Cummins p pump tuning

Cummins p pump tuning DEFAULT
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Name: Kronic_187

Title: Mekanical injection junky

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Join Date: Sep 2009

Location: British Columbia, Canada

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pump pinned and motor pinned @ tdc = stock timing eh....

so this pump i have that was suppoed to be set @ 16 degrees, was pinned from the shop///

got put back on my truck which was pinned @ tdc

stock timing.....

F#ckin pump shops................

96:CCLB/4x4:NV4500/3250 Quiet,188/220,.024's,5x.020,155*,2095,4GSK,A1's,63/68/.9-82/92/1.1,Hammy VS/PR,Dual 3.5 Pusher, Bigline/Dual Fed,ProFab Bar,6" longarm,Junkyard Freespin Kit


We hear it all the time, timing makes power. But how much power? Well, there are a number of variables but it was a question we decided to try and answer with our pretty much stock 12v P-Pump Cummins project Green Monster. In our last installment we had put in a set of Scheid Diesel 5×0.018-inch injectors and gained a whopping 117 horsepower on the dyno. Since we were driving the turbo harder, boost also went from 19 pounds to 38 pounds which was part of our vast increase in power. To make the most of these new injectors though, we needed to add timing.


Injection timing in a diesel works very similar to the timing curve that you would find in a gasoline engine. One of the main differences however is that you can run a lot more timing with boost in a diesel engine thanks to their direct injection and robust nature. The factory sets timing at 12 degrees, which is fine for cold startups noise concerns and overall power, but we wanted to tell the balance a bit towards the power part of the equation. This meant ramping up the timing well above our 12-degree starting point.


One of the main considerations when it came to setting timing is that we were still on the stock 270,000-mile head gasket with factory re-tightened headbolts. We have run up to 30 degrees on trucks with ARP 625 head studs and fire ringed head gaskets but we would be limited (for now) by our factory parts. Many hot street trucks or folks that tow and want a little better mileage ought to go just a few degrees over stock which is what we did. We felt that a 5 to 7 degree bump would be adequate, and in the end we decided to go from 12 degrees up to 18 degrees of timing.


We had the folks at Brown’s Diesel help us in setting timing the “correct way” which is to use a dial gauge on the delivery valve holder. You’ll need the specifications of your pump (160hp, 180hp, or 215hp) but as long as you have that you should be good to go. The actual process didn’t take that long, but it was good to have two people on the truck. We also marked one side of the crank position sensor to see how far it moved for those who may not have a dial indicator. The rumor was that moving the engine from one side of the crank sensor pickup to the other with the pump gear off was worth about 10 degrees, as it turned out, the Internet was close, and it actually turned out to be closer to 12 degrees.


Once on the dyno the truck was a little louder, but nothing that bad, and cold start and other driving aspects of the truck remained unchanged. It should be noted that we did have to adjust the idle up which was performed at the back of the pump with a 19 mm wrench. On the dyno, we were quite pleased with the power game, as we picked up an additional 30 horsepower over what we had made with just the injectors alone. The additional timing also actually made the boost drop from 38psi to 35psi so in an apples to apples comparison the extra six degrees of timing may have been worth even more than 30 horsepower. With 400 in sight, our next move will to be to install a lift pump from Power Driven Diesel to see if we can break the 400rwhp mark. As for now, we learned that even six degrees will make quite a difference in power, and in our case was worth almost 10 percent!

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High performance diesel trucks are more popular than ever, and with advances in turbochargers, tuning, and high-pressure injection, it’s possible to have a fuel efficient high-powered daily driver that can still tow and blast down the quarter mile. Common rails have been popular for some time now, but they’re far from the original high-performance diesel powerplant. That distinction goes to a mechanical marvel of the mid 90s known as the 6BT Cummins.

When they left the factory, the 6BT had a horsepower rating somewhere between 160 and 215 horsepower, and the torque figures came in between 400 and 440 lb.ft. While that’s pretty dismal by today’s standards considering the 2019 HO Cummins is rated at 1,000lb.ft., back in the mid 90’s, that was a very competitive rating. Low power numbers aside, the 12-valve is a very solid engine. The 100% mechanical design requires no electronic intervention to run other than a starter motor, and the design is so well sorted out they will run forever with nothing more than basic maintenance, and they are very simple to work on. If you were able to find a bone stock truck and put it on a chassis dyno today, it would put down somewhere around 150hp to the rear wheels. When it comes to adding power, the stock internals are way overbuilt for how much power they came with, and it’s not uncommon to make 700 horsepower or more on the stock pistons, rods, and crank.

