Horsepower
12-31-2005, 01:35 AM
#16
Three Wheelin'
Nothing you said there is wrong.(at least the part that I could understand, this here is a bit hard to follow: "reaching a maximum at 90 degs when the torque will be PAS/2. where S2 is half the stroke"). Are you trying to talk about power transmission angles? That has nothing to do with our arguement.
You basically proved that when you make a modification to a given engine you want to see if it increases torque at a certaint point to evaluate its usefullness for your goals, which I agree to.
But we are trying to compare 2 cars, like the first poster stated. The most efficient way to compare them remains hp vs any kind of time curve. Torque is not king, as you said you can increase power without increasing torque by increasing engine speed. That means the car with more torque curve can be slower. But the car with more power at each moment in time wins the race.
I am done for the night.
You basically proved that when you make a modification to a given engine you want to see if it increases torque at a certaint point to evaluate its usefullness for your goals, which I agree to.
But we are trying to compare 2 cars, like the first poster stated. The most efficient way to compare them remains hp vs any kind of time curve. Torque is not king, as you said you can increase power without increasing torque by increasing engine speed. That means the car with more torque curve can be slower. But the car with more power at each moment in time wins the race.
I am done for the night.
12-31-2005, 01:39 AM
#17
Originally Posted by mark944turbo
Torque is not king, as you said you can increase power without increasing torque by increasing engine speed.
But not in our cars. Large piston do not respond well increases in speed.
12-31-2005, 01:40 AM
#18
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Originally Posted by streckfu's951
Better yet, why don't we take a look at how an engine produces power... shall we...
The torque at the crankshaft depends,first, on the force generated piston (PA) and, second, on the angle between the rod and the crank, reaching a maximum at 90 degs when the torque will be PAS/2. where S2 is half the stroke. As both P and the crank angle avary continuously, it helps to think ofthe torquse ans a steady mean pressure and a constant mean value for the stroke/rod factor.
Questions?
The torque at the crankshaft depends,first, on the force generated piston (PA) and, second, on the angle between the rod and the crank, reaching a maximum at 90 degs when the torque will be PAS/2. where S2 is half the stroke. As both P and the crank angle avary continuously, it helps to think ofthe torquse ans a steady mean pressure and a constant mean value for the stroke/rod factor.
Questions?
12-31-2005, 01:43 AM
#19
Originally Posted by mbonner
What horsepower does the 83 944 engine put out? I just bought back a Mazda RX7 GSL SE that I sold to a kid six years ago, this 13B rotary motor puts out 135 HP. It's a pretty quick and nimble car, just wondered how it compared to the 944 motor. I owned several RX7's no issues, just batteries, mufflers, they went on for ever.
Mike
Mike
Returning to the original post. The nature of the rotary engine does not allow much torque. Therefore you'll have to keep the revs higher than teh 944 to make the same power. The 944 will respond better at slower engine speeds and be a more enjoyable car in more circumstances.
12-31-2005, 02:33 AM
#20
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Why not just cut it short and say it's the "low rpm horsepower" that moves you along...torque is a static force,you need some rpm to go..even in just-over-idle conditions. The torque curve basically tells you where in the rpm range the engine makes the most hp VS the rpm... Monster low-rpm TQ? Then it makes LOADS of hp (comparing to an engine with a high-end tune) at that (presumably low) rpm. That's why it pulls down a brick ****house at just over tick-over.
12-31-2005, 09:39 AM
#23
Drifting
Also don't believe the hype, especially with the RX-8, the rotary is 2.6L, not the 1.3L they advertise. They love saying how much power they get from 1.3L. Sport Compact Car did a very nice tech article in how the rotary is falsely measured in terms of displacement.
12-31-2005, 10:47 AM
#24
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Well, quite the discussion. I thought the RX-8 was advetised as being 656(someodd)cc's x 2? Therefore it is a 1.3L....hmmm. Interesting. Tell me(us) more.
I also thought the HP of an n/a was 143...but I was trying to be broad in my terms, so the guys who have measured 130 something and the guys who've measured 150 didn't complain. That's all.
