Uphill Battle To A 4-Digit LB7

Getting to 1,000 rwhp is harder than you think

Published in the October 2009 Issue October 2009 Build, Duramax

on the dynoIn the last issue of Diesel Tech Magazine, we covered the tear down and initial buildup of a 1,000 horsepower LB7 Duramax that Jim Jones of Texas Performance Diesel is building. We started from a problem child of a core engine to battling finding parts that were useable to finally getting a good short block.

At the end of a very long process, we were still heading in the right direction. The bad parts were discarded and good parts were machined and balanced. New parts were added and with the expert hand of Guy Tripp from SoCal Diesel, we managed to build up a stout short block that should handle as much power as any Duramax can currently produce.

In this issue, we'll cover the finished buildup, briefly touch on the installation and then to the dyno.


The short block (block, crank, pistons, rods, cam) was assembled using ARP studs and bolts to help ensure that everything stays together. Once the short block was assembled it was time to install the heads. Tripp and Jones decided on an experimental copper head gasket to help improve sealing under high boost applications. This is the first engine to use this new gasket. To hold down the heads, ARP studs were chosen as well. New upgraded chromoly pushrods (the wall thickness is .083 inches compared to the factory .054 inches) were installed to reduce the deflection in the push rods under the higher lift and increased spring and boost pressures. With the long block done (block, crank, pistons, rods, cam, heads and valvetrain), the motor was shipped back to Jones for final assembly of the accessories and installation into the truck.

To truly build a high horsepower engine, the engine must be able to inject a lot of fuel and move a lot of air. Since the Duramax engines are common rail engines, there are multiple components that need to be upgraded to support large amounts of air. A stock CP3 fuel pump is good from the mid 500 to low 600 horsepower range. So, Jones sent out his stock CP3 fuel pump to Floor It Diesel to have it modified to flow more fuel.

After Jones and John Isaacs (owner of Floor It Diesel) talked about it, they decided to use a twin CP3 setup using Isaacs' Stage II pumps instead of the traditional twin stock pumps. This will ensure that the fuel injectors will always have enough fuel and fuel pressure to feed whatever size injectors are being used.

On the injector side, Dynomite Diesel extrude honed the injectors to 40 percent over. Once they were done honing the injectors, they flow tested them to ensure they are balanced, which on a Duramax, perhaps even more so than any other engine, is extremely important when trying to keep an engine together with more than 700 hp.

With the long block finished, the motor out of Jones' truck was pulled out and set next to the long block. The Duramax wiring and accessories are fairly complicated and intricate. Reassembling the new long block with the old motor right next to it is pretty much the easiest way to ensure proper order of installation. As each component was removed from the old block, it was either cleaned or set aside.

After each component was cleaned, new gaskets were used and the pieces were assembled.

With all of the wiring and plumbing on the engine, it was time for the remaining few components to be installed before the engine went into the vehicle. Jones opted for a 66 mm stainless steel wastegated turbo for his high pressure turbo. This was previously used as a single when he was able to lay down 730 hp with spray (nitrous) and is a great option for reaching the 1,000 plus horsepower.

Once the final components were mounted on the engine, it was set into the engine compartment and bolted down. Then the rest of the goodies were installed. Supplying the majority of the air flow, Jones opted for an 80 mm BorgWarner turbo for the low pressure. This turbo is rated for up to 1,300 hp and will easily supply enough air for Jones. While packaging is tight, Texas Performance Diesel has a compound kit that makes assembly a breeze.

To ensure that the fuel injection control module doesn't get too hot and start causing issues, it was rerouted to the top of the engine as part of the Texas Performance Diesel compound kit.

Finally finished, the truck was driven for a few hundred miles to initially break in the engine. Then it was loaded on the trailer and brought to SpeedTek to tune the engine. Upon arriving, a Quadzilla Adrenaline module was installed.

Quad Banker from Quadzilla took over the dyno and started working his magic. When the truck first hit the rollers, it was laying down 558.7 hp. Within the first hour, the truck was laying down 789.39 hp (on straight No. 2 diesel) and was maxing out the dyno's 1200 ft. lbs. of torque.

Shortly after operating the dyno, Banker hooked up a Tech 2 Flash. This enabled him to stop the transmission from shifting into overdrive.

Banker was slowly creeping up on 800 hp but needed more air. So the wastegate on the high pressure was changed.

Even with the addition of more air, the truck was still putting out a substantial amount of black smoke, which told us that it was capable of a lot more horsepower.

Banker kept working the dyno for the next hour. He was mainly changing pulse width and rail pressure, trying to come up with the right combination. He was trying to reach more than 800 hp with only the Quadzilla Adrenaline. Once he hit that, he was going to stack it with a programmer and see where that would take them.

During one of the cool down periods we noticed that the truck was starting to leak oil. After doing some investigating, it was determined that it was coming out of the driver's side valve cover.

After two hours, Jones' truck was laying down 815.14 hp on straight No. 2 diesel. But during the last few pulls, we noticed that the tires started losing grip on the rollers. So, the rear tires were aired up to the maximum amount to help reduce drag and free up some extra horsepower.

The rear of the truck was also strapped down from the rear most part of the frame to help load the tires better.

Jones kept an eye on things as the day got longer. At one point in time, the oil leak started dripping on the y-pipe and caught on fire. Jones, being a fire captain, explained that it was only a little fire and put it out quickly with a small squirt bottle of water.

Unfortunately, after 48 dyno pulls, the truck started running rough and eventually died. After checking the usual culprits (fuel and air) Jones scanned the processor and found codes for the crank and cam position sensors. At this point in time, it was after 5 p.m. and there wasn't a place where he could get new sensors. So, day one on the dyno ended with 815.14 hp on No. 2.

The truck was winched back onto the trailer and taken back to Emory, TX, where Jones lives. The next day, the crank sensor was pulled out and Jones noticed that the sensor had been scuffed. Thinking that was odd, he took out a flashlight and screwdriver. Jones shined the light up the crank sensor hole and touched the reluctor ring with the screwdriver.

To his surprise, the reluctor ring had come loose. There are four bolts that should be holding the ring tight against the crank and it should not move.

To get to the reluctor ring, the front cover has to be removed. So Jones took the front end of the truck apart, all of the accessories off and removed the balancer.

As luck would have it, two of the three bolts were no longer threaded in and the third bolt was just barely holding on. Maybe that is why the LBZ's went to a four-bolt design.

Since magazine production runs have strict deadlines, we are unable to show you the final dyno run in this issue. Check www.DieselTechMag.com to see the 1,000-plus dyno sheet.


Carillo Rods

Dynomite Diesel Performance

Floor It Diesel


Ross Racing Pistons

SoCal Diesel

Texas Performance Diesel

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