If you show up at a diesel event today, you’re guaranteed to find at least a couple of old 12-valves still spooling their turbos. The trucks they’re installed in are very inexpensive to buy compared to their modern counterparts, performance parts are cheap, and the 2nd gen Rams are pretty light which makes them a great entry level racing platform. While that’s all great news, it does take a few carefully planned steps to reach a higher horsepower goal.

Starting at the Bottom

To add performance to any diesel, the steps are the same regardless of how old or new it is. You need to push more air and fuel into the engine to add the power and then strengthen a few areas to contain the extra heat and pressure which you create. Right off the bat, a free-flowing 4” exhaust will allow more airflow out of the engine and give it a tougher sounding exhaust note. If you don’t want to spend a ton of money, then an MBRP aluminized turbo back single exhaust will get the job done and leave some change in your pocket for future mods. It will connect to the factory turbo and hangers for an easy install, and even if you opt for the muffler and stainless tip, it still comes out to less than $375. On the opposite end of the turbo we need to let more air into the compressor housing, so an intake from S&B can be thrown on which moves almost 40% more air than stock, plus the filter is isolated from engine bay heat so it’s truly a “cold air” intake. Remember: cold and dense air is always the goal.

There will be two separate injection pumps we’re talking about today, the earlier VE rotary style which was used between ’89 and ’93, and the later P7100 which was used from ’94 to ’98, and both are very easy to modify to deliver more fuel. Regardless of which style of pump you have, it needs two basic changes at first: 1) the governor RPM needs to be raised to allow the engine to spin faster, and 2) the fuel rate needs to be modified to allow more diesel into the engine. On a VE pump, this is accomplished with a BD Fuel Pin & Governor Spring Kit which has everything you need under one part number, and adds 40 horsepower and 90lb.ft. or torque, and the best part is it installs in about 2 to 3 hours and costs only $164.

If you’re rocking the more popular P-Pump version of the 12-valve, the power is controlled by the shape of a flat piece of metal called the fuel plate. While you can buy several different profiles or even grind your stock plate to the desired shape, a better option would be to install a Dynomite Diesel Adjustable Fuel Plate. This will add anywhere from 25 to 140 additional horsepower, and you can simply adjust it to grow with your changing fueling requirements. And if for any reason you need to lower fuel output, you can do that as well. To compliment the increased fuel delivery, you also need to raise the RPM range of the engine with a governor spring kit from PacBrake. The stock spring will defuel the truck around 2,700 RPM which puts the engine way below its peak power after a gear shift, so the higher RPM springs will help keep the engine where it wants to be. Combine those inexpensive parts with a few careful adjustments to the AFC housing, fuel rack star wheel, and a deeper rack plug, and you’ll have approximately another 80 horsepower. But that’s just where things are getting started.

Middle of the Road

Once the inexpensive upgrades are done, you’ll be making somewhere around the 250hp to the wheels, but there is still room for improvement. You do have to make a few decisions about the next stage however: if you want to max out the stock turbo and call it a day, adding a set of BD-Power 45hp injectors should get you close to that magic 300hp figure, which will double your stock horsepower. However, if you want to push further, it doesn’t make sense to stop halfway, so I would start thinking about your final power goal and select an injector that matches. Dynomite Diesel offers Stage 1, 2,or 3 injectors which can support 400, 500, or 700 horsepower respectively. When driven conservatively, a set of larger injectors can even deliver an increase in fuel mileage, and you will have to advance the injection timing a bit to suit the size of your new sticks.

You would however be a fool to modify your pump and install some massive injectors but leave your stock turbo in place. Take my word for it, you will have a smoky, high temperature engine which is no fun to drive. You need to match the increased fuel delivery with an increase in air with a larger turbocharger. It is extra critical you select the correct size turbo on a 12-valve truck, since the mechanical injection pump has static timing and no variable vanes in the exhaust housing. The stock specs for a 12-valve Holset HX35 will vary from year to year and whether the truck was a manual or auto, but the compressor inducer will be between 54 and 56mm. While popular upgrades for common rail trucks range between 64 and 67mm, a hot street 12-valve 5.9 needs to be a bit smaller. If the 500hp mark is what your sights are set on, the Super B Killer SX-E turbo kit is the ideal size, with a 61mm compressor wheel, and a tight 0.80 A/R ratio on the turbine housing. The turbocharger utilizes a wastegate just like the stock unit, so it is protected from overspeed and high drive pressure and will spool very quickly for its size.

