Generally speaking, how do each of these characteristics affect the performance of a car? (i.e.
0-60 times & 1/4 mi times vs. final speed)

Then, more specifically, which one makes a more noticable difference in most daily driving?

Is there a preferred range where the ratio of torq/hp should be targeted?

 

Apeckz,

Welcome to the forum!

Torque and horsepower are related to each other, you can't have one without the other. What generally affects a car's time is the area under the torque curve. The more area you have under the curve, the faster the car will be. The area, and not the peak number, is critical...you can have a car with a lower torque peak go faster than one with a higher torque peak if the area under the curve is greater (i.e. the curve is flatter)

Generally speaking, the peak HP number can tell you what trap speeds you'll run in the 1/4, and it will also tell you what a vehicle's top speed will be, assuming the gearing is optimal.

Quote:

Then, more specifically, which one makes a more noticable difference in most daily driving?

Again, torque and HP are directly related, so they both have the same effect on driving. What really makes one car easier to drive is the quality of the curve. A car with a broad, flat torque curve in the rev range that you drive will be the easiest to drive daily.

Quote:

Is there a preferred range where the ratio of torq/hp should be targeted?

As I said already, torque and HP are related, so the ratio is fixed for all cars...the ratio is HP/TQ = RPM/5250

Hope that helps.

 

The more lowend torque (and consequently horsepower) you have the better it will be for daily stop and go driving. The engine usually stays down here. For racing if you only have low end power but no topend then you gear around this. The way our cars are geared favors the higher side of the rpm spectrum so we generally go for more power in this area. The higher rpms are where you stay at for most of a race. Decide your goals and figure accordingly. It is possible to have a mega horsepower streetcar but don't expect low end power or drivablility to be very spectacular. But it will fly! You could design a car for fantastic gas mileage and tons of low end but don't expect a whole lot as the tach needle climbs higher and higher.

Red Rotary Rocket is correct. There is a fixed ratio. Some people say otherwise but they don't know how math or physics works. That formula is incomplete. I just drew a blank thinking about it but I do know the number is 5252 rpm. Below 5252 rpm you can not have more horsepower than torque. Above 5252 rpm you can not have more torque than horsepower. This has nothing to do with where your horsepower and torque peak are though. At 5252 rpm you will always have equal horsepower and torque. Look at dyno charts and see where the lines cross at. Some of them look a little misleading because the horsepower lines are on the same graph as the torque lines but the scale is different between the two. If they don't cross at exactly this point then the dyno made an error. Usually it is only very slight if at all.

 

Assuming that Torque is in lbs-ft, the equation is:

Horsepower = (Torque * RPM)/5252


What everyone has been getting at is that horsepower is simply torque compared to rpm. Torque is a measure of the force of torsion or rotation, while horsepower is that force in motion over time. The 5252 is just a conversion factor.

Also, if you look at that equation and input 5252 for the RPM variable, then torque will always = horsepower. This is why a dyno chart will always show the hp and lbs-ft torque curves meeting at 5252rpm.

Here are some generic formulas for estimating drag times and speeds. They aren't very accurate because they don't take into account a lot of variables, but they should be close enough. You can buy special computer software if you want more complex and accurate calculations.

ET = 5.825 * (Weight lbs / Horsepower)^-3

MPH = 234 * (Horsepower / Weight lbs)^-3

Other links:
http://www.turbofast.com.au/Drag.html
http://www.prestage.com/carmath/
http://www.timmcamis.com/calculators.html

 

Great info and good links, here's one to add - http://www.vettenet.org/torquehp.html

 

also every lb/ft of torque gained in the upper rpm range is worth more power than in the lower range, because theseunits of torque are comming faster, thus providing more power 1 lb/ft at 5250 rpm would be 1 hp, 1 ft/lb at 10000 it is worth 1.9 hp, at 20000 rpm 1 ft/lb is worth 3.8 hp, so its not so much torque, as opposed to hp, its where your torque is. If your care made 300 lb/ft of torque from 0-5250 you would be rated at 300 hp, however if it made 300 lb/ft@5250 from 5250-10000 rpm you would have 571 hp @ 10000rpm, the second car would be faster, however the first car would be easyer to drive in the city. RPM is a way of getting more horsepower out of the displacement of your motor. keep in mind that the farther you shift the powerband up, the worse it will be down low, and generally the narrower the rpm range the peak or near peak torque will occur, unless you work magic, like vdi's, and 6 ports do. your goal should not be to develop a peak hp for a street car, or tune it soley for torque, but to take whatever torque you have and extend it to as high an rpm you can. and one last thing,.. you own a rotary it will allways have more hp than torque, unless you seriously messed with the ports (filled them in some) and runners