MINI2

Lucky Dave · Apr 30th, 2008, 04:15 PM

The question is does running different sized wheels make a differance to RR figures.

Im thinking differing overall sizes.

Im running 215/35/18 at present but have in the past ran 205/45/15 which is way smaller!

The question is do the smaller wheels give more torque?

The run down losses measure friction of a moving mass which I think may not be 100% spot on as the other is torque?

I hope someone can explain or even try my theory on the dyno!

GTT 280 · Apr 30th, 2008, 04:18 PM

different wheel sizes will have a bearing on the bhp figure, as will your tyre pressures. All this has been debated (at great length and pain) in the forums. Just search for Rolling Road BHP WHP.

Cheers,
K.

Ant FR · Apr 30th, 2008, 04:22 PM

cool i best get mine re rollered

GTT 280 · Apr 30th, 2008, 04:25 PM

Quote: Originally Posted by Ant FR (original)

cool i best get mine re rollered

...be sure to wear the full sparco race suit and helmet if you do... just in case.

Cheers,
K.

Silent1 · Apr 30th, 2008, 05:24 PM

Providing the dyno is set to the gearing of the car there shouldn't be any difference

MarkW · Apr 30th, 2008, 05:58 PM

it is one of the many many inaccuracies in rolling roads.

MINI-Morgan · Apr 30th, 2008, 05:59 PM

Smaller overall size of tyre/wheel combo must give more torque as less torque is required to accelerate with a smaller wheel. But does the dyno account for this on the run down?? surely yes as a smaller wheel will require more torque to turn that a bigger one. Think about bigger and smaller pulleys but also factor in drag from friction

Lucky Dave · Apr 30th, 2008, 06:44 PM

Im thinking its a bit like doing a dyno run in 3.5 gear.

And runs in 3rd have given more power in the past if it will grip.

Bhozar · Apr 30th, 2008, 10:35 PM

Would be good to try out a few different size wheel combo's and a hub dyno, to see if there are any differences.

Silent1 · Apr 30th, 2008, 11:11 PM

Quote: Originally Posted by Bhozar (original)

Would be good to try out a few different size wheel combo's and a hub dyno, to see if there are any differences.

To use a hub (proper) dyno the wheels are taken off!

Do you mean a chassis dyno, i.e. one you drive on?

Bhozar · May 1st, 2008, 09:07 AM

Quote: Originally Posted by Silent1 (original)

To use a hub (proper) dyno the wheels are taken off!

Do you mean a chassis dyno, i.e. one you drive on?

Nope. I mean put the car on a chasis dyno with several different sets of wheels, then put it on a hub dyno without the wheels.

Paul · May 1st, 2008, 09:14 AM

Then take the engine out and put it on an engine dyno, so you know the drivetrain losses too.

Ant FR · May 1st, 2008, 09:34 AM

then take the engine out on the back of a trailer driving at 80 mph whilst dynoing on a mobile dyno to see what really happens in real world.

Failing that bung the oprator a tenner and get him to mess around with the settings and increase your BHP

Lucky Dave · May 1st, 2008, 10:59 AM

Quote: Originally Posted by Ant FR (original)

then take the engine out on the back of a trailer driving at 80 mph whilst dynoing on a mobile dyno to see what really happens in real world.

Im liking this idea!

Apr 30th, 2008, 04:15 PM	#1
Lucky Dave Thinking Minis My Classifieds Join Date: Jun 2005 Local Time: 09:06 PM Posts: 811 Offline	Wheel sizes on rolling roads The question is does running different sized wheels make a differance to RR figures. Im thinking differing overall sizes. Im running 215/35/18 at present but have in the past ran 205/45/15 which is way smaller! The question is do the smaller wheels give more torque? The run down losses measure friction of a moving mass which I think may not be 100% spot on as the other is torque? I hope someone can explain or even try my theory on the dyno! For All Your Mini's Needs 01905 620011

Apr 30th, 2008, 04:18 PM	#2 (permalink)
GTT 280 The Power Cube My Classifieds Join Date: Jan 2002 Local Time: 09:06 PM Posts: 2,348 Offline	different wheel sizes will have a bearing on the bhp figure, as will your tyre pressures. All this has been debated (at great length and pain) in the forums. Just search for Rolling Road BHP WHP. Cheers, K. Too many mods to list, PM me if the cat needs killing...

