Performing an autopsy on our Corvette’s blown engine

Update by Colin Wood to the Chevrolet Corvette Z06 project car
Mar 18, 2024 | Corvette, c5, Project car, Blown Engine

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Few things can ruin a track day more than the sound of a horrendous thump, followed by the sickening “clackclackclackclackclack” of iron hitting aluminum. And then lots of smoke and lots of oil.

Since we didn't see any flames, we coasted our Corvette project car until we were in sight of a fire extinguisher. Once stopped, we popped the hood and assessed the situation.

It didn't take long to figure out the cause of all the noise and mess: Our Corvette's 525-horsepower LS3 was done forever and off to engine heaven.

Oh, and did we mention we had a buyer on the other line?

Photography Credit: David S. Wallens

Luckily, the buyer was still interestedall we had to do was repair the damage. And yes, that meant pulling the dead V8.

After removing the engine–and dealing with the mess of said blown engine–we had our mechanic, Jesse Spiker, of Spiker Motorsports, look over the engine and call the builder, BluePrint Engines, with his findings.

The most likely conclusion to the engine failing? A faulty rod seems to have snapped near the crank journal, and the portion of the rod still connected to the crank punched out through the oil pan on a subsequent rotation. 

There weren't any signs of bearing failure, however, as the portion of the rod still connected to the crank continued to spin smoothly and freely on the journal. There were also no obvious signs that too much pressure was being applied to the rod. All we did see was a cleanly snapped rod.

The snapped end of the rod had contacted the inside of the block on subsequent rotations and became a hammer. Photography Credits: J.G. Pasterjak

After communicating this with BluePrint, the company then asked for pictures and documentation, as well as questions about how the engine was used, how it was installed and how it was driven on track. In turn, BluePrint honored the warranty.

We're not going to say that every engine builder should replace every blown engine, but we will say that documentation is your friend. We had proof that, although we pushed the engine hard, we always operated the car within proper temperature and pressure parameters.

After a few delays–namely peak covid-era supply chain slowdowns and having to tune the new engine–we had the new engine installed and the car sold to its buyer.

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David S. Wallens
David S. Wallens Editorial Director
3/19/24 12:00 p.m.

Yup, it went boom. Someone decided to add a new window to the room. 

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
3/20/24 9:42 a.m.

So, tensile failure? Looks like it from the one pic.  If so, I'd call that a substandard part. What kind of rod was it? Stock 6600 rpm redline?

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