Ultimate IDI Engine/Transmission Combo for DD/Towing

[tuckerd1]

I would like to stay with the 6.9/7.3. I've been thinking 6.9 as a starter engine with zf5 or zf6 behind it. Maybe a brownie box aux transmission.

Having the $$ resouces available, what engine and transmission modifications would be the ultimate setup for daily driver and towing up to 26,000# GCWR. I'm also looking for something that will last 200,000 miles or more. No full blown race engines please.

 

[icanfixall]

I can speak form the 7.3 point of view but this holds ture for the 6.9 too. Machining the block is important. You want to deck the block. The facory min from the top deck to the centerline of the crank is 11.137 to 11.141. This is difficult to measure too. Now the mains need to be noned or align bored to true them up. Now are you going to sleeve the 7.3. If so maybe using the flanged top sleeves would be best abd going back to 6.9 bore... The cam is important. Typ4 (Russ) is the only option we have so make that dicission long before you get deep into this build. The heads.... Buy a new set of aftermarket heads. They are build much heavier than stock in all the correct places. Porting them is important to get the flow in and out. Pistons and rings.... The oem was Mahle so I prefered to use them. You can mill a max of 20 off the tops. Any more and you risk damageing the top ring because of the expoure to the heat. They have a low comp piston available. What they do to achieve this is mill the pin 10 thousands higher up in the piston. That drops it this amount in the cylinder. My porting is changing plenty to the flow in and out of these heads. I cut away most of the valve guide in the exhaust port. When you look in you will see what I'm talking about. Having Russ build a special turbo would really help things too. Running a Moose pump and Moose Misters (injectors) will wake up the dead thats for sure..... Adding propane or water-methonel injection will help too. Most just run blue window washer fluid to this. A shot od nos can be added too but how many added injectables can you control... The bottom end will handle anything to throw at it without requireing any upgrades. The oil pump needs to be checked for excess running clearances. Shimming to pressure regulater is optional. It kinda a touchy job so think about it. I shimmed mine 70 or 80 thousands. A cold startup pegs the 80 lb pressure gauge. Warm idle is 25 to 30 lbs usually and 55 at around 1800 rpm warm... Hope this helps you make some dicissions...

 

[crashnzuk]

What ever engine you have, and a wide ratio manual trans with a looowwww 1st gear and the ability to split all of the gears via an aux box of your choice. That would pretty much get the job done.
Travis..

 

[RLDSL]

If you are going to tow that heavy, you would really love a three speed brownie. That ultra low range is simply amazing for really steep spots, you can walk right up them where without the thing it might be call out a tractor and a chain time. Then being able to split the upper gears in the mountains has you pulling where the engine wants to instead of either lugging or screaming. Just being able to get the 4 over position for general highway towing brought my fuel mileage up about 3 mpg and made it where I rarely have to shift on fairly level interstate, where I used to have to constantly row between 4 and 5

 

[icanfixall]

One more thin that has been missed..... How are you going to stop that much weight. A dually 1 ton brakes can't pull that much weight to a safe stop in a hurry. Driving down a mountain grade or panic stopping because some ******** stops attempting a freeway onramp in front of you makes me shiver.... When you have enough time to plan a stop with that much weight is fine.... Its just the unplanned stops that might tag you. Then insurance starts asking questions and here we go....

 

[Diesel JD]

I would say the best engine build would be to copy Icanfixall's build. No one could complain much about that setup. I'm always in favor of manual transmissions. If money and some fab work are not an obstacle you could probably come up with quite a few options. I share Gary' concern about stopping 26,000lbs in a panic situation. Hydroboost and very good trailer brakes would be a must. Even then it's probably at the edge of what is safe. I know you're an experienced driver and these trucks can really take more than what they're rated for so it might be on the right side...but that's your call...depending on what you are comfortable with in the economy of risk.