Apr 30th, 2008, 04:25 PM	#4 (permalink)
GTT 280 The Power Cube My Classifieds Join Date: Jan 2002 Local Time: 09:06 PM Posts: 2,348 Offline	Quote: Originally Posted by Ant FR (original) cool i best get mine re rollered ...be sure to wear the full sparco race suit and helmet if you do... just in case. Cheers, K. Too many mods to list, PM me if the cat needs killing...

Apr 30th, 2008, 05:59 PM	#7 (permalink)
MINI-Morgan MINI Obsessed... My Classifieds Join Date: Nov 2003 Location: Southampton, Hants Local Time: 09:06 PM Posts: 4,679 Offline	Smaller overall size of tyre/wheel combo must give more torque as less torque is required to accelerate with a smaller wheel. But does the dyno account for this on the run down?? surely yes as a smaller wheel will require more torque to turn that a bigger one. Think about bigger and smaller pulleys but also factor in drag from friction One Man, One Project......find out what happens next at MINIProject.co.uk For MINIs in the south it can only be South Coast New MINI Club

Apr 30th, 2008, 06:44 PM	#8 (permalink)
Lucky Dave Thinking Minis My Classifieds Join Date: Jun 2005 Local Time: 09:06 PM Posts: 811 Offline	Im thinking its a bit like doing a dyno run in 3.5 gear. And runs in 3rd have given more power in the past if it will grip. For All Your Mini's Needs 01905 620011

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Apr 30th, 2008, 04:22 PM	#3 (permalink)
Ant FR MINI2 Master My Classifieds Join Date: Oct 2006 Local Time: 09:06 PM Posts: 1,922 Offline	cool i best get mine re rollered

Apr 30th, 2008, 05:24 PM	#5 (permalink)
Silent1 Supercharger Noiseaholic Join Date: Nov 2006 Location: East Anglia Local Time: 10:06 PM Posts: 180 Offline	Providing the dyno is set to the gearing of the car there shouldn't be any difference

Apr 30th, 2008, 05:58 PM	#6 (permalink)
MarkW XR3i / JCW MCS Join Date: Aug 2007 Location: Full Throttle Local Time: 09:06 PM Posts: 454 Offline	it is one of the many many inaccuracies in rolling roads.

Apr 30th, 2008, 10:35 PM	#9 (permalink)
Bhozar Overly excited!! My Classifieds Join Date: Aug 2006 Location: Worcestershire Local Time: 09:06 PM Posts: 1,280 Offline	Would be good to try out a few different size wheel combo's and a hub dyno, to see if there are any differences.

Apr 30th, 2008, 11:11 PM	#10 (permalink)
Silent1 Supercharger Noiseaholic Join Date: Nov 2006 Location: East Anglia Local Time: 10:06 PM Posts: 180 Offline	Quote: Originally Posted by Bhozar (original) Would be good to try out a few different size wheel combo's and a hub dyno, to see if there are any differences. To use a hub (proper) dyno the wheels are taken off! Do you mean a chassis dyno, i.e. one you drive on?

May 1st, 2008, 09:07 AM	#11 (permalink)
Bhozar Overly excited!! My Classifieds Join Date: Aug 2006 Location: Worcestershire Local Time: 09:06 PM Posts: 1,280 Offline	Quote: Originally Posted by Silent1 (original) To use a hub (proper) dyno the wheels are taken off! Do you mean a chassis dyno, i.e. one you drive on? Nope. I mean put the car on a chasis dyno with several different sets of wheels, then put it on a hub dyno without the wheels.

May 1st, 2008, 09:14 AM	#12 (permalink)
Paul Trained Monkey My Classifieds Join Date: Jan 2001 Location: Bedfordshire Local Time: 09:06 PM Posts: 40,354 Online	Then take the engine out and put it on an engine dyno, so you know the drivetrain losses too. Our trials and tribulations living in a "bleeding edge" eco house... Oxley Woods Living

May 1st, 2008, 09:34 AM	#13 (permalink)
Ant FR MINI2 Master My Classifieds Join Date: Oct 2006 Local Time: 09:06 PM Posts: 1,922 Offline	then take the engine out on the back of a trailer driving at 80 mph whilst dynoing on a mobile dyno to see what really happens in real world. Failing that bung the oprator a tenner and get him to mess around with the settings and increase your BHP

May 1st, 2008, 10:59 AM	#14 (permalink)
Lucky Dave Thinking Minis My Classifieds Join Date: Jun 2005 Local Time: 09:06 PM Posts: 811 Offline	Quote: Originally Posted by Ant FR (original) then take the engine out on the back of a trailer driving at 80 mph whilst dynoing on a mobile dyno to see what really happens in real world. Im liking this idea! For All Your Mini's Needs 01905 620011

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