Video: 1,080-Horsepower Jeep Engine Autopsy With Newcomer Racing

Recently, we brought you the video of Keith Newcomer of Newcomer Racingpushing his turbocharged Jeep inline-six engine to north of 1,000 horsepower, making it the most powerful Jeep engine in the world. Since it was such a technically impressive feat, Jeff Huneycutt from The Horsepower Monster was eager to follow along as Newcomer tore the Jeep engine down to inspect it for any signs of damage after those brutal runs.

“We’re just going to look at everything and make sure it’s healthy,” says Newcomer of why he’s tearing the engine down. “Some of the main concerns in the past are the stock main bolts, the stock main caps – that they just won’t hold the power. There’s preconceived notions that they will fail at 400 horsepower or 600 or whatever. We’ll take it apart and see if there’s anything weird, and if not, we’ll put it back together and turn it up more.”

The first step in the teardown is a basic one, but one that could absolutely indicate problems: draining the oil. “We ran 20W-50 Valvoline VR-1,” says Newcomer. Luckily as the oil drained into the catch pan, it was a solid brown, without any glittery bits, that might have indicated excessive parts wear. After pulling the valve cover, the rocker arms were inspected for any abnormal wear.

Your oil can tell you a lot about what was going on inside your engine.

Checking the Top End

With a clean bill of health, the rest of the valvetrain was inspected, with no detrimental results. Then, the pushrods were pulled out and checked for any excessive wear, damage, or any signs of being bent. However, they measured out straight as an arrow, for a clean bill of health for the Jeep engine’s valvetrain.

However, as soon as the head studs were unfastened and the cylinder head removed from the block, there was a sign of failure. “It lifted the head,” says Newcomer. “In between the studs, the head lifted up and started letting combustion pressure out. I’m not saying this was the cause, but this was a used head gasket. We ran this on another engine. It probably would have still lifted the head, but it didn’t kill the gasket or hurt the block.”

The valvetrain was probably the least-worried-about part of the engine, since Newcomer used good parts throughout the top end.

The gasket indicated that combustion was escaping from the numbers two, four, and five cylinders. Extremely minor in the grand scheme of things, when you consider what failed gasket can cause, but also, a pat on the back to the .041-inch-thick MLS gasket for staying together in multiple builds. “It’s a standard Fel-Pro MLS gasket — nothing heavy-duty. The whole point of R&D is to find the limits and it looks like we found them here,” says Newcomer.

Disaster averted on the block’s deck, Newcomer turned his attention to the cylinder head sitting on the workbench. While the R&D cylinder head wasn’t a full-boogie head, it did have significant improvements over the out-of-the-box Edelbrock head it started life as. The exhaust valves told the story of uneven fuel distribution from the carbureted manifold, from the center cylinders, outward.

“The exhaust valves indicate that fuel distribution with the intake manifold is still an issue,” Newcomer explains. “If we had fuel injection, we could have dialed each cylinder in, individually, so that fueling is spot on for each cylinder. I really think that with fuel injection, if we could keep the cylinder head down on the block, 1,500 horsepower is achievable. People thought I was crazy when I said 1,000 horsepower out of this, too. So, we’ll see.”

These are all cylinders 4 and 5. On the left, you can see the head. In the middle you can see the head gasket. On the right, you can see the deck of the block. Newcomer dodged a bullet here, with absolutely no damage, other than a .001-inch warp in the cylinder head.

Getting into the Short-Block

With the top-end off of the engine, the next point of concern was the very bottom end of the engine. While the rotating assembly is made up of quality components, Newcomer use completely stock, unmodified main caps and main bolts along with the OEM main girdle. If there was going to be a failure, this is where it would likely appear.

“The bearings look good…” says Newcomer as he inspects them. “No bad bearings. No cracked caps. No stretched bolts. Everything [on the bottom] looks fine.” With the mains getting a clean bill of health, the rotating assembly was inspected for any signs of distress, only to find none. “These pistons look a lot worse that they really are, because that’s just the coating that’s scuffed, and this engine was already beat pretty hard, naturally aspirated, with probably 100 dyno pulls on it.”

Another question mark in the bottom end was the OEM Jeep block itself. On Newcomer’s last world-record-setting runs, the used a filled block. This time, it was completely stock. “Previously, we went through a lot of trouble to fill in the block and use an upgraded main girdle,” says Newcomer. “But on this one, we went .030-inch over[bore] and kept everything stock on the block. It’s a normal block, nothing special.” Newcomer points out that according to the internet, the block would have likely been deemed “no good due to core shift” because of the location of the bolt holes in the bosses. “Obviously, this block is good. Just like every other block we’ve had that left the factory.”

It’s always a good day when you pull your bearings and they look amazing.

With all of the components inspected, Newcomer seems satisfied with the engine’s performance. “I’m very pleased with this engine. I didn’t think we would have been able to take it as far as we did. But, it took it. We could turn this engine to 7,000 rpm no problem; we only ran to 6,600 rpm on the dyno. We just did this to see what it’ll do. There’s nothing special in this, it’s all off the shelf stuff,” he says.

“It’s not done making power yet, and it’s not broken,” is an interesting statement, especially when coupled with his previous comment about the engine being capable of 1,500 horsepower. We’re eager to see the next chapter of this engine, as one thing is for sure. Newcomer isn’t done resetting his own horsepower records.

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Greg Acosta

Greg has spent nineteen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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