Who will swap for the new 7.3 V8!

[GT Pony]

Top Fuel cars do not shift....as in zero gears.

From start to finish, those engines are essentially revving very near or at the peak HP RPM, and the clutch is setup to slip as required to obtain max acceleration without excessively spinning the tires. In other words, putting as much HP (and of course T because HP and T are connected at the hip by RPM) as possible to the rear tires from start to finish of the run. The rear tires are typically the weak link as any top fuel dragster has plenty of HP to smoke the tires if all the power is put to them.

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[millhouse]

Actually you're both "wrong" but I think "over simplified" or "incomplete thoughts" are more appropriate. AVERAGE max power wins assuming all other variables are the same like gear ratios, weight, etc.

No, it's area under the curve. Integrating the curve between selected RPM intervals gives you the total area over the desired RPM range. This is the work that your car is doing. Taking the average horsepower doesn't tell you anything.

Yes, thanks for proving my point! Notice he uses horsepower to figure out the torque? When you are at rest, no work is being done at the rear wheels (you are stationary), therefore the torque value is going to be what's propelling you forward. It's not until after you are in motion that horsepower actually means something.

 

[WildHorse]

 

[TexasRebel]

No, it's area under the curve. Integrating the curve between selected RPM intervals gives you the total area over the desired RPM range. This is the work that your car is doing. Taking the average horsepower doesn't tell you anything.




Yes, thanks for proving my point! Notice he uses horsepower to figure out the torque? When you are at rest, no work is being done at the rear wheels (you are stationary), therefore the torque value is going to be what's propelling you forward. It's not until after you are in motion that horsepower actually means something.

You folks are saying the same thing.

maximizing the area under the curve is the same as maximizing the average power in the RPM range.

One thing that hasn't been addressed much in this thread is time. While you want to maximize the area under the curve, you want to minimize the sweep time of the curve. That's where weight, traction, and distance between the peaks comes into play.

 

[nastang87xx]

You folks are saying the same thing.

maximizing the area under the curve is the same as maximizing the average power in the RPM range.

One thing that hasn't been addressed much in this thread is time. While you want to maximize the area under the curve, you want to minimize the sweep time of the curve. That's where weight, traction, and distance between the peaks comes into play.

After rereading, yes, I missed the area under the curve part, which yes, is average power across the operational RPM range.

 

[millhouse]

Lol, you are confusing what is really happening. Rear wheel torque is what at the starting line, at the instant you start moving you need the maximum available torque. Remember, this is instantaneous, there is no time involved...so torque is the only thing you're measuring. Horsepower simply takes that torque and converts it to power which gives a better understanding of...well, power.

If you have more horsepower and less torque, you need gearing to multiply the torque down low. You do this however at a cost...more gear shifts and more gears required to stay within the power-band. Those shifts (especially in a manual) can be costly. Cars with more torque can have gearing to allow them longer between shifts. This was often a trick to minimze 0-60 times.

Rear wheel torque is going to give you an idea of how well a vehicle is going to get out of the hole. The overall horsepower curve is going to give you an idea of what happens after that.

 

[WildHorse]

The idea of drag racing is to keep the rpm very close to peak hp. There is no powerband or a super narrow one ideally. My best 60fts was launching well above my peak torque. He explains that in both vids which you seem to ignore.

 

[nastang87xx]

Take one guess as to who's winning this race, red or blue. Note, blue has the highest peak torque number by FAR.

 

[millhouse]

The idea of drag racing is to keep the rpm very close to peak hp. There is no powerband or a super narrow one ideally. My best 60fts was launching well above my peak torque. He explains that in both vids which you seem to ignore.

a=F/m

Guess what force stands for (It's not horsepower)?

At the instant you launch (given you have enough traction) your acceleration will be maximized by the most rear wheel torque applied to the ground. That's unless of course you are disagreeing with newtons second law of motion.