Along with the larger turbocharger, it will be wise to change a few more parts on the airflow side, starting with the intercooler and then moving along to the intake horn. If you have a 1st gen with no intercooler, you’ll have to do some custom fab work to get one mounted behind the grille, but for the 2nd gen crowd, the AFE Bladerunner fits all 1994-2002 Rams. It’s 25% larger than the stock intercooler, and will withstand up to 100psi of boost, so the air coming from your turbo will be nice and cool by the time it makes its way up to the engine. Mounted to the driver’s side of the cylinder head, the stock intake manifold is very restrictive and only has a single opening, but the Banks TwinRam Intake has a larger port on the front and back of the cylinder head for double the area of the stock manifold, and even air distribution, which means more consistent temps across all cylinders, a longer lasting engine, and everybody’s favorite combination; more horsepower and fuel mileage.

Finally, we need to address the flow between the exhaust port and the turbocharger, and that means a new exhaust manifold. The stock piece is prone to cracking and has very small internal passages, so a freer flowing BD Pulse 3-piece Exhaust Manifold is made from a stronger alloy which will prevent cracks from forming, and the ports are much less restrictive which leads to lower drive pressure and lower EGT, and of course, more power.

Call in the Troops

Once you start to push the horsepower levels toward the extreme, it becomes necessary to do a few reinforcements underneath the valve covers to keep the parts where they belong. You’ve heard dozens of times the benefits of valvesprings and studs on a Cummins, and the 12-valve is no different. Stronger ARP 2000 Head Studs will keep the gasket clamped firmly between the block and the head to seal the combustion pressure inside, and Hamilton Springs will keep the valves opening and closing when they’re supposed to, which is especially important if you go over 30 pounds of boost and 3,500 RPM, both of which you can easily exceed.

If you are familiar with modifying a gas engine, you know one of the first things guys will change out is the camshaft. It’s responsible for opening and closing the valves at the correct time, and an aftermarket cam will hold the valves open longer and open them further, letting more air into the engine, and adding more power. The same holds true with a diesel engine, especially the 12-valve. It can benefit from a larger cam, and the one name to turn to is Hamilton. They make a wide range of camshafts and valvetrain parts for all Cummins engines, and there are several cam profiles to choose from, but just like with a gas engine, the cam you select needs to match your desired usage. For an all-around truck that spends time on the street, the track, and hauls a trailer once in a while, the Hamilton 184/214 offers the best of both worlds: an increase of torque in the midrange and more responsive turbo spool-up, but also a bump in high RPM horsepower as well, and this means an exciting truck to drive that also gets better fuel mileage.

24-Valve Notes

Midway through 1998, Dodge introduced a new engine into their pickups, and it was vastly different from the mechanical 12-valve which preceded it. The 5.9 now had 24 valves and fueling was controlled by the electronic Bosch VP44 injection pump and a computer mounted to the side of the block. This new pump had the ability to dynamically vary injection timing for a wider torque curve and was the grandfather to modern common-rail injection. From a performance standpoint, this delivered more flexibility for tuning, and higher initial power gains before you needed to touch a wrench, however, from an all-out racing standpoint, the earlier P7100 pump still holds the crown.

Just like with the older 12-valve, the 24-valve needs help in the induction and exhaust department, and since the engines are similar, most of the parts selection can overlap, like the size of the turbocharger, injectors, cam, intercooler, and more. You will still need head studs and valvesprings (just more of them), but the main difference in building a 24-valve is tuning and the pump. With a P7100, there are many user serviceable parts which can be changed to add horsepower, but on the VP44, there’s nothing you can easily swap out to add power. Industrial Injection can modify a VP internally and increase the output of the pump. They’ve created the legendary HotRod VP44 Pump which will add another 80-100 horsepower at the rear wheels over the stock pump, and of course when you combine the pump with larger injectors and tuning, the gains will be even greater. While on the topic of fuel, don’t forget about the importance of a quality lift pump on the 24-valve, since the faulty stock electric lift pump has caused the failure of many VP44s. The FASS Titanium Signature Series is a much more reliable replacement which will also clean the fuel better and remove water and air, plus it will never leave you stranded.