-The Kid
I also thought the HP of an n/a was 143...but I was trying to be broad in my terms, so the guys who have measured 130 something and the guys who've measured 150 didn't complain. That's all.
-The Kid
12-31-2005, 11:09 AM
#25
Drifting
I wish I still had that article. It talked about how they only measured the open space in the chamber and not total capacity. They said it's like measuring a conventional engine just on bore and not stroke.
12-31-2005, 02:00 PM
#27
re HP vs Torque
My 2 cents on the orginal post topic...
If it was only about torque then diesel engines would be the king. They are not becasue they only make power at reletively low RPM's. After 4000RPM, the power starts falling off.
I have always argued that it is all about the "area under the curve". You can have less total HP and be faster if you have more power (other than peak) over the usable RPM range. Cars with wide and flat power curves between 2000 and 5000 RPM's that have let's say 300HP will out accelerate a car with 400HP that has a very steep, peaky power curve that only makes power between 4500 and 6000RPM's.
If it was only about torque then diesel engines would be the king. They are not becasue they only make power at reletively low RPM's. After 4000RPM, the power starts falling off.
I have always argued that it is all about the "area under the curve". You can have less total HP and be faster if you have more power (other than peak) over the usable RPM range. Cars with wide and flat power curves between 2000 and 5000 RPM's that have let's say 300HP will out accelerate a car with 400HP that has a very steep, peaky power curve that only makes power between 4500 and 6000RPM's.
12-31-2005, 02:35 PM
#28
Torque has no effect at all on how fast a car is
This is the idea that I was arguing against. In 4 stroke motors, TQ has almost everything to do with power as the power is defined by TQ applied over the rpm range of the motor. The only way to increase power without affecting TQ is to increse engine speed and large pistons do not like to move that fast.
Unless you plan to spin a 944 motor to 8 or 9k, the only way increase power is by increasing torque.
Sonce the original post was refering to an NA, the variables regarding turbos are not a factor and the engine characteristics are already defined.
12-31-2005, 08:46 PM
#29
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Mark,
Horsepower is a calculated measurement taken from TORQUE. An engine doesn't produce "horsepower." An engine only makes TORQUE. From there, the horsepower is calculated (as on a dyno).
To say "torque is a worthless number" is dead wrong.
Horsepower is a calculated measurement taken from TORQUE. An engine doesn't produce "horsepower." An engine only makes TORQUE. From there, the horsepower is calculated (as on a dyno).
To say "torque is a worthless number" is dead wrong.
12-31-2005, 10:24 PM
#30
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Tsk Tsk Tsk...
All I have to say is...
Horsepower depends on Torque. Torque gets you OFF the line; Horsepower gets you AWAY from the line.
Veyron makes 1001HP and has a "proclaimed" top speed of 252mph. If it had 500HP, It's top speed wouldn't be cut in half, but it would be drastically less. Like said though, Torque gets you off the line, Horsepower just gets you away from the line.
Other then that, the debate is stupid. We all know, the more torque, the more horsepower, the faster you are. It's pretty much a fact (excluding semi's and all other diesels and what not that are geared at like 293,476:1).
To the question...
944- 143hp
944 S- 207hp
944 S2- 208hp
944 Turbo- 217hp
944 Turbo S- 247hp
Not 100% sure on the S and S2 hp output's, but I know one makes 207hp, other not positive.
Man, gotta love those Turbo S'
All I have to say is...
Horsepower depends on Torque. Torque gets you OFF the line; Horsepower gets you AWAY from the line.
Veyron makes 1001HP and has a "proclaimed" top speed of 252mph. If it had 500HP, It's top speed wouldn't be cut in half, but it would be drastically less. Like said though, Torque gets you off the line, Horsepower just gets you away from the line.
Other then that, the debate is stupid. We all know, the more torque, the more horsepower, the faster you are. It's pretty much a fact (excluding semi's and all other diesels and what not that are geared at like 293,476:1).
To the question...
944- 143hp
944 S- 207hp
944 S2- 208hp
944 Turbo- 217hp
944 Turbo S- 247hp
Not 100% sure on the S and S2 hp output's, but I know one makes 207hp, other not positive.
Man, gotta love those Turbo S'