Batenswytch

I have to ask: Ford rates a stock S197 GT at 300 hp. From reading around the forums here, in actuality its less. How much less? And where's the missing hp? Is the 300 hp something produced under ideal conditions in a lab somewhere, or projections made by a computer? What's up with that?

Also, has Ford always inflated the numbers? I ask b/c we have a 68 T-bird with a 429 Thunderjet... and everything I find on that car says, paraphrasing, "As with most cars of the day, Ford seriously UNDER rated it at 360hp."

Sooooo? Did they used to UNDER rate them (for obvious reasons) and now they INFLATE the ratings for sales?

BruceH

The difference you see is flywheel and wheel horsepower. When we go to the dyno power is measured at the rear wheels. In order to get there the power goes through the clutch, transmission, driveline, and rear end. All of those components use some of the engine hp while transmitting it to the rear wheels. The standard formula for correction is rwhp divided by .85 = flywheel or brake hp. This is for a manual transmission. An auto would be divided by .80. These numbers represent drivetrain losses of 15% and 20%.

Batenswytch

Ahhh. Okay. I see. *nods* That makes sense. Hence the difference between RWHP and HP.

But that leaves me wondering now - on the T-bird, in 68, would the rating of 360 hp really be underrated or would that be more what it actually is after the losses through the drivetrain?

SirKnightTG

I think for the most part, 300 is under rated as most tend to get 265 rwhp or more stock (with the few exceptions). 265rwhp w/ a manual would mean 312 bhp or 331 bhp if that was an auto.

Unfortunately, I don't have a clue what mine was stock, nor do I know what it is now. I just assume it's what it should be in theory.

thedrod

Watch this video.....keep in mind the hosts are very biased against american cars. They bring out a dyno later in the show.

http://www.youtube.com/watch?v=O46E0gCF5os

Jokeurmnd

Am I the only one that got pissed off at the host when he wrote on the car? It's not a rally car it's a stright lane car. I think most people know that buying the stang

05 Mustang

Before I supercharged my 2005 Mustang GT, that's exactually where it base-lined at on a Mustang Dyno..265rwhp

SirKnightTG

Is it auto or manual?


edit: Oh, I noticed you underlined the manual part too so I assume manual.

SirKnightTG

I hate those Top Gear guys.

05 Mustang

not a problem SirKnight...it was a 5spd.