The final piece of the puzzle on a VP truck is the calibration of the fueling, and things aren’t as simple as with a common rail truck; if you’ve heard of the term “stacking” it’s likely been in the context of a 24-valve Cummins. The Smarty S03 is a flash programmer and is great place to start. It can get inside the computer and modify the calibration for fueling and boost, and you can customize the settings to suit your tastes with 10 different levels from daily driving, to fuel mileage, to all out performance. This will make the truck more responsive and fun to drive, but if you want to get the absolute most power out of your 24-valve, you need to add an in-line tuner that taps into the injection pump like the Edge Comp Box. With both an inline tuner and a re-flash stacked together, you will have a fire breathing monster. Just make sure to keep the Smarty on a setting which doesn’t add injection timing, since the Edge does, and that is the one parameter you don’t want to double up on.


One of the best attributes of the 24-valve is the higher flowing cylinder head, and as we know more air in and out means more power, but the pump does have its limits. The highest powered VP trucks are somewhere around 700 horses, so if you’re stuck wanting more power but aren’t ready to make the leap forward to common rail, you might consider going back in time and stealing a few parts from the 12-valve to make a hybrid P-pumped 24-valve. It combines the best parts of the newer engine with the reliability and insane horsepower capability of the P7100 and mashes them together to create the ultimate pre-common rail Cummins. It does take a lot of wrench turning, but the Industrial Injection P-pump conversion kit takes all the guesswork out of the equation by offering all the parts needed (minus the pump) underneath one part number.

There is one last airflow modification which we haven’t yet talked about, and that’s compound turbos. They can be installed on any year Cummins, and work by combining both a small responsive charger with a larger higher flowing turbo for a much wider powerband than any single turbo could deliver by iteself, and the best part is how well they control EGT under towing or performance driving conditions. The BD Tow and Track Compound Kit combines a 64mm S300 high-pressure charger with a 74mm S400 low pressure unit for a total airflow of 107 pounds/minute which can support up to 850 horsepower while remaining cool as a cucumber.

Why Wouldn’t You Want One

If you are worried about an impending EMP attack taking out all the electronics in the entire world, a 12-valve Cummins might be the rig for you considering it can be run entirely without any form of electricity as long as you can get it started. For more practical individuals, it can also be daily driven and get excellent fuel economy, haul a trailer, and have fun at the races, plus there are more performance parts available for it than nearly any other diesel. Granted, the trucks are at least 20 years old by now and are likely worse for wear on the cosmetics and chassis side, but it’s nothing a little elbow grease can’t fix. At the end of the day, there’s nothing that beats the sound and feeling of an old-school diesel, and driving that old rig just means you’re saving a ton of money every month from not having a banknote, and that’s just more money you can spend on the go fast goodies. That is a proposition I can support.


How to Get More Power From Your P-Pump Cummins

Any time we write about the 12-valve 5.9L Cummins, we can always count on plenty of feedback from readers. The very mention of this legendary mill seems to reinvigorate the never-ending mechanical vs. common-rail debate, reminding us where diesel performance stemmed from or (it never fails) kick off a brand loyalty brawl. But, this isn’t another holy grail piece where we worship the almighty 12-valve. Instead, we’re highlighting the biggest reason for this engine’s celebrity: the Bosch P7100.

That’s right, the injection pump hanging off the side of the renowned and revered ’94-’98 5.9L Cummins is more important than the engine itself. The Bosch P7100 is arguably the single most recognizable symbol of diesel performance. It represents easy horsepower for those handy with a wrench, huge horsepower for anyone willing to spend some money and — like the Cummins engine it was bolted to — million-mile durability.

In this article we’ll explore all the components within the P7100 that can be modified to improve its performance. We’ll begin with the mods that won’t cost you a dime, but that can add more than 100 hp. Then we’ll explore the internal upgrades that can take this pump from mild to wild.

Your free P-pump tutorial starts here.

