Listen to the Cadillac LMDh Car's Screaming V-8

When Cadillac revealed its new Project GTP Hypercar, it didn't release many technical details. It simply stated that the LMDh race car had an all-new 5.5-liter DOHC V-8. Even though the Corvette C8.R also uses a 5.5-liter DOHC V-8—one related to the LT6 in the upcoming Z06 street car—it seemed like the Cadillac engine would be different, though the company wouldn't confirm that. Now we have a bit more to go off of. Cadillac released a teaser video Tuesday of the race car testing, and it sounds radically different than a C8.R.

The C8.R and Z06 notably use a flat-plane crankshaft in their V-8s, which results in a Ferrari-esque sound. This sounds like a classic American V-8 with a cross-plane crank, albeit one that revs to the moon. In a word, it sounds rad.

LMDh regulations allow for the use of a bespoke (i.e. not production-based) engine, as long as it fits certain size requirements, and revs no higher than 10,000 rpm. Output at the rear axle is set between 644 and 697 hp depending on Balance of Performance, but automakers can choose how much of that power comes from the internal-combustion engine and how much comes from the energy-recovery hybrid system (ERS).

Porsche's 963 and BMW's M Hybrid V8 are both using flat-plane twin-turbo V-8s. Based on the sound in this short clip, it sounds like Cadillac's V-8 is naturally aspirated. If that is indeed the case, the Cadillac would likely be the only top-level sports prototype racing next year not to rely on forced induction. So far, all cars built to the FIA's Le Mans Hypercar (LMH) specs run turbo engines as well, and it sounds like Ferrari's entrant will too.

Turbochargers are great for generating low-end torque, and allow for lower engine speeds, but big V-8s make lots of torque too, and a lack of turbos will keep weight down and make thermal management easier.

Cadillac will continue testing its LMDh car over the next few months, with a racing debut set for next year's Daytona 24 in January. Like Porsche, it will also enter a car into the World Endurance Championship, where it will compete in the Hypercar class alongside LMH cars from Toyota, Peugeot, Glickenhaus, and possibly more.

Between this and the Chevrolet Camaro Cup Series car, GM will bring some V-8 scream to Le Mans next year. We can't wait.

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