands for 3 cylinders on each side (like a v6 gas motor) and the 71 stands for 71 cubic inches per cylinder.

Carrying this to a straight 6 you would have a 671L or 671R that stands for straight 6 with a Left or right hand rotation 71 cid. The Detroit's could be a 8V71R or 8V71L you could even have a 12v71 or 16V71 if you bolt two motors together. Most people don't denote R&L when they are talking about there Detroit's

Some of the more common ones are the 71 series - 92 series - 53 series. The 92 series were also know as the silver 92's.

These were all 2 stroke motors. Meaning they would be on a compression stroke every time around. More power and smoother throttle response, but because of the scavenging affect not that environmentally friendly.

These motors are not being made for trucks anymore but I believe you could still get one new in a boat. The motors are good but tended to leak. These motors even had a tube on each side of the airbox that dripped motor oil onto the roadways - these are called drip tubes.

Most people with a 92 or 71 Detroit carried around a "Drip Pan" and used them when parked. They would say "buy a Detroit and get free undercoating" and "Two Stroke Joke"

I loved working on these motors and have rebuilt many of the 71 Series and 92 series. If you hear a 2 stroke diesel running and taking off it sounds a little strange but unmistakable.

I have seen many of these go over 250,000 miles most going 500,000 miles before rebuild.

------------------


1991 Barth Regal
460 EFI C6 Transmission
33' Oshkosh/John Deere Chassis

http://www.TruckRoadService.com/

"Without Trucks,

America Stops"

[This message has been edited by Bill (edited January 26, 2006).]

"I loved working on these motors and have rebuilt many of the 71 Series and 92 series. If you hear a 2 stroke diesel running and taking off it sounds a little strange but unmistakable."

The 8V71s were common in busses for years - now I'd guess they'd use the 6V92 - the 2-cycle sounds like a four cycle with twice as many cylinders, and the scavenging blower adds to the "whooshing" sound.

"I have seen many of these go over 250,000 miles most going 500,000 miles before rebuild."

Indeed they should - I should have made it clearer that those numbers I mentioned were for truck fleets (where my experience lay), where the drivers were far less concerned about engine longevity than a private owner.

The engine I was talking to the guy about is a V671. I guess that means it's a V6 with each cylinder 71 cubic inches. That works out to be 426 cubic inches. He said it was rated at 356HP. Is that a bad thing? He also said that with the Allison 4-speed, it got 8-9mpg on the flat, 6 on hills. The reason for this drift is that we're beginning to talk about full timing for a year or two before I get too old to do it at all, and I don't think the 28' Regal 454 will work for that. We'd probably rent the house to provide a little extra income. I'll start that on another post.

A 6v71 rated at 356 hp? does it have a turbo? my 8v71 is rated at about 318 hp with the larger injectors...stock injectors it is only rated at about 275 hp.

It would have to be turbocharged at that - the 671 rated at 318 HP had a lot of problems (mostly heat-related). Sadly, GM's "fix" was to advertise it as "The Cool One", but it quietly disappeared from the market at that rating.

Even if it is "rated" at 356 HP, depending on the size/weight of the coach, I can't imagine that power ever being used except for brief moments. In my experience as an oil peddler selling to about 20 truck lines of any size, the 8V71 seemed to be trouble-free, as was the 12V71 (both naturally aspirated).

That HP sounds a little high. Maybe it is. If he changed the injectors to the black tag injectors and put on a bigger turbo...Maybe. Unlike Rusty's experience with that motor I haven't seen very many problems with the 6v71's.

Now, If these were put into a linehaul operation... it would have to be overloaded. The 6v71 should have been a city operation motor.

The common problems I have seen were...
1) Oil leaking into the intake from a ruptered blower causing the engines to over rev and blow
2) The blower drive gear snapping
3) A stuck injector rack from a bad injector

These motors for being inside of a coach are an easy assignment for them. If it starts up cold it might "hum and surge" a little (rev up and down) for a minute or so. Nothing to be to concerned about. Have the racks run and the valves and injectors set. Take the motor to a bus garage as those are very common motors to a bus mechanic.

The 6v71 is a good motor 8-9 miles a gallon is good. Check were they park it and look at the drip tubes (1 on each side) a little bit of oil is nothing.

------------------


1991 Barth Regal
460 EFI C6 Transmission
33' Oshkosh/John Deere Chassis

http://www.TruckRoadService.com/

"Without Trucks,

America Stops"

[This message has been edited by Bill (edited January 28, 2006).]

Bill, the 6V71 wasn't on the market for trucks back then - the experience I had was with the inline. IIRC, the 6V53 was, but I never encountered it.

I'd also add that the 671 in the marine market gave no trouble, so it appears that cooling was the major issue all along (although USMC AMTRAKS had fits with water spray incursion into the Rootes blower - but that wan't the engine). I never did fully solve that one...even with reduced scavenging, the suckers still ran (proved by the smoke screen).

As an aside, GM attributed the problems to the use of a "high ash" detergent (>0.5%) and so recommended low ash oils across the board. The issues arising in the 671/318 were manifested in ring belt deposits resulting in cylinder scuffing and piston slap.

I always liked the GM modulars for the smooth running of the 2-cycle and the fact that they were very easy to work on, and after-market parts are widely available.

The only problem I personall ever had was with twin sidewinder 453s in our workboats when I was a ship's Chief Engineer...and it wasn't the engine, it was the ridiculous HP air starting system - an engine-driven compressor was supposed to pump an accumulator to 3000 psi. But the check valves always leaked, and one does not throw out a hose to pump up tanks at that pressure...fortunately, when I came up with a Rube Goldberg way to start 'em, they fired right up.

quote:

Originally posted by humbojb:
I want to educate myself on diesel engines and would like to know a good web site I can use. Just want to be conversant on what's good and what's not so good. As an example, I was talking with a guy today who has a D671 with an Allison 4-speed and I really didn't know if that was a good engine or not.
Jim

Are you looking for something other then a Barth? Tisk tisk!

quote:

Originally posted by Rusty:
Bill, the 6V71 wasn't on the market for trucks back then.

I only remember seeing the straight 6-71 and the 8v71 in trucks. I did work on a boat with twin 6v71R & 6v71L and some small city buses with the 6v71.

We will file this under "strange but true":
I met someone who dropped a 6v71T in a Dodge pickup but that cat was strange to begin with. Don't ask me why! A waste of a good motor!

I had both the 6-71 and the 8v71 in trucks. I was told that to make them run you did like you did at the kitchen table... feet flat on the floor! I always kided that you didn't need to grease as often since they slobbered oil back under the truck,also kept away the rust factor.

Not really looking for a sob. Just want to understand diesels a little better and determine which would be the best in a Barth, Detroit, Cummins or Cat. Now if something like Shadows bus came along and I had the money and decided to go full timing-----????

while on the topic of diesels, I would like to know about normal engine maitainence.
I would not likely be doing my own oil changes / coolant R&R and such due to problems with disposal of waste oil.
So, how much would the "average' oil change go for, in the little 5.9 Cummins/Breakaway? How about the bigger CAT 3208/Regency?
Is general upkeep quite a bit more for a diesel than a 454 Chev or 460 Ford?
Thanks
Don

quote:

Originally posted by humbojb:
Not really looking for a sob. Just want to understand diesels a little better and determine which would be the best in a Barth, Detroit, Cummins or Cat. Now if something like Shadows bus came along and I had the money and decided to go full timing-----????