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PKRWUD · 10-03-2001, 11:47 AM

When you're riding your mountian bike uphill, and you have to stand up in your seat in order to pedal over the top... that's torque. When your flying down the other side... that's horsepower. They each play an important role. While you certainly aren't flying up the hill, you are making it. But, if you tried to use all that power to go fast, you'd hurt yourself. Imagine flying down the hill while trying to pedal faster standing up. At the same time, the horsepowere aspect, flying down the hill, you're crouched and pedaling quickly in short strokes. It works killer for going fast down hill, but try climbing the hill like that. You wouldn't get very far. Generally, stroke and compression are the biggest factors. A long stroke will generate more torque, while a short stroke allows the engine to rotate faster, creating horsepower. Bore is important, but not as big a deal as stroke. Horsepower = speed. The faster an engine can turn, the more hp it can generate, bores being equal.

Another way of looking at it is a test my college engine rebuilding class did 16 years ago. About 20 miles from where I live is the Conejo Grade. It's part of the 101 freeway, and basically goes straight up a 1800' incline in less than 2 miles. It can be brutal to small, weak vehicles. Anyway, we had received as a donation two brand new VW Rabbits. One was a diesel and the other was a GTI. The diesel redlined at 3000rpm, and the GTI went to 7000rpm.We raced them up the Conejo Grade. Obviously, the GTI kicked *** , the first time. The second time, we attached a trailer with a few engine blocks on it to both cars. The added weight was close to 1500 pounds. The diesel won the second race. In fact, the diesel finished within 20 seconds of the time it took to reach the top the first time. The GTI didn't even make it to the top. We ended up driving the diesel around again, and towed the GTI's trailer for it.

What we learned from this was that while high speed horse power is desirable, low speed torque is more practical. At least in an application with such a small engine. Most street racers think they want horse power, but what they really want is torque. To build a high horsepower engine, you are sacrificing torque, and creating an environment where you need to maintain high rpms. A 700 horsepower engine doesn't do well grocery shopping, or cruising for that matter, but a high torque engine will snap your neck and bark your tires.

I hope that helped.

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

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10-03-2001, 11:47 AM	#5
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	When you're riding your mountian bike uphill, and you have to stand up in your seat in order to pedal over the top... that's torque. When your flying down the other side... that's horsepower. They each play an important role. While you certainly aren't flying up the hill, you are making it. But, if you tried to use all that power to go fast, you'd hurt yourself. Imagine flying down the hill while trying to pedal faster standing up. At the same time, the horsepowere aspect, flying down the hill, you're crouched and pedaling quickly in short strokes. It works killer for going fast down hill, but try climbing the hill like that. You wouldn't get very far. Generally, stroke and compression are the biggest factors. A long stroke will generate more torque, while a short stroke allows the engine to rotate faster, creating horsepower. Bore is important, but not as big a deal as stroke. Horsepower = speed. The faster an engine can turn, the more hp it can generate, bores being equal. Another way of looking at it is a test my college engine rebuilding class did 16 years ago. About 20 miles from where I live is the Conejo Grade. It's part of the 101 freeway, and basically goes straight up a 1800' incline in less than 2 miles. It can be brutal to small, weak vehicles. Anyway, we had received as a donation two brand new VW Rabbits. One was a diesel and the other was a GTI. The diesel redlined at 3000rpm, and the GTI went to 7000rpm.We raced them up the Conejo Grade. Obviously, the GTI kicked *** , the first time. The second time, we attached a trailer with a few engine blocks on it to both cars. The added weight was close to 1500 pounds. The diesel won the second race. In fact, the diesel finished within 20 seconds of the time it took to reach the top the first time. The GTI didn't even make it to the top. We ended up driving the diesel around again, and towed the GTI's trailer for it. What we learned from this was that while high speed horse power is desirable, low speed torque is more practical. At least in an application with such a small engine. Most street racers think they want horse power, but what they really want is torque. To build a high horsepower engine, you are sacrificing torque, and creating an environment where you need to maintain high rpms. A 700 horsepower engine doesn't do well grocery shopping, or cruising for that matter, but a high torque engine will snap your neck and bark your tires. I hope that helped. Take care ~Chris ------------------ Retired Moderator MustangNet My site: JimPorterRacing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!