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  #136 (permalink)  
Old 05-16-2010, 08:45 PM
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Quote:
Originally Posted by red65mustang
http://craig.backfire.ca/pages/autos/horsepower

(that article link does also answer clearly many items raised in this thread)
You are correct, this article does answer some of these questions. And they all prove that maximum average horsepower delivered to the pavement is what wins races. Some quotes from this article:

"It can be seen from the comparison of the above three engines that the most powerful one gave the highest force, and the two which made the same power as each other made the same force as each other as well. The two engines with the same power had a different amount of torque and revs, but the acceleration force was equalized by the final drive gear. This clearly shows that the engine's power, regardless of how much torque it is making or how high it is revving, determines the car's acceleration force. "

My point exactly. How does this statement IN ANY WAY PROVE THAT TORQUE, NOT POWER, WINS RACES!!!

"Between the two cars, the one with the made-up V8 is going to be faster than the one with the made-up I4, because the V8 has a higher average power level throughout its rev range."

Again, this proves my point.

"...If both cars were fitted with a Continuously Variable Transmission (CVT) that had an infinite ratio spread which can hold both engines at their horsepower peaks, the acceleration of both cars would be identical."

Interesting. Two cars with identical horsepower peaks equpped with CVT's holding the engine at the HP peak, and the acceleration is identical. Sound familiar?

"Gear shift points should always be chosen in such a way that the engine is putting out the highest average power to the wheels."

"It does not matter if the engine makes power by revving high or making a lot of torque, because drivetrain gearing can be used to adjust the torque and revs proportionally."

And the best of all... Peak power sells cars. High average power wins races."

And now 355nova is accusing me of being ap72. Seriously?

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  #137 (permalink)  
Old 05-16-2010, 09:02 PM
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Not accusing just thought you were man I wasn't the only one.
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Old 05-16-2010, 09:04 PM
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Ay we are back to Torque and HP again. Well I'm a believer in torque. Like I said before all depends on combo and driver.
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  #139 (permalink)  
Old 05-16-2010, 09:16 PM
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Quote:
Originally Posted by 355Nova
Ay we are back to Torque and HP again. Well I'm a believer in torque. Like I said before all depends on combo and driver.
I love torque as much as the next guy.

As long as that torque is maximized at my wheels and not the flywheel!
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  #140 (permalink)  
Old 05-16-2010, 09:24 PM
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Ok time for some real world proof of why torque is what makes you faster in the 1/4 mile.

I don't know if many guys here watch the NEDRA Nationals (National Electric Drag Race Association), these guys build electric cars for fun and some are quite spectacular.

Here is an electric RX7 drag racing a 500HP+Dodge Viper, now before you say..."Yea but the electric car is a lot lighter!"...keep in mind it has way less than half the HP and more than 2/3 the weight.

http://www.youtube.com/watch?v=G32E4...eature=related

If that isn't a demonstration of why its torque that accelerates you down the track I don't know what is.
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  #141 (permalink)  
Old 05-16-2010, 09:29 PM
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Quote:
Originally Posted by 4 Jaw Chuck
Ok time for some real world proof of why torque is what makes you faster in the 1/4 mile.

I don't know if many guys here watch the NEDRA Nationals (National Electric Drag Race Association), these guys build electric cars for fun and some are quite spectacular.

Here is an electric RX7 drag racing a 500HP+Dodge Viper, now before you say..."Yea but the electric car is a lot lighter!"...keep in mind it has way less than half the HP and more than 2/3 the weight.

http://www.youtube.com/watch?v=G32E4...eature=related

If that isn't a demonstration of why its torque that accelerates you down the track I don't know what is.
I bet that guy in the Viper had some serious buyer's remorse after getting beating by what sounded like my De Walt power drill!
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  #142 (permalink)  
Old 05-17-2010, 12:17 AM
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I am going to be real blunt here...

all the so called smart guys
that are saying Tq wins races....
and they are referring to engine Tq

are not as smart as they think.

IF you have gears to work with...

