Topic: Flat Tq or Flat Hp, which one and what for?

[Kelu]

I opened this discussion to debate about how a car performs depending on tq, hp plots from a dyno graph, numbers been irrelevant here assuming they are corresponded.

The HP value depends on TQ by the relation:
Power (HP) = ( Tq x RPM ) / 5252

For more info: http://en.wikipedia.org/wiki/Torque
So the Hp and and Tq are interconnected based on RPM range.

Two cases:
a) Tq being flat (parallel to the horizontal RPM axis), the Hp plot in this case is ascended to the whole range the Tq is constant.
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b) Tq reaching a maximum point and descending with the Hp being flat and constant in this case (I have market the area where the rpm is for a drag racing).
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I deliberate removed the axis and numbers not be influenced by those. Red being Tq and Hp being blue.

Which one is better for drag racing let's say, which one is better for daily driving, which one is weak and where.

[Critterman]

Torque gets you moving HP keeps you moving.

I will take the first chart anyday over the second one.

[Kelu]

Critterman that's all your best? 

It wasn't something which one do we prefer because then we all gonna choose case one, but then I have to hit you with an additional question, having power same value (case 2) in a drag race makes you faster rather then having lower hp value at the beginning and a higher value at then end range (case 1)?

[NormSky]

Allot depends on the transmission these days as some compliment certain hp or trq plots better than others  and what it's used for.

Carrying torque longer into the rpm band is the key to accleration.

Torque we drive, horsepower we buy. 

Norm

[perris]

I think gearing trumps everything!

also, if you have a long power band (horsepower or torque, doesn't matter) then you can make use of either one just as effectively through gearing

[edit] oops

I see norm said the same thing using differant words, and in that case what he said;^^^^^^^^^^^^^^^^^^^^^^^^

[Mallard]

To me, flat torque is desirable in all those situations. Cars with flat HP curves tend to feel like they fall on their face while the car with a flat torque curve will continue to pull through the entire rev range.

[Mac]

torque motors you can get away with longer splts in the trans gearing and a deeper rear set. since the motor has pull it will like to feal gearing the sol has a long split in 3rd to forth a bit to much for our cars torque value and much to long for hp. 4th is 1:1 what is 3rd anyone know? feels likabout 1:60ish

[1LILNDN]

The 47 Pontiac I just sold had just about 418 HP at the wheels . The torque was up around 550 . I had a Turbo 400 w/2800 stall . I had a 2.73vPosi 10 bolt Rear . In the 1/4 mile with 26 in.  diameter Street tires and close to 4,200 LB . I did the 1/4 in 12.8 at 109 MPH . The Torque Made it Happen , The motor was aPontiac 455 punched out to 468 Cu.In.


       

[kennysabarese]

This is a simple quesiton... If you are drag racing and want to win, just look at what guys running in the 9's and 10's have on their dyno slips and try to tune for that.

If you are autocrossing and want to win, see this article. http://farnorthracing.com/autocross_secrets15.html

Notice that most supercars that are not turbo charged have a power curve that is 45 degree angle. that is desired when you are NA, it means when you double RPM you double your power.

[perris]

If you are autocrossing and want to win, see this article. http://farnorthracing.com/autocross_secrets15.html

interesting, he says exactly what myself and normsky said;

OK, another quck aside: horsepower and torque are the exact same thing - the HP curve is mathematically derived from the torque curve, so the one implies the other. All the Internet flame wars over torque vice horsepower are utter wastes of time, because they are talking about two aspects of the same thing. The key here is that the thing that determines the rate of acceleration of the car is the delivered horsepower, and to maximize acceleration you want the highest possible average HP in the operating RPM range of the engine. Biasing the torque curve lower in the RPM range tends to flatten the power curve at the expense of peak HP, and biasing the torque curve later in the RPM range tends to make the power curve "peakier" but delivers a higher peak HP value.

he then goes on to tell you gearing trumps everything

If you are a drag racer or road racer, you go for peak HP and then regear the transmission to move the operating RPM range to bracket the HP peak - and you go faster because you have the highest average delivered HP in the RPM range. Autocrossers can't afford the time spent shifting all the time, so they are better served by wide and flat power curves. Big displacement engines or forced induction are ideal for autocrossers; high-strung, high-revving peaky motors are not. Had I stayed in the sport, my next motor iteration was going to be a 2.4l stroker with a faster-spooling ball-bearing turbo.