 

[icanfixall]

If I was building and driving for myself I would have done a zf5 speed and GV but.... I had to think about my wifey who is shiftless.... I know she can shift a standard very easily. I had a 61 ford van with a standard and an early 63 healey 3000. She drove them fine... She just wont drive long and heavy in anything but an auto so.... I spent almost $8,000.00 on the BTS and GV setup. The amount hurt but the results are way better than anything going on right now out there. A Browney is truely the ultimate setup behind a 4 or 5 speed trans. Years ago my father had a Reo cement truck with a 4 speed browney backing up a 5 speed main box.. That gave him 20 forward gears and 4 reverse gears.. In 1st and 1st you could *** faster that it could travel done the road... It weighed 48,000 lbs loaded and 22,000 lbs mt.. I like a standard trans but home life requires an auto trans....

 

[towcat]

My '92 is the best towing combo I have as far as pickups goes. Only addition I am working on making is a motor in better shape and a E350 disc brake dualy rear with intergrated e-brake.
Still, as equipped, there isn't a soul on this earth who have driven the truck and complain about the ride, power, stopping and towing capabilities of the truck read my sig for the details on the drivetrain.

 

[The Warden]

Still, as equipped, there isn't a soul on this earth who have driven the truck and complain about the ride, power, stopping and towing capabilities of the truck read my sig for the details on the drivetrain.

That is a very true statement!! I've only driven his truck once and just around the block, but I can't imagine any better IDI rig for towing...although I still think that 4.10's with a double-OD is the cats meow for retaining the ability to haul heavy and keep empty freeway RPM's down for fuel economy purposes...

As to engines....I haven't tried this myself, but based on what I understand, I think that the ideal engine would be a 7.3l block that's been resleeved, with sleeves thick enough to run 6.9l pistons instead. This way, you get the larger head bolts (or, better yet, studs), and you also minimize the risk of cavitation. If I ever build up a second engine, that's what I plan to do...but, barring any catastrophic failures with my engine, that's in the distant future...

 

[rjjp]

On a side note, could you drill and tap a 6.9 block to accept the head bolts from a 7.3?

 

[Diesel JD]

On a side note, could you drill and tap a 6.9 block to accept the head bolts from a 7.3?

I believe it's been done, doing it right would not be easy. The only thing I disagree with about the sleeving a 7.3 down to 6.9 specs is
1) Dry sleeves are expensive escpecially from a repected and experienced machinist who's don lots of DIESEL work, preferably a lot of cavitated 7.3 IDIs and CAT 3208s that people just didn't want to toss when they could bore them no more. Probably $800-1000 in machine work alone...which is halfway to custom pistons or more maybe
2) Choosing 6.9 pistons you lose the ability to run the IDI turbo rods. As far as I know the big manufacturer, Mahle, Sealed power etc, don't make any 6.9 pistons that bolt to the IDI turbo rods.
3) The knowledge exists on this board to design a custom 6.9 piston to bolt to turbo IDI rods with lower compression. We could have a big argument about how low is enough to be worth it and how low might be too low to reliably start.
4) ARP studs for a 6.9 done right will easily hold as much pressure and boost as a headbolt of a 7.3 IDI.
Again I'm floating ideas spending your money, but Gary's motor with a Moose Pump and Moose Misters plus an intercooler would be the best thing we've seen yet. All my idea are experimental until I secure a core block, space to use it, and about 3000 bucks I don't have to use to meet my bills/obligations.

 

[The Warden]

I believe it's been done, doing it right would not be easy.

I could have missed it, but I don't recall anyone actually doing it...people have talked about it, but I don't remember any finished results. The concern I've always heard is that it would be extremely difficult to get it perfectly centered, and even if you did, some of the original threads would remain...meaning that the fresh-cut threads for the 7.3l bolts/studs would be weaker. Again, I'm going on what I've heard...never tried it and I don't recall anyone actually doing the machine work. I could always be wrong.