Horsepower wins EVERY TIME.

it's called "power to weight" for a reason, not Tq to weight....
it's why calculators use Hp to determine acceleration, not Tq

you can have 1 million ft/lbs Tq.. and zero Hp.. and hence ZERO WORK

BUT if you have only .000001 ft/lbs and .000001 hp.... there IS work
and therefore MOVEMENT/ACCELERATION

Tq breaks parts, Hp wins races.
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  #143 (permalink)  
Old 05-17-2010, 12:17 AM
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The scary thought that enters my mind is this is done with cellphone batteries...hundreds of them. None of this stuff is light of course and the motors are nowhere nearly beefy enough to handle super high current discharges or very light.

Whats going to happen when the new supercapacitors come out and ultra high current light weight motors with no brushes get large enough to be installed in a car.

I worked on a brand new surgical handpiece that was completely electric that replaces pneumatic powered versions a few years ago, it wasn't much bigger than a pencil and put out 5HP on 240 volt according to the mfg. Not believing one bit of the claim I grabbed the chuck on this little surgical die grinder to feel what kind of torque it could put out, the pneumatic powered versions I could stop easily in my hand.

Needless to say, it burned me pretty badly since it hit full rpm without even feeling my resistance...it spun up to speed instantly...the smell of burnt flesh wafted through my office as I ran to the sink to cool my hand.

Scale that thing up 200 times and thats 1000hp...from zero rpm...no brushes to replace and it ran very cool since it was designed to be used continuously in a surgeons hand for long periods of time. Much of the problem with the pneumatic versions was they would get very cold in use and had poor starting torque which was a problem in cranial surgery where they need precise control of the burr.

Say goodbye to gears and clutches and all that nonsense, 100% torque from zero rpm is where its at baby!
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  #144 (permalink)  
Old 05-17-2010, 06:28 AM
How fast is fast enough?
 
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Quote:
Originally Posted by 4 Jaw Chuck
Ok time for some real world proof of why torque is what makes you faster in the 1/4 mile.

I don't know if many guys here watch the NEDRA Nationals (National Electric Drag Race Association), these guys build electric cars for fun and some are quite spectacular.

Here is an electric RX7 drag racing a 500HP+Dodge Viper, now before you say..."Yea but the electric car is a lot lighter!"...keep in mind it has way less than half the HP and more than 2/3 the weight.

http://www.youtube.com/watch?v=G32E4...eature=related

If that isn't a demonstration of why its torque that accelerates you down the track I don't know what is.
How does this show anything regarding torque? As the speed increases the torque falls... But power remains constant. That is assuming no drive controls, which i highly doubt. Perhaps what it really shows is the power contained in controlling your power output, and a reduction of parasitic losses.



CE is Civli, not chemical, ChemE is chemical. Not important, just letting people know.

People here can misunderstand the facts or skew them as they please. PontiacPhil got this after only two pages of discussion so I know the material is there for anyone to pick up and understand. I still can't understand how some people can be so blind to the truth, but "if they don't already know, you can't tell them." My goal was to dismiss a myth that MANY hotrodders believe, and while some people got it I have found that ignorance of simple physics rules and definitions is a lot more widespread than I originally assumed.
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  #145 (permalink)  
Old 05-17-2010, 08:08 AM
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pontiac,
the only thing the 3 motors compare in the link tells you is that with more cubes to make more TQ and more rpms you can make more TQ on the tires...
Do note:
for all three motors the "results" compare is written in flb/ft on the tire which is torque...
the HP value is not used in the math....

you can not determine acceleration rate to determine ET directly from a calculated HP,,,you must first interpolate back to the measured TQ value at that rpm to plug it into any acceleration equation....
(which he did do using HP versus mph in the example well above the motors example but still the HP/mph results are written in TQ ft/flbs!!!!)

for any motor to have a higher/better HP average over a rpms range there has to be a higher/better average TQ in that range aka a "flat TQ curve"...
(he should have had both lines on his graph)
but for what he goes on to explain with a X-Y only graph,,,why a "peaky" TQ motor needs a close ratio 6 speed tranny to match a 3 speed tranny "flat TQ motor (to reach a same "velocity" mph at the same time),,,HP is the logical X axis notation...

no dis-respect but you are seeing only what you want to see,,, and taking text out of context...

heck, the only car race form where HP does matter is at Bonneville...
it takes XXX HP to "maintain" YYY miles per hour velocity over the whole mile trap length....
it was the TQ that accelerated you to that terminal max velocity...
it's fair to say the "calculated" HP value kept you at that velocity...

if/when drag strip winners are determined by who went thru the lights at the fastest mph,,,then you will be correct,,,knowing HP matters...

