Converting 1/4 mile times to HP ratings???
08-19-2002, 02:12 PM
#1
AudiWorld Super User
Thread Starter
Join Date: Jun 2002
Posts: 3,732
Likes: 0
Received 0 Likes
on
0 Posts
Converting 1/4 mile times to HP ratings???
Saw this on a site someone posted earlier...Anyone know if there is any validity to this formula? I have serious doubts how accurate that can be....
[((1/4 speed)^2/E.T.) x (Car weight/1000)]/9.1 = Horsepower
Anyone with timeslips and dyno graphs wanna do the math and see if this is anywhere close to being accurate?<ul><li><a href="http://www.porttuning.com/technote2.htm">>CLEEK<</a></li></ul>
[((1/4 speed)^2/E.T.) x (Car weight/1000)]/9.1 = Horsepower
Anyone with timeslips and dyno graphs wanna do the math and see if this is anywhere close to being accurate?<ul><li><a href="http://www.porttuning.com/technote2.htm">>CLEEK<</a></li></ul>
08-19-2002, 02:17 PM
#2
AudiWorld Uber User
Join Date: Apr 2000
Posts: 40,289
Likes: 0
Received 0 Likes
on
0 Posts
typically drag race calculators...
are fairly accurate with DEDUCTIVE formulas (ie...trap speed = HP) but horrible with PREDICTIVE formulas (your weight + hp = E/T) because of the tremendous number of variables (conditions, tires, launch etc etc etc).
I've found that a decent drag calculator CAN reasonably give you HP numbers FROM a timeslip but you are guaranteed to be disappointed when your 11 second car runs 13s hehehehe.
I've found that a decent drag calculator CAN reasonably give you HP numbers FROM a timeslip but you are guaranteed to be disappointed when your 11 second car runs 13s hehehehe.
08-19-2002, 02:18 PM
#3
Senior Member
Join Date: May 2001
Posts: 8,006
Likes: 0
Received 0 Likes
on
0 Posts
I rather use ¼ MPH trap speeds to calculate HP...
The time itself is every dependent on driver skill. From the calculations I've done, MPH tends to be consistent across every HP/Weight combo.
HP = (((MPH / 234)^3) * Weight)
Maybe do both and take the standard deviation.
HP = (((MPH / 234)^3) * Weight)
Maybe do both and take the standard deviation.
08-19-2002, 02:21 PM
#5
New Member
Join Date: Aug 2002
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
go to www.nismo.org
then to the middle of the page where the links are then all the way to the bottom. you can find out your fly wheel hp and 1/4 times. if you have trap speed and weights the page will do the math for you.
Trending Topics
08-19-2002, 02:24 PM
#8
AudiWorld Uber User
Join Date: Apr 2000
Posts: 40,289
Likes: 0
Received 0 Likes
on
0 Posts
Here's a pretty good one....
typical of the ilk...I plugged in my 996 numbers and was surprised to pretty much hit it right on!
Your mileage may vary.<ul><li><a href="http://www.europartsinc.com/zonker/eng_et.htm">http://www.europartsinc.com/zonker/eng_et.htm</a</li></ul>
Your mileage may vary.<ul><li><a href="http://www.europartsinc.com/zonker/eng_et.htm">http://www.europartsinc.com/zonker/eng_et.htm</a</li></ul>
08-19-2002, 02:25 PM
#9
AudiWorld Expert
Join Date: Oct 2000
Posts: 25,510
Likes: 0
Received 0 Likes
on
0 Posts
That formula gives me 153HP
I know my car can be AT LEAST .3s faster with a good driver. I had the car dyno'd last year and it put 104.1HP to the ground and is rated for 150 crank HP. Recalcing using the numbers Car & Driver 'got', I get 168HP, a number that clearly is not correct (or has Audi underrated my car by 18HP?