Military 8V71T engines OK for our use?

bevans6 · October 18, 2010, 08:01:14 AM

Just googling around and I see lots of Military rebuilt 8V71T's for sale, for widely ranging prices. I have in the back of my mind that these are not good donors for an engine change for us (putting an 8V71 in where an old worn out 8V71 currently is, so a pretty straight swap, except for the turbo). But they keep looking interesting... I expect that you would have to put the old flywheel housing on, swap the flywheel over, put all the accessory drives for alternator pulley, air compressor and power steering on. Any experience or thoughts on this?

Brian

TomC · October 18, 2010, 08:08:47 AM

Most of the military 8V-71T's were rated at 600hp @ 2,500rpm. They use a huge turbocharger that really doesn't get working until high in the rpm range. To compensate for the big turbo, the engines use 15 to one pistons that smoke alot at startup. Basically-a military engine should not be installed in a bus as is. If you want to use the block and head as a base to rebuild your engine-then that would be good. But, cams, pistons, liners should be replaced. Good Luck, TomC

Don Fairchild · October 18, 2010, 10:58:03 AM

The military engines are good cores to use however you do have to change over several items from your old engine. It all depends on how the military used the engine as to what is on the inside. Tom I have not seen any of the 15:1 engines in several years in fact two of the four that I have in the yard are 18.7:1 4 ring piston engines with S90 injectors. On those I will change the pistons and liners but the cams are fine for bus use.

Don

Highway Yacht · October 18, 2010, 01:35:26 PM

I've got a military 8V71T installed in my MC-9. Not sure about the internals but it does have a huge turbo and larger injectors. The engine was installed by a bus company in Roanoke VA before I purchased the bus. From what I was told the military engine was installed back in 2005. Only thing I have noticed is some black smoke when in a hard pull but she's got lots of power.

Rick 74 MC-8 · October 18, 2010, 04:12:07 PM

600hp @ 2,500rpm Lets go by the time anyone complains about the smoke Ill be gone (LOL)

Rick 74 MC8

Van · October 18, 2010, 04:37:40 PM

Smoke em' if ya got em'

Highway Yacht · October 18, 2010, 06:06:55 PM

Quote from: Don Fairchild on October 18, 2010, 10:58:03 AM
The military engines are good cores to use however you do have to change over several items from your old engine. It all depends on how the military used the engine as to what is on the inside. Tom I have not seen any of the 15:1 engines in several years in fact two of the four that I have in the yard are 18.7:1 4 ring piston engines with S90 injectors. On those I will change the pistons and liners but the cams are fine for bus use.

Don

Not sure if it is true or not but I was told my 8V71t was a surplus Tank engine. I'd like to know just how many HP I actually have.

RJ · October 18, 2010, 11:28:54 PM

Highway -

Crawl into the engine compartment and pull a valve cover. Probably easiest on the curb side.

On the injectors there will be a round medallion with a letter-number combination on it.

Let us know what that combo is and we can tell you what HP your Detroit's set up for.

Be sure to wear your "dirty" overalls, and be CAREFUL putting the valve cover back on!

FWIW & HTH. . .