Bosch P7100

Back in the mid ‘90s, long before common-rail injection had debuted and horsepower wasn’t quite as easy to come by, this was the four-barrel carburetor of the diesel world. If you wanted your truck to make 500 horsepower (a big number back then), it wasn’t going to happen with what the competition was offering (the HEUI-fired 7.3L Power Stroke or GM’s indirect injection 6.5L, respectively).

Contrary to what some would have you believe, the P7100’s robustness, performance and reliability don't make it simple. This marvel of mechanical engineering is fairly complex. Think of the P-pump as a mini inline-six cylinder engine bolted to the side of your inline-six cylinder engine. There are many moving parts inside.

Air Fuel Control

At the back of the P7100, you’ll find the air fuel control (AFC) assembly. In addition to dictating when the governor arm hits the AFC arm, the AFC is in charge of controlling the pump’s fuel rate at low boost. By sliding the AFC housing forward (toward the front of the pump) and backing out the pre-boost screw (on the backside of the AFC housing), fueling can be brought in at a much lower rpm, the governor linkage is altered and the rack is adjusted forward. And when combined with a star wheel adjustment (located within the AFC housing), as much as 200 lb-ft of torque can be added, along with a peak horsepower increase of 50 to 60 horsepower.

Turning the Star Wheel

As for the aforementioned star wheel adjustment, turning it toward the passenger side of the truck opens the fuel rack more. The fuel rack controls the amount of fuel that’s allowed to enter the pump’s plungers and barrels. The star wheel is accessed via the top of the AFC housing, and adjustments should be made in very small increments. If you go too far, heavy smoke will result. Go too little, and you won’t see the power gains you’re after. It’s up to you to find the right balance here.

Increased Rack Travel

While adjusting the star wheel increases rack travel, the factory rack plug will only allow so much fuel into the plungers and barrels. The popular “Mack rack plug” shown above increases rack travel from 19 mm (stock) to 21 mm. While 2 mm might not sound like much, the Mack rack plug adds roughly 70 cc’s worth of fuel to the mix and can be good for anywhere between 10 to 35 additional horsepower depending on your pump’s overall combination (specific P7100 model, delivery valves, fuel plate setup and injectors).

While not a “free” mod, this one will only set you back $10 to $15. It’s important to note that the best way to install the Mack rack plug is with the pump off the engine. If the pump stays in place, some grinding of the timing cover will be in order. In addition, the Mack rack plug isn’t typically recommended for 215 hp pumps (the P7100 used on ’96-’98 trucks with five-speed manual transmissions).

Removing the Fuel Plate

The fuel plate controls the maximum fuel output of the P7100, and the stock unit is conservative to say the least. While there is no shortage of aftermarket fuel plate options (along with plenty of custom-made, one-off versions), removing the fuel plate completely will yield more rack travel and considerable power gains (typically 35 to 40 hp).

On a ’94-’98 Dodge sporting the factory injectors, a full-forward AFC housing, turned star wheel, no fuel plate and an untouched stock turbocharger, 85 to 100 hp can be gained. Disable the wastegate on the turbo (increasing boost production by 10-to-15 psi) and you could find another 10 to 20 hp. As far as performance investments go, picking up 100 to 120 hp for free is a no-brainer!

Delivery Valve Holders

Going beyond the freebie mods, the next logical step is to take a look at the pump’s delivery valves. The delivery valves are positioned inside delivery valve holders, both of which are positioned between the plunger and barrel assemblies and the injection lines that feed fuel to the injectors. Aftermarket delivery valve holders with a larger internal orifice (shown above) allow more fuel to travel through them.

Delivery Valves (DVs)

Delivery valves isolate the plunger and barrels from the injection lines (making sure reverse flow doesn’t occur) and also allow for a pressure drop in order to facilitate the precise closure of the injector nozzle during the injection event. Aftermarket delivery valves offer higher flow (up to 100 cc’s), with some being application specific (i.e., some are good for towing, some good for daily driving, while others are reserved solely for performance). Common delivery valves used in the P7100 are 181’s, 191’s, 024’s, 022’s and full cut units, with the full cuts typically being reserved for dedicated sled pull, drag race or dyno applications.

