horse power loss

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Greg Erickson
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horse power loss

#1 Post by Greg Erickson »

question....if a engine is putting out 145hp.....what would it be making at the wheels? and if the car weighed 1840 lbs.......what would a 0 to 60 time be?
any thoughts?
Greg

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Matthew Devereux
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Re: horse power loss

#2 Post by Matthew Devereux »

5.6 seconds :)
There are lots of calculators out there like this one http://www.060calculator.com/
I've read that the loss is around 15%
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Vic Skirmants
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Re: horse power loss

#3 Post by Vic Skirmants »

Those must be metric seconds.

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Matthew Devereux
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Re: horse power loss

#4 Post by Matthew Devereux »

It might be too good to be true. Add a driver and gas and you are at 6.2 seconds. All the calculators come up with the same number. Damn theory :)
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Greg Erickson
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Re: horse power loss

#5 Post by Greg Erickson »

Matt,
Weighed my 1960 coupe with 8 gallons of gas ....1840 lbs....add me...it's about 2020,
Depending on what I had for dinner the night before.
So I was thinking the time would be in the 6.8 to 7 sec region.
Still I am wondering how much power is lost to the wheels.
Greg

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C J Murray
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Re: horse power loss

#6 Post by C J Murray »

Is that rear wheel power? A '67S w/160 at the crank(136 rear wheel?) and 2200 pounds is around 7 seconds. A super 90(76.5 rear wheel?) roadster, 1900 pounds, is around 10.5 seconds I think. Does that jive with the calculator?
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Matthew Devereux
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Re: horse power loss

#7 Post by Matthew Devereux »

The calculator comes up with 6 seconds and 8.2 seconds. The slower the car the bigger the discrepancy. Its an optimal number I think and must factor some loss through the drive train.
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C J Murray
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Re: horse power loss

#8 Post by C J Murray »

Those times are not realistic.
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Greg Erickson
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Re: horse power loss

#9 Post by Greg Erickson »

6 seconds sounds good me.....sometimes it feels like it.
Not bad for an old car....I have no problem keeping up with all the cookie cutter cars of today.
Driving it,
Greg

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Matthew Devereux
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Re: horse power loss

#10 Post by Matthew Devereux »

As a reference just look at the original 0 to 60 performance times of these cars. I'll think you'll find that they were rated in the 11 -12 second range. I've never found Porsche's to be great off the line cars anyway. Its more about higher speed performance and handling amongst other things.
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Greg Erickson
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Re: horse power loss

#11 Post by Greg Erickson »

Matt,
Totally agree....when you have it about 4 Grand.....and a couple of S turns in front of you.....
Ahhhhhhhh so much fun.
Greg

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Neil M. Fennessey
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Re: horse power loss

#12 Post by Neil M. Fennessey »

http://www.060calculator.com/

Looks like this is a multivariate statistical model with four independent variables: horsepower, weight, drive wheels and transmission type. It is not based on physics. He wouldn't have access to rear-wheel horsepower data.

http://www.060calculator.com/articles/s ... ulator#how

As to the model's predictive viability, that's tough to say other than to believe his "validation" remarks. What you don't know are the five model coefficient t-ratios which explain the statistical "significance" of each variable and the model's coefficient of variation, which explains the overall model "worth." Lacking these factors, you can't estimate a confidence interval.

It is also important to consider which "horsepower" to use. SAE Gross horsepower? SAE Net Horsepower? German DIN?

"(James) Watt (while marketing his steam engine) found by experiment in 1782 that a 'brewery horse' could produce 32,400 foot-pounds per minute." James Watt and Matthew Boulton standardized that figure at 33,000 the next year. The fluid dynamics students love this historic nugget.

From the 912 registry website, the Porsche 912 engine is rated 102SAE / 90DIN@5800

http://en.wikipedia.org/wiki/Horsepower#SAE_gross_power

FYI, if you dropped your 356N, 911S or Cliff off a cliff, it/he would make 60 mph in about 2.3 seconds. <smilie face>
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Re: horse power loss

#13 Post by Jeffrey Leeds »

Hmmm, which to drop off the cliff to test this; the 356N, the 911S, or Cliff ? Tough choice.
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Re: horse power loss

#14 Post by C J Murray »

Jeffrey Leeds wrote:Hmmm, which to drop off the cliff to test this; the 356N, the 911S, or Cliff ? Tough choice.
Me obviously! Don't hurt the cars!
Neil M. Fennessey wrote:FYI, if you dropped your 356N, 911S or Cliff off a cliff, it/he would make 60 mph in about 2.3 seconds. <smilie face>
Even with me in the car? Does that account for aerodynamic drag? Would it matter if I was screaming, flailing my arms, and trying to get to the top of the falling car to avoid the impact?
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