Convert from 8V-92 to Series 60

[antioch01]

I am considering swapping our 8V-92TA to a series 60. Our coach is a 1990 40' Liberty Prevost. The throttle is by wire, not sure if it is the same as series 60. Does anyone know if the HT750 trans will mate ? Does the Allison HT750 ATEC system mate with the series 60 DDEC 4 ? Will the harness from the DDEC 3 on the 8V-92 work with the DDEC 4 series 60 ? Is the 8V-92 rotation the same as the truck Series 60 ?
Lots of questions, not sure if someone here knows the answers or I need to check with Detroit Allison.

I have seen 40' Prevost with the series 60 so I assume the clearance is there. There is a panel that can be removed in the floor behind the bed that looks like it would allow the clearance.

I know we will get some "why don't you just trade up to a series 60". But we love the floor plan, Liberty quality, colors and real wood bleached oak cabinets. All the newer coaches seem to have the laminates. Just not what we want. Also we have a series 60 engine available.

The 8V-92 runs great and has had the 500 HP upgrade. It runs circles around the series 60 coaches I have tested. Just concerned with the MPG and would like to swap engines prior to some lengthy travel.

[travelite]

Hi Robert,

This is a great set of questions to post on http://www.dieselenginetrader.com/di...es.cfm?catid=9.

[Jerry Winchester]

Robert,

You need to drive a few more Series 60 coaches. I've had two since I had the 40' with the 8V92 and either one of them would hammer the 92 in every category - except sounding cool. Between the low end torque and the big fuel mileage improvement I would be hard pressed to own anything else.

As for the swap, I have to think you'll need to break out the chainsaw for the back closet.

[Jon Wehrenberg]

Prevost was unable to install the Series 60 into a 40 footer until the shorter "World" transmission (the 6 speed) became available due to the increased length of the engine / transmission duo.

I also believe the tag axle geometry had to change, but I am not sure of that.

My reaction is that must be one hell of a Liberty that makes the swap justified compared to just going out and buying one with the Series 60 already in place. You should run the numbers. I am not sure you will escape interior changes as Jerry suggests. Our 87 Liberty had a north/south bed and the only impact of the higher Series 60 would have been to change the flat access cover under the bed to a "dog house", but if you have an east / west bed the cabintery across the back may also be affected.

I am not sure I buy into the theory that the Series 60 is a more powerful engine. It has more low end torque, but once the 8V92 comes alive (over about 1500 RPM) if does quite well. That may be attributable to the 5 speed transmission hanging in gear to 2100 compared to the 6 speed which will shift long before the engine is wound out unless you manually shift it. The only advantage I can see with the Series 60 apart from the low end torque getting you moving quicker from a stop is the fuel mileage, but the cost of converting will require a lot of miles of fuel savings to before those savings are realized.

[ajducote]

Robert,

I know some "Bus Nuts" who have converted seated coaches to motor homes. Some of these bus nuts are incredibly talented. I have seen old buses turned into works of art. I have seen old 6V's and 8V's replaced with Series 50 and 60 engines and with Big cat engines. In every case, the owner said it was a lot of work and expensive to covert the engine over. Cooling, wiring, engine and transmission mounts, custom fabrication, possible vibration issues if not mounted correctly, the list goes on. I'm sure it can be done, I even saw one that used a manual transmission, if I remember correctly had 9 gears. But in every case the owner said it cost more then they had planned and took a lot longer to finish the job then they ever thought. Just a thought, how about having a "Hot Rod" 8V built and replace the engine you have now? Simple remove and replace, add water misters to the radiator to remove extra heat. Drive it like you stole it, and put the original engine back in when the hot rod engine melts down. That last line was "tongue in check"

Whatever you decide, I sure it will be an interesting project,. Take lots of pictures and post often so we can follow along.

[rahangman]

Robert, I am a long, long way from being very knowledgeable concerning Diesel engines, etc. but, in this change out you are contemplating, the knowledgeable guys are mentioning cooling. I replaced (recored) my radiator this past fall on my 8V92T and got by very cheap at $2000 final. If that gives you an idea on the associated costs, let alone the cost of the S60, then good luck.