Anyone Mud their diesels?

[ruhrinec]

Hey Just joined this great site and i want to see who's out there playing in the dirt and mud with their trucks and how things hold up?

My Truck is getting a 93 MFI motor because i think its Cool, and i feel this diamond in the rough has been overlooked due to the DS4 being able to flow just a little more fuel.

I like a challenge, so my thinking is Since the DB2 can currently output only so much fuel, how do we make the most of it?



Here's My truck, already posted in photo section but i figured some may not see it so here it is again.

http://www.thedieselpageforums.com/photopost/data/500/medium/truck1_0.jpg

[ken93]

Don't mud mine as its 2wd, but you are right about 1 thing. Way more possibilities, and greater reliability with the manual IP. Real simple, marine injectors(higher pop off and way more fuel capacity) new glow plugs, bigger exhaust, tweek the turbo, a1/8th turn on the metering screw, and you gained 50hp. Much more and get ready to spend.
And pushing those tires, before anything, pyrometer and boost gauge.

[ruhrinec]

I found a donor engine with 125,000 miles in a truck that was wrecked in the rear. Engine has a 6 month guarantee so I'm going to pull the pan off as soon as I get it and take a good look at the webs.

If those are good I'll take off the main caps and inspect the bearings, I'll also check for obvious worn out rod bearings but not going to loosen a cap unless I plan on reconditioning them. if they are good the heads come off and look for damaged pistons and cylinder walls, head gasket leaks, prior machine work and see if there are any cracks in the head.

If I'm real lucky and the cylinders look good I'll leave it alone and re assemble it and if I blow it up everything can be transferred and I wouldn't have sunk $$$$ into machine work.

I have most of this stuff already, here's the plan:
Gm-8 with turbo master @ 15psi
1/4 turn on pump, 2 degrees advance timing.
Flowmaster High flow crossover and 3" down pipe going into 4 inch exhaust
Port match intake and exhaust manifold
Head studs with .010" thicker felpro gaskets
Main studs and fluidampr
Penninsular intake hat, and the most efficient intercooler I can fit behind grill
HO coolant pump, 180 degree thermostat, duramax fan and heavy duty clutch.
Optimized crank breather system.
Cast rocker setup
High quality EGT and Boost gauge.
High flow intake and filter.

[ken93]

Well, looks like your already ahead of the game. 1/4 turn might be a bit excessive at 15psi, but if you dont mind a little smoke, and keep your eye on the egt it won't kill you. Especially since your not hauling anything with it. I would make sure that bottom end is super tight though.

Which axles are in it and what ratio?

[ruhrinec]

The bottom end is the biggest thing I worry about, I'm keeping my fingers crossed and hoping the plastigauge tells me good things.

I'd like to run the gm-8 to just below the edge of its efficiency range and use the large intercooler from the 94-02 cummins to compensate for intake temps.

The truck came with a front Dana 60, 14 bolt full floater rear and 4.56 gears.

The transmission is a th400 so the weak link is the np241c transfer case which I have the boxes to do a 203/205 doubler to make it bullet proof, improve driveshaft angles and put a little more weight towards the rear of the truck.

I'd also like to put a suburban 40 gallon gas tank setup for diesel between the rear frame rails under the bed instead of the little 20 gallon tank on the drivers side.

[ken93]

Well I don't think you are going to worry about twisting an axle shaft, but you may consider
At minimum throwing some type of mechanically controlled locker in that 60. Every cucv we ever got hung up was due to the weight of the front end. Even with 40g tank and the heavier t-case, you would be suprised how small of a downhill grade and semi loose/wet ground it takes to burry that front end. the mechanics cucv cound back up a phone pole with all the tools in the back, but the chow trucks and support trucks, forget it.

Was the pintle on the bumper when you got it? if so keep it. If that is a cucv rear bumper you will never break it (assuming the braces havent rotted out). Get online and buy 5 or 6 eccessed q-tips (sling legs) and a few screw pin shackles, you will have a recovery system to last a lifetime.

[phantom309]

Real simple, marine injectors(higher pop off and way more fuel capacity) .

higher pop off yes,.
more fuel capacity ,. no
Injectors are capable of flowing more fuel than the pump can put out.

!/8th turn will not be enough,.

[ruhrinec]

Ken93-


Every cucv we ever got hung up was due to the weight of the front end

This is exactly why I am not going the cummins route, along with wanting to keep the front end weight down I also wanted to keep drivetrain strain reasonable.

I'll be figuring in a Detroit locker for the front axle rebuild when the time comes.

This truck was virtually stock besides 4 inch lift blocks and flat 4 inch front springs so I'm building it from scratch.

[DmaxMaverick]

IMO......

