Updated ATS-V LF4 SAE HP

[Bruce Nunnally]

Cadillac Updated the ATS-V Release with final hp numbers:

The ATS-V arrives next spring, powered by the first-ever twin-turbocharged engine in a V-Series. Rated at an SAE-certified 464 horsepower (346 kW) and 444 lb-ft of torque (601 Nm), the engine is the segment’s highest-output six-cylinder and enables 0-60 performance in 3.8 seconds and a top speed of 189 mph.

I was predicting 500+ hp. Something doesn't add up here if the 18 psi 464 hp 444 lb-ft TT 3.6L V6 LF4 has 6 psi more boost than the 12 psi 420 hp, 430 lb ft LF3. The added boost level should generate ~24% more power, or 105 hp for 535 hp. If tuners are getting 500+ hp from the LF3, this may suggest the LF4 can be tuned for a lot more.

if we look at it another way, a 12 psi boost on the LFX for the LF3 added 420/321 hp or 30.8%. That's a relatively low 2.57% per PSI. At that rate, 18 psi would add up to (1+18*.0257) * 321 = 469 hp, which matches well with the result.

However, we would expect 12 psi of boost to (ideally) add 12/14.7 or 82%, or 82/12= 6.8% per psi. After efficiency losses this real-world turns out to be around 4% per psi. So the LF3 seems to be under-achieving at 12 psi and the LF4 seems under-achieving at 18 psi, even though 420 hp and 464 hp are nothing to sneeze at.

[Cadillac Jim]

"A horsepower rating is exactly what I mean when I say it, nothing more, nothing less." - Mad Hatter, paraphrased

[Bruce Nunnally]

I suspect the turbos are selected for low end torque and the LF3/4 never reach full boost at redline, so never reach full power potential.