Peak HP, Avg HP, or Area under the curve; which is the better measure of HP?
10-22-2010, 08:38 PM
#61
Not the sharpest tool in the shed
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Wow! Tim's car is brutally fast. It even accelerated into the future. Note the dates of the "Main" versus "1st Comparison" runs. Was Michael J. Fox driving that thing?
10-24-2010, 07:12 PM
#62
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if anybody really cares about selecting the best shift point it is described in a book written by a master driver and engineer, Paul Frere: Sports Car & Competition Driving
Chapter 1: Bascis, page(s) 19-22 'When to Change Gear'
it is all based on thrust (overall delivered torque/tire radius)
the basic premise is you want to shift where the next gear achieves the minimum differential (or equal) thrust as compared to the previous...
he actual calculates a few examples...
Chapter 1: Bascis, page(s) 19-22 'When to Change Gear'
it is all based on thrust (overall delivered torque/tire radius)
the basic premise is you want to shift where the next gear achieves the minimum differential (or equal) thrust as compared to the previous...
he actual calculates a few examples...
10-24-2010, 07:20 PM
#63
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Which is shorter, Pauls book or Mark's posts?
10-24-2010, 08:05 PM
#64
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10-25-2010, 01:01 PM
#65
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really, 4 pages to just find you HP curves and just shift when the resulting RPM is the same HP? Its correct, its easy to grasp and It only needs to be told once if you listen and UNDERSTAND!
Acceleration=power/(mass x velocity) Newton and GOD says so!
Acceleration=power/(mass x velocity) Newton and GOD says so!
if anybody really cares about selecting the best shift point it is described in a book written by a master driver and engineer, Paul Frere: Sports Car & Competition Driving
Chapter 1: Bascis, page(s) 19-22 'When to Change Gear'
it is all based on thrust (overall delivered torque/tire radius)
the basic premise is you want to shift where the next gear achieves the minimum differential (or equal) thrust as compared to the previous...
he actual calculates a few examples...
Chapter 1: Bascis, page(s) 19-22 'When to Change Gear'
it is all based on thrust (overall delivered torque/tire radius)
the basic premise is you want to shift where the next gear achieves the minimum differential (or equal) thrust as compared to the previous...
he actual calculates a few examples...
10-25-2010, 01:05 PM
#66
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Did I mention that its easier to use the HP curve and RPM drops based on gear spacing? 
I just thought I would say it again, in case you missed it the first time.
You know, its funny, when you make an argument, and you disagree, all you need to do is bring up some relevant proof to prove them wrong. I made a simple statement, but yet over pages and pages of you disagreeing, you yet to find ONE actual example in REALITY, where it can be proved wrong and ineffective to just use HP curves.
again, 4 pages to say, "just shift at the point where the hp is equal post shift"???? wow, I would say, that is 1000 times longer!
I just thought I would say it again, in case you missed it the first time. You know, its funny, when you make an argument, and you disagree, all you need to do is bring up some relevant proof to prove them wrong. I made a simple statement, but yet over pages and pages of you disagreeing, you yet to find ONE actual example in REALITY, where it can be proved wrong and ineffective to just use HP curves.
again, 4 pages to say, "just shift at the point where the hp is equal post shift"???? wow, I would say, that is 1000 times longer!
10-25-2010, 01:08 PM
#67
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Bob, and you still think that the 300hp (one having engine torque of 150 ft lbs vs 300ft-lbs) would have any acceleration differences at ANY vehicle speed with the same spaced gearing. (you never did answer my question way back when you posted your contradictory post).
(you never did answer my question way back when you posted your contradictory post).
10-25-2010, 01:23 PM
#68
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since a x m = Force (thrust)
you are complicating it by back substituting P/v for force, it's silly
why not call it it a = p/M to make it really confusing (Momentum = mv)
we know, you're smarter than Frere (and every other real authority on the subject who uses thrust) and a better driver too...
the guy who Sir Jackie Stewart said he would trust to drive his family thru the Alps in a snowstorm...
and who has degrees in engineering and worked as a consultant for many manufacturers, Porsche included...
