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Engine Build: Triple Turbo 6.7L Cummins Engine

Growing up on a farm, Ben Francis was always tinkering with tractors, trucks and dirt bikes along with his dad. He quickly got into racing dirt bikes, motocross and hare scrambles at a young age, and without the money to take bikes to professional shops, Ben and his dad would work on them in the garage themselves.

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“That sparked my interest,” Ben Francis says. “I got out of high school and started making my own money. I started working at a couple local shops on the dirt bike side of things. Then, I got my first common rail truck and started tinkering with it.”

While Ben’s dad helped get him interested in engine work, Ben’s high school friend, James Vannest, got him into the diesel world.

“I went to high school with James Vannest,” Francis says. “My dad knew his dad, Brian Vannest, who started Vannest Performance, so we were always out there growing up. Brian got the shop started over 25 years ago. They specialize in Dodge Cummins, but they do regular maintenance, tuning, engine builds, and transmission builds.”

Ben has a full-time job as a union carpenter, but in the evenings and weekends he can be found at Vannest Performance helping out the shop with anything he can.

“I try to learn as much as I can while I’m there,” he says. “Once James and I got out of school, we just started hanging out more and more, and I started coming out to the shop as much as I could as long as my schedule allowed it. Now, we’re working pretty much everyday side by side together.”

One of the bigger projects Ben and James have been tackling lately is Ben’s 2008 6.7L Dodge Cummins they’re building up for the King of the Street competition this fall.

“Once I got that common rail truck, my ’08 6.7L, we started tinkering with it – changing turbos, changing the fuel system,” he says. “I started hanging around the shop more and more, and it kind of just snowballed from there.”

Initially, the 6.7L Cummins was kept mostly in stock form – stock bottom end, stock internals – and they added as much bolt-on stuff as they could. This is until this past year.

“Last year, James and I built a stock block with billet internals, a stock crankshaft with a standard bore,” Francis says. “We went with 250% over injectors from Industrial Injection. We built a set of compounds for it – a 467 over a 485 Barder turbos. We did some head work, but still kept the stock shelf on it. James did all the custom tuning and we played around with it.”

That was enough until they got the idea to enter the 2020 King of the Street competition, and they quickly got to work building an even better engine for the truck.

The King of the Street competition is a well-rounded competition – we have to eighth-mile drag race, dyno, do a 100-mile street drive, sled pull, and then they have a dirt drag,” he says. “We’re trying to build this to be a well-rounded, all competitive truck, but the main focus other than the King of the Streets is drag racing. Maybe every once in a while we’ll go sled pull.”

This latest 6.7L Cummins build started with a call to Zach Hamilton of Hamilton Cams, who Ben and James used for numerous components in this engine.

“We’ve always run his products for years through the shop,” Francis says. “We were looking at a deck plate engine and originally had a deck plate and we got to talking to Zach and he offered his comp wet block to us at a really good deal and said that we shouldn’t have any issues with it, but we’ll want to go ahead and sleeve it for the possibility of a failure. We went ahead and got a Hamilton Cams comp wet block, their steel pistons, billet tappets, a custom-ground camshaft, and a lightened crankshaft.

“We put all that together as a rotating package, along with Apex Diesel triple beam, billet rods on the bottom end, along with Mahle bearings and an Apex 14mm diesel girdle.”

Vannest Performance took the the 6.7L to Jams Motorsports for any machine work such as the boring and sleeve work, drilling and tapping and all the head work. Vannest Performance did the port and polish work in-house.

“We ended up going with a King Speed billet top draft intake and oil pan, and a Manton valvetrain on it with Hamilton pushrods,” he says. “We went with a dual rate valve spring from Liberty Performance Components. We tried to utilize the best components out there to avoid a failure and to be as reliable as we can at a high horsepower.”

To really kick this build into high gear, Ben purchased Lavon Miller’s old triple S400 turbos.

“We had Dustin Harrison at Apex Diesel rework the manifold charger, so it’s a custom S476 with two S472s feeding it,” he says. “Then, for the fuel side of things, we got in contact with Exergy Performance and went down there for a tour and got to see the facility and all of their machines. We decided to go with their fuel system.

“We ended up going with a set of the 400% over 5.9L injectors, two dual 12mm stroker pumps connecting to their billet feed rail, high pressure lines, bar sensor, and all that good stuff. On the fuel side of things, we should have absolutely no issues with it. For the lift pump, we went with a Fass 290 to feed the fuel system.”

In addition to the parts and pieces already mentioned, Ben also got a billet front cover, front pulleys and accessory drive from Beans Diesel. Randy over at Old Skool Fab did the valve cover and Peak Powder Coating and Devon Mistak at Rudy’s Diesel also helped in the build.

“We’ve had a lot of great help from a lot of different companies,” Francis says. “James Vannest has helped me through this whole thing from the get-go, spending late nights and sometimes through 4am and then we’d turn around and get back up at 8am and put another full day in just to try to get stuff done. We’ve learned a lot. I’ve learned a ton and it’s established some really good relationships and got our foot in the door in some places. We’re hoping to make a really good impression on people in the industry come this fall at King of the Street.”

Looking to make a splash in the industry with their triple turbo 6.7L Cummins, Francis says they’re hoping for around 1,700 hp on fuel and more than 2,000 hp on nitrous!

“For the King of the Street competition, we’re allowed nitrous for dyno and drag racing, so we’ll have a Nitrous Express system hooked up to it, and we’re hoping to see a 2,000-plus hp number on nitrous,” he says. “I’m really hoping to do well at King of the Street.”

Engine Builder magazine’s Diesel of the Week is sponsored by AMSOIL.

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