The 6.5, in just about any build, is the wrong powerplant for a mudder in the configuration you want to build. It just won't have the HP to turn those 44's. And, cooling will be a deal ender, even if you include a secondary cooling stack with CAC. What you will need is somewhere in the range of a WELL built Cummins or Duramax. Your recipe, in the other world (non Diesel), calls for a well built big block in the 400+ HP range, minimum. The 6.5 just can't compete, there. It was never designed nor intended for such use. Either it will just not work, or you'll kill it trying.

Also, you'll want (need) a manually engaged locker for the front. Anything else will be a disaster. An open diff is better than ANY auto-locker, of any design. ARB or Eaton would be a good choice.

[ruhrinec]

That's why this engine and setup is such a bargain. I'll have less into the whole truck and it will be bulletproof for less than I could buy a stock duramax which would still need lift tires axles etc.

I agree though if I was running rockwells and tractor tires I wouldn't dream of using a 6.5 but I want to be able to drive this truck to and from the mud pit because to me it's my own personal test of build quality and design.If I was running rock wells and tractor tires id have to have a trailer to haul it and a separate truck to pull that trailer hauling my actual mud truck. I don't yet have the space nor funds to do such a thing.

But I can do all the labor myself and buy parts a little at a time and be very choosy to ensure that the whole truck works as a complete package.

I believe this engines biggest enemy is heat and a lot of it has to do with the two banks exhaust pulses being crammed into one manifold on one side of the engine creating imbalance and inefficiency.

I have some ideas regarding that but not willing to spill the beans yet.

[AKMark]

I wheel the K-5 and it loves mud as long as my wheelspeed is high enough. Switching to a SM465 4-speed trans was a night and day difference from a Turbo 400. Unlocked several ponies and it rolls nicely down the trails.

I did mud with the Turbo 400 too, but again had to find the right gear selection and then it rocked.

[ruhrinec]

What gears on the th400 did you find the best and what tire size were you running?

[AKMark]

I had 3.73's with 36's. I found low range (208 T-case with 2.72:1 ratio) and 2nd gear in the Tranny would spin the 36's enough to clear them.

Now with the 4.10's a Rockwell T-221 T-case (1.76:1 low) I typically use Low range and the 3rd gear of the transmission (counting low as 1st) I spin the 36's great.

I do hope to step up to 39's or 38's at some point. I don't use this vehicle on the street at all, so I'm leaning toward 4.88 or 5.13 gears if I regear.

[ruhrinec]

That's why I'm thinking to do a 203/205 doubler, besides helping driveshaft angles and weight distribution as well as durability, it gets me a 1:1 high a 1:2 low and a 1:4 extra low transfer case options.

My axles are 4:56's and tires 44's would allow me to use third gear in 4 low I think would clear the tires pretty good.

[More Power]

Welcome to The Diesel Page.

Your project sounds/looks cool! A 6.5 built for long-term durability can be made to produce a seat-of-the-pants performance similar to a well running 454. Jim

[ruhrinec]

Thanks Jim, I'd like to see what the mechanical pumped 6.5 is capable of with the right combination of parts.

One thing I haven't yet found is any real benefit to the stamped rocker arms over the cast. Pulling the cast rockers out of my 6.2 made me go WOW these are nice for factory pieces. Looked tough and had perfect wear patterns on the both sides.

So when I saw a cheap set of used rockers with pushrods and valve covers I jumped at the chance. But when I got them I said WOW what pieces of crap. I had no idea how much slop they had! They may have been worn a bit but the end that touched the valve stem looked like it only hit on half of the surface area it's whole life creating weird half moon shapes, I can only guess that any gains brought by lighter stamped steel rockers are offset by uneven and inconsistent firing if each cylinder is filling differently if only slightly.

I assume the stamped rocker and plastic retainer were done for cost as the cast rocker system is much more involved.

So my question is, has either rocker system been known to be a failure point and which one is better for high performance use?

[More Power]

Weight is one factor that makes the stamped-steel rockers better. The other is wear. A cast rocker is bushed with a bronze bearing. If that bearing wears out (due to the unavoidable abrasive nature of soot) the cast iron will quickly wear into the steel rocker shaft. I've seen pics of heavily grooved shafts.

The stamped steel rockers, on the other hand, never seem to wear out. Sloppy perhaps when there's no load on them, but when installed there's not a lot of play.

Go with the stamped steel parts....

[ruhrinec]

Mine seem to be in good condition so far as I can tell, I'll look closer at the bushings though now that you mention it.

So far as I've found I've only seen valve train issues with the stamped steel and plastic buttons. I'm hoping the cast rockers equipped in the early 6.2's were designed as precautionary overkill for the 3600 rpm redline, 200 higher than 6.5. I also feel that weight is less an issue with the lower rpm of a Diesel engine as the cam is still spinning half crank speed and I doubt I'll float a valve unless huge boost is used.