I recently bought my first Dodge, a 12v 91.5 D250. It's in pretty decent shape and only 2 owners, original owner then his son. Trying to come up with a comprehensive plan for my system and have some questions. I'm looking for maximum reliability and am willing to pay more to get it... at this point I have more $ to spend than I have skill or time, so I'll probably shop *a lot* of this out but will also be doing a little work myself. Sorry if this post is rambling and disorganized, my head is kinda swimming with all the info I'm trying to piece together (and not starting with a strong knowledge base).

Will occasionally tow 8,000-9,000lb trailer, so I need to boost power but don't want lots of smoke/high EGTs. Decent MPGs would be nice, but maybe that's asking too much! Not thinking it will be my daily driver but it IS a possibility, and getting good mileage would be a huge plus in that case.

Truck already has: 40hp injectors, 3600 governor spring, 4 inch exhaust, 16cm exhaust housing, air shocks, boost gauge, egt gauge, fuel pressure gauge. Less than 350 miles on new auto transmission (an A518 from a 91 D350). Also new: converter, flexplate, engine mounts, front suspension, balljoints, bushings, springs, tie rods, idler arm.

Easier mods I'm planning include installing a transmission temp guage and a 3-piece exhaust manifold. Larger projects would be upgrading the turbo, the IP, and the transmission to provide/handle more torque. Someone told me to shoot for 700-800 ft lbs of torque on this engine for my towing needs, does that sound right? Seems like maybe overkill to me.

Upgrading the turbo... The more I read the more confused I become :/ Currently has stock Holset H1C (with an exhaust leak, but not much play in the turbine). I was thinking of installing an internally wastegated dual ballbearing Garrett GTX3076R because a mechanic I know recommended it and said a larger single turbo is better for towing, and that twins are more for racing applications. But I found the exact opposite opinion here Beginners Thread - Read First! - Dodge Cummins Diesel Forum, "The difference is that a towing rig requires fast spoolup and good street manners (twins), where a drag truck set at the same HP level will likely have a big single turbo." Elsewhere on that page is a recommendation for s300/s400 twins for 600HP+ applications.

There's also this, from this article - Dodge Cummins Diesel - Injectors - Diesel Power Magazine
"If you want to step beyond 500 hp, then it is time for twins. An HT3B or S400 off of a semitruck can be used as a low-pressure turbo in conjunction with an HX35 or upgraded WHC1 if you or a friend knows how to fabricate, but the turbo system probably won't spool right without a small exhaust housing, big injectors, and a 14mm injection pump head."

Then this article Turbo Comparisons recommends HX40/HT3B PDR Twins for a street 550HP – 700HPset up.

Injection pump... the VE6 needs a rebuild, leaks like a waterfall. Have a seal set and Denny T stage 2 fuel pin to go into it.
Prev owner adjusted power screw all the way in, adjusted afc and starwheel, installed previously mentioned 3600 gov spring. I was initially thinking I would switch the VE6 pump out for a P7100, but after looking into all that entails I'm rethinking that. I've read that you don't want to push the VE6 torque past 500, but if I made it as stupid as possible (14mm head, ultra high-flow lift pump, 4k gsk, the Denny T fuel pin), could that be sufficient for my needs without going past the point of reliability on that pump?


Transmission upgrades from here: Proper Upgrade List for Transmission - Dodge Cummins Diesel Forum, plus also maybe a steel planetary? Since it's a new tranny already, I figured doing the upgrades would make sense instead of buying an already built tranny. Though since this is probably one of the things I'll have a shop do, the labor involved in upgrading the existing tranny might be more than getting a built one put in. Guess I'll find out once I start actually shopping around.


I think I'll also need:
Even larger injectors - 5x.014
Head Studs
4K GSK
60# valve springs (Do I also need HD pushrods?)

Other questions:

Doesn't have tachometer, I heard they're not easy to install has anyone done it? I'd like to be able to dyno it after all this work.


