What It Really Takes to Make Reliable High Horsepower Diesels

This one turns into a battle royale fast, with Myer and John wasting no time getting into a heated shop floor debate about extreme diesel performance and what really works when you are pushing the limits.

The conversation dives straight into drag racing setups, large single turbo strategy, and the tuning challenges that show up when you are chasing real, repeatable power. A major focus is why mechanical injection setups often seem to extract more out of big single turbos compared to common rail, especially when dyno testing at higher elevation. For diesel enthusiasts who actually build, tune, and race their trucks, this matters because it directly affects spool, drivability, consistency, and whether a setup survives repeated passes or starts melting parts.

One of the key discussions centers around a fuel only goal of 1,500 horsepower on a 6.7 Cummins running a 98mm GT55 style turbo. They break down how the dyno testing process worked by starting with low fuel quantity and timing, then gradually stepping things up until timing stopped making gains and fuel became the deciding factor. Myer explains why pushing past that range started to hurt the truck’s manners and why nitrous became the tool for setting peak power while keeping the truck responsive and controllable instead of lazy and unpredictable.

They go deeper into why large single turbos struggle more at altitude, particularly on common rail trucks that burn fuel so efficiently in cylinder that there is not enough heat left to drive the turbine. The discussion covers attempts to tune around that limitation, including lowering rail pressure to mimic a more 12 valve style burn, the dangers of overfueling a big single, and why once the setup falls off there is often no saving it mid pull. They also talk through future plans like switching to a ten bar map sensor, experimenting with pressure and timing, and trying to find the balance between clean combustion and enough exhaust energy to keep the turbo lit.

Real world shop experience is layered throughout the episode, including nitrous strategy for drag racing, why compound setups can feel more foolproof even with the added weight, and a nitrous backfire that blew an intake pipe off and dented a hood during testing. If you are into diesel performance, Power Driven Diesel shop talk, Cummins builds, VP44 discussions, dyno testing, turbo upgrades, drag racing, and truck builds, this episode delivers straight insight from guys who live it. Subscribe for more episodes and stay locked in with everything happening at Power Driven Diesel.