Applying Torque vs Horsepower

[HoosierDaddy]

So 182hp, 109 ft-lb vs 176hp, 127 ft-lb vs 179hp, 190 ft-lb. All geared to reach the same top speed. Which wins, which loses, and by how much? Any guesses on the enigines that that produced those numbers?

Sorry these were the closest match I could get for HP while tyring to get significant differences in torque using real data. Charts to follow.

Not enough information. It all depends on the areas under the parts of the curve used for the run.

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[Hack]

So 182hp, 109 ft-lb vs 176hp, 127 ft-lb vs 179hp, 190 ft-lb. All geared to reach the same top speed. Which wins, which loses, and by how much? Any guesses on the enigines that that produced those numbers?

Sorry these were the closest match I could get for HP while tyring to get significant differences in torque using real data. Charts to follow.

You need more than just one datapoint to give that information. Ideally you want to compare the areas under the HP curves. Assuming that the cars weigh the same and the transmissions are the same, whichever has the largest area under the HP curve will win. We've seen that the GT350R is significantly faster than the regular GT350 just due to lighter wheels, so there are many variables when considering actual car performance.

 

[Norm Peterson]

Not enough information. It all depends on the areas under the parts of the curve used for the run.

There's almost enough information there to fit torque curves reasonable enough for most comparison purposes . . . for each of them. Post #11.


Norm

 

[TexasRebel]

Good question, but I am not being tricky so about where you expect them to be based on the engine type.

182Hp @10,500 (91 lb-ft) & 109 ft-lb @ 7500 (156 HP)
176Hp @7500 (123 lb-ft) & 127 ft-lb@7000 (169 HP)
179Hp @5500 (170 lb-ft) & 190 ft-lb @3000-3500 (127 HP)

all set up for the same top speed though gearing?

win what?

are these motorcycles?

 

[Grintch]

So what happened to all the "HP wins sales, Torque wins races" folks?

So Kawasaki ZX-14R 1.4L, Honda Integra Type R 1.8L VTEC, VW GTI 2.0L Turbo. I was astonished how close they came out with equivalent gearing. I expected the fat turbo torque band and bigger displacement to give a big win to the GTI.

Anyone notice the issue with the shift points?

 

[Grintch]

Really shows how gearing can substitute for torque, and how well HP by itself can predict performance

Based on this I would predict that in the same vehicle -
In a drag race:
GTI motor wins, followed closely by the ZX-14R motor

On a road course or open road:
The ZX-14R motor wins, with a very close race between the GTI & Integra motor (Integra looks mostly faster in 4th & 5th gears, with GTI faster in the lower gears).

But a surprisingly close race all around (based on wildly different torque ratings, and engine sizes, and configurations). Of course on the street, cruising at 2000 rpm the engine with more power & torque at 2000 rpm (the GTI) wins (of course at 10,000 rpm, every engine but the ZX-14 has already blown up).

 

[GT Pony]

When you open up the restriction on the intake and exhaust you generally lose peak torque, but shift the peak upward in RPM.

Other than that, your post is in complete agreement with mine, so why the hostility?:shrug:

LoL ... you call that hostile? Just trying to have a discussion ... don't take it wrong.

Shouldn't be loosing peak torque with mods that make the engine breath better. The torque peak will usually shift out to a higher RPM and may even increase some, which results in more HP at the higher RPM range.

 

[dgc333]

Just an interesting story regarding gearing. My wife gave me a Mario Andretti driving experience a couple of years ago. They are advertised as Indy cars but are actually tube frame cars with fiberglass bodies. They weigh less than 2000 lbs and are powered by a 600HP GM LS crate engine.

The interesting thing is they do not have a gear box. There is a clutch but it is either in gear or out of gear. I do not know what the potential top speed the final drive gearing would allow but they limit the speed track to track with a rev limit chip in the MSD ignition box. The car can not pull away from a stop, they have to be pushed up to about 45mph with a quad before you could pop the clutch and drive away. Even at 45 the rpm is pretty low and the engine was not happy.

I did this at NH Intl Raceway which is a 1 mile relatively flat oval. They were limiting the cars to 160 mph. Once up to speed the car would rocket out of the corners and I was hitting the rev limiter just past 1/2 way down the straights. The cars had no instrumentation so I couldn't tell you what the engine was doing but it didn't seem like I was reving much past 5000 rpm before coming up against the rev limiter.

 

[Trackaholic]

So what happened to all the "HP wins sales, Torque wins races" folks?

So Kawasaki ZX-14R 1.4L, Honda Integra Type R 1.8L VTEC, VW GTI 2.0L Turbo. I was astonished how close they came out with equivalent gearing. I expected the fat turbo torque band and bigger displacement to give a big win to the GTI.

Anyone notice the issue with the shift points?

Did you specifically choose gearing for each vehicle to make them shift at the same road speeds, or was that just coincidental?

It's funny that on the GTI, you actually lose performance by shifting at redline. I have one, but haven't gone through this excercise (although I did do a similar comparison between the GT350, Z/28, and 350Z).

-T

 

[Grintch]

Equivalent gearing.

I started out with the stock gearing, but it's very hard for a motorcycle to get almost 200hp to the ground. So the ZX-14R gearing was drasticly different than the Integra Type R. Like 1st gear was taller than 2nd gear for the ITR. Even then they converged in the upper gears (3rd +), but wanted to remove the extra variable.

Or if you need 180hp to overcome the aero & rolling drag for a given speed, you gear the car to reach that speed no matter what the associated rpm is.

I am not sure what the redlines are, can only guess for the power curves. And most power curvers (like the ZX-14 & ITR) don't run the car to redline. But good job on picking up that the GTI curves should have used an earlier shift point (and vice versa for the ITR & ZX14).

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