The Great Debate

[67 Tiger]

I used to teach a basic Science class. This is from my class." When measuring work two factors must be considered:Force and distance. The amount of work done is equal to the product of force times distance. The resulting unit of work is expressed as foot-pounds, or torque."
"In a series of experiments, the English inventer, James Watt found that a dray hourse could continue for a reasonble length of time to work at the rate of 550 ft-lbs per second. The formula for calculating HP is Torque divided by 550 times time (seconds) or FT.-LBS / 550x seconds."
You cant get horsepower without torque. Torque gets you of the line, horsepower gets you topend. Which is more important? Hotrodders have been arguing about this for longer than Ive been alive. Personally I like more torque, over horsepower, but I also ride a Harley, which is all torque.

 

[Duke Mk1a]

The most I can possibly have of both will almost be enough.

Torque wins drag races.
HP wins land speed contests.

454.47 crank HP
446.47 crank Torque

 

[hottigr]

It depends on the usage...I have owned a couple of Yamaha RD 400's that had very little torque down low and would wheelie in the first couple of gears once they got on the pipe- just what I was looking for in the 'need for speed' department. I have a 2000 Dodge Durango that had a choice of a 4.7, 5.2 or 5.9 V8. I didn't want the 5.9 because of mpg. The 4.7 made as much peak horsepower as the 5.2 and had better mileage, but not as much torque. I chose the 5.2 (the old 318) -it had 300 ft/lbs of torque @ 1500 rpm, got better gas mileage than the 5.9, and had more torque than the overhead cam 4.7. My need here was the occasional pulling of a horse trailer. In my Tiger, I like a little of both. I have what amounts to an RV cam in a 302 with heads re-worked that will take 6200 rpms. I usually shift at about 5500 when I'm serious and, when I grab that next gear, it's all business! So for me, it's all about the application.

 

[cadreamn67]

Hottigr,

I have some questions about your setup if you don't mind. Purely for my own education and enlightenment.

Do you happen to have an dyno data on your motor? I have always thought that an RV cam will build a lot of torque at relatively low rpms, but that horsepower would also peak relatively early and tail off from there. If true, I do not see the benefit of being able to turn 6200 rpms and shifting at 5500.

The conventional wisdom as I have come to understand it is that one shifts at the rpm in gear A such that when power is applied in the next gear up, the motor starts at the rpm where peak torque is developed. So in the case of a car with Duke's motor, he would get the best results by shifting out of first at an rpm that would have the motor running at 4500 rpm (peak torque) when he hits the gas in 2nd. I would think, not knowing any better, that an RV cam would be producing maximum torque at considerably less than 4500 rpm.

Maybe it is just that your power band is pretty flat and for pure enjoyment in a street driven environment, the sound of the motor turning 6200 rpm is well worth any suboptimal power production. I can certainly envision that.

Anyway, just curious since your experience seems different from my theoretical understanding.

Thanks for humoring me.

Gene

 

[hottigr]

Gene,

Your points and your questions are very valid.

My answer will be very vague

My car has not been on a dyno. The engine was built by Barry Greenberg back in the 80's before I purchased the car. The engine build info that I have ('RV cam') is from Barry himself the one time I was able to contact him several years ago. I have never turned the motor to 6200, that's just what the valve train can handle. Usually, I'm shifting by ear because the tach can't keep up, anyway.

A little more info on the motor...Performer RPM manifold, Carter AFB Comp carb 625 cfm, Ford mechanical dual point distributor, headers, '64 289 heads reworked with screw in studs and guideplates- it's kind of a throw back motor, but I like the performance curve.

 

[cadreamn67]

it's kind of a throw back motor, but I like the performance curve.

And at the end of the day that is all that really matters. Enjoy it!

Gene

 

[chirodoc]

HP VS TORQUE

Camshaft duration is the determining factor in the HP vs Torque discussion. Back in the 60s Ford had MUSCLE PARTS and offered 3 camshafts. The C90-Z or hipo hydraulic at 218 degrees at ,050 lift. The C30Z, solid lifter HIPO at 228 degrees @ .050, and the C7FE LeMans cam at 250 degrees @ .050. They went from mild to wild. My first built 289 was built with the Boss 302 cam specs with 238 degrees @ .050. The motor would pull hard to 7000 rpm at the track, but had no torque at low speed and was not the best for a street driver. Ford made a compromise between drivability ( torque) and power (HP) with the 5.0 cam with 224 @ .050. My present Tiger engine has the C9OZ HIPO hydraulic with 351 Windsor heads which makes a nice street motor with 325 HP, but my 289 HIPO engine on the engine stand is a little wilder with an Edelbrock cam with 224@ .050 with Aluminum heads (365 hp). If you throw in stroker motors into the discussion it's like a[pples and oranges and cubic $$$$. Take your pick.