10-25-2010, 01:29 PM
#69
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None of that changes the fact that using the gear ratios to find the power-equating rpms on a dyno graph is by far the easiest way to find the approximately correct shift points. (Approximately correct because they don't account for the time lost in shifting.)
F = ma, much simpler
since a x m = Force (thrust)
you are complicating it by back substituting P/v for force, it's silly
why not call it it a = p/M to make it really confusing (Momentum = mv)
we know, you're smarter than Frere (and every other real authority on the subject who uses thrust) and a better driver too...
the guy who Sir Jackie Stewart said he would trust to drive his family thru the Alps in a snowstorm...
and who has degrees in engineering and worked as a consultant for many manufacturers, Porsche included...
since a x m = Force (thrust)
you are complicating it by back substituting P/v for force, it's silly
why not call it it a = p/M to make it really confusing (Momentum = mv)
we know, you're smarter than Frere (and every other real authority on the subject who uses thrust) and a better driver too...
the guy who Sir Jackie Stewart said he would trust to drive his family thru the Alps in a snowstorm...
and who has degrees in engineering and worked as a consultant for many manufacturers, Porsche included...
10-25-2010, 01:55 PM
#70
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Arthur Arthur Arthur!
Why? you ask, Ill answer you. So, please for the love of Tom and Jerry, just to understand.
It is because with a=Fm or F=ma , you NEED To know the Force at any vehicle speed. you need to do some pretty cumbersome calculations to get that. (i.e thrust curves, points, etc) Why use " acceleration=power/(mass x velocity) and the (m x v) part? because for I dont want to further distill the combination of newtonian identies, as well as I want it to be clear that for a given mass, acceleration will be proportional to and be inversely proportional to vehicle speed. It more clealy shows the relationship of the factors.
WITH a HP curve, by definition and by nature, it ALREADY incorporates a major element, that of RPM!!! because it incorporates RPM , HP is more useful from the perspective of saving time, and even quickly eyeballing an answer.
Now, as far as Frere, well lets just say that Cort Wagner was out there this weekend at laguna in a 800hp Ferarri 430 supercharged, on the best DOT slicks money can buy, and with a team of engineers. I wonder how I was able to spin a faster time of 1:36 vs his 1:37 on a 25 year old 928, driven to the track on garbage can tires , with half the hp.
Joking aside, Ive never said I am smarter than Frere, (a better driver than anyone, as most guys at the top levels can spin a fast lap time. ), but what I will say is that you dont understand the point, are incredibly arrogant, and lack, what seems to be basic common sense and comprehension. NONE of the books written about the subject are wrong. in fact most all of them are absolutely right. However, based on the topic of when to shift you car, there is an equally correct and simple way to determine those points by using HP curves and gear spacing. thats it, nothing more. dont make a big deal out of it.
Why? you ask, Ill answer you. So, please for the love of Tom and Jerry, just to understand.
It is because with a=Fm or F=ma , you NEED To know the Force at any vehicle speed. you need to do some pretty cumbersome calculations to get that. (i.e thrust curves, points, etc) Why use " acceleration=power/(mass x velocity) and the (m x v) part? because for I dont want to further distill the combination of newtonian identies, as well as I want it to be clear that for a given mass, acceleration will be proportional to and be inversely proportional to vehicle speed. It more clealy shows the relationship of the factors.
WITH a HP curve, by definition and by nature, it ALREADY incorporates a major element, that of RPM!!! because it incorporates RPM , HP is more useful from the perspective of saving time, and even quickly eyeballing an answer.
