Question about Gears

[CobraKevin]

Ok guys...got a question for you physics majors.

 

I raced Adam(99TA) about 2 hours ago and I must say right off the bat that it was exciting to say the least. I did not expect to win because of my horsepower disadvantage. I did, however, do rather well because of my gears. This brings me to my question: My dad believes that if I had gone into 5th gear and laid on the gas, I would have pulled on Adam, although he has much more horsepower. I don't think this is true because I had read previously that gears are a multiplication of torque factor, not horsepower(which is what is theoretically more important in high speed runs). First of all, Adam, what gears do you have in your TA? So the question is: With my steep gears, would I have been able to reach, say, 130mph faster than Adam, or would his horsepower pull him to that mph quicker than me? I would like a technical, in-depth, physical explanation on why I would or would not pull past him.

 

Kevin

[Science Abuse]

Originally posted by YellowStinger:

With my steep gears, would I have been able to reach, say, 130mph faster than Adam, or would his horsepower pull him to that mph quicker than me?

depends on your HP handicap. if you had identical horsepower, yet steeper gears, you would reack speed X faster, however the chalower geared car would rech speed X...and keep on goin.

Despite your gears, you still nee the HP to turn them. Also, you have to consider the transmission gearing, manual or auto, weight of the car, aerodynamics, planetary alignment, etc tongue.gif

But in fuzzy math theory, you would reach the speed first.

[GRN96WS6]

Well let's see if he has more HP then obviously he will also have more TQ so no I don't think you going into 5th would have helped you at all.

 

Adam has 3.42 gears in his car and a descent HP number pushing them.

 

I'll let him devulge those if he so desires.

[ORourke]

Originally posted by YellowStinger:

My dad believes that if I had gone into 5th gear and laid on the gas, I would have pulled on Adam, although he has much more horsepower

no.

 

The thing to remember about horsepower is it is just a measurement of how fast you deliver torque. Its basically torque in a given period of time. HP=(Torque/5250)*RPM. At 5250 RPM horsepower and torque are always equal because the equation for horespower uses torque divided by 5250 and multiplied by engine speed to give you a horsepower number. Gearing mainly does two things. It inreases your mechanical advantage to the wheels, and it allows the engine to reach high RPM's more quickly when accelerating.

 

I'm not sure if I'm reading this right, but your dad said if you were in 5th gear and floored it you would have pulled him? That is way off. The whole reason you have 4.56 gears in your cobra is so that you can get to the higher RPM's where your 4.6 DOHC makes power. If you started in a .67 overdrive gear you would bog the hell out of the engine.

[CobraKevin]

Your pretty close to understanding, but he didn't mean from a stop. He simply said that if I would have gotten into 5th gear, because of my gears, my 5th would have kept pulling and allowed me to gain ground. I said "no" because there is no way I would catch up in 5th if I was being left back in 4th. He disagreed.

 

[ 30 September 2002, 10:31 PM: Message edited by: YellowStinger ]

[smokin5s]

Originally posted by YellowStinger:

Your pretty close to understanding, but he didn't mean from a stop. He simply said that if I would have gotten into 5th gear, because of my gears, my 5th would have kept pulling and allowed me to gain ground. I said "no" because there is no way I would catch up in 5th if I was being left back in 4th. He disagreed.

I put a 4.10 gear in my camaro.... it deffenatly accelerates quicker on the bottom end, but I did loose power on the top end putting in the gear. If you would have shifted into 5th then you would have lost worse. Unless you ran out of room to go higher on the tach, but you still would have had a hard time. How bad did he beat you?

[99 TA]

Yep a stock 3.42 rear. It was exciting at first. Once I hit third it was giddy up time. I dynoed at 386 rwhp and 388 rwtq. Not to bad for a N/A car. I think that from a dig you will still need a little more power though. It was a good run.

[CobraKevin]

Originally posted by 99 TA:

Yep a stock 3.42 rear. It was exciting at first. Once I hit third it was giddy up time. I dynoed at 386 rwhp and 388 rwtq. Not to bad for a N/A car. I think that from a dig you will still need a little more power though. It was a good run.

Thanks man. Your car is damn fast. I'd like to run you at the track sometime on the ET Streets. I mean, that is what my bro designed it for.

 

Josh, we were dead even roughly 1/2 through third, but that's where Adam began to pull. I let off at the end of 4th and he was probably, I don't know Adam - what would you say? 2-3 car lengths, give or take 1? We should get it on tape sometime. However, that's where the problem comes in. Because I'm 16, my mom HATES the idea of me racing ILLEGALLY and because she found out about the races, she basically put her foot down and said I'm not allowed to hang out with you guys on Saturdays anymore. So, I'll guess I'll see you guys next season at the airport meets (if we still have them next season). Other than that, I'll be out when I turn 18. C ya later.

 

Kevin

[smokin5s]

I think that the hanging through half of third came from his power hit mid way through 3rd.... I think Adam has the hammer cam which is a pretty good cam.... (I don't know where the power band is on his CAM.) That sucks taht you can't hang out.... I have a digi video camera if you do want vid's taken... although I am a little slow getting them posted.... as a few people from Dyno know... (I know guys, I'll get them to you)