Panman From Trinidad and Tobago, joined Aug 1999, 789 posts, RR: 0 Reply 1, posted (12 years 11 months 4 weeks 1 day 22 hours ago) and read 5851 times:
I've got it written down in my Piston Engine notes at home. Expect a reply in about 3-4 hours from now
Aaron atp From United States of America, joined Mar 2000, 533 posts, RR: 2 Reply 2, posted (12 years 11 months 4 weeks 1 day 22 hours ago) and read 5847 times:
Power = (force * distance) / time
1 HP is 746 Watts, which is 746 newton.meters per second
Dnalor From Australia, joined Mar 2000, 369 posts, RR: 0 Reply 4, posted (12 years 11 months 3 weeks 4 days 23 hours ago) and read 5811 times:
isnt it BHP and DIN
then on dyno's there are two distinct methods of measuring horsepower/kilowatts and torque:
one is where the engine is accelerating thru its rev range constantly and measured consatntly hence the engine has an accelerated momentum, then the other is where the computer allows the engine to accelerate in 1000 RPM increments then holds the engine under load and measures the power.
Bit of useless information there for you to chew on
Aaron atp From United States of America, joined Mar 2000, 533 posts, RR: 2 Reply 5, posted (12 years 11 months 3 weeks 4 days 20 hours ago) and read 5815 times:
BHP = (Brake Horsepower = SHP - system losses), a measurement of useful horsepower: "power at the prop" or "power at the wheels." 746 Watts
SHP = (Shaft Horsepower) mechanical power produced by the engine with no system losses factored in. 746 Watts
Kilowatt = Standard metric measurement of mechanical power, 1000 Watts
[not Din, but Dyne = outdated measurement of force instead of power, compare to the newton]
Notwithstanding, there are two types of HP Metric HP = (75 Kg.m)/s = 735 watts English HP = (550 lb.ft)/s = 746 watts
-properly defined as 33,000 lb.ft per minute, but 33000/60 = 550
the terminology is damning in of itself...
Dnalor is certainly right about the methods, but here is a more specific way to get brake horsepower/torque measurements to be done....
to measure BHP:
1.load the propulsion system (a car for instance) on the dyno so that 100% of the rated RPM is reached at full throttle
2. measure the torque in ft.lbs
3. increase the load to reduce RPM by 500 RPM (or any increment you choose
4. measure the torque in ft.lbs
5. go to (3) until you reach idle RPM
Torque Produced * (RPM / 5252) = BHP at that RPM
Then you can plot a Torque-RPM scale and a HP-RPM scale to get your respective curves.
Sabenapilot From Belgium, joined Feb 2000, 2697 posts, RR: 49 Reply 8, posted (12 years 11 months 2 weeks 5 days ago) and read 5761 times:
When are Americans finally going to quit calculations in:
°F,
ft,
NM,
HP,
lbf,
GAL,
lbs.
...
There is no relation between those units!
Use:
°C (or K),
m,
km,
N,
W,
l,
kg
The relations between them are obvious.
Dnalor From Australia, joined Mar 2000, 369 posts, RR: 0 Reply 9, posted (12 years 11 months 2 weeks 4 days 14 hours ago) and read 5755 times:
Aaron, sorry mate I'd have to disagree, if anyone lugged a my car down thru the rev range under boost in 500 rpm incraments they'd be building me a new motor, especially if its a turboed engine. Great way to detonate a motor.
I have sat in on many dyno sessions and the load must only be held briefly UP thru the rev range to allow the motor/turbo some respsite, heat soak is always a major consideration while on a dyno, I have witnessed engine failures due to higher stress levels on the dyno than on the track or road
Aaron atp From United States of America, joined Mar 2000, 533 posts, RR: 2 Reply 10, posted (12 years 11 months 2 weeks 4 days 13 hours ago) and read 5751 times:
sounds good to me...
sorry for the inacurracy guys, just trying to show the relationship between horsepower and torque... I've never used a dyno, and just sort of hypothesized the process...
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