While not relevant SPECIFICALY to the 2005 Mustang, this topic does concern us all. I wanted to make sure everyone takes a peak at this. Mods, forgive me, feel free to lock this topic. I just want it to get some notariaty since I feel it's extremely relavant to ALL of us.

http://forums.bradbarnett.net/index.php?showtopic=19547

 

Torque....the other white meat....

 

Let's just put it this way.


"Horsepower sells cars, Torque wins races"
- Caroll Shelby

 

NICE! LOL! Thanks for that Altoid! Never heard that before!

 

I like the quote, too. Nice, Al.

 

Tourque is King!, long live the King...

Tftlbs *RPM / 5252 = HP

310*5500/5252=324HP

320*4500/5252=274HP**

320*5000/5252=304HP

**Strange... seems the published HP/Tourgue numbers for the GT don't add up.... I only get 274HP using 320FTlbs@4500RPM...

Bueller, Bueller...Anyone...Anyone...

 

Tofu and Torque, life is good!

 

StangerX and I posted this topic in the Autoweek forums. Read and ENJOY THE FUN! We're dukin' it out!

http://forums.autoweek.com/thread.jspa?for...=13869&tstart=0

 

I also came to this conclusion, my only explaination is that maybe when the third valve is engaged and the charge motion plates open up it expands the hp from 274 to 300?

 

Must be HP at the rear wheels.

274/.85 (for 15% powertrain loss) = 322 HP at crank?

dunno

 

Nyvolt,

The only way to really resolve this is to have a look see at an Engine Dyno run... the 320FtLbs @ 4500RPM may be where Peak tourque "begins"... it (tourque) may stay somewhat flat at around 320Ftlbs in a band from 4500RPM to 5200RPM therefore this might explain the disconnect in the numbers...

 

the older hummer models used in war (not sure about the ones now) had 100 hp but about 600 torque = ]

 

I just did a look see of the Mustang specs page...

Horsepower (SAE net @ rpm) 300 @ 5750

I got the following from www.musclecarclub.com

"SAE Net Horsepower became the standard measurement in 1972, and is still used today. SAE Net horsepower is the horsepower generated by the engine at the flywheel with all accessories attached. This change was made to reflect the numerous energy sapping accessories that cars began to have, such as an A/C Compressor and alternator, and thus was a better representation of the actual power generated by the engine. This number is always lower than the SAE Gross horsepower. Therefore, the same engine could have been rated in 1971 as 360 SAE Gross Horsepower and in 1972 as 300 SAE Net horsepower without any reduction in "power.""

Clearly, horsepower has a direct relationship to torque - it is all in the ability to do work... it is just how you get the work done that makes the difference... For example; say we have 100 kegs of beer in the end zone of a 100yd football field - our job will be to move the 100 kegs of beer from one end zone to the other... We have two contestants. Contestant No.1 is Mr. Mega Tq, and contestant No.2 is Mr. Hyper HP.... Mr. Mega Tq goes first. He loads up his giant wagon with all 100 kegs of beer and slowly pulls the entire load to the opposite end zone in 100 seconds... Next, it’s Mr. Hyper HP's turn... He loads his very light wheel barrow with 1 keg at a time, speedily delivering each keg speratley to the opposite end zone; he makes 100 round trips in 100 seconds... Who wins?...

No one, it's a tie... So, to say that high tourque is better than high HP is not really possible as they are really one in the same...

Bueller, Bueller... anyone....

 

It is a simple equation: HP = torque * rpm / 5252. So torque will always be higher than horsepower (torque in lb*ft and power in hp) below 5252 rpm and hp will always be higher than torque above 5252.

So the REAL simple answer to the question is that HP is basically irrelevant. You can NOT measure HP! And before all the dyno guys jump in, not even a dyno can measure HP! It measures torque and the rpm the engine was turning (notice it is the engine rpm that matters, not the wheel rpm, so techincally, it doesn't matter what gear you are in, but different gear ratios have different losses plus the dynos are designed to use higher gears. They speed up way to fast in first!) and then uses the above equation to calculate the HP. HP is really just a way of saying "how much torque can I make at higher engine speeds?".

