M816 SLOW ... More freeway speed needed and more power, suggestions....

[Thehammatts]

Hi. I am fairly new to being a member but I have been watching the board for two or three years now. I had a stroke last summer. I suffer from weakness in the right arm, tremors and memory issues...so, the drs. are allowing me to drive a car and my family needs to eat and we are all willing to work. We are going to open an offroad recovery business for those wanabees who put 37" on their Ford or Chevy with a six inch lift and end up in the ditch or stuck in the mud while they forgot to buy the winch or are ultra stupid a broke something....Ok, the drama is out of the way....

The real issue after reading so many posts and suggestions, we got an m816. (I still am looking for a m936 too so if you have one....I am willing to trade solar panels, jets skis, boat, guns....just depends on your 936). On the way home we realized how LOUD they are inside. But the real issue was 55mph TOP speed going downhill. Uphill the best I could do was 40. Slow at best. I need two modifications and we are very mechanical. How would you get more freeway speed? And how would you keep the speed going uphill?

My thought was to do a twin turbo HB3T. One from the exhaust and the other near the inlet. This will keep pressure and heat down yet more boost from the air. And would you add some type of overdrive gears...like a new transmission or sixth speed?

Thank you. Chris

 

[gimpyrobb]

Are you going by gps or the speedo? How long has the truck been in operation? If it is just getting out and about, I'd put some fuel conditioner in and wait to see how it perks up. I towed my wrecker with an M105 behind it, and a NHC250 in a can in the trailer, AND over a ton of tools with an M819 and it towed fine and had good road speed.

 

[Floridianson]

I would think if you are very mechanical just drop in a 400 big cam Cummins, anything else I think will disapoint you.

 

[Thehammatts]

GPS. Had a chase vehicle. They noticed no smoke issues. Yes, NHC 250 motor made in 1972. I have already towed a trailer with about 12,000 pounds and notices no real performance changes. She just needed to be started in first instead f second gear. Going up hill we lost about 15 pct power.

Cost is an issue...so changing to a 400 is prohibitive at this moment

 

[73m819]

What you have is what you have, these are NOT fast trucks, they have the power to do what they were designed to do. if you want FAST road recoveries, get a civi rig.

 

[AMGeneral]

Ron is right,the 816 and 819 wreckers are heavy and not speed demons by any stretch of the imagination.

Larger tires will net you more speed,at the cost of power.

A 7,8,9,10 or 13 speed transmission will keep the 250 in it's power range,but will require major modifications and you will lose your PTO for the front winch.

You can add a turbo to the 250,essentially making it a 290 Cummins,but once again,it requires fab work and isn't cheap.

The NHC 250 does not have piston cooling nozzles like other large displacement diesels,and you are looking at a major damage if it is turned up too far.

Having driven my M816 all over the east coast on many recoveries,I can tell you,they aren't fast or powerful,but they'll get you there and back if taken care of.

Just my 2 cents.

 

[Thehammatts]

Ron is right,the 816 and 819 wreckers are heavy and not speed demons by any stretch of the imagination.

Larger tires will net you more speed,at the cost of power.

A 7,8,9,10 or 13 speed transmission will keep the 250 in it's power range,but will require major modifications and you will lose your PTO for the front winch.

You can add a turbo to the 250,essentially making it a 290 Cummins,but once again,it requires fab work and isn't cheap.

The NHC 250 does not have piston cooling nozzles like other large displacement diesels,and you are looking at a major damage if it is turned up too far.

Having driven my M816 all over the east coast on many recoveries,I can tell you,they aren't fast or powerful,but they'll get you there and back if taken care of.

Just my 2 cents.

Thank you, thank you. I was hoping for a different answer. So, we agree. Slow go keep her in tip to shape and listen to lots of tunes!!!!

 

[wreckerman893]

My two best M816 days were the day I unloaded it off the truck and the day I watched a civilian wrecker haul it off. The 250 is a turd engine with little or no way to increase power. If you turn the fuel to it you will either melt it down on a long pull or blow a head gasket.
They weigh about 36K pounds bone dry. That goes up with what ever you haul around for recovery equipment, fuel, crew and weight of towed load.
By the way, if you don't have commercial tow insurance your insurance company may not know you if you have an accident pulling something on the public roads. I had a farm policy on mine and my agent told me I could not tow my stuff or anybody else's unless I paid for commercial tow insurance. It is not cheap.
And if you get it stuck you better have the vehicle recovery TM memorized and know how to use snatch blocks and mechanical advantage. If you can't self recover a commercial tow service will bend you over if they will even go off road to get to it. For what you are going to be pulling out the M816 is a lot of overkill.
You mention that you have health issues and some issues with your arm. Winching with these trucks can be a rough workout, the cable is heavy and you have to be able to remember how to engage all the drives and PTO. You have to be able to rig the cable and heavy snatch blocks if you are recovering something heavy.
Another factor is the heat that builds up in the cab during hot weather. If you are in a desert environment you are going to know how a turkey feels on Thanksgiving Day. There is no way to get relief from the heat if you are sitting still or barely moving.
Just my rambling thoughts.

 

[EMD567]

Military vehicles are not speed demons. They do NOTHING fast. However, they will get you there. I love my M814, but when I drive it, I have to remember it is not my Sterling. 50 mph is all you will get, so just plan on getting there a little later.

 

[Floridianson]

The good thing about a 400 BC is you will not get much more speed but what speed you get you can hold up a hill. My friend has one in his M816 and has not had any problems. He does take it easy but that beast will hold on most any hill without a drop in gears.

 

[73m819]

I just dropped the fuel button by 5 (27 to 22), you can really tell the difference, where I had to drop from 5th to 4th now pulls nice in 5th, may blow some smoke but pulls real nice, the problem is not really the motor but that P.O.S. trans. that has hole so DEEP between 3rd and 4th that you could loose two wreckers, what is needed is a 8 or 10 speed, this would allow the rpms to stay up where they are needed and make these trucks a LOT better driving.

 

[Thehammatts]

My wife says I am not ready for this venture and after reading your post I may second guess my thoughts....but it makes sense. We have a lot of towing companies out here and no one recovers off road. I spent 80 pct of my time in Kuwait getting howitzers and m105 un stuck. We used an 888 and a 816 modified for our guns. When we got really stuck we had to call another unit who brought out some cool newly modified 936 that looked like the Oshkosh trucks. Thank you for your rumblings.

 

[Recovry4x4]

The speed/power issue has been covered but I'd like to point out another issue. Despite the fact that this truck is all wheel drive, at 36,000# it will suck on soft ground. If you are going after modified 4x4s in the woods you need to reconsider the truck you need. An all wheel drive medium duty would be a little better but probably best would be a 1 ton 4x4 wrecker modified for off road. If you want a winching brute, look at a Holmes 480. PTO powered winches and swing out booms lets you winch easily from 3 sides. Add a heavy hydraulic to the front and you can certainly do some recovery. Check out youtube and search for BSF Recovery Team. Gives you an idea of capability.