Governor Spring Kits

Because the factory P7100 on ’94-’98 Dodge trucks governs the engine to a grandpa-like 2,700 rpm (with the factory governor actually starting to defuel around 2,400 rpm), an aftermarket governor spring kit should be one of the first items you add. Popular kits from Dynomite Diesel Performance, PacBrake, BD Diesel and Industrial Injection provide full fueling up to 4,000 rpm, with even higher governor springs being available for competition-ready pumps that have been properly set up on a test stand.

The ability to fuel at high rpm is what opens the door to all kinds of horsepower potential with the 12-valve engine. It’s important to note, however, that stiffer valve springs need to be installed in the head if you plan to spin the engine beyond 3,500 rpm or run big boost. For all-out competition pumps, companies like Scheid Diesel and Columbus Diesel Supply offer governor springs that provide full fueling up to 7,000 rpm!

Larger Plungers and Barrels

Just as an engine can have its cylinders bored to add displacement, the P7100 can be bored to accept larger plungers and barrels — and that’s exactly what happens in the extreme segment of the diesel aftermarket. Increasing the diameter of the plungers and barrels from stock (12 mm) to 13 mm adds immense fueling potential.

For example, a 12 mm pump is capable of flowing a maximum of 550 cc’s of fuel (possibly 600 cc’s on a good day or a friendly test bench), while a properly setup 13 mm unit can flow 850 cc’s or more. Shops like Scheid Diesel, Columbus Diesel Supply, Northeast Diesel Service and Hart’s Diesel are highly reputable in the 13 mm (or larger) P-pump world.

Radical Camshafts

Also similar to a miniature engine, the P7100 utilizes a camshaft. The cam features one profile for each individual plunger and as the cam rotates the plungers are driven up and down within their respective barrels. In extreme horsepower applications, the cam inside the P7100 is swapped out in favor of a unit with a more radical profile. With a more aggressive cam, more fuel is injected — and it’s done at a quicker rate. The camshaft pictured above comes from Hamilton Cams; when it’s used in a 13 mm P7100, it can inject 11 percent more fuel volume than a stock cam. It’s also good for as much as 80 additional horsepower.

Timing Is Everything

To be sure, injection pump timing has a lot to do with overall power output. A P7100 set at the factory timing mark will only mildly benefit from the modifications explained above. However, a pump that’s set at 18 to 20 degrees of timing advancement will see impressive gains. The 18 to 20-degree mark is the unofficial sweet spot for timing on a P-pumped Cummins in that it allows for good all-around power, drivability and cold-start performance. While considerably more power might be made with 25 or 26 degrees of timing, drivability will trend downward — not to mention that getting the engine to fire up in cold weather can become a chore.


Don’t forget that the automatic transmissions offered by Dodge during the ’94-‘98 era were easily overmatched by the Cummins in front of them. And while the five-speed NV4500 is very strong, the clutch in front of it will waste no time slipping once it’s tasked with harnessing even more low-end torque. If you plan to tinker with your P-pumped Cummins, know that you will likely be performing some type of upgrade to the transmission in order to enjoy the added horsepower and torque.


P tuning cummins pump

Here's Why The Cummins 12-Valve Is One Of The Greatest Truck Engines Of All Time

A 90s-era Ram 3500. Photo: Dodge

No diesel engine on earth is as legendary as a 12-valve Cummins. Not only is the inline-six known for its awesome stock torque figures, but the 1,100 pound iron hulk from Columbus, Indiana has a reputation for being almost literally unkillable, even after it’s been modified to produce prodigious power figures. The “five nine” is a tough sunovabitch. Perhaps the toughest of all sunovabitches

Image for article titled Here's Why The Cummins 12-Valve Is One Of The Greatest Truck Engines Of All Time

Today, in the fourth installment of “Engines You Should Know,” I’m breaking out some heavy weaponry to convince you once and for all that inline-sixes are simply the best engines of all.

If somehow the modern all-aluminum 4200 Vortec Atlas engine from General Motors didn’t convince you, I guess I can understand. If the supremely mod-able 2JZ-GTE in the Toyota Supra still didn’t have you nodding your head, then perhaps you need to see a doctor. And if after those two, the bulletproof Ford 300 inline-six wasn’t enough for you to see the light, well, I have the antidote to your ailment: the legendary Cummins 12-valve, the engine that served as the backbone of the now-bustling diesel performance community.