Something else to keep in mind: There is one HUGE difference between a high torque motor and a high HP motor: The high torque motor will make MORE HP at lower engine speeds than the high HP motor can! That is all physics and what rpm the engine hits peak volumetric efficency. This is why diesel engines always feel stronger than gas engines off the line. Your 300 hp desiel might be making 150 hp at 1100 rpm. That 350 hp gas engine is probably making less than 100 hp at the same speed. It is only when the gas engine is able to spin up to higher rpms is it able to develop as much (and then more) power than the slow torquey diesel.

 

EXACTLY! Horsepower technically does not exist. It is merely a number that is calculated using an equation from the torque an engine produces. That "seat of the pants" feel you get is not the horsepower, it is the torque that you feel.

 

here is some proof that torque to weight ratio really does make a difference.

A Honda S2000 has 240hp and 162 torque.

Weight is 2835. It's hp to weight ratio is .085hp per lbs. The torque to weight ratio is .057 TQ per lbs.

This is a mid to low 14 second 1/4 mile car with a 6 sec 0-60.

The Mustang GT has 300hp and 320 TQ and weighs around 3500 lbs.

Hp per lbs is .086 hp per lbs and it's tq is .091 per lbs.

The Mustang is pretty consistant as a mid 13 sec car in the 1/4 and 5 sec 0-60.

Both cars have almost identical hp/weight ratios .085 for the Honda and .086 for the Mustang.

The key to that is the Mustang has .091 tq per lbs and the Honda .057, thats about a 30% difference in favor of the Mustang. It doesn't seem to be a HUGE advantage but it is definately an advantage.

Thats straight line performance though.

 

nynvolt,

I've got to call you on your analagy. The problem is that it only uses the PEAK hp (and torque to weigth) to weight ratio. That is a really irrelevant number when you get right down to it.

A car is accellerated by the power under the curve, not just a peak value. Given how low the torque is on the Honda compared to it's HP, it is pretty clear it is a "peaky" engine. The Mustang, on the other hand, has more torque than HP, so it clearly makes more power down low than the Honda can. Which means it will be accellerating faster at lower engin speeds (say right off the line and after a shift) than the Honda. Which, of course, leads to the Mustang being quicker, even though they have the same hp/weight ratio.

 

Those are just raw numbers, got the numbers from motor trend (nov 04 issue page 176) They ran a 14.2/99 1/4, and 0-60 in 5.8 in the Honda. The Mustang numbrs come from Road and Track (april 05 page 69) the GT got 4.9 0-60 and 13.5/102.4 1/4.

Was just pointing out that the mustang was quicker and they had almost equal hp/wt ratio, so the only reason the mustang is faster is because of it's higher tq value, about 30% more.

Thats not considering at what RPM either car is making power, just comparing performance numbers drawn from magazines and why the Mustang has a better 1/4 and 0-60 time than the Honda.

I think it's pretty safe to assume that the TQ advantage in the Mustang is making the differance.

I know gearing and how quickly the car makes power is a factor, but in that case the S2k has an advantage of having shorter gears (6 speed manual versus a 5 speed in the Mustang). The gearing is very close ration in the s2k and keeps the engine in the sweet spot, and rev's very freely.

 

How about this:

1 hp = 550 ft-lb /sec

'Horsepower' is a measure of the energy per time the engine can put out.

'Torque' is a measure of the force in the rotation of the engine.

hp = Torque * RPM * (2pi/33000)

Torque = hp * 33000 / (2pi * RPM)

33000/2pi ~ 5252 hence the more torque under 5252, more horsepower above 5252 statement above.

Based on the specs for the 2005 Mustang GT
hp at peak Torque = 274.18 hp @ 4500 RPM
torque at peak hp = 274.02 ft-lb @ 5750 RPM

Edit:
After quickly glancing at the other topic I saw the comment about Torque-Weight ratios. The problem with a Torque-Weight ratio is that the resulting number will be a distance.

i.e. 3500lb with 320ft-lb of torque... 320ftlb/3500lb = 0.091 ft ... now how can you advertise a cars strength in feet? That, with the fact that horsepower is more widely used, is why you'll see more Power-Weight ratios than Torque-Weight ratios.