New Engine

Ok eventually i am going to get around to getting a M715, Are they reliable? and what kind of engine swap do ya'll suggest, i would like a cummins.

Stock motor is great for what it is designed for. Slow off road manuvers.

A 4bt works great in them with an overdrive trans. The Tcase, np200 is prone to burning up its seals if you travel over 50 for long. Lots of guys swap in the 205 to fix that. The Ebrake band is swap-overable with little machining. If you go to the 4bt, 1008 axles are good, cause you will step up to 4.56 r&p and get sronger axles with disc brakes. The rear conversion kit is about 50-100 bucks. 38" tires fit with no lift. Anything else?

The old standby is the 350 chevy. Goes onto the stock motor mounts and Novak Adapters makes a plate to mount the T-98 to the GM bellhousing. Uses stock radiator, you can keep the 24 volt waterproof ignition if you can find a distributor from a M114 APC. Motor screams at highway speeds just like the Tornado.
6.2/6.5 goes in easy too but you HAVE to do some kind of overdrive unless you are 100% ranch/off road use.

A 6.2 works fine with the stock gears and no overdrive. That is, if you only expect MV-type speeds out of it. With 11.00's and the stock t-case, I'd guess I was rolling around 65 or so mph for about 4 hours straight once. It was howling for sure, but it held together fine. Not something I'd want to do every day, though.

Is it possible to get a 6bt?or is that pushing it and how much do they cost? and if i got one what would i need to do to outfit the truck for it?

I have a 396 Big Block with a NV4500 in mine. Works great.

My students are real close to wrapping up a 350/3053A swap for Pistolnut in one of his M715's. That should work good too. Both of the above swaps could be done in a weekend if you planned ahead, have a welder and basic fabrication skills.

My class is also doing a M715 for Sermis. That one is getting a 6BT/Getrag from a '92 Dodge truck. If you want to run a mechanical cooling fan, sheet metal will have to be cut. We are cutting the valence to move the radiator forward instead of the firewall to move the engine back.

The 6Bt is also a 1200 pound engine and will probably tax the stock front axle too much. Yes, it is a D60. But, a 1967 version of the D60. Think modern D44 for strength comparison. So, a CUCV gave its axles for the 6Bt truck project. We did a spring over for plenty of oil pan to pumkin clearance and to allow bigger tires.

When looking at 6Bt engines there are several things to consider. The '96 I think and new ones have the massive P7100 pump. Lots of power. However, the turbo is lower and further back than the 1st generation version. With 1/2" clearance between the block and the firewall, there isn't enough room for the exhaust to leave the turbo in the M715.

The 1st generation engines had a smaller pump that didn't make as much power. But, the oil pan is shaped just right to clear the front axle, the exhaust will be close to the firewall, but not into it. '92 was the year they started using intercoolers in front of the radiator. The M715 doesn't have much room in front. Getting a non intercooled 1st generation 6Bt makes things real simple.

You can do it anyway you want since it is your truck. The 6Bt is very tempting, but a 6.2 is real easy, a Chevy gas engine is easy and cheap. How much are you going to drive the thing? I get 10 mpg city and about 11-13 highway running a NP200 t-case imposed 54 mph limit with Michelin XZL tires. The extra cost of a diesel will never be repaid unless you drive a lot. Having written that, I want to go diesel just because on my next one. Or rather the one after I do an all stocker one and then maybe after my son builds one. Anyway, Someday I plan to do a diesel one.

Well i'll drive it every day but i would like it to be easy, and cheap. If i put a 350 would i still get enough power for off road? and would there be any thing i would need to change on the truck, i really would prefer a nice diesel turbo though. and do know of any places i could find an engine?

A 350 will get you through any mud you find. Power wise that is.

If you just plan to drive this thing around town and in the mud, don't care about highway speeds and want a real simple swap. Find a K20 or K30 from the '70's with a V8, SM465 and married NP205. Pull all 3 out together, put them in the M715 together, make up 1 new cross member while getting rid of 2 and make up new length drive shafts. Presto chango! You now have a drive train that parts can be bought just about anywhere for, works because it was designed to be together and if you swap in the axles and power brakes from the same donor truck. 4 wheel disc brakes will help you stop.

a couple things to point out:

Barrman said:

... When looking at 6Bt engines there are several things to consider. The '96 I think and new ones have the massive P7100 pump. Lots of power. ...

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the p-pumps are found on '94 to early '98 motors. also found on industrial motors starting about the same time, but continuing on a little longer.

Barrman said:

... However, the turbo is lower and further back than the 1st generation version. With 1/2" clearance between the block and the firewall, there isn't enough room for the exhaust to leave the turbo in the M715. ...

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the exhaust manifolds can be interchanged and even flipped upside down to aide in turbo location. also, industrial applications had several turbo arrangements that would help put the turbo anywhere you wanted.

Barrman said:

...The 1st generation engines had a smaller pump that didn't make as much power. But, the oil pan is shaped just right to clear the front axle, the exhaust will be close to the firewall, but not into it. ...

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oil pan and pick-up are also interchangeable between the motors. again, lots of options w/ industrial applications.

Barrman said:

... '92 was the year they started using intercoolers in front of the radiator. .... Getting a non intercooled 1st generation 6Bt makes things real simple. ...

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an intercooled motor can be run w/out the intercooler as well - just put the non-IC'd intake horn on. i wouldn't bother w/ the 6bt unless you kept the intercooler - you wouldn't be able to turn the power up much if at all. and for stock power levels, you'd be better off w/ a intercooled 4bta with the fuel turned up a bit. that way, you'll have the same power but better mileage potential.


as far as pricing is concerned, you could see a take-out 6bta for anywhere between $1200 - $3500. a low mileage motor might be as much as $4500. 4bt's are pretty popular right now, so you could expect about as high of price as a 6bt, but expect at least $2500.

cummins = lots os $$$$$$$$$$ most expensive route to go 15k avarage. sbc is best imo got a few of both.......... i prefer sbc

bcowanwheels said:

cummins = lots os $$$$$$$$$$ most expensive route to go 15k avarage. ...

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and how did you come up w/ that "average" figure?

HummerRecovery said:

Is it possible to get a 6bt?or is that pushing it and how much do they cost? and if i got one what would i need to do to outfit the truck for it?

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Have that ( 6bta ) in mine ... the best engine you could swap !! With all the goodies and the trailer loaded (m104a1) , this engine do not have any problem moving all that iron .... and i'm talking about 15000 pounds !! Still able to run 50 mph at highway speed. But i have $20k invest in that truck ..... Costly but it give is money back !!