Why 5252 rpm

[Q45tech]

"Answers to Readers QuestionsBy: Sarah Forst * read every issue especially her comments!http://www.nissanperformancema...arah/

Q: What changes can I make to get the maximum torque increase? I want to keep my torque curve above my power curve at all times. Sean

Sarah: Short of shifting at 5252 rpm, that's impossible. Torque is the end result of the combustion process that forces the piston downward and rotates the crank and horsepower is a function of torque. The formula for horsepower dictates:

(Torque * engine speed)/5252 = Horsepower

The torque curve will always be higher before 5252 rpm and lower after 5252 rpm. Their curves cross over at 5252 rpm. This is a result of the conversion from pound-feet of torque to horsepower. Why that number? 1 horsepower is 550 foot-pounds per second while torque is measured in pound-feet. To convert from torque to horsepower, multiply by engine speed, which is measured in rpm (revolutions per minute); to convert horsepower to torque, divide by engine speed. A revolution uses radians, the length of an arc divided by the length of a radius, for units. Calculating for the circumference of a circle, there are 2 * pi radians in a revolution and 60 seconds in a minute so 1 rpm equals (2 * pi)/60, or 0.10472 rad/sec. 550 foot-pounds divided by 0.10472 radians per second equals 5252, our magic conversion number. "

Used the number for 20 years but never thought where it came from

[nlzmo400r]

yea, not many people know that, but damn, she is good

[EZcheese15]

I actually knew that already, but I'm glad your passing on the info for others.

And oh yeah, Sarah is a goddess (cute too :boink)

[Def]

Whoa... a girl that is into the maths and cute? Is she single?

[nlzmo400r]

i had the same thoughts

[EZcheese15]

Whoa... a girl that is into the maths and cute? Is she single?

Um...who are you talking about?

[Q45tech]

Hormones, light duty temporary chemical castration is the answer to focusing on school and work.....................about as appropriate here [this forum] as girlie comments.

[maxnix]

Whoa... a girl that is into the maths and cute? Is she single?

"maths"? I don'think she would be impressed.

[nomuken]

"maths"? I don'think she would be impressed.

there's nothing wrong with saying "maths":

http://dictionary.reference.com/search?q=maths

[nomuken]

Their curves cross over at 5252 rpm

i don't understand, is she saying that on every dyno plot the torque curve crosses the power curve at 5252rpm?

[Q45tech]

That is the definition of horsepower that the two are equal and only equal at 5252 rpm ...........doesn't have anything to do with a dyno which ONLY reads torque then has a software program to also display the HP by multiplying the torque by the ratios of rpms [rpm divided by 5252] x torque= HP.

HP is like squirrels and rats they are relatives.

[nomuken]

so, hp is derived from torque using a formula containing the constant 5252, making the curves always intersect at the same point, makes sense now.

is it possible to measure hp directly? it would be interesting to compare the real hp curve to the calculated one.

[Nathan]

No...it's not possible because there is no REAL hp curve, its derived directly from torque. In fact, some could argue that knowing the hp of a car is not even important, just the torque. I really dont know enough to expound much further upon this

[maxnix]

there's nothing wrong with saying "maths":

http://dictionary.reference.com/search?q=maths

Sorry, new age newbie web dictionaries don't have any credibility for me. Math is a contraction of the word mathematics. Maths is a word like dis or mods; i.e. - new age ebonics for the illiterate.

She would not be impressed. Eamil her if you are curious. Reading a few of her columns would enlighten many of us.

New "maths" (sic) or not.__________________Brian1995 Q45 & Q45t

Discover the power of the button!

[nomuken]

i know that this is a car forum, but someone has to stand up for the English language

Sorry, new age newbie web dictionaries don't have any credibility for me.

if you cared to read the definition you would've seen that the source is The American Heritage® Dictionary of the English Language, Fourth Edition

if that's 2 n00bie 4 U, how about Merriam-Webster (est. 1843)

http://www.m-w.com

look it up

Quote »Maths is a word like dis or mods; i.e. - new age ebonics for the illiterate.[/quote] wrong again

DefinitionMain Entry: mathsPronunciation: 'mathsFunction: noun pluralDate: 1911chiefly British : MATHEMATICS

[QShip]

Sorry, new age newbie web dictionaries don't have any credibility for me. Math is a contraction of the word mathematics. Maths is a word like dis or mods; i.e. - new age ebonics for the illiterate.

She would not be impressed. Eamil her if you are curious. Reading a few of her columns would enlighten many of us.

New "maths" (sic) or not.

I could not find eamil in the dictionary. Is that ebonics?

[maxnix]

how about Merriam-Webster (est. 1843)

http://www.m-w.com look it up wrong again

DefinitionMain Entry: mathsPronunciation: 'mathsFunction: noun pluralDate: 1911chiefly British : MATHEMATICS

Last I checked this is still the USA, not the UK. And yes, I did live in both and did attend school in both. I am quite of aware of the British English peculiarities. But hey, they and William Shakespeare invented the modern form, so they are the reference.__________________Brian1995 Q45 & Q45t

Discover the power of the button!

[nomuken]

Last I checked this is still the USA

how did you check that? last i checked this was http://www.nissaninfiniticlub.net (63.247.129.101)

p.s. we are so gonna get erased for being way off-topic :pface