Torque vs. HP Revisted

[Jerry Clayton]

Horsepower on the Fly with AEM’s AQ-1 Data Logger and Dyno-Shaft | Dragzine

Found this ---------

I guess that since I've always been trying to get down or around a track in as few seconds working toward ZERO TIME, I must be working away from HP and towards TORQUE as HORSEPOWER has a time factor-----------

Also find I'm working away from RPMin as I want less revolutions as possible(way under 1000)

Also want to go to the salt flats to see if I can actually turn the earth backwards(well the way things are now, maybe I should try forward-------)

[AL427SBF]

Ok, nothing of consensus reached, but interesting getting the different view points. Glad some view torque as I do, I suppose there will always be a divided opinion on this.


Final thoughts, those believing we should have addressed this at the "power" level really didn't understand the question, this discussion has always been about the two components of power, and which one should be given priority when building/tuning a motor. Imbedded in that was my assumption (right or wrong) that the boundary conditions for the motor were kind of understood -


V8's from 289 up to say 460 max, and operating in the 3-6k range


So we agree to disagree, happens more often than not in these here parts.


I also noticed some of our prominent motor builders decided to sit this one out. Can't blame 'em, I'm sure they have been down this dirt road before, no need to choke on all that dust to a known dead end

[eschaider]

Originally Posted by Jerry Clayton

Horsepower on the Fly with AEM’s AQ-1 Data Logger and Dyno-Shaft | Dragzine

Found this ---------

I guess that since I've always been trying to get down or around a track in as few seconds working toward ZERO TIME, I must be working away from HP and towards TORQUE as HORSEPOWER has a time factor-----------

Also find I'm working away from RPMin as I want less revolutions as possible(way under 1000)

Also want to go to the salt flats to see if I can actually turn the earth backwards(well the way things are now, maybe I should try forward-------)

+1 Jerry!

I think I also remember something about giving it 5, 5 and 5 just before the last round


Ed

[eschaider]

Originally Posted by AL427SBF

Ok, nothing of consensus reached, but interesting getting the different view points. Glad some view torque as I do, I suppose there will always be a divided opinion on this.


Final thoughts, those believing we should have addressed this at the "power" level really didn't understand the question, this discussion has always been about the two components of power, and which one should be given priority when building/tuning a motor. Imbedded in that was my assumption (right or wrong) that the boundary conditions for the motor were kind of understood -


V8's from 289 up to say 460 max, and operating in the 3-6k range


So we agree to disagree, happens more often than not in these here parts.


I also noticed some of our prominent motor builders decided to sit this one out. Can't blame 'em, I'm sure they have been down this dirt road before, no need to choke on all that dust to a known dead end

I think you have your answer after a fashion AL427SBF. Take a look at the dyno chart back in my post #58. You don't have to rely on opinion. Those numbers that make up the graph are empirical evidence of how important big torque early in the usable rpm range and out through your 6000 rpm target really is. The HP curve is literally a straight line upwards - it don't get any better than that! Albeit the big torque starts lower than your target 3000 rpm starting point but that's all the better - in the real world.

BTW remember those are RW numbers divide by 0.85 for flywheel. TQ is absolutely your friend and as Jerry pointed out the more you can get and the sooner you can get it, the better it is.


Ed

[AL427SBF]

I need no convincing, if you jump away from "Club Cobra ... world's largest non-biased Cobra site!" you find all sorts of interesting stuff ...


Bill Hancock
Mechanical engineer and the founder and former owner of Arrow Racing Engines for almost 30 years. He has presented numerous papers and seminars on dyno testing and tuning. He and his longtime friend, Harold Bettes, formerly the VP of SuperFlow Corporation, recently co-authored a book entitled, “Dyno Testing and Tuning”.


"Hot Rodders and beginners like to talk about horsepower and are usually enthralled with only one number, the peak horsepower produced. Professional Engine builders will talk about the shape of a torque curve, where it starts and where it noses over."