Photo: Cummins

To help tell the tale of the “five nine,” I reached out to Cummins’ marketing director David Goggins, who told me that the engine’s durability is rooted in its design for grueling industrial applications, saying:

A lot of the reason that engine is as durable as it is is because we designed it to be a heavy duty, commercial kind of engine.

He went on to say that the 5.9-liter engine actually originally started as a joint venture between the Indiana-based diesel engine company and Case Corporation, which builds tractors and construction equipment.

This 1988 Champion 710A Road Grader is powered by a Cummins 6BT. Photo: Machinery Trader

And indeed, starting in 1984 (well before the 5.9-liter engine ever found itself powering a Dodge Ram), Cummins offered three different variants of the 5.9-liter called the 6B, 6BT (turbocharged) and 6BTA (turbocharged, aftercooled), which served duty in tractors, combines, excavators, road graders, pavement rollers, boats, field sprayers and even school buses.

This Hagie 2100 field sprayer has a 5.9-liter Cummins in it. Photo:

These are all seriously heavy duty applications. Add that to the fact that these engines were available in dozens of different markets with different climates and work environments (like Russia, China and India), and you can imagine how relatively understressed that Cummins Turbodiesel was once it finally made its way into a Ram pickup in 1989.


When Dodge put the Cummins Turbodiesel into its Ram in 1989, a legend was born. GM and Ford couldn’t compete with their relatively gutless diesel offerings; the Cummins blew them out of the water. Even though the Cummins 12-valve only cranked out 160 horsepower, with its long-stroke and undersquare design (4.02-inch bore, 4.72-inch stroke), the engine made 400 lb-ft of pavement-destroying grunt. Chevy’s 6.2-liter and Ford’s 7.3, by comparison, weren’t even making 250 and 350 lb-ft, respectively.

But perhaps even more impressive than its factory torque numbers is the engine’s reputation for longevity. Once you start looking at the mechanical bits, you begin to see just how overbuilt the B-Series engine really is. The block and head are cast iron, the crankshaft and connecting rods are forged, the seven main bearings are massive, and like many heavy-duty diesel trucks, the crank and cam are connected by a steel timing gear—not a chain or belt like you’d find in normal cars and trucks. The Holset turbos are also know to last until the end of time.

The Cummins uses timing gears. Photo: The Diesel Stop/YouTube (screengrab)

There’s really not a lot going on with this engine; simplicity, really, is what makes the silky-smooth inline six unkillable. The cam is in the block, actuating pushrods to open and close two valves per cylinder, the geroter-style oil pump is right up front on the accessory drive, there’s no aftertreatment system (just a muffler), and the fuel injection system is purely mechanical.

I talked with Tyler from Diesel Power Products, a Washington-based Diesel performance parts supplier, and he told me the basic formula for why the Cummins 12-valve is such a beast, saying it’s just “too dumb to die.” And that mechanical fuel injection system, he says, is the key to what truly makes the 12-valve “dumb” (but in a good way).

Unlike the later 24-valve ISB model that came around in mid-1998—which used a Bosch VP44 electronic rotary style pump—the 12-valve offered between 1989 and 1998 used a fully mechanical fuel injection system that used the cam to time when fuel was injected into the cylinders.

This, Tyler told me, made the engine “The most reliable, simplest, as basic-as-it gets, fully-mechanical diesel engine” a diesel tuner could ever ask for; in fact, the vehicle literally only needed a couple wires to turn the motor over with a starter; and once it was running, the engine needed no electronics at all. Compare that to the bag of snakes all modern engines have under hood, and you realize just how simple this motor is.

Perhaps even more interesting than reliability and simplicity, Tyler says, is that the fully mechanical fuel system gave the end user “complete control” of how the engine generates its power.


The Cummins 12-valve is hilariously simple and reliable, but what puts it over the top as the greatest diesel pickup truck motor of all time is how easily it can be modified to produce hilarious power numbers. Tyler told me “there’s no other platform like it in the diesel industry as far as control.” And a lot of that control comes from what’s known as the coveted “P-Pump.”


Early diesel Rams (’89 to ’91) came with a mechanical VE rotary fuel injection pump that really wasn’t so great for tuning. But from 1994 to 1998, Cummins threw on the Bosch Bosch P7100 mechanical injection pump, also known as the “P-Pump”—a part that changed the diesel tuning world forever.

