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What is the frontal area and CD of a Clio 172





I know BenR Ive been reading a really good article on this backed up by J.B.Heywood

Rolling resistance power
Air resistance power

This article is backed up with real cars which is good.

Do you reckon the Clio 172 frontal area is around 20 square feet?
 


its all true though.

dunno bout the frontal area.

but 20 sq/ft sound about right...calculation woud turn out better if u used 21! hehe
 


OK,

Have found out a way of calculating the frontal area of any car !!

Park the car against a concrete wall at night and use a spotlight and someone to help trace the outline of the car.

The shadow can then be measured to give the frontal area.

Simple things like removing the wing mirrors reduces the frontal area by 1% which increases the top speed by 1%. Lowering the car by 2 cm reduces the frontal area by 1 % and reduces the drag because the body covers more of the wheels. These two procedures alone add about 3 mp/h to the top speed.

CAN PEEPS PLEASE DO THIS FOR THEIR CARS THEN WE CAN STICK THE RESULTS ON THE CAR SPECS FOR FUTURE REFERENCE !!

Cheers,

Simon
 
  Pug 206 SW, 172 CUP
Very old thread this!

Was brought here by a google search.

The only info i could find lists the 182 as having a frontal area of 1.94 square metres or 20.88 square feet.

Evo tested a 182 at millbrooks bowl and got just over 133mph but they did say you add on 1mph for every 10mph over 100.

I can't find any info for evo's test weights other than its two up and a full tank of full so i've added autocars test weigh of 170kgs to renault's kerbweight as an example. Renaults touring guide lists fuel as 90% full for a Clio 3 but thats all the info i can find so i haven't included any extra for that.

so for a top speed of 136mph and weighing 2778lbs the little clio would need
142.17hp at the wheels or approx 169hp at the fly to attain that speed. Seems high compared to what people get on rolling roads. Epecially as evo's test weight seems higher than autocars.

Autocar claimed 138 so they must have had a special one as you'd need almost the standard claimed power for that!?

Or the frontal area is squiffy but it's seems reasonable considering the size of the front bumper!!
 
  Pug 206 SW, 172 CUP
Finally found something more likely! The 2005 1.5 dci has a nice deep front bumper and has a frontal area of 20.34 which sounds better as the 20.02 i found seems to relate to the previous generation clio and 20.88 is almost as big as a sierra cosworth at 21!

So with that changed the figures work out to 138 at the wheels and 165 at the flywheel which sounds about right. Even if the Evo car was 50kgs heavier than the autocar test it doesn't make a massive differance to the top speed power requirement as i found. The weight changes the acceleration figures more but even with a heavier car Evo managed 6.6 to 60 and 17.5 to 100 against autocars 6.3 and 17 and they even managed 17.9 to 100 in the wet.

So basically even if all 182's have 10bhp less than the KW (iso) rating converted into hp the car still does damn well with it and who drives around with 2 people in the car, a full tank of fuel and a bunch of equipment all the time anyway :)


As for Autocars top speed of 138 i don't think they did top it out as they usually give a mean and best result if they do. It's just a maximum speed in 5th they put.
 
  Pug 206 SW, 172 CUP
Weight is required in the working out of rolling resistance but your right it doesn't make much differance, if any. Even chucking an extra 100kgs in pounds either way made very little difference. 1bhp at the most. The air resistance of just trying to do 2mph more is the biggest factor. How renault managed to get a 182 cup to do the 140 claimed in the brochure over the standard 182's 139 when as you say weight makes little differance. It even has a 0.01 higher Cd than the standard car i assume because of the spolier kit.

Anyway was just doing this for fun really as other people are watching bad TV. Wasn't out to prove or disprove anything
 


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