Hi,

After reading a lot of different stories here and there, I would like to ask the question here. I have two cars in France for which I am sure about the number of horsepower (in DIN hp):

- A beloved 1986 Porsche 911 Carrera (231 hp) (http://epimates.com/%7Egreedy/pictures/Automobile/Porsche%20911%203.2L/resized/Porsche%20911%203.2L_00001.jpg.jpg)
- An humble (but very fun to drive) Peugeot 205 GTi (130 hp) (http://epimates.com/%7Egreedy/pictures/Automobile/Peugeot%20205%20GTI/resized/Peugeot%20205%20GTI_00003.jpg.jpg)

Now the question is, what about my 1967 289 2v Mustang? Some websites say 200 hp (wikipedia for example), some other say 225 hp, some other say 145 hp, etc.

I am really getting confused with all the different types of horsepower (and also very surprised when I read that some classics can have 500+ hp).

Why would people use different metrics? Today Ford says that the 2007 V6 develops 210hp and the 2007 V8 develops 300hp. Are we talking here about the same kind of horsepower than in the Porsche 997 S (355 hp) for example?

Thanks a lot.

Horsepower numbers can be decieving. HP in the 60s was measured in (correct me if Im wrong here) gross horsepower. It didnt take into account things like power steering, alternator, or many times even the water pump. It also didnt always use the stock and often restrictive air cleaner and exhaust. So the 225hp it was rated at is more like 190hp or lessmeasured by todays netstandards. I couldnt tell you exactly how much power your car was rated at, there were several engines used, but 200hp for the 2v sounds about right. If you post the engine code on the drivers door tag, or the 5th character of the VIN someone can tell you exactly.

To the best of my knowledge there is only one type of horsepower, however there are different spots where they measure them. Most manufacturers measure horsepower as brake horsepower (bhp)or horsepower power at the crank, samething. But most car owners that mod their cars go for horsepower to the rear wheels (obvioulsy only on RWD cars), wheel horsepower is harder to obtain and is substantially less than bhp because you lose a good amount of power through the drivetrain. Since your Mustang has a 289 2V it should be around 200 hp stock at the crank I believe.

I hope that this answered your questions, and if any other members find any of my info to be incorrect please feel free to correct me.

The only way to get an accurate horsepower rating is to put it on a dyno.

Quote myself from another post a few weeks ago because it seems relevant:

There was a change from net to gross HP rating in 1975. 150HP Net SAE rated is roughly equivilant to 210-220 HP Gross SAE rated.

All motors used to be measured by SAE gross. They changed that it in the early 70s and are now measure by SAE Net. That is why your power house of a v8 powered mustang from 1965 runs close to a 16 second 1/4 mile in stock form (with a 4 speed not an auto - 15.7 is exact quote from attached source) the 66 289 auto ran 17s

http://wikicars.org/en/HP
http://www.albeedigital.com/supercoupe/articles/0-60times.html

An 86 Lincoln Mark ran 16s in stock form in a car that weighs significantly more with an advertised significantly less HP rating....why you may ask? Because they changed the way HP was rated. This is also why just about decently equipped mini van from the mid 90s will out accelerate a completely stock 60s mustang GT.

yep. I've known about the horsepower differences for awhile. I gurantee my stock "200 hp" 66 2v is probably putting 120-130 at the wheels. MAYBE. lol. My 2000 GT puts down 260 at the crank, and about 215-220 at the wheels.

Yeah, gross hp was LAME. They use it because it was easy to fudge, you had to because it was a lot of guessing. They under rated performance cars for insurance reasons, and over rated typical family cars as a selling point. And yeah, that's why the "high horsepower" muscle cars of the 60's struggle to keep up with a new 05+ Mustang that only has 300hp, because they are honest in hp rating these days(though Ford under rated the newer Machs and the new Mustang GT's possibly). And yeah, the only way to measure power is on a dyno, but even dynos can be wrong, that's why the BEST performance rating is how the car runs. Many cars, especially carb'd cars, that get dyno tuned often pick up hp but end up running slower. How a car performs on a dyno vs real world can be completely different

ORIGINAL: _Remi

(and also very surprised when I read that some classics can have 500+ hp).



The reason that many people claim 500 HP now in older Mustangs, is because the original engines have been either modified, updated, or replaced, this to the end of more HP.... :D

My son and I have done this tothe 1970 351W engine that we have installed in his 1966 Mustang. We used the 351Wengine to replace the 200cid original. Even so, this stock 351 cubic inch displacement enginewas highly modified from it's stock displacement (to 408 cid) and consists of very few original parts, really just the engine block is stock.

Most of the classic Mustangs on this forum will have their engines modified to one degree or another in the interest of increased HP and/or reliability.

When the US government created procedures in the early 1970sfor auto manufacturers to determine the HP levels for their cars, it was done so in order to bring some consistency to how HP was measured.

ORIGINAL: _Remi


Why would people use different metrics?

To sell cars -

Yes there is a specific definittion of horsepower.
http://www.web-cars.com/math/horsepower.html

But there are different means and methods for measuring horsepower, check out:

http://neptune.spacebears.com/opine/horsepwr.html