Are 5.7 Hemis Under rated?

[SRT-Tom]

OntarioStreetCar.com posted an article on October 28, 2009, entiled, "Underrating Horsepower, back from the 1960s." The article claims that the new 5.7 Hemi tests out at 400 hp at the flywheel. Here is the article:

The last time auto makers commonly underrated actual horsepower levels was back in the muscle car days in the 1960’s and early 1970’s. Initially everyone wanted more power than the other, but after a few years, all that meant was your cars were hit with larger insurance costs and the consumer notion that it would be considerably worse on fuel.

Chrysler Corp was the poster boy for it as most of their engines were all well known to be underrated (especially the 426 hemi) but Don Yenko Chevrolet dropped Corvette LT1 350’s into mundane Chevy Nova’s in 1970 so buyers could pay the standard insurance rate that you would be charged for a normal 350 powered Nova. Except the Yenko Nova’s had 360 horsepower and could destroy most of their big block powered brethren.
Today it seems quite rampant all over again, but the reasons why are different.
The late model BMW 335i coupe with its twin turbo 3.0L inline 6 cylinder is rated at 300 horsepower and 300 lb-ft of torque, yet the car runs 0-60 times in 4.8 seconds and the 1/4 mile in 13.3 seconds. Its “big brother” M3 with a 414 horsepower V8 runs 0-60 in 4.2 seconds and the 1/4 in 12.7 seconds…hmmm. Sounds like the 335i has closer to 360 HP, but it’s rated lower so it doesn’t interfere with M3 sales.
Chrysler is still at it too, this time with the new variable cam timing 5.7L hemi. The engine is rated at 390 horsepower when it is put in the Dodge Ram, yet only rated at 372 hp when put in the Challenger R/T. Independent tests have resulted in the engines producing 400 horsepower at the flywheel, so why pay extra for a Challenger SRT 8 that only has 25 more ? Unlike the BMW’s where the M3 has still held an advantage over the 335i, in the Mopar camp its not common for Challenger R/T’s to run quicker acceleration times than the SRT 8 model. However, next year the SRT will make you forget with its much more powerful 6.4L hemi.

And now the newest player, Audi with their new 333 horsepower, 325 lb-ft of torque supercharged S4. VW / Audi tuner APR just strapped one onto their all wheel drive dyno and pulled 331 horsepower and 336 lb-ft of torque at the wheels. Drivetrain losses amount a lot more through all wheel drive than front or rear drive, to the tune of about 20%, making the new S4 a true 400 horsepower German super sedan. Just don’t tell the guy that paid thousands more for an RS4 with 20 additional ponies.

[Old Bike Guy]

Interesting, I remember those days when insurance was the issue. I could not afford anything with real power back then so it was kind of moot. Wonder what the real rationale for understating is in today's market? Has anyone done the extrapolation based on current stock RT dyno runs?

Just curious.

[Challenger370]

The typical R/T 5.7L VVT engine produces 330 hp to the rear wheels. That translates to abotu 390-395 to the flywheel. The SRT-8 produces 360-365 to the rear wheels, its 425hp rating is accurate.

Take your car to the dyno to see for yourself.

I agree its underrated, maybe they will make a tweak or 2 and then properly rate it after updating the SRT-8 next year. Currently if it was rated at 400hp and the $10k more SRT-8 was rated at 425 you would say $10k for 25hp? So thats another reason to under rate it.

Not saying anything agains the superior SRT-8 because it has a lot of better parts and is a superor car as far as performance goes, but there is only about 30hp difference in the real world.

Short tube headers, under drive pulley and a custome tune will make the R/T match the SRT-8 output.

[climberccm]

At our dyno day a completely stock R/T came in at 321 RWHP and 356 RWH Tq. Slightly modded R/Ts (CAI, exhaust, and predator) were coming in at 345 RWHP and 376 RWTQ. Two completely stock SRT8 (2010 and 2009) came in at 375 RWHP and 376 RWTQ. I believe both cars are underrated; the R/T more so than the SRT8.