I just want to confirm, but i am assuming the engine files are for crank horsepower not rear wheel.
Thanks
Correct as far as I know (there's a transmission efficiency coefficient that gives you the wheel power from the crankshaft power).
Correct.
crankshaft power -> -2% -> clutch power -> -5% to8% -> rear wheel power
Thats why the efficiency is set to 0.92 ;)
Is the efficiency at the crankshaft for 2 stroke engines slightly better than a 4 stroke? I only ask because I'd have thought with less moving parts(and therefore less inertia/friction drag) the 2 stroke would come out as slightly more efficient on the crankshaft power output?
Hawk.
Short answer: no.
Relatively longer answer: the efficiency only models the power loss between the crankshaft and the rear wheel, so that's due to the transmission (clutch, gearbox, chain) so I see no particular difference between 2 and 4 strokes. Extra parts in 4 strokes (wrt 2 strokes) have side effects like additional rotating inertia, smaller specific power etc.
Power at crankshaft already includes the power that is lost to operate other engine components (valves, pumps etc).
Quote from: HornetMaX on December 11, 2015, 01:58:27 PM
Short answer: no.
Relatively longer answer: the efficiency only models the power loss between the crankshaft and the rear wheel, so that's due to the transmission (clutch, gearbox, chain) so I see no particular difference between 2 and 4 strokes. Extra parts in 4 strokes (wrt 2 strokes) have side effects like additional rotating inertia, smaller specific power etc.
Power at crankshaft already includes the power that is lost to operate other engine components (valves, pumps etc) .
That is exactly why I would've thought that the power output at the crankshaft would've been slightly different between the 4 stroke and 2 stroke engines - simply because the power at the crankshaft already includes the
"power that is lost to operate other engine components (valves, pumps etc) ", being said that the 4 stroke has obviously a lot more
engine components the power can be dissipated through?
Therefore in my thinking, because there are more engine components in a 4 stroke than a two stroke then surely it must follow that the power output at the 2 stroke crankshaft must be more for a given capacity than a 4 stroke? Or am I totally misunderstanding the term "power output at the crankshaft" and the way it's calculated? :-\
Hypothetical example of my thinking due to more components in a 4 stroke engine:
4 stroke power-loss at crankshaft = 2%
2 stroke power-loss at crankshaft = 1.5%
Hawk.
Quote from: Hawk on December 11, 2015, 03:54:27 PM
That is exactly why I would've thought that the power output at the crankshaft would've been slightly different between the 4 stroke and 2 stroke engines
The output at the crankshaft is different (in our GPB case) if the .engn files are different, no matter of 2 or 4 strokes (or whatever else). All is included in them (in terms of output power).
Quote from: Hawk on December 11, 2015, 03:54:27 PM
Therefore in my thinking, because there are more engine components in a 4 stroke than a two stroke then surely it must follow that the power output at the 2 stroke crankshaft must be more for a given capacity than a 4 stroke? Or am I totally misunderstanding the term "power output at the crankshaft" and the way it's calculated? :-\
It's not calculated, it's measured on a bench most of the time. And what you measure is the engine output, with all it's component (but no clutch and gearbox).
Asking how much power a 4 strokes loses due to it's "extra" components is not very relevant as without the "extra" components, it wouldn't work.
Quote from: Hawk on December 11, 2015, 03:54:27 PM
Hypothetical example of my thinking due to more components in a 4 stroke engine:
4 stroke power-loss at crankshaft = 2%
2 stroke power-loss at crankshaft = 1.5%
There's no such a thing as a "power loss at crankshaft", at least not in practice.
The power loss (efficiency factor in GPB) is for the transmission.
Quote from: HornetMaX on December 11, 2015, 04:14:26 PM
Quote from: Hawk on December 11, 2015, 03:54:27 PM
That is exactly why I would've thought that the power output at the crankshaft would've been slightly different between the 4 stroke and 2 stroke engines
The output at the crankshaft is different (in our GPB case) if the .engn files are different, no matter of 2 or 4 strokes (or whatever else). All is included in them (in terms of output power).
Quote from: Hawk on December 11, 2015, 03:54:27 PM
Therefore in my thinking, because there are more engine components in a 4 stroke than a two stroke then surely it must follow that the power output at the 2 stroke crankshaft must be more for a given capacity than a 4 stroke? Or am I totally misunderstanding the term "power output at the crankshaft" and the way it's calculated? :-\
It's not calculated, it's measured on a bench most of the time. And what you measure is the engine output, with all it's component (but no clutch and gearbox).
Asking how much power a 4 strokes loses due to it's "extra" components is not very relevant as without the "extra" components, it wouldn't work.
Quote from: Hawk on December 11, 2015, 03:54:27 PM
Hypothetical example of my thinking due to more components in a 4 stroke engine:
4 stroke power-loss at crankshaft = 2%
2 stroke power-loss at crankshaft = 1.5%
There's no such a thing as a "power loss at crankshaft", at least not in practice.
The power loss (efficiency factor in GPB) is for the transmission.
Highlighted in your first paragraph is what I was thinking(I think. Lol) So that's good to know. :)
Thanks for explaining Max. ;) 8)
Hawk.
http://www.pit-lane.biz/t117p820-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-1-locked
post number 3
...frits overmars designed the rsa 125 engine btw (with jan thiel).
Quote from: vin97 on December 11, 2015, 07:10:46 PM
http://www.pit-lane.biz/t117p820-gp125-all-that-you-wanted-to-know-on-aprilia-rsa-125-and-more-by-mr-jan-thiel-and-mr-frits-overmars-part-1-locked
post number 3
And what's the point ?
i thought we were talking about transmission losses, no?
Ah OK, I thought there was something else in frits' post.