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Diesel of the Week

World’s Fastest 7.3L Powerstroke

When Brian Gray ended his professional Motocross racing career, he needed to find something to occupy his skills and time. Brian turned to the diesel industry and opened Gray’s Diesel Performance in 2012. The shop primarily works on Ford and Chevy diesel trucks and is home to the world’s fastest 7.3L Powerstroke. Click to find out how this used Ford truck and engine went from slow to ‘whoa what was that?!’

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As an ex-professional Motocross racer, Brian Gray was introduced to the wonders of speed at a young age. As a professional rider, Brian would often have to do work on his own bike, and that kind of tinkering got him into working on engines. Before he knew it, he was into Mustangs, four-wheel drives, doing frame swaps and changing transmissions. His passion for this industry only escalated from there.

“When I was done with racing, I was looking for a career, so I went into the diesel field,” Gray says. “We opened Gray’s Diesel Performance in August 2012. We started at a smaller, 5,000 sq.-ft. shop, and then we switched over to renting a 10,000 sq.-ft. shop in 2013. Then we built our own 10,000 sq.-ft. shop and moved in August 2015.”

The four-employee, Middleburg, FL-based shop focuses mostly on light-duty repair and service, but does do some performance work as well.

“We’re pretty much solely Ford and Chevy diesel,” he says. “We kind of pick and choose what we want to do on the Dodge stuff. I like to be the best at everything I do. I’m definitely not a jack of all, master of none. That’s the complete opposite of me.”

While performance work isn’t the majority of what Gray’s Diesel Performance does, the shop does lay claim to owning the world’s fastest 7.3L Powerstroke, and the second fastest Powerstroke of any displacement.

“We have 1,656 horsepower at the crank, running 4.92 at 144.24 mph in the 1/8th mile,” Gray says. “That’s normally the limit on those engines. There’s only been a couple of people who have ever made 1,200-1,300 horsepower.”

Brian says this engine and truck build came into his life when he wanted to buy a house, but needed some extra money for the down payment.

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“I sold my new truck at the time and got a used truck so I could afford the house payment,” he says. “From there, that used truck slowly progressed into a fast, four-wheel drive, street truck. I had to build the engine right off the bat because it had been sitting for five or 10 years. The truck and engine just slowly progressed into what it is now.

“Our goals with this truck changed when we wanted to beat the record and thought we could beat the record. The old record was 6.39 in the 1/8th and 9.09 in the quarter, and we’re running 4.92 now in the 1/8th.”

When Gray’s Diesel Performance managed to get the 7.3 up and over 1,500 horsepower, the shop did start to have a problem with the pistons cracking from the piston pin to the second ring. Fortunately, they were able to find that issue before a failure occurred.

“Everything above the top ring land was flawless, so it wasn’t anything to do with the tune,” Gray says. “We just flat out overcame the power potential or power capability of the stock pistons. After we started cracking the pistons, we did switch bore size. Stock bore size is 4.110˝. Right now, we’re running a top fuel 4.188˝ bore. We have top fuel piston rings from Mahle and a top fuel bore size. Today, we also have some billet Diamond pistons with my bowl design in the engine.

“Despite that, we’re not very exotic compared to some of the guys we’re racing against with all billet engines – billet blocks, billet heads, billet cranks, etc.”

Hypermax rods and Diamond pistons

Gray’s approach to this engine has been one of upgrading parts and aspects of the engine as needed or where the shop felt a certain upgrade would make an improvement. The 7.3 Powerstroke has forged Hypermax rods and a forged crank in the stock, cast block, which is half filled. It also has stock ported heads. The shop did zero balance the engine and upgraded parts such as the dampner and the flex plate.

“We also have an individual runner intake and individual runner nitrous system, which is the first of its kind,” he says. “We did this stuff to try to show the engine’s capabilities, and I feel it improves the reliability of the engine, because there’s more even power across all eight cylinders instead of just the middle four cylinders trying to make all the power. That’s one reason why I think our 7.3 lives.”

The biggest downfall of the 7.3, according to Gray, is the injector. The injector is very slow to do what it needs to do. It doesn’t just empty itself like you want it to and takes a long time, but that hasn’t slowed down Gray’s Diesel Performance.

“We’ve really pushed the envelope and it’s been a lot of my time and money trying to develop new pieces inside of this engine,” Gray says. “We really have made some leaps and bounds that allow us to get more power in the cylinder and then bring the power range up in the rpms, which definitely helps a lot in our drag setup. We did a front mount turbo and made some long tube headers for the engine, which has definitely seemed to open up our top end power a little bit.

“We’re already at 144 mph and have our tongues hanging out on the red line. We have a top fuel gear and the tallest tire Mickey Thompson makes to try and get as much gear ratio as possible. It’s huge if we can get a few hundred rpms additional out of it.”

To aid in that regard, Gray has added an 85mm Garrett turbo to the engine. He’s tried an 88mm as well and will be trying a 94mm turbo soon too. Gray also runs an ATI dampner up front, a flex plate they modified, some big 7/16ths pushrods, and COMP Cams beehive valve springs. Everything else in the engine is pretty much stock, except Gray did need to add a dry sump oil system to the engine.

“We were the first to dry sump the 7.3 with this type of injection system,” he says. “We’re using the factory injection system, so the same injectors and the same high-pressure oil pump that comes in all 7.3s, we have on this engine. We do have a secondary pump to help feed it, but we are running the stock stuff.

“The reason we had to dry sump it was the chassis builders put the engine down in the truck way too low and it came back to me with the oil pan dragging on the ground, so I had to figure out how to dry sump this engine.”

Despite hitting obstacles due to power and speed such as cracked pistons, having to upgrade the cage, transmission failures and slipping issues, Gray says he will keep pushing the boundaries with this truck and 7.3 Powerstroke engine.

“We’re already past where we thought we’d ever get to, but we just keep finding new things that allow us to push the limits,” Gray says. “One of my goals, and it’s actually coming rapidly now, is to be the first Powerstroke to hit 2,000 horsepower. That is our goal now, and it should be here in the immediate future.”

As it is, Gray’s 7.3 Powerstroke is churning out a heart-pounding 1,656 horsepower and roughly 2,000 ft.-lbs. of torque. We hope Brian Gray and his shop continue to find ways to up the ante! Watch the truck run below.

The Diesel of the Week eNewsletter is sponsored by AMSOIL.

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If you have an engine you would like to highlight in this series, please email Engine Builder magazine’s Editor, Greg Jones at [email protected]

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