Another how much HP with a twist....

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MadBill
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Re: Another how much HP with a twist....

Post by MadBill » Mon Oct 15, 2018 12:21 am

Didn't check the Wallace site, but here's a very easy one: http://www.apexgarage.com/tech/horsepower_calc.shtml It includes rolling resistance, but that's a fairly small factor and you can cancel it out by reducing the weight input to zero.

I looked up a table of vehicle CDs and areas in an aero book by Joseph Katz and based on the CDs for a couple of lumpy compacts (VW Beetle and Citroen 2 CV, 0.49 & 0.52) I believe your Willys would be ~ 0.53. Similarly, based on several mid-size European sedans, the frontal area should be ~ 19 square feet.

You can of course compare power requirements of a slipperier body by changing the inputs; CDs of many modern cars are around 0.30 or less but the areas are likely a little more, e.g. 21 ²ft. for a mid-eighties Camaro.
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Re: Another how much HP with a twist....

Post by redliner » Mon Oct 15, 2018 6:45 am

af2 wrote:
Sun Oct 14, 2018 6:59 pm
redliner wrote:
Sun Oct 14, 2018 6:12 pm
af2 wrote:
Sun Oct 14, 2018 5:31 pm
Looking at 3' x 2' then 5'x 1' HMMMM? Total of 5' x 4' ? And Flat?
I think I estimated my flat nose 42 Stude to be about the same as a pickup
Did you come up with a formula? Thanks Adam
I will look some more.

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Re: Another how much HP with a twist....

Post by redliner » Mon Oct 15, 2018 7:15 am

redliner wrote:
Mon Oct 15, 2018 6:45 am
af2 wrote:
Sun Oct 14, 2018 6:59 pm
redliner wrote:
Sun Oct 14, 2018 6:12 pm


I think I estimated my flat nose 42 Stude to be about the same as a pickup
Did you come up with a formula? Thanks Adam
I will look some more.
Go to wallace Calc and find " Calculate H.P. for speed" and see how that works for ya.

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Re: Another how much HP with a twist....

Post by ijames » Mon Oct 15, 2018 9:33 am

What et goes with that 2300 lbs and 138 mph? It's a pretty car. Aerodynamically the rear of the car is twice as important as the front, and while yours slopes down faster than it should the overall drag might not be as bad as you imagine.
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Re: Another how much HP with a twist....

Post by af2 » Mon Oct 15, 2018 10:58 am

Thanks Guys. I found newer calcs on that site that weren't there before.
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Re: Another how much HP with a twist....

Post by Erland Cox » Mon Oct 15, 2018 6:07 pm

Beautiful car.
My first drag racer was a 41 Willys 4 door with a 305 Chevy small block.

https://www.grc.nasa.gov/www/k-12/airplane/dragco.html

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Re: Another how much HP with a twist....

Post by af2 » Mon Oct 15, 2018 8:42 pm

Thanks Erland.
LOL my 6.04 1/8th is exacly the same as the 9.56 1/4 et. The speed is down though and is what got me thinking LOL
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Re: Another how much HP with a twist....

Post by 77cruiser » Mon Oct 15, 2018 9:18 pm

This one shows that the mph would be the same.

http://www.wallaceracing.com/etcalc.php
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Re: Another how much HP with a twist....

Post by MadBill » Mon Oct 15, 2018 9:40 pm

Drag is a pretty small factor re E.T., which is what counts. Decades ago, a number of efforts to improve TF performance via aero body shapes all failed. The few pounds of additional bodywork more than cancelled out any drag reduction effects.
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Re: Another how much HP with a twist....

Post by af2 » Mon Oct 15, 2018 9:44 pm

77cruiser wrote:
Mon Oct 15, 2018 9:18 pm
This one shows that the mph would be the same.

http://www.wallaceracing.com/etcalc.php
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