Dan87951

What is the math equation for figuring out engine liters and engine displacement?

IceShark

Pretty easy, did you ever graduate from high school math? Pi R (R is radius = 1/2 diameter) squared times stroke. Times how many cylinders you have.

So for Turbo, bore of 100mm/2 = (radius)50mm^2 x 3.14 (pi) = 7850 x 78.9mm (stroke) = 619365 x 4 (cylinders) = 2477460mm cube. Then shift decimal places to convert to liters (1000 x 1000 = 1,000,000) and you wind up with 2.477 liters. Though my Porsche book says 2.479 liters so I guess we have some differences here, maybe Pi taken out to a bit more decimals by Porsche, but you can understand how to figure this out following the formula stated above. Just basic math that shouldn't scare ya.

PorscheG96

[quote]Originally posted by IceShark:
<strong>Pretty easy, did you ever graduate from high school math? Pi R squared times stroke. Times how many cylinders you have.

So for Turbo, 100mm/2 = 50^2 x 3.14 = 7850 x 78.9mm = 619365 x 4 = 2477460mm square.</strong><hr></blockquote>
Square millimeters for volume, huh? I think the rest of us convert CUBIC millimeters to CUBIC centimeters dividing by 10^3 [equal to milliliters] and divide by one thousand to get the displacement in liters.

IceShark

Square or Cubed, agree that is important, but it is late and I'm tired, you got the drift. And I didn't see your sorry butt answering the man's question.

dk944s2

NOW who's the high-school math genius!

(Sorry, couldn't resist)
<img src="graemlins/a_smil17.gif" border="0" alt="[blabla]" /> <img src="graemlins/icon501.gif" border="0" alt="[icon501]" />

IceShark

May as well pile on. Hope you don't want a headlight wiring harness. <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" /> They are all sold out anyway, so is an empty threat. But I'll make up a ban list just for you.


My question about high school math was a legit one, if he never "got it", like many, he just needs to step back a bit and learn it. This is real world application and might stick as relevant.

Steve Lavigne

[quote]Originally posted by PorscheG96:
<strong>
Square millimeters for volume, huh? I think the rest of us convert CUBIC millimeters to CUBIC centimeters dividing by 10^3 [equal to milliliters] and divide by one thousand to get the displacement in liters.</strong><hr></blockquote>

Way to lay the smack down Trevor!

Robby

Hig school math ended at the end of my 10th grade year when I was barely 15- fat lot of fu**ing good it did me- look where my half-way prodigy *** ended up! Anyway, if you use a fraction for pi, 22/7, you get 2479.714286cc's or, 2.48L- the 106mm bore that some are getting now is like 2.78- several people were calling it 2.82- don't know where they got that- I asked john about it and he wasn't sure- said someone must have done the math wrong- an honest mistake I'm sure- I'm also pretty sure it wasn't him, for the record. Anyway, try the 87.9mm stroke of the 968 w/the 106mm bore and you get 3104cc's- a MONSTER ENGINE!!! SOOOO, when is someone going to go for it? John, Tim, anyone, Bueller???

IceShark

Robby, The 22/7 is the general rule of thumb for those of us that need to work pi. However, the more accurate number is programed into the 'puters these dayzs. 22/7 gives a pretty good result considering how fallible we humans are in execution, though.

Robby

VERRRRRY INTERESTING! What the hell are you still doing up anyway?

Dan87951

"did I ever graduate high school math"?? Yes went to Advance Algebra in 11th grade. Didn't realize this was a idiotic question?? Sorry for the post guys! Yes I’m familiar with math but didn’t know engine formulas 101 was a mandatory course. I take offense to what you said IceShark so I’m going to be the bigger man here and not ridicule someone else’s intelligence to make myself feel bigger. Low self of steam buddy?

I’m done with this thread!

97xray

Dan,
I've had more math than I care to remember, and still, I have to look at the inside cover of my old text books to remember these equations.
People who memorize them (no offense Iceshark) often times use them daily or weekly, so they HAVE TO, but us normal folk - screw it! We just look it up in a book.
And truly, getting through multivariable calc, differential equations, and linear algebra (and more) won't help a bit.
So: Math genious or not, these geometric problems often require a reference to good old equations.

IceShark

Well I'm sorry I upset some folks, but these old formulae get used all the time in everyday work.

jim968

A comment or three...

A) pi is more correctly 3.1416 (picky bastid, me)...

B) those getting upset about the 'squared' vs. 'cubed' thing need to stay well away from an engineering course called Strength of Materials, where a common unit is inches to the fourth... 'I' or the moment of inertia of a shape, the product of multiplying inches of distance squared times cross-sectional area...

C) the fundamental problem is that math in school is taught mainly by math majors, who have _never_ held a job that required practical application of what they teach. They go to college, get their degree & teaching credentials, then start teaching what they were taught... fine if you're trying to produce math majors, but worse than useless for communicating basic math skills in a way that engages the student. Math becomes an frightening or impenetrable subject, students develop a mental block, and "Math sucks!" becomes their mantra. The same, BTW, applies to physics.
<img src="graemlins/soapbox.gif" border="0" alt="[soapbox]" /> <img src="graemlins/jumper.gif" border="0" alt="[jumper]" /> <img src="graemlins/icon107.gif" border="0" alt="[icon107]" />

As a teacher, I really hate the way this scars & scares students who come to think that they are in some way inherently dumb.. math really isn't hard; it's all the artifical, mostly useless theoretical bulls*&t that math majors have invented to pad their subject and provide teaching employment for more math majors. <img src="graemlins/icon501.gif" border="0" alt="[icon501]" />

Jim, "There are three kinds of people in the world; those who can count & those who can't...."

Perry 951

Depends on your line of work.

I rarely use math, and if I do, it is "cash math" in figuring payroll and budgets.

I'd have to look it up as well.