Car and Driver's Long-Term CT5-V Blackwing Blew its Engine During Performance Testing

The CT5-V Blackwing is an unreasonably good sports sedan.Image: Cadillac

If you assume that automotive publications are hard on cars that they test, the answer to that is generally a big fat yes. It’s our job to put vehicles through their paces, pushing them harder than a normal owner might in order to discover any shortcomings before you put your hard earned money down on one. Most of the time, the cars take it in stride, but sometimes, something goes wrong.

Enter the fine folks at Car and Driver who recently had a big problem with their long-term test (read: they keep the car for six months to a year for a more realistic view of the ownership experience) Cadillac CT5-V Blackwing. The fast Caddy’s normally stout, supercharged LT4 V8 engine experienced a serious failure after repeated launch control tests, but what exactly went wrong?

According to Car and Driver’s report, which was published on August 26, the number six cylinder appears to have partially melted a piston, scored a cast iron cylinder liner and broken a spark plug ground strap. But how? To find out, Car and Driver had their friendly local Cadillac dealer pull the engine and send it back to GM’s powertrain HQ for a forensic investigation.

2022 Cadillac CT5-V Blackwing | MotorWeek Track Test

GM’s own small block assistant chief engineer, Mike Kociba, pored over the engine once it had been torn down to bits and, surprisingly, was unable to give a conclusive answer as to the reason for its failure.

The fact that the engine’s damage was limited to one cylinder bank with one cylinder getting the brunt of it would preclude something like bad gasoline being the culprit. The working theory seems to be that either a potential obstruction in the fuel rail for the affected bank of the engine, leaning out the mixture and causing severe detonation, or that an obstruction of some kind in the cooling system caused that specific cylinder to overheat dramatically. The catch is that there’s no real evidence of either of these things.

Now, to be totally clear, this isn’t Car and Driver’s fault, and GM’s engineers back that up. This kind of thing isn’t totally uncommon, and ultimately its a good opportunity for a manufacturer to find new modes of failure before their customers have to deal with it. GM, in particular, is good at looking at things in this light, which is pretty cool.

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The whole engine replacement process for Car and Driver’s busted Blackwing took around six weeks (because supply chain), but the car has a new engine, the team at Car and Driver went through another strict break-in process and repeated their launch control testing only to have absolutely nothing go wrong this time. They even beat GM’s advertised 0-60 times by launching manually, resulting in a final time of 3.7 seconds. The car also ran an 11.7 second quarter mile time at 124 mph.