## Would This Theoretical Car Reach 160 MPH?

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I was just having a chat with a friend about BHP and Torque and this came up...

Due to its low BHP, would the following be able to reach 160 MPH?

1. 1500kg
2. Average drag for a road car.
3. 500 lbft @ 1000 RPM
4. Rev limit ? 1001 RPM
5. Pefect gearing, CVT if you like.

It only has 95 BHP, which in a 1500kg road car would never be enough to traditionally get to 160, it would probably only rach 115 MPH.

Will the 500lbft make up for that? Is the BHP irrelivent?
Fred444

Joined: 14 Sep 2011

P = F * V = (1/2 * Air Density * V^3 * Frontal Surface*Cx) + (m * a ) * V + (Kfricc*V) +(4 * Inertia of rotating masses * acceleration of those masses / Rrm^2)

To simplify, cut %10 of your power and forget about the 3rd and 4th terms.

You have got:

P = F * V = (1/2 * Air Density * V^3 * Frontal Surface * Cx) + (m * a ) * V

Air density = P[hpasc] * (287 / 100 * T[ºK])

At 20ªc sea level and normal pressure is 1.2 Kg/m^3

Cx in road cars can vary from 0,3 to 0,5 so you will have to find it, most manufacturers publicate it.

Frontal surface, you can measure.

No torque, no gearing, no rev limit involved

BTW, CVT transmission is far from perfect...
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Belatti

Joined: 10 Jul 2007
Location: Argentina

Fred444 wrote:1. 1500kg

Will the 500lbft make up for that? Is the BHP irrelivent?

When you can have an infinite amount of gearing, your input torque becomes irrelevent, all you have to consider is power.

Rolling resistance is also negligable at high speeds compared to drag, so we can safely ignore the weight aspect (as we aren't considering acceleration).

So it neatly boils down to:
Vmax occurs when Pdrag = Pinput.
http://en.wikipedia.org/wiki/Drag_%28physics%29#Power
xxChrisxx

Joined: 18 Sep 2009