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  #171  
Old 13th November 2010
dewrew's Avatar
dewrew dewrew is offline
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Mad Max,

Just some 2-cents from a college student.

the m/s2 measurement does indeed have a squared time value on bottom but it should be looked at, in a way, as two seperate terms:

an accel of 8.0 m/s2 is really just increasing your speed by 8.00m/s /s (per second). So every one second, 8m/s is added
thus m/s2
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  #172  
Old 4th December 2010
boxcardenny boxcardenny is offline
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to much to read,shut the the hell up!
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  #173  
Old 12th October 2011
Ugly_1 Ugly_1 is offline
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Quote:
Originally Posted by MadMax25 View Post
Hi Fe Head,
Good to hear from you.

Acceleration needs 2 time parameters...
as in meters per sec, per sec.

On a dyno chart, we can say that
the bottom RPM scale is always one minute.
The divisions are for the # of RPMs during
one minute.

How is the second per sec derived.

Also, given the same engine being tested...
if the throttle is increased let's say from idle
to WOT over 2 seconds or over 5 seconds,
the resulting dyno chart curves should be the same.
After all, it is the same engine.
Why should the curves differ?

Does the dyno really care how fast the
throttle was increased?
Won't it produce the same curves either way?

Thanks for your input.
So now that Fe Head has explained how dynos work and in the process showed ASW was correct all along and you incorrect what about an apolgy? Based on your previous irrational rantings I would doubt you'll man up to it but it sure is clear to this reader what happened here. You were actually rather rude and ASW amazingly patient and polite given the circumstances.
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  #174  
Old 10th May 2013
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IXL2Relax IXL2Relax is offline
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Quote:
Originally Posted by Ugly_1 View Post
So now that Fe Head has explained how dynos work and in the process showed ASW was correct all along and you incorrect what about an apolgy? Based on your previous irrational rantings I would doubt you'll man up to it but it sure is clear to this reader what happened here. You were actually rather rude and ASW amazingly patient and polite given the circumstances.


Yep - It's amazing to see how some people can stubbornly refuse to admit they're wrong, continue to move their position, while claiming they were there all along, then move again, as though no one will notice the dancing...

This has been a frustrating read --- inspite of Aarons looooooooon suffering approach - I found myself thumping my fist in my hand and shaking my head... and even yelling at the screen....

But in the end, there were enough interesting, accurate, and lucid posts to make it informative...

Keeping the simple ultimate truths in mind can help you work carefully and thoughtfully at trying to minimize your engines limitations at reaching the purest implementation of power...

Thanks Aaron for posting such a down-to-earth analogy of the basic TQ/RPM/HP relationship...

....~\
__o~~o__
IXL2Relax
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  #175  
Old 8th June 2013
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mikethebike61 mikethebike61 is offline
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Quote:
Originally Posted by NRHS Sales View Post
Cbass,
You are assuming that the big scoop is done quickly which is wrong. The big scoop takes a very long time to dig into the ground, then pick it up and dump it. Until it dumps it you have nothing. During the same time the small scoop is moving lightning fast and has scooped many many loads.
That is why a 287 cid SBC that revs 13,000rpm vs a 427 cid BBC that revs 9,000...assuming they both weigh the same per cubic inch of displacement.....2870 vs 4270 @ 10lbs.....the SBC should win the 1/8 mile and the BBC should run him down and win the 1/4 mile.
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  #176  
Old 8th June 2013
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mikethebike61 mikethebike61 is offline
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Quote:
Originally Posted by boxcardenny View Post
to much to read,shut the the hell up!
I just need across how many rpm does the engine make 80% of max torque. Anything more than that clogs up 64 year old brains.
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  #177  
Old 10th June 2013
Peterson Peterson is offline
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Wow, superb.... I've seen vary little material of this type at this level. You have tell about one of each vary briefly in a vary nice manner. Also the nice appraisals were there.
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  #178  
Old 8th June 2014
Good Iron Good Iron is offline
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Thumbs up Good use of time

Thanks for your post. Usually if guys are bored (and the cant go for a ride) They will pop in their favorite DVD and veg. Nice to see someone being constructive and helpful in their down time.
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  #179  
Old 7th February 2018
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thecarfarmer thecarfarmer is offline
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Quote:
Originally Posted by aswracing View Post
And what determines the acceleration?



It gives you the power at any given rpm, doesn't it?

That's half the equation. The other half is how much mass is being accelerated.

You seem to be suggesting that acceleration rate is some independent parameter that goes unmeasured by the dyno. That's not true. The dyno shows the power at any given rpm. The power determines the acceleration rate.
(emphasis added)


So in your view, power produced below the horsepower peak doesn't count? You have to get all the way up to the horsepower peak before you have any power that does anything?
Doing a little thread necro here... if I can ask for a point of clarification, I presume you're talking out an inertia dyno here?

I am more familiar with dyno sheets from car engines done on brake dynamometers, where a load (generally computer controlled) is continuously adjusted to allow the engine to hold a constant acceleration rate, and the torque is measured (generally a load cell under a reaction arm on the engine cart) directly.

As opposed to an inertial dyno, where the torque is calculated by the gain in velocity of the mass of the drum.

Car engines are frequently tested at 300 RPM/sec (gaining 300 RPM for every second of the pull); some guys will run tests at 600 RPM/sec or some other value.

Of course, I think bike guys almost universally test engines in the bike on a chassis dyno... but Internet pissing contests seem to be the same.

-William

Last edited by thecarfarmer; 7th February 2018 at 08:47.. Reason: My typing sucks
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