The P-Pump opened up a whole new array of tuning options; Tyler says the P-pump is so versatile, it allows owners to add power with almost no effort whatsoever, saying:

It’s pretty much the only platform in a truck where you can literally not spend a dime and gain 70 horsepower without opening your toolbox.

The P-Pump, as Tyler puts it, is “basically a little engine in itself.” Driven by the engine’s cam gear, the P-Pump is an injection pump that gets fed fuel from the lift pump (which takes fuel from the tank). The injection pump’s six plungers—which ride on a camshaft in the pump housing—move up and down in barrels. That upward movement pressurizes the fuel and pushes it through the delivery valve, which meters the fuel and sends it into the engine’s cylinders through an injector.

The way the P-Pump is set up allows for lots of easy modifications. Among those mods are fuel plates with different “cuts” to reduce the restriction of fuel flow at high engine speeds.

Between installing a new fuel plate (or just hacking up the old one with a grinder), replacing the governor spring with a stiffer one (usually owners go with a 3k to 4k spring) for better throttle response, and tuning the preboost screw (for better low rpm fueling) and starwheel (for improved throttle response), basic adjustments to the P-Pump can add 150 horsepower to a Cummins 5.9. This, of course, assumes that the injectors, lift pump and turbo have been adjusted accordingly.

Tyler puts it simply: “You can turn up the little engine to turn up your big engine.”

There’s even more Cummins 12-valve owners can do to add power besides fiddling with the P-Pump. With a different intake and exhaust, bigger turbos, a better lift pump, bigger injectors, perhaps a beefier crankshaft damper, new valve springs and pushrods, some basic head tweaks, and maybe a girdle at the base of the block to prevent crank wrap, many of the stock internals can handle 1,000 horsepower without issue.

It’s A Legend

A snapshot of a 1983 brochure for B-Series industrial motors. Photo: bargnboys/Ebay 

While Ford and GM have swapped out their diesels a number of times since 1989, architecturally, the Dodge’s Cummins has remained fairly similar to the original.

Still, the Cummins 5.9 saw a number of little throughout the years. A few years after its introduction in mid 1991, the engine added an intercooler. Then in 1994, the motor changed from a rotary Bosch VE rotary pump to the P-Pump.

The 12-valve went away in 1998, replaced by a 24 valve which offered better breathing. At the same time they made the swap to 24 valves, Cummins put in Bosch VP44 electronic fuel injection; though the injection pump was still driven by the cam, the timing of fuel injection was no longer mechanical, instead driven by a solenoid.

In 2003, the Ram’s 5.9-liter switched to a Bosch common rail system. The big change happened in 2007. For the beginning part of the model year, the 5.9-liter stuck around. But starting in January of 2007, the 5.9 was finally replaced by a bored and stroked version with 6.7-liters of displacement. The change brought a fairly complex after treatment system with it to meet emissions, which warranted the increase in displacement to maintain performance.

Many diehards decry the complex emissions components and the electronic fuel injection system, as they both do a number on tune-ability. Regardless, the 6.7-liter Cummins, and frankly any truck with a big chrome “C” on the fender, gets tons of respect from diehard diesel enthusiasts around the world.

But undeniably, of all Cummins pickup truck engines, the 12-valve 5.9-liter is the king. Cooper from Diesel Power Products says “It’s probably the most reliable platform ever made on any diesel truck.”

The killer dowel pin has been known to wreak havoc on Cummins 12-valves. Photo: The Diesel Stop/YouTube (screengrab)

It wasn’t perfect, as many 12-valves were plagued with the “Killer Dowel Pin,” (seen in the picture above) which could back out and get squeezed between the cam gear and the gear cover, ultimately destroying the engine. But that’s a fairly straightfoward fix, and if you look at the nearly 10,000 people who are part of the Cummins High Mileage Club, and the dozens of 5.9-liter owners who have crested 1 million miles, you realize why this motor is regarded by many as the very best diesel engine ever put into a pickup.

Turning Up our Cummins P Pump!!!!

Chatted about her love life. About her mug boy who throws diamonds and expensive vacations on the islands, about the lack of work, about the lack of good sex. During this time, she ran on tiptoe several times to top up her liquor. I already had time to think how boring and corny it all is.

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There is an erogenous zone. there will be more buzz. " I started massaging there and jerking off a member.

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