1) Dry sleeves are expensive escpecially from a repected and experienced machinist who's don lots of DIESEL work, preferably a lot of cavitated 7.3 IDIs and CAT 3208s that people just didn't want to toss when they could bore them no more. Probably $800-1000 in machine work alone...which is halfway to custom pistons or more maybe

That's a valid concern...OTOH, I had the impression that $$ wasn't a major consideration in this build in any event, I still think that this is the best sure-fire way to minimize the risk of cavitation...or, just start out with a 6.9l block.

2) Choosing 6.9 pistons you lose the ability to run the IDI turbo rods. As far as I know the big manufacturer, Mahle, Sealed power etc, don't make any 6.9 pistons that bolt to the IDI turbo rods.

You make a point; OTOH, finding a good set of turbo rods is getting increasingly and increasingly difficult...honestly, I'm at a point where I'm not even thinking about that as a viable upgrade unless you happen to have a turbo block or you're in a patient mood...

4) ARP studs for a 6.9 done right will easily hold as much pressure and boost as a headbolt of a 7.3 IDI.

You're right and in fact, a studded 6.9l should be able to hold MORE pressure and boost than a 7.3l bolt. OTOH, a 7.3l stud should be able to handle more pressure than a 6.9l stud.

Just some thoughts...

 

[1994IDI]

You have a lot of hands.

 

[tuckerd1]

Combined List

Thanks all for your replys. I know I said unlimited $$ resources, but I'm going to start this list with the things that are a must first.

Driveline items excluding engine:
1. ZF5/ZF6 - My E4OD is very wel built now with all the upgrades and a billet low stall converter, but I'm inclined to go straight

2. Brownie Box 3 spd aux transmission. Most bang for the buck over Gear Venders or US Gear. Based on my understanding probably the most dificult to operate of the 3 though. Enlighten me here if I am wrong. If not Brownie Box then I go with US Gear over Gear Venders because of design. I like the gear setup over hydraulics and the ability to use in reverse.

3. DRW 4.10 rear axle w/discs and LSD or Lock-Rite locker. With this setup in my situation I will exclude 4WD. I don't use it enough.

4. Hydroboost brakes.

5. Air Ride for leveling load.

6. 19.5 tires/wheels for extra load capacity. Also, taller gear for highway.

Cooling:
1. Aluminum radiator and MS Tech fan clutch. I like the idea of electric fan if one is available to provide adequate cooling for 26,000# GCWR.

2. If the E4OD is used then aftermarket cooler with electric fan.

Engine: (Remember, we are sticking with 6.9/7.3 for purists sake. No Cummins, DTs or others.)
1. 7.3 with sleeves if done right would be great. Otherwise the 6.9 gets my vote due to cavitation and cooling issues.

2. Lower compression thru offset wrist pin pistons that Gary mentioned plus shaving the tops. Can you get thicker head gaskets to eliminate shaving the piston?

3. Port and polish heads.

4. Head studs.

5. Turbo/intercooler setup. How big can you go with lower compression? 25# boost?

6. Moose pump and injectors.

7. Oil pump and regulator shims.

8. Typ4 reground camshaft.

9. Line bore crank mains. Should we do camshaft and cylinders also?

10. What about engine balancing? Is it worth the effort/cost?

This just starts the list. Add to it at will.

 

[Diesel JD]

I think a lowered compression 6.9 could surely take 20-25 psi boost with studs and a recent set of head gaskets, I could be wrong though. Your Hypermax may be different but most Banks and ATS kits are out of their efficiency range at 12-15 psi, might be looking at a non stock turbo. I hope to find out how hard the brownie is to operate behind my T18, but the way funds are looking ad a full school schedule in the fall it may not be anytime real soon. RL loves his, but then he used to drive old school big trucks.
@Tim, Diesel Direct may or may not have gone under but they used to have a ton of factory turbo IDI rods and priced competitively. If they did go out of business you'd think that inventory would pop up somewhere. Hopeully it didn't all just get melted down and sent to China....