posted
Hello, This is my first post. I have several questions seeking answers. First, how does Horse Power equate to Torque? Webster's Dictionary defines Horse Power as "a unit of power equal in the U.S. to 746 watts" and Torque as "a force that produces rotation" (measured in foot pounds for vehicles). Would not a foot pound of torque equate to a measurement of watts? If not, why? If so, why have two different measures of force that are basically the same and why do various bhp's and lb-ft of torque on various vehicles not proceed on a set ratio? Example - 2003 Dodge Viper SRT-10 has 500 bhp & 525 lb-ft torque, while a 2003 Porsche 911 Turbo has 450 bhp & 457 lb-ft torque, both at approximately the same rpms and test weight. The ratios do not match. Probably a very simple answer, I just don't see it. Also, using the above example why does the Porsche beat the Dodge from 0 to 100 even though it weighs more and has less bhp & torque. Is that reflective of gearing and/or rear wheel vs all wheel? Lastly, I have a 2001 Camaro SS with the SLP exhaust upgrade (335 HP), what should be my first upgrade/addition to make Betsy scream off the line a little faster (street legal)? What can I do to prevent Betsy from "kicking-out" when cornering and stomping on it? Is this what they refer to as Understeer?
Thank you kindly for your responses.
Posts: 4 | From: Clearwater, Florida | Registered: Jul 2003
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1) Then you turn into a corner and the read end comes out and you have to correct by straightening the wheel, that's over-steer. If you turn into a corner and the car plows straight ahead or you have to turn the wheel more into the corner, that's under-steer. 2) As far as the Porsches beating the Viper to a hundered, you've already answered that. It's gearing and traction. 3) There are so many things you can do to change the handling of your car, that rather than list them it would be easier to go to http://www.camaroz28.com/ in the Road & Track section and do a search or just browse around. Another good site is http://www.personal.psu.edu/users/b/d/bds198/phor/Brian%20Beckman's%20Physics%20of%20Rcing%20Series.htm (Beckman Physics of Racing). 4) If I remember this right HP and Watts are a measure of work and includes Time. Torque is a measurement of force or energy and has no time element. But I always get this one wrong?
Posts: 376 | From: Friendswood, TX | Registered: Jun 2002
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quote:Originally posted by Ptah2112: what should be my first upgrade/addition to make Betsy scream off the line a little faster (street legal)? What can I do to prevent Betsy from "kicking-out" when cornering and stomping on it? Is this what they refer to as Understeer?
Hi, and welcome.
First off, you'll probably find a little more traffic on the SSOA front porch which could generate a bit more response.
You don't say whether you have an automatic or manual transmission, but gears (4.10's for a manual, and 3.73's for an automatic) are one of the favorite upgrades for waking these cars up on the street.
As for cornering, what you are experiencing is power induced oversteer. These cars simply have more power than the tires can put to the ground in a corner. Modulate the throttle. You can also raise the limit with stickier tires.
Posts: 4222 | From: Winnipeg MB CA | Registered: Feb 2000
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Welcome to the board! I would upgrade anything that actually increases the hp and torque at the the same time,kinda like when long tube headers are installed on a vehicle that had exhaust manifolds. A gear change will not change torque or hp,it will just move the hp/torque curve.
-------------------- Current ride is: 2002 Brickyard 400 35th Anniversary LE convertible #22,SLP build# 0036,35th Anniversary Build #47 EMCC Member #234 www.emcamaro.org WCA Member #197582 MMCC Member #28 NEOCC Member #634 Posts: 5682 | From: Dearborn,Mi. | Registered: Feb 2002
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Here is my two cents. Sorry it is a little long.
There is a relationship between torque and horsepower, but I can not remmeber the formula....it's been decades since I looked at that sort of thing. The torque and horsepower ratings for an engine are the peak values obtained on an engine dyno....and they occur at different RPMs. The answer as to why that is so is complicated, but a very gross oversimplication is it depends on how good an engine functions as an air pump at various rpm's and how well it burns air/fuel at various rpms.
For our use, just remember that it is torque that accelerates a vehicle while it is horsepower that will determine its ultimate velocity. The higher the torque the faster it will accelerate. The higher the horsepower, the higher the terminal velocity with all other factors being equal. So a high horsepower low torque engine will make a car feel like a pig leaving a light but it will go very fast on the highway (but it will be relatively slow getting to that speed).
Oversteer is the back end losing grip before the front in a corner. This is also referered to as a car being "loose". Understeer is when the front end loses grip first. This is also referred to a car having "push".
As others have hinted at, before an answer can be given on what you should add to the car, you first have to determine what your objective is. For instance, is to have better traction on a drag start, or is it to increase the cornering characteristics of your car.
Equally important, you have to determine what you are willing to give up to get the result you want. This is becasue any suspension setup is the result of a set of trade-offs that have been made to get to its present state of tune. Change any part of the setup and you change the tradeoffs. For instance, lower springs will increase steering and braking response. However, they will also result in less ground clearance over bumps, a stiffer ride, and (depending on how low you go) bump steer in the steering wheel. Other parts will firm up the suspension so steering, throttle and braking responses are increased or sharpened. However, they will also dramatically increase road and driveline noise in the car.
Having said all that, the first modification I would make that has very minimal side effects is to install a set of sub-frame connectors. They will increase the body stiffnees, postpone squeals and rattles, and provide a better foundation for any future modifications.
Hope this helps.
Bill M 98 TA
Posts: 383 | From: Oakville, Ontario Canada | Registered: Jan 2003
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Simple formula. At 5252 RPM, HP equals torque. At any OTHER RPM, it is related by the above equation.
Posts: 67 | From: Monroe, WA | Registered: Jun 2002
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never forget the engineering way of addressing torque and horsepower. . .in all racing applications, "torque gets you there, and horsepower keeps you there."
Posts: 45 | Registered: Apr 2002
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