Last edited by red65mustang; 05-17-2010 at 08:15 AM.
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  #146 (permalink)  
Old 05-17-2010, 08:13 AM
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Quote:
Originally Posted by red65mustang
pontiac,
the only thing the 3 motors compare in the link tells you is that with more cubes to make more TQ and more rpms you can make more TQ on the tires...
Do note:
for all three motors the "results" compare is written in flb/ft on the tire which is torque...
the HP value is not used in the math....

you can not determine acceleration rate to determine ET directly from HP,,,you must first interpolate back to the TQ value at that rpm to plug it into any acceleration equation....
(which he did do using HP versus mph in the example well above the motors but still the results are written in TQ ft/flbs!!!!)

you can use TQ=HP x 5252/rpms

for any motor to have a higher/better HP average over a rpms range there has to be a higher/better average TQ in that range aka a "flat TQ curve"...
(he should have had both lines on his graph)
but for what he goes on to explain with a X-Y only graph,,,why a "peaky" TQ motor needs a close ratio 6 speed tranny to match a 3 speed tranny "flat TQ motor (to reach a same "velocity" mph at the same time),,,HP is the logical X axis notation...

no dis-respect but you are seeing only what you want to see,,, and taking text out of context...

heck, the only car race form where HP does matter is at Bonneville...
it takes XXX HP to "maintain" YYY miles per hour over the whole mile trap length....
it was the TQ that accelerated you to that terminal max velocity...
it's fair to say the "calculated" HP value kept you at that velocity...

if/when drag strip winners are determined by who went thru the lights at the fastest mph,,,then you will be correct...

Actually, PontiacPhil has it right, as he proved a while ago. Read his posts since you can't understand mine. I thought he did a good job of explaining it in another manner, perhaps more easily understood than my posts.
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  #147 (permalink)  
Old 05-17-2010, 08:30 AM
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Quote:
Originally Posted by red65mustang
no dis-respect but you are seeing only what you want to see,,, and taking text out of context...
red65mustang,

No disrespect taken, and mutually so, none intended from my end. I have arguments like this with colleagues every day and we end up talking about it over a beer after the workday is over.

The article that you posted proved my point exactly. Nothing was taken out of context, as the very context of the article was that horsepower to the rear wheels wins races.

http://craig.backfire.ca/pages/autos/horsepower

I'm confused as to why it is being used to disprove my premise: The guy who puts the highest average horsepower to the pavement during the race wins, NOT the highest average engine torque. All I can do is repeat the conclusion at the end of the article: "Peak power sells cars. High average power wins races."
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  #148 (permalink)  
Old 05-17-2010, 08:43 AM
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ap,
LOL,,,how in the world did you manage to get so much "wrong" information in your head!!!

a electric car motor TQ output is "constant" over the entire rpms range!!!

it's why and how a 2800lb Tesla roadster does accelerate 0-60mph in only 3.7 seconds with the first motor rated at only about 200ft/lbs (and 248HP at 6k) ...

it also why the re-configured the motor to have about 280 ft/lbs so it would turn in a respectable 1/4 mile ET...

http://en.wikipedia.org/wiki/Tesla_Roadster
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  #149 (permalink)  
Old 05-17-2010, 08:52 AM
How fast is fast enough?
 
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Quote:
Originally Posted by red65mustang

a electric car motor TQ output is "constant" over the entire rpms range!!!

[/url]

Only some do, many do not.
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  #150 (permalink)  
Old 05-17-2010, 09:01 AM
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Quote:
Originally Posted by red65mustang
a electric car motor TQ output is "constant" over the entire rpms range!!!
My understanding of electric motors (which is relatively basic) is that power consumption remains constant, such that torque decreases as rpm's increase. Once the motor reaches a speed where torque is barely enough to overcome internal friction the motor will stop accelerating and remain at a constant speed.

Again, I'm no expert on electronics so maybe they used a constant-torque motor.
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