I've been looking at CAIs and note that K&N, Airaid, and AFE all post before and after dyno runs that show the factory horsepower of the Hemi at about 260HP, not the 360HP that Chrysler claims. No, I am not confusing the 3.7V6 with the Hemi, and no we're not talking about the difference between crank and wheel horsepower. Horsepower ratings have all been "at the wheels" for many years.

So - Chrysler is claiming 100HP more than three separate vendors got? My 2005 Hemi Durango was rated at 335HP and it did feel quicker than my 2012. What's up?

 

Car companies advertise SAE horespower which is motor on a stand with accessories attached but does not take into account drivetrain losses. Rearwheel horsepower from a roller dyno is always lower. Generallly 10-20 percent depending on the efficiency of the transmission, etc.

 

I havent seen a manufacturers horsepower rating as whats at the wheels in the time i'm driving and likely longer than that. My guess is any dyno run you've seen of 260 hp is likely whats at the wheels on these trucks as typically through an automatic tranny you lose 18%-22%!

 

I know manufacturers used to advertise crank horsepower, which would be without the transmission or accessories - but I thought the govt made them go to wheel horsepower since crank horsepower is misleading.

 

They included accessories in engine horsepower testing since 1971. Before that it was engine horsepower without accessories. Factory horsepower number sstill don't include drivetrain losses due to trans, rear end, etc. (approximately 10-20% depending on efficiency of drivetrain components)

 

If 260hp is the real-world average at the wheels, then either the drivetrain is consuming 28%, or Dodge is over-advertising the SAE hp.

 

I don't see why not. We've Dyno-ed a Subaru STI advertised at 300 HP, and got like 230 HP at the wheel, and it is a Stick shift.
AWD + Automatic consumes a lot of drivetrain loss.

 

All vehicles are advertised at bhp not whp, its just marketing. Typical loss for auto trans cars is ~18%. And as others have said the tranny, heavy 20 inch wheels and tires and especially AWD would easily take away 25% by the time it was measured at the wheels. As for the 2005 I would expect the difference is weight and gearing but I am not familiar with the previous generations. The 360 is SAE certified and would be very difficult to misrepresent.

 

Guys, I just checked the HEMI specifications on Dodge Durango's website, where it reads "5.7-liter HEMIŽ V8 MDS dual Variable Valve Timing engine packs 390 horsepower at 5,800 rpm and 407 lb-ft of torque at 4,200 rpm".

I remember that a month ago or so the same website read: 360 HP and 390 lb-ft. Is this a new/modified engine? A new software/computer? Or what?

 

Never saw that on the Dodge site. Always saw 360/390.