Now, as far as Frere, well lets just say that Cort Wagner was out there this weekend at laguna in a 800hp Ferarri 430 supercharged, on the best DOT slicks money can buy, and with a team of engineers. I wonder how I was able to spin a faster time of 1:36 vs his 1:37 on a 25 year old 928, driven to the track on garbage can tires , with half the hp.
Joking aside, Ive never said I am smarter than Frere, (a better driver than anyone, as most guys at the top levels can spin a fast lap time.
), but what I will say is that you dont understand the point, are incredibly arrogant, and lack, what seems to be basic common sense and comprehension. NONE of the books written about the subject are wrong. in fact most all of them are absolutely right. However, based on the topic of when to shift you car, there is an equally correct and simple way to determine those points by using HP curves and gear spacing. thats it, nothing more. dont make a big deal out of it.F = ma, much simpler
since a x m = Force (thrust)
you are complicating it by back substituting P/v for force, it's silly
why not call it it a = p/M to make it really confusing (Momentum = mv)
we know, you're smarter than Frere (and every other real authority on the subject who uses thrust) and a better driver too...
the guy who Sir Jackie Stewart said he would trust to drive his family thru the Alps in a snowstorm...
and who has degrees in engineering and worked as a consultant for many manufacturers, Porsche included...
since a x m = Force (thrust)
you are complicating it by back substituting P/v for force, it's silly
why not call it it a = p/M to make it really confusing (Momentum = mv)
we know, you're smarter than Frere (and every other real authority on the subject who uses thrust) and a better driver too...
the guy who Sir Jackie Stewart said he would trust to drive his family thru the Alps in a snowstorm...
and who has degrees in engineering and worked as a consultant for many manufacturers, Porsche included...
10-25-2010, 02:02 PM
#71
Rennlist Member
Exactly, but even with thust curves, you need to know shift points , so the approximation, and answer will be indentical. in fact, you can visualize the other factors and take them into account easier by using HP curves. Certainly, computer programs easily do this, and thats how it is done. But for us, looking at a set of HP curves, gear ratios, engine speeds, torque curves, its just far easier to use the HP curves and plot a straight line across based on RPM drop of a shift, (adding 100rpm based on gear change time)
Arhur, will still argue, prove himself wrong and continue on the rant. remember, he is the one that said his audi RS6 was to be shifted at max HP and just under redline for the taller gears, yet I proved that to be dead wrong.
The answer that is easy to prove, was to shift at as high of an RPM as possible in his car for max thrust to the ground. He will never conciede.
Arhur, will still argue, prove himself wrong and continue on the rant. remember, he is the one that said his audi RS6 was to be shifted at max HP and just under redline for the taller gears, yet I proved that to be dead wrong.
The answer that is easy to prove, was to shift at as high of an RPM as possible in his car for max thrust to the ground. He will never conciede.
10-25-2010, 02:49 PM
#72
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Arthur, I was trying to remeber what book ive read about racing that probably was most useful in the early days. Tune to Win, comes to mind. on page 142 Carroll Smith who knows (SOMETHING ) about racing, winning and tuning, speaks about this very subject. he starts out talking about the 'agonies" that racer go through over gearing. He then specifically talks about not needing computers or complicated formulas. Just a HP curve and in fact, on the opposing page, he has a graph, depicting the very concepts Ive been advocating here. I never paid much attention to that chapter, because I already had a firm grasp of the concepts, but in looking at it 5 mins ago,he almost writes verbatim, what I have been saying. "HP curves,, rpm drop, maximizing are under the HP curve, etc). So, here you go. you want credentials, someone saying the exact same thing, here it is.
you are amazing!
Mk
you are amazing!
Mk
10-25-2010, 03:05 PM
#74
Rennlist Member
tune to win
right from the book from an engineer and racer. Guys like Andretti and Foyt have driven his cars!
so, dont take my word for it, here it is in print!
enjoy
Mark
right from the book from an engineer and racer. Guys like Andretti and Foyt have driven his cars!
so, dont take my word for it, here it is in print!
enjoy
Mark