The don't race your honda uphill theory.... and it's BS.
11-24-2002, 06:25 PM
#1
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A recent experiment was done by my college friend and their group in physics. There was a lot more calculations done that I won't go into, but here's the gist of it.
Let's say we have two cars. One weighs 2000lbs. The other weighs 2200lbs. The 2000lb car has an 8000rpm redline 100lb/ft of torque and an average of 1000lb/ft of force at the wheels.
The 2200lb car has a 4500rpm redline and has 200lb/ft of torque and an average of 1000lb/ft of force to the wheels. Assuming torque curves are similar, this is how it works.
As you can see, one car has 100lb/ft the other has 200lb/ft, but their gearing evens them out, meaning both cars would accelerate at roughly the same rate from a roll, meaning they would be dead even to say 100mph.
Now go uphill. The 200lb/ft car wins, right? Wrong. When going in a straightline on a level surface, you have the force of your car's weight, aerodynamic drag, and tire friction working AGAINST the force your car is producing. When you go uphill, a new element is added. We have the original 3 PLUS the force of having to move the weight against gravity as well as forward. TRANSLATION? Gravity could give a rat's ass how much torque you have at the crank. It only cares how much FORCE you are producing.
What this means is that if two cars produce the same wheel force, and race uphill, the heavier one loses. That's because the new force added working against the car is greater on the car weighing more, since more weight is harder to move upward against gravity, and this subtracts more force away from what the car is producing.
Now, go downhill, and just the opposite occurs. The car with more weight has the advantage, because now gravity is HELPING and ADDING force to the cars. And since the one car weighs more, that force is greater going downhill than the one that weighs less.
This was a physics experiment a friend of mine did for college. We actually used our cars. A 2001 Honda S2000 and a 1997 LT1 camaro SS.
Of 10 runs from a 45mph roll on a flat surface, our cars were dead even every time to 100mph. When we went uphill, the S2000 pulled. When downhill, the Camaro pulled.
Wanna try a little experiment to see what I mean? Time yourself running up a hill as fast as you possibly can. Now, take some time, relax, gain your energy back, and grab a 20lb bag of salt.
Now run up the hill with the 20lb bag of salt. I gaurantee your time will be slower. Why? You produce the same amount of force running up the hill no matter what. However, that added weight subtracts from your own force since it fights gravity going uphill.
Let's say we have two cars. One weighs 2000lbs. The other weighs 2200lbs. The 2000lb car has an 8000rpm redline 100lb/ft of torque and an average of 1000lb/ft of force at the wheels.
The 2200lb car has a 4500rpm redline and has 200lb/ft of torque and an average of 1000lb/ft of force to the wheels. Assuming torque curves are similar, this is how it works.
As you can see, one car has 100lb/ft the other has 200lb/ft, but their gearing evens them out, meaning both cars would accelerate at roughly the same rate from a roll, meaning they would be dead even to say 100mph.
Now go uphill. The 200lb/ft car wins, right? Wrong. When going in a straightline on a level surface, you have the force of your car's weight, aerodynamic drag, and tire friction working AGAINST the force your car is producing. When you go uphill, a new element is added. We have the original 3 PLUS the force of having to move the weight against gravity as well as forward. TRANSLATION? Gravity could give a rat's ass how much torque you have at the crank. It only cares how much FORCE you are producing.
What this means is that if two cars produce the same wheel force, and race uphill, the heavier one loses. That's because the new force added working against the car is greater on the car weighing more, since more weight is harder to move upward against gravity, and this subtracts more force away from what the car is producing.
Now, go downhill, and just the opposite occurs. The car with more weight has the advantage, because now gravity is HELPING and ADDING force to the cars. And since the one car weighs more, that force is greater going downhill than the one that weighs less.
This was a physics experiment a friend of mine did for college. We actually used our cars. A 2001 Honda S2000 and a 1997 LT1 camaro SS.
Of 10 runs from a 45mph roll on a flat surface, our cars were dead even every time to 100mph. When we went uphill, the S2000 pulled. When downhill, the Camaro pulled.
Wanna try a little experiment to see what I mean? Time yourself running up a hill as fast as you possibly can. Now, take some time, relax, gain your energy back, and grab a 20lb bag of salt.
