6v92 VS 8v92

[ccbmster]

I am looking for a bus to replace my MC9.  I am seeing a lot of 102A3's on the market and most of them have either an 8v92 or a 6v92 in them.

Now I know that the current condition of the engine in question trumps all but my question is, all other things being equal, what are the pros and cons of each of these engines when each is compared with the other?

Thanks
Mike

[bevans6]

With an OEM installation, I would think just more power in the 8V92.  Probably lower fuel mileage if you make happy use of the more power...  the usual cooling issues if a retrofit.  If I were in the market for a newer bus I would try to get a S50 or S60, probably.

Brian

[kyle4501]

. . . . if you make happy use of the more power...  

I didn't realize there was any other use for "more power" . . .      

[ccbmster]

A series 50 or 60 or a cummins M11 would be great for sure.....but anything I have seen with those engines is about twice the money.  Given that you just cant get these things financed if you are not putting them into service the price of units with those engines is beyond me at this point.

Mike

[kyle4501]

The 92 series was (& still is) a good engine, especially if it is already installed & running well. There are some driving differences between the 2 stroke vs the 4 stroke.

Personally, I'd lean heavily towards the 8V92 as the extra power provides more options if you need them.

Usually, there is a fuel penalty for having more power available, but it is possible to get better mileage out of the more powerful engine, but you have to drive it just right (IE, use the power only as required to keep the cruise speed at the most fuel efficient rpm).


Enjoy your search, now is a good time to pick & choose.
Besides, you know that as soon as you buy something, the great deals start falling out of the trees. . . . 

[ccbmster]

Kyle, so the extra power is the only real difference?  I was just wondering if there is a perceived quality difference.  I know in cars there are certain engines you just want to stay away from and others that are usually solid as a rock and often the two are from the same manufacturer....just a different design or whatever.

[kyle4501]

No real significant difference that I've heard about, just small things.
Same bore & stroke, The small one has 6 cylinders & the other has 8.
The 6V92 weighs ~340# less than the 8V92.
The small one is 552 ci & the big one is 736 ci displacement.
Standard HP ratings for the 6V92 range from ~270 to ~350 HP & for the 8V92 the range starts at ~350 & goes up past 475 HP.

Both are turbocharged & have engine coolant directly on the cylinder liners (The 71 series have dry liners).

Treat them both the same & the only difference you'll see is the power. 

[robertglines1]

Gave up 1.8 mpg  gained much more hill climbing power ,don't have to work engine as hard.like going from a 4cyl car to a v-8...now looking foward to 60 series in my new coach an having both more power and better feul milage looking to get that 1.8 back plus another 1 mpg...6-v92 to 8 -v92 to 60 serries...left out 8v71 in first coach that was very much like the 6v92...Bob

[ccbmster]

Yeah...I have an 8v71 right now and it is great....if you live in Kansas or something.  The mountains in SoCal kinda take the fun out of driving an 8v71 though.

[happycamperbrat]

I specifically shopped for a 6v92. I knew it wouldnt climb hills as quickly as a 8v92 but it's injectors are less expensive (by quite a bit from what I have been told) and it would be easier to run veggie oil with (which for me out weighed the issue of fuel mileage).

[steve wardwell]

for what its worth, I've heard from some trucker friends that the 692,s hold up better than the 892's  opinions from guys that have actually lived with  them. one thought it was something Harmonic as to why they didn't stay togather Most of them are into  60 series and big cats,cummons now.

[TomC]

Both the 6V-92TA and the 8V-92TA are excellent engines that can go 500,000 miles between overhauls.  In an equal weight vehicle like a bus, the 8V-92TA will have to work less, probably lasting longer-as long as you don't overheat it.  I personally had both 6V-92TA an 8V-92TA in trucks, and you could definitely feel the difference in power between the two.

If you have an 8V-71N now and don't like the power, consider turbocharging the engine.  I did it to mine, going from 300hp and 800lb/ft torque (brown tag N65 injectors) to 375hp an 1125lb/ft torque (9G75 injectors).  With a 8V-71TA block, Detroit had an 80 injector option that put out 400hp and 1200lb/ft torque.  Really flatens the hills and makes driving a lot more enjoyable.  Good Luck, TomC

[ccbmster]

I would think about adding a turbo to my 8v71 but since I am being advised to retire that unit due to rust anyway I will just make sure I dont get another 8v71.

About the cheapest I have seen anything with a series 50, series 60, or Cummins m11 is 21k.  That is just a bit out of my price range without financing available for the purchase.

[robertglines1]

8v92 in my 89 prevost =5mpg----several coaches seated like this ander 10 grand...no major problems with this engine just the routine problems that crop up with all of the 2 strokes..fyi most prevost seated coaches from factory were of the 400hp vintage..36,100 scaled weight of coach..