This engine doesn't have a KDP, right? There's conflicting info online, with some sources saying it's only 2nd gens or engines with the P7100 pump, and others saying it's ALL 5.9 Cummins 12 Valve engines from 89-98.

 

The earlier 12V also have the KDP problem, but I find it more of an issue with the P-pumped 12Vs myself though. My friend and I, have discussed it over a beer that maybe it has something to do with the heavier p-pumped injection pumps weight on the timing case that helps the KDP work its way out...or maybe it not.

700-800 FT # of torque is not an out of the question # on a 1st gen to achieve.
I would start with small mods and drive the truck in between them rather than do a hole mess of mods and then drive it.
It is easier to find what works and what may not if you do the changes to the motor one at a time.

 

Good suggestion to do the mods one at a time. I need to address both the IP and turbo immediately though because they are both leaking.

 

If you can find a stock second gen HX35W Turbo, it sure impresses me...... And the price should be right.

Then do the pump right and see how your Trans reacts.

 

I think you are over thinking what mods you actually need for towing and daily driving.

Your truck in almost stock form will tow those weights no problem....and get decent mileage doing it. You might not be the fastest going up the hill, but you'll get to the top with no harm done. But with the mods already done, and a upgraded turbo I think you'll be happy with your results.

I would go with either a HX35 or a HE351....that should work for your needs. Also a piston lift pump upgrade wouldn't hurt either. The 3 piece manifold is nice, but not necessary IMO. The VE IP will do fine with just the basic free mods, and the 3200 spring, and perhaps a M/H timing spacer.

As for a tach...the 91.5 does not have the signal for a tach like the 92/93 trucks, so you will have to use a magnetic pick up kit on the harmonic balancer, and corresponding tach...Geno's or The Hungry Diesel should have what you need.

 

HX35 + tranny temp gauge = nice but optional. However, the HX will pair itself nicely with a six pack of 5 hole Bosch 190s if you can find an "NOS" set (todays 190s are 4 holers). More usable power, & fuel efficiency doesn't take a hit with the 5 hole 190s.

Tach - nice, but the gov spring will rev limit itself.

KDP fix + piston lift pump would be where I would start for a strong hauler.

Tweak your A518 and VE pump and thats 90% of what a single turbo can accomplish.

 

Glad to hear that! I just kept reading/hearing that the VE6 pump couldn't reliably handle more than 500 ft lbs of torque, and that boosting the power a bunch (esp by installing a P7100) would require all these other mods to keep from starving the pump/getting high EGTs/thrashing the tranny. And since I was shooting for 700-800 ft lbs I figured I needed to do all that. But I'd much rather not

I'll look for an HX35W, and also look into getting a piston lift pump. I hadn't heard of the M & H spacer before, so thanks for cluing me in on that! I already have a Stage 2 Denny T fuel pin that came with the truck - would there be any harm in throwing that in while the pump is apart, with my current setup?

 

What's your opinion on tranny tweaks - would you recommend a shift kit, Billet Servo and Billet accumulator?

 

If you have any thought's On playing with the Trans I would look into the 47rh swap .Hands down don't waste your money on building up a 518 unless you are happy with just Over drive . 47rh has Lock up converter and Man what a Difference it makes .

 

Lockup converter sounds interesting.
What exactly are the advantages ?

 

Trampin- a shift kit is nice but you can achieve most of what it does by a couple valve body tweaks.

Accumulator piston assembly, servo, band strut, definitely.

Anything that keeps line pressure up and prevents leakdown is a plus. "Billet" is far better than decades old plastic for keeping bore diameters constant.

 

Lock up is like 5th gear in a stick .but no Stinking Clutch Pedal to mess with .it lock's the trans as 1 with the engine .Awesome Feeling

 

Apparently you can put a lock up converter into an A518: 1stGen.org ? View topic - 47rh

 

I believe Angry Johny has a build thread on a lock up A-518 he built, on a thread here at DTR as well.

 

Yes you can or find a 47rh and just build it up .Either way is Great