 

[millhouse]

Take one guess as to who's winning this race, red or blue. Note, blue has the highest peak torque number by FAR.

Totally depends on the gearing and the distance of the race.

 

[WildHorse]

Guess what force stands for (It's not horsepower)?

The higher the usable rpm the more horsepower you make. Torque drops like a stone after 5250 rpm. Especially if you peak torque is before that. But you horsepower climbs. Go figure.

 

[EcoVert]

It's hard to believe that this thread is still going

 

[millhouse]

The higher the usable rpm the more horsepower you make. Torque drops like a stone after 5250 rpm. Especially if you peak torque is before that. But you horsepower climbs. Go figure.

You really don't understand anything I posted nor do you understand either video you posted.

Here is something for you to chew on. Ever wonder why drag racers typically choose torque converters that stall just slightly past peak torque? Maybe a light-bulb will come on for you now.

 

[GT Pony]

Torque with no RPM (zero HP) is only useful for torque wrenches when they click.

Torque = force (twisting). Force x distance = work. Work done over time = power. HP is the measure of force x distance (work) done over a certain length of time. More HP means more work is done over the same amount of time, or it means less time is required to do the same amount of work (ie, accelerating 3500 lbs over 1320 ft). A larger amount of HP expended over a fixed distance (all other variables equal) will result in more acceleration and hence less time to cover said fixed distance (ie, quarter mile times). The vehicle with the most integrated amount of HP put to the rear wheels over a fixed distance will always win if all other variables are constant (weight, properly matched transmission and differential gearing, perfect gear shifting, clean launch, traction, aerodynamic drag, etc).

Less HP will never result in better acceleration unless the gearing is totally mismatched to the peak HP of the car with more HP. If the same car is shifted at the peak torque point it will not accelerate as fast as it would if shifted at the peak HP point (especially if the peak T is at a much lower RPM than its peak HP RPM). Two different engines with the same peak HP, but with much different peak HP RPM, can essentially accelerate the same if each is geared perfectly to take advantage of their peak HP. Obviously, 0 to the end of first gear (off the line) can be different depending on the where the peak torque is, but cars with higher peak torque just need to be launched at a higher RPM where that peak torque lives. More low end torque typically makes launching easier.

 

[millhouse]

Torque with no RPM (zero HP) is only useful for torque wrenches when they click.

Torque = force (twisting). Force x distance = work. Work done over time = power. HP is the measure of force x distance (work) done over a certain length of time. More HP means more work is done over the same amount of time, or it means less time is required to do the same amount of work (ie, accelerating 3500 lbs over 1320 ft). A larger amount of HP expended over a fixed distance (all other variables equal) will result in more acceleration and hence less time to cover said fixed distance (ie, quarter mile times). The vehicle with the most integrated amount of HP put to the rear wheels over a fixed distance will always win if all other variables are constant (weight, transmission and differential gearing, perfect gear shifting, clean launch, traction, aerodynamic drag, etc).

Less HP will never result in better acceleration unless the gearing is totally mismatched to the peak HP of the car with more HP. If the same car is shifted at the peak torque point it will not accelerate as fast as it would if shifted at the peak HP point (especially if the peak T is at a much lower RPM than its peak HP RPM). Two different engines with the same peak HP, but with much peak HP RPM, can essentially accelerate the same if each is geared perfectly to take advantage of their peak HP. Obviously, 0 to the end of first gear (off the line) can be different depending on the where the peak torque is, but cars with higher peak torque just need to be launched at a higher RPM where that peak torque lives. More low end torque typically makes launching easier.

Pretty much everything I've already said...however, it doesn't take a "total" mismatch on gearing for a car with less horsepower to win in some occasions...such as a 0-60 race. If car A has more RWTQ off the line and does not require a shift through the 60', it's entirely possible for for car A to beat car B. The more gears you throw in (10 speed) and as well as faster shifting (10 speed) negate these concerns almost entirely. Manual transmissions however are more susceptible this this issue.

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