"You will learn that the top tuners really focus their work on shaping the torque curve. If a torque curve has too many humps and dips, the driver will never be able to effectively pedal the car at the edge of traction and ultimately will settle for a part throttle setting that is controllable but not competitive."


"Driving a car with a lumpy torque curve is like trying to dribble a football."


http://www.aera.org/engine-professional/dyno-numbers/

Those who take exception to the above, please address directly with Bill Hancock lol.

[scottj]

Which posts advocate PEAK hp over average torque?

Originally Posted by AL427SBF

...how one would try to tune/build their powerplant for best performance regarding torque and HP... curious on what the tuning or engine building tricks are to get that strong torque curve from say 3-6.5K?

My answer to the actual questions:

1. Build it as big as possible (cid)
2. Build as much compression as your fuel will allow.
3. Match the cylinder head to the airflow requirements for your cid @ 3-6K rpm.
4. Run a big solid roller.

of course, my idea of "best" performance may differ from yours... what unit of measure are you using to quantify "best"?

The parameters for my build were:

1. Small Block
2. Pump gas
3. 3-6K rpm
4. single 4-barrel, naturally aspirated
5. street/road course

My build specs (eng #1):

434 cid
9.6:1 compression
AFR 210 Head
Solid Roller 264/272 @.050, .650 lift, 106 LS
750 Stealth Racing Carb on a Victor jr w/1" spacer

Originally Posted by scottj

Every performance engine I've ever owned was developed to have the widest, flattest, torque curve possible... "tune for a big flat torque curve" is stating the obvious.

Of the 4 engines I've had in my Cobras, I've always built them for max power in the 3-6000 rpm range... because I drove them on the street as well as the track. An frankly, the power we made in that rpm range was probably more than my average skills could use anyway.

[Jerry Clayton]

But Scott----did you ever show your dyno sheets to anyone at Run N Gun??????????
I bet there were several there with some big numbers -----------

[patrickt]

Originally Posted by Jerry Clayton

...did you ever show your dyno sheets to anyone at Run N Gun??????????
I bet there were several there with some big numbers -----------

Yep, carry it with me wherever I go.

[scottj]

Originally Posted by Jerry Clayton

But Scott----did you ever show your dyno sheets to anyone at Run N Gun??????????
I bet there were several there with some big numbers -----------

No Jerry, I never showed my dyno sheets to anyone at R&G. In anything I've ever raced we (the drivers) have never discussed HP. I've never been beaten by HP either... only by better cars or better drivers...

and for what it's worth, I've never discussed peak HP with my engine builder either... isn't even on the dyno print out... the dyno software prints out the average HP/TQ #s

[olddog]

Originally Posted by AL427SBF

"Hot Rodders and beginners like to talk about horsepower and are usually enthralled with only one number, the peak horsepower produced. Professional Engine builders will talk about the shape of a torque curve, where it starts and where it noses over."


"You will learn that the top tuners really focus their work on shaping the torque curve. If a torque curve has too many humps and dips, the driver will never be able to effectively pedal the car at the edge of traction and ultimately will settle for a part throttle setting that is controllable but not competitive."

You won't find me talking about peak horse power, unless I'm comparing farm tractors used to plow large fields.

Once you have settled on a certain engine and rpm range, of course your tuning is focused on shaping the torque curve. That's all there is left to do.

However if you are trying to decide if you should build a big block or a small block on a certain budget, then Hp is the only way to compare. A 289, with its short stroke, is capable of a lot of rpm, where a 428, with its long stroke, is not. Sure you can make a 4" stroke spin fast, if money is no object, but since we are constrained by a budget, it is fair to say that for the same money these two engines will operate in different rpm ranges. Additionally these two engines will produce very different amounts of torque. The 289 less torque and higher rpm. The 428 more torque and less rpm. So to compare these two engines, Hp (the average Hp over its intended range) is the only way to compare how each engine will perform. Obviously the gear ratio would be different for the two engines.

Originally Posted by AL427SBF

"Driving a car with a lumpy torque curve is like trying to dribble a football."

I couldn't agree more.

[COBRA427]

Just curious, @ what rpm were your peak Hp and torque #'s ?