jalalski
Date Registered: 02-2004
Location: SUTHERLAND, SYDNEY
TOTAL POSTS: 29100
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Wheel to Flywheel Power Conversion
Hi Guys,
I am trying to establish a relation between at the wheels power vs. at the flywheel power and was wondering if you know the formula to calculate this.
We always see manufacturers quote the flywheel power figures, but when we do performance mods and dyno our cars, we get at the wheels figure which is obviously less, so it would be good to get an idea how much at the flywheel we ended-up getting to put into perspective and compare it to the factory set-up.
If you know the way to calculate this, please post it here.
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17/Jan/2008, 12:57 pm
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jalalski
Date Registered: 02-2004
Location: SUTHERLAND, SYDNEY
TOTAL POSTS: 29100
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Re: Wheel to Flywheel Power Conversion
I found THIS converter, but it's also pretty limited in what it can calculate.
I realize that each car is different, just wanted to find out the approximate figures, but I agree that for that we would need to know the exact loss caused by the exy driveline.
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17/Jan/2008, 6:33 pm
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Revhead Kev
Date Registered: 10-2006
Location: Mona Vale, Sydney, AUSTRALIA
TOTAL POSTS: 6355
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Re: Wheel to Flywheel Power Conversion
Is the loss a percentage or a fixed power amount ?
Surely friction does not change as power changes.
--- Kev X450(c) T30 Guru
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18/Jan/2008, 7:24 am
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Naff
X-TRAIL VETERAN
Date Registered: 09-2005
Location: QLD
TOTAL POSTS: 786
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Re: Wheel to Flywheel Power Conversion
It'd be a percentage surely... it's the losses resulting from the gear ratio and friction etc. So as Matt said, if you took a stock dyno result, and then took the flywheel result and calculated the percentage loss between them, you would then be able to apply that figure to the mod dyno results.
Here's a link... Flywheels Vs Wheels suggests that for a FWD car, the loss is 15%, and for AWD, 25%.
I'd say every car, even within the same make is different. The transmission and drivetrain, depending on it's age, wear etc. will have different resistance. And I would suggest that the 132kW figure given by Nissan is a maximum value and most of the cars would be slightly less, probably within a -10% tolerance.
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18/Jan/2008, 7:39 am
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jalalski
Date Registered: 02-2004
Location: SUTHERLAND, SYDNEY
TOTAL POSTS: 29100
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Re: Wheel to Flywheel Power Conversion
OK Guys,
I have worked it out as Matt suggested from the dyno charts I have and our xtrail (Auto that is) is loosing about 40-45% in driveline, which is massive indeed.
We have previously discussed this in the Hi-Tech Exhaust thread HERE
Based on these figures and since I have a total of 34KW extra at the wheels (99.5KW total ATW), it would translate to approx. 188.6KW (34/0.6= 56.6 +132= 188.6) at the flywheel compared to a stock auto exy with 132KW at the flywheel.
That's 16.4KW less than an xtrail GT at the flywheel (which outputs 205KW)
If I can get those 16.4KW extra, I won't need to worry about buying a GT. hehehehehe LOL
Last edited by jalalski, 18/Jan/2008, 8:32 pm
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18/Jan/2008, 8:16 am
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jalalski
Date Registered: 02-2004
Location: SUTHERLAND, SYDNEY
TOTAL POSTS: 29100
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Re: Wheel to Flywheel Power Conversion
Hi Brett,
Yeah, I have researched this mod last year or the year before and didn't like it.
We have discussed it HERE
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18/Jan/2008, 10:31 am
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