how fast do the pistons travel at 9k per minute?
05-30-2004, 10:16 PM
#11
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I agree with this post ^^. Just calc I stuff.
But I am willing to be the 4906 fpm or so is NOT average speed but maximum speed.
To find avg speed, it would be necessary to take the rms value right? Or we could be lazy and just multiply by .707 to get the average.
Not trying to correct anyone, just asking for informational purposes?
But I am willing to be the 4906 fpm or so is NOT average speed but maximum speed.
To find avg speed, it would be necessary to take the rms value right? Or we could be lazy and just multiply by .707 to get the average.
Not trying to correct anyone, just asking for informational purposes?
05-31-2004, 02:11 AM
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ok, someone who is a calculus whiz, may need to be employed here. i think, what the kid who posted would like to know, is what MPH do the slugs travel at full speed. id also like to know, but this will take some trick math, cause they are haulin ass.
heres what i figured, and it cant be right, sounds too slow, so i figured someone with a math brain may be able to help with what will probably be an exponential calculation.
5280 ft in 1 mile, so at 60 mph you go 1 mile in 1 minute. thats 316800 ft in 60 minutes.
ok he asked at 9k, at 9 k the f20c slugs will be at 4906 ft per minute. now if you put into 4906 into 316800 you come up with 64.57 mph. to travel the same mile. it just doesnt seem right in my head, that the pistons would only be going 64 mph?someone show me what factor i missed to come up with the correct answer.
later dave
heres what i figured, and it cant be right, sounds too slow, so i figured someone with a math brain may be able to help with what will probably be an exponential calculation.
5280 ft in 1 mile, so at 60 mph you go 1 mile in 1 minute. thats 316800 ft in 60 minutes.
ok he asked at 9k, at 9 k the f20c slugs will be at 4906 ft per minute. now if you put into 4906 into 316800 you come up with 64.57 mph. to travel the same mile. it just doesnt seem right in my head, that the pistons would only be going 64 mph?someone show me what factor i missed to come up with the correct answer.
later dave
05-31-2004, 06:13 AM
#13
Average piston speed
P = (S * R) / 6
Where:
P = Piston Speed in feet per minute
S = Stroke in inches (3.31 for S2000)
R = RPM = Revolutions per minute
----
I had a hunch the motion of a piston is approximately a sine wave but when you look at the math it isn't exactly, which becomes more clear at the 2nd derivative (acceleration): http://www.wfu.edu/~rollins/piston/
This is because the connecting rod DOES NOT move in a straight line, but instead moves around the crankshaft.
So to know the maximum piston speed, you need to know the redline RPM, connecting rod length, and stroke. If you are REALLY interested in the fastest instantaneous velocity of the piston, do the math
----
Here's a quote I found:
"Current lubricants limit maximum piston speed to about 4100 feet per minute. Make the piston move faster than that and you lose lubrication and burn up the engine. "
P = (S * R) / 6
Where:
P = Piston Speed in feet per minute
S = Stroke in inches (3.31 for S2000)
R = RPM = Revolutions per minute
----
I had a hunch the motion of a piston is approximately a sine wave but when you look at the math it isn't exactly, which becomes more clear at the 2nd derivative (acceleration): http://www.wfu.edu/~rollins/piston/
This is because the connecting rod DOES NOT move in a straight line, but instead moves around the crankshaft.
So to know the maximum piston speed, you need to know the redline RPM, connecting rod length, and stroke. If you are REALLY interested in the fastest instantaneous velocity of the piston, do the math
----
Here's a quote I found:
"Current lubricants limit maximum piston speed to about 4100 feet per minute. Make the piston move faster than that and you lose lubrication and burn up the engine. "
05-31-2004, 11:00 AM
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well, ive been searching for a few, and still cant find the formula to see what the piston speed would be in MPH. so with more head i think this can be answered. feet per minute is a good start. but i think theres more to it, to find out what mph the piston travels at. laterz dave
05-31-2004, 11:05 AM
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For an '04.
90mph doesn't sound very fast. But the piston accelerates from 0 to 90 mph twice per revolution, in a distance of a couple inches.
Code:
Angle(deg) miles/hour 0 0.00 9 -17.23 18 -33.77 27 -48.96 36 -62.22 45 -73.06 54 -81.15 63 -86.29 72 -88.47 81 -87.85 90 -84.73 99 -79.52 108 -72.70 117 -64.70 126 -55.94 135 -46.76 144 -37.39 153 -27.97 162 -18.60 171 -9.28 180 0.00 189 9.28 198 18.60 207 27.97 216 37.39 225 46.76 234 55.94 243 64.70 252 72.70 261 79.52 270 84.73 279 87.85 288 88.47 297 86.29 306 81.15 315 73.06 324 62.22 333 48.96 342 33.77 351 17.23 360 0.00
05-31-2004, 11:10 AM
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fpm to mph is an easy conversion . . . . . if we are just talking about converting units at this point.
7959 ft/min *1mile/5280 ft*60 min/1 hr = 90.44 mph
BTW, jankemi don't you just love excel for this stuff!
7959 ft/min *1mile/5280 ft*60 min/1 hr = 90.44 mph
BTW, jankemi don't you just love excel for this stuff!
05-31-2004, 11:48 AM
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nice calculations guy, but there's still an outstanding issue:
something doesn't make sense, either rollin's model is too much of a simplification or there's way more to the quote vtec4-2 found. does it just mean engines that rev higher than 4100rpm burn oil? if this is the case then it's true for our cars. or the quote is outdated...
Originally posted by VTEC4-2
Here's a quote I found:
"Current lubricants limit maximum piston speed to about 4100 feet per minute. Make the piston move faster than that and you lose lubrication and burn up the engine. "
Here's a quote I found:
"Current lubricants limit maximum piston speed to about 4100 feet per minute. Make the piston move faster than that and you lose lubrication and burn up the engine. "