Un-T4 Turbo Swap The World? Does KC Turbo’s Drop-In Turbo Really Outperform In The Real World?

Pulling off a T4 Turbo swap on a classic 7.3-liter Power Stroke takes some serious cash and many long garage hours. A lot of builders expect immediate power gains after bolting on a custom S300 setup. But, is it really always the right solution?

Testing The T4 Turbo Swap

Matt from Gearhead brought his modified Super Duty to KC Turbos with hopes of fixing a few annoying performance issues. Despite packing big injectors, his configuration felt sluggish off the line. So, first things first. Dyno testing the truck gave it a solid baseline. With a Borg Warner S364 the truck cranked out 585 horsepower. But when they tried testing it on the street, it revealed a different story. It actually produced a puff of smoke and the rig lagged hard while lugging in overdrive around 1,700 rpm. The custom turbo piping also created fitment headaches and an exhaust leak. Charlie Fish noted: “I’m not here to trash on T4. I think they run fantastic. But, you know, it’s just a good opportunity to test them back to back and see how they run.”

Swapping To The Stage 2

The crew at KC then removed the custom piping and T4 turbo. They then installed the company’s Gen 3 Stage 2 drop-in unit, which allowed them to utilize factory mounting points and clamps. Hitting the dyno again, the new configuration laid down 578 horsepower. While the older setup edged out the new unit by 7 horsepower at the absolute redline, the drop-in replacement spooled significantly faster. It generated massive torque gains much earlier in the powerband.

Dominating The Street Test

Next, hitting the asphalt proved exactly what the dyno graphs suggested. The annoying bottom-end lag completely disappeared. Both Charlie and Cameron felt instant throttle response when rolling into the pedal from a dead stop. Comparing the low-end performance directly against the custom setup made the decision easy. Evaluating the immediate torque delivery, Charlie Fish stated: “At this level, if you ask me which one I’d take, there’s no question it would definitely be our stage two over the 364 and a half.”

Reviewing The T4 Turbo Swap

Imagine spending thousands of dollars on custom piping just to lose daily driveability. It surely would hurt any diesel builder. Matt dumped money into his T4 Turbo swap only to face frustrating lag and annoying exhaust leaks. Watching a drop-in replacement completely fix the sluggish throttle response proved that peak dyno numbers mean nothing on the street.