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when automakers give the horsepower rating of their new cars as bhp are they measuring from the rear wheels or flywheel???
 

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bhp = block horsepower (I think).

Anyways, the measure it at the flywheel. At least I think they do.
 

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please explain the difference to me between BHP listings (I see this in euro car mags a alot) and HP listings. for instance, Im assuming HP listings in car mags are what power the engine makes with all the accessories bolted on, but BEFORE the power gets to the wheels (dyno HP). so what is BHP?
 

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BHP stands for brake horsepower. I can't remember the technical definaition between BHP and HP but basicly they are the same as far as numbers go. If you see a car with 160hp and a car with 160BHP it's the same. Both are numbers of the power measured at the flywheel with the engine in the car and all acessories hooked up. Now Gross hp is the measurment of hp of an engine that is out of the car with no accesories hooked up, also known as a engine dyno. This is how cars back in the 70's and older were measured. Thats why a 300hp mustang from that era doesn't run anywhere near as fast as a 300hp car today. Relating to Z's this is a common mix up for newbies. The 280z was rated at 170 gross hp but by todays method only has 145hp. Still people pick up a 280z and wonder why Nissan would make the 300zx with only 160hp when it has a bigger engine compared to the older 280z with 170hp. They just don't realize that the 170 number is a gross hp number. So to break it down:

BHP- Brake HP measured at flywheel

HP- 1BHP=.986HP so for most cars the difference would only be off by 1, also measured at flywheel

Gross HP- old way, HP of motor only-no accesories and out of car, also measured at flywheel.
 

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It should not be too hard to look up the SAE standards for Gross and Net hp measurement.
You would probably find that the Euro market tends to use the "PS" ("Pferdestärke") measurement for output, which is a bit like a metrified hp and is not exactly the same.
Manufacturers would gererally not quote measured rear wheel horsepower.
 

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Well explained 280z.
 

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Actually as far as Nissan goes I believe they switched from gross to SAE net in 79. Thats why the 75-78 Z is rated at 170hp and the 79-80 Z is rated at 135hp and the 81-83 is rated at 149hp. The fact is that the 75-80 have the same motor but the 75-78 has 145 vs the 79-80 that has 135hp. The 10hp loss is said to come from the addition of power steering and a couple other small things. However if you find a 79-80 ZX with no power steering, the base model, then it still has the 145hp out put. The 81-83 engine had a raise in compression as well as a head change which bumped hp up to 149hp to help compensate for the increase weight that was happening every year for safety and luxary reasons. Like Mister T said do a google on SAE net or Gross hp or BHP and I'm sure you'll find lots of info on the different measurments.
 
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