View Single Post
      06-11-2013, 02:26 AM   #115
Brigadier General

Drives: 130i
Join Date: Nov 2011
Location: QLD, Australia

iTrader: (0)

Originally Posted by swamp2 View Post
Wow, where do I even start. As CanAutM3 mentioned, it does sound like you failed one or more of your "mechanics of force" classes. By the way I've never seen such a course title in any undergrad or graduate school engineering course catalogs...

Just for kicks though since you are degree dropping mine and in physics and mathematics and I've also worked as a Mechanical Engineer.
Australia.. can't remember the exact title of the course but i have a bigass 'statics of materials and mechanics' book to use as a sweet paperweight.

quite surprising at your job though lol. i mean.. ok not really, you got all the other stuff spot-on and in great detail. you clearly know most of your stuff!

Originally Posted by swamp2 View Post
100% positively false. As I and CanAutM3 have shown, gearing is required information to compute shift points. Period. You've not shown jack but reference some random web pages with non verifiable algorithms...
verifiable via hand

(i worked it out on paper with a calculator first)

Originally Posted by swamp2 View Post
Do they plot and show potentially intersecting force at the wheels as a function of speed gear by gear? Until you can plot those and compare with mine we don't have any basis for comparison.
yeah the page i posted with the REALLY GOOD calculator seems to still be down

really saddening, GREAT online tool.

Originally Posted by swamp2 View Post

You should google the plethora of good and lengthy debates here on this forum about power vs. torque. You clearly don't get it.

i have, they're nearly literally word for word what i'm saying, you should take your own advice and have a google

power is torque over an RPM. fact... verified by the conversion formula.

Originally Posted by swamp2 View Post
Let's review 100% independent of torque and gearing! Two cars A and B at the same speed and same weight. The car that can produce the most power (to the wheels of course) at that speed will always out accelerate the other. Period, no if's and's or but's

The problem is many peoples understanding is reconciling that statement with the additional fact that peak in gear acceleration (less some drivetrain inertial effects) occurs at the rpm where the peak torque is produced.
well, close... the car with the higher AVERAGE of power over the accelerating rev-range will out accelerate... you can have a car that momentarily has WAY (or more realistically, slightly) more power, but throughout the revs has slightly less... if you're talking at specifically 6547 RPM car vs car identical gearing... for that RPM, yeah, of course.

your second paragraph is inaccurate... if you have peak torque at say... 6000RPM.. redline at 10k... and torque drops by 5% of the peak value linearly to redline.... well, peak acceleration will continue to redline, as the value of torque is applied more times per second than it was at peak... it's like.. hm... say 500ft-lb 6000/min is 3,000,000... where at 10,000RPM it's 4,000,000... your car is making more power but less torque. ... 571whp vs 761whp... at less torque.

so ... i guess previous discussions weren't taking into account how many times the force is applied per timeframe AS WELL as gearing. if you haven't thought about this... well.. think about it.

which of the above RPM's are you going to make peak acceleration gearing taken into account now?

Originally Posted by swamp2 View Post
Hint: At a given speed a lower gear may be available which will often increase rpm, power and torque (to the wheels, the only place it matters, all the while REDUCING it at the crank)

Once you truly understand both of these statements (in bold above) and the fact that they are not contradictory, you may finally understand why power is both more important and more fundamental in vehicle performance.
yeah... that's not even up for debate haha

second paragraph.. well yeah, it's all related.. power being more important is kinda my point (though i didn't know how to fully voice it until now, my bad),

Originally Posted by swamp2 View Post
Power is not torque over time. Power is fundamentally a product (literally multiplication or vector dot product) or a force and a velocity. In the case of rotating things the velocity is and angular velocity or rpm.
HP = Torque (lb/ft) * rpm / 5252

RPM = time in this case... maybe i should say 'over a frequency'.. bu

yes, it's what you're saying (in arbitrarily more complex terms than they need to be).. however, the multiple in the real world is time... or frequency, if you want to be more accurate.

for 99% of the population, my explanation is a LOT easier to understand and give them that 'oh' moment haha

Originally Posted by swamp2 View Post

We are really digressing here into a debate I'm really quite tired of having...

yeah every post it gets more and more off topic and i have no idea why we're arguing, or really what we're arguing about... it's not even in the 100% real world where temperature variations, fuel quality, the direction of the wind, how you hold your pants up... effects how well a car accelerates, and shift points lol.
Appreciate 0