950-HP 7.3L Powerstroke Engine - Engine Builder Magazine
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Diesel of the Week

950-HP 7.3L Powerstroke Engine

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With how widespread and diverse the engine building community is, we find people all over the planet with interesting builds. Social media, motorsports events, word of mouth, you name it – we get in contact with builders no matter what the medium.

David Keyser first reached out to us about a week ago on Facebook Messenger, asking where he could enter to be in Diesel of the Week. What some of our readers may not know is that it’s as easy as that! There is no entering process for our Engine of the Week or Diesel of the Week series; if you think you have an interesting build that our audience would like to see, simply send us a direct message on our social media channels (Instagram, Facebook or Twitter) or email our Editor Greg Jones at [email protected].

When David Keyser messaged us, he outlined his 7.3L Powerstroke that makes nearly 1,000 horsepower, so naturally we wanted to know more. Keyser works as an over-the-road heavy equipment technician and on the side, he started GapTrain Performance, a small diesel performance and off-road business. On first sight, we were curious to know if David was related to Travis Keyser, another engine builder we spoke with early this year. Interestingly, their shared name is simply a coincidence.

“No, I’m not related to him…. and it’s an uncommon name,” Keyser says. “The funny thing is we raced together at the same event one day. They called out Keyser and I spoke up thinking they made a mistake.”

The one thing both Keyser’s do share is a love for Powerstrokes. Travis’ 6.0L was a sight to see, and now David’s 7.3L is our next fixation.

David first started playing in the diesel world around 2013, when he purchased a garage kept, bone-stock ‘97 F-250. A few years in, he decided to take the build more seriously and improve the factory rated 225 horsepower. At that point around 2016, Keyser was working on diesel trucks every day in a local shop gaining valuable experience and insight into how he could improve his truck’s performance.

“The original goal was to just put in a small set of injectors, a drop-in turbo, and then do a mild built transmission,” he says. “The setup was a 180/100 injectors, a T500 high-pressure oil pump, a mild built transmission, and then we left the stock turbo in it. Well, I wanted more, so we put an S369 on it along with some bigger injectors, 275/200 I believe.”

Unfortunately, Keyser said that on the first trial, the setup broke six rocker arms, a rocker pedestal, and bent a connecting rod. At that point, he had two options – reduce the power output or double down and build an engine that could hold the power it made. He chose the latter.

The new engine belts out nearly double the horsepower and is far and away more reliable. Keyser doesn’t daily drive the truck anymore, but still drives it often. Just a few weeks ago, he drove it seven hours straight to Virginia Beach and back, proving that it can throw down on the dragstrip and party on the street.

“I got 350/200 injectors from Full Force Diesel Performance, a Swamps Motorsport Gen3 high-pressure oil pump and a big, Forced Inductions S476 turbo that works pretty well with the Irate Diesel T4 turbo mount. There’s also a CSF intercooler for a 6.0L that I swapped into it and that manages the 55 psi of boost.”

On the bottom end, the engine features an Irate girdle, Manley connecting rods, ARP main studs, and fly-cut standard bore pistons. A set of ported cylinder heads from Crutchfield Machine with 165-lb. valve springs and ARP studs anchoring them to the block sit above o-ringed head gaskets.

“It was nice because I didn’t really have to get anything machined,” Keyser says. “I was able to use stock size pistons, so really the only thing I had done was getting the crank balanced at my local machine shop.”

Right now, Keyser’s 7.3L Powerstroke is capable of around 950 horsepower and 1,630 lb.-ft. of torque, which has gotten him a 7.11 second pass at 99.8 mph in the 1/8th mile. While he admits that his 60 foot time is “pretty terrible,” he’s already working on improvements to make his F-250 faster than it is now.

Diesel of the Week is sponsored by AMSOIL. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor Greg Jones at [email protected]

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