Now run up the hill with the 20lb bag of salt. I gaurantee your time will be slower. Why? You produce the same amount of force running up the hill no matter what. However, that added weight subtracts from your own force since it fights gravity going uphill.
11-24-2002, 10:06 PM
#5
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Interesting study.
Another factor you should consider gearing to be a more determining factor as to who would climb up the hill. You should do the study with a stock S4 vs the S2000
Similar horsepower, S4 being about 700lbs heavier but the gearing is very closely matched.
My money is on the S4
Another factor you should consider gearing to be a more determining factor as to who would climb up the hill. You should do the study with a stock S4 vs the S2000
Similar horsepower, S4 being about 700lbs heavier but the gearing is very closely matched.
My money is on the S4
11-25-2002, 04:47 AM
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Go to the Road Beat column of the Mountain Democrat.
http://www.mtdemocrat.com/auto/
The test reports include 0-60, 50-70 MPH and 50-70 MPH uphill. Instrumented. Some cars fare better than others up a hill. He tested the S2K in 2000 so check the archive section. He did 50-70 in 2nd-3rd AND 3rd only which shows part of why you need to be in the right gear. The time lost shifting is swamped by the time saved by being in VTEC. Larry is the only guy I have found that always includes an uphill acceleration test.
Stan
http://www.mtdemocrat.com/auto/
The test reports include 0-60, 50-70 MPH and 50-70 MPH uphill. Instrumented. Some cars fare better than others up a hill. He tested the S2K in 2000 so check the archive section. He did 50-70 in 2nd-3rd AND 3rd only which shows part of why you need to be in the right gear. The time lost shifting is swamped by the time saved by being in VTEC. Larry is the only guy I have found that always includes an uphill acceleration test.
Stan
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11-25-2002, 06:47 AM
#8
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Thread Starter
Thanks for the link E30M3. 
SHIRI, why would I run both cars uphill at 4500rpm? You can't say "run one car in it's power band, and the other car below it's power band". That isn't how people race. That's just as stupid as saying "race me with your S2k but shift at 4500rpm". why? My car was built with the power it has, and the 9000rpm redline.
S4dukar, though I know the S4's gearing is close to the S2k's the S4 is still at the disadvantage due to weight. Again, FORCE is the number you get once all is said, done, and calculated. Tire diameter, power/torque, gearing, etc, etc. So again, the S4 would be at the disadvantage uphill. The force being put out is the same uphill or downhill. The only fator that affects anything is weight.
By the way, I saw an S4 for the first time up close, and my god that's a beautiful car. But hey, nothing wrong with the good ol' shoe either.
SHIRI, why would I run both cars uphill at 4500rpm? You can't say "run one car in it's power band, and the other car below it's power band". That isn't how people race. That's just as stupid as saying "race me with your S2k but shift at 4500rpm". why? My car was built with the power it has, and the 9000rpm redline.
S4dukar, though I know the S4's gearing is close to the S2k's the S4 is still at the disadvantage due to weight. Again, FORCE is the number you get once all is said, done, and calculated. Tire diameter, power/torque, gearing, etc, etc. So again, the S4 would be at the disadvantage uphill. The force being put out is the same uphill or downhill. The only fator that affects anything is weight.
By the way, I saw an S4 for the first time up close, and my god that's a beautiful car. But hey, nothing wrong with the good ol' shoe either.
11-25-2002, 06:57 AM
#9
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[QUOTE]Originally posted by Wisconsin S2k
[B]Let's say we have two cars. One weighs 2000lbs. The other weighs 2200lbs. The 2000lb car has an 8000rpm redline 100lb/ft of torque and an average of 1000lb/ft of force at the wheels.
The 2200lb car has a 4500rpm redline and has 200lb/ft of torque and an average of 1000lb/ft of force to the wheels.
[B]Let's say we have two cars. One weighs 2000lbs. The other weighs 2200lbs. The 2000lb car has an 8000rpm redline 100lb/ft of torque and an average of 1000lb/ft of force at the wheels.
The 2200lb car has a 4500rpm redline and has 200lb/ft of torque and an average of 1000lb/ft of force to the wheels.
11-25-2002, 07:00 AM
#10
Registered User
Originally posted by SHIRI
Secondly, try running both cars at 4500rpm and see whether the result is still favourable.
Secondly, try running both cars at 4500rpm and see whether the result is still favourable.