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New HP Calc

 
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SMOKEmUP
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Joined: 30 May 2002
Posts: 3169

65097.54 points


1979 Chevrolet Camaro

PostPosted: Wed Apr 06, 2011 7:31 pm    Post subject: New HP Calc Reply with quote

Awhile back Clay posted something about differences in the HP calc between 1/8 mile and 1/4 mile. This got me thinking and I finally got off my butt and sat down to come up with a better HP calculator. The calculator takes into consideration the weather conditions, wind resistance, and rolling resistance.

For the new calculator you enter the following info:
* Run date and time
* Select dragstrip
* ET
* Trap Speed
* Vehicle Weight
* Drag Coefficient
* Frontal Area

Here is a sample output from my run (I'm guessing on the weight).
Code:

You Entered:
Vehicle Weight - 3600 (lbs)
Trap Speed - 110.57 (mph)
Drag Coefficient - 0.340
Frontal Area - 21.60 (sq/ft)
Drivetrain Loss - 20 (%)

The closest weather results for 09/28/2006 at 11:08 am

Time recorded 10:55 AM
Temperature F 62.6
Dew Point F 57.2
Altimeter Setting 29.99 Inches Mercury
Absolute Pressure: 29.86 Inches
Density Altitude: 523.4 feet
Track Elelvation: 125.2 feet

UnCorrected ET:
12.327 (sec) @ 110.57 (MPH)


Corrected ET to Sea Level (NHRA):
12.259 (sec) @ 111.192 (MPH)

Uncorrected:
  Rear Wheel HP - 399.7
  Crankshaft HP - 499.6
  Power to Weight (rwhp) - 9 (lower is better)
  Power to Weight (crank hp) - 7.2 (lower is better)

Corrected (SAE J1349):
  Rear Wheel HP - 375.1
  Crankshaft HP - 468.9
  Power to Weight (rwhp) - 9.6 (lower is better)
  Power to Weight (crank hp) - 7.7 (lower is better)


Give it a try and let me know what you think.
http://www.smokemup.com/auto_math/hp_mph_plus.php

NOTE:
I have not formally posted this yet.

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af2
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Joined: 01 Sep 2003
Posts: 5558
Location: grassvalley, ca
71227.76 points


1933 Willys Coupe

PostPosted: Wed Apr 06, 2011 8:08 pm    Post subject: Reply with quote

Seems high?

Quite a bit more HP than the old calc. Could be the DC.

I am not complainen, I went from 350 to 600+ Laughing
I do have a barn door to push.
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clay
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Joined: 24 Nov 2002
Posts: 3209
Location: South Carolina
318129.23 points


1972 Chevrolet Nova

PostPosted: Wed Apr 06, 2011 10:42 pm    Post subject: Reply with quote

I like it too - but I agree with af2 - it seems a bit too high. Using the following data:
3930 lbs
139.99 - 1/4 mph
9.67 - 1/4 et
113.17 - 1/8 mph
6.19 - 1/8 et
67 - 69 Camaro body style which gave 0.400 and 25.10
20% loss
December 4 at 4:30 pm
Darlington Dragway

Old 1/4 calculator gave 732 wheel and 915 crank
Old 1/8 calculator gave 773 wheel and 967 crank
New calculator gave 925 wheel and 1156 crank

Don't remember exactly what boost I was running - around 16 lbs and I just don't see how it will make 1156 at that boost level - granted I would like to think that but in reality ----- no. It does look like an all inclusive calculator and really cool, maybe a constant is off somewhere - I'm not smart enough to go much farther. I'll have to bow to you and let you go at it. Thanks for all the work you put in. Clay

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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Thu Apr 07, 2011 12:48 am    Post subject: Reply with quote

I went over the numbers and I think they're correct. I'll take a look at this tomorrow and see what I come up with, maybe I missed something.

Clay, have you tried comparing numbers between 1/4 mi runs and 1/8 mile runs? One thing to note is the track you select determines if the calculator uses numbers for 1/4 or 1/8 numbers. So you would need to use two different runs at two different tracks. Provided the car setup is similar, running the same boost in your case, the corrected numbers should be in line with each other.

I think my car's corrected numbers of 375 HP sound more in line with the mods on the car but it may be a bit on the high side. The dyno numbers I've seen for cars with similar mods put it in the 350 - 390 range.

One of the things i plan to do is make a trip to the dyno then head directly to the strip with a datalogger and G-meter hooked up. That way I'll know for sure how accurate the calculator is and have good data to analyse for future enhancements.

Let me know if you think of anything else you'd like included in the calc. I was thinking of adding transmission, gearing, launch rpm, and shift points. This along with 60', 330' 660' 100' times and velocity I should be able to come up with some interesting data.

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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Thu Apr 07, 2011 11:15 am    Post subject: Reply with quote

I think the numbers are pretty good. Taking your example and just calculate the wind resistance using that calc here's what I come up with. At 140 mph you need 184.2 HP just for the wind.

Drag Coefficient:0.4
Frontal Area:25.1
MPH...Force (lbs)....HP Required
10......2.5..........0.1
20......10.1.........0.5
30......22.7.........1.8
40......40.3.........4.3
50......62.9.........8.4
60......90.6.........14.5
70......123.3........23
80......161.1........34.4
90......203.9........48.9
100.....251.7........67.1
110.....304.6........89.3
120.....362.5........116
130.....425.4........147.5
140.....493.4........184.2
150.....566.4........226.6
160.....644.4........274.9
170.....727.5........329.8
180.....815.6........391.5
190.....908.7........460.4
200.....1006.9.......537
210.....1110.1.......621.7
220.....1218.3.......714.8
230.....1331.6.......816.7
240.....1449.9.......927.9
250.....1573.3.......1048.8
260.....1701.6.......1179.8
270.....1835.1.......1321.2
280.....1973.5.......1473.6
290.....2117.........1637.1
300.....2265.5.......1812.4

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clay
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Joined: 24 Nov 2002
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1972 Chevrolet Nova

PostPosted: Thu Apr 07, 2011 8:55 pm    Post subject: Reply with quote

At Dwaynes Fast Track I entered the same date and time. Using the mph and et from my Darlington pass it showed 873 wheel and 1091 crank. Still shows that 50ish hp difference. What stands out also is using the old calculators the 1/8th one would show a higher hp. With the new ones it's reversed. Still about the same difference just now the 1/4 mile is higher. That's a really cool feature that it automatically picks the 1/8 or 1/4 mile based on the track chosen. Clay
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af2
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1933 Willys Coupe

PostPosted: Thu Apr 07, 2011 10:29 pm    Post subject: Reply with quote

I am just wondering what the real DC is on my Willys. No pud intended you jokers!!
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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Fri Apr 08, 2011 3:44 pm    Post subject: Reply with quote

af2 wrote:
I am just wondering what the real DC is on my Willys. No pud intended you jokers!!

I'm working on a calculator to determine your drag coefficient. I will have two versions. One using a datalog and the other using manual entries. Basically you need to do a cost down from 60 mph to zero on a flat stretch of road in both directions a couple of times. You'll need to accurately enter the frontal area of the car, weight, and altitude (used to calculate air density). From this we can determine drag coefficient.

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af2
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1933 Willys Coupe

PostPosted: Fri Apr 08, 2011 8:24 pm    Post subject: Reply with quote

Smoke, Going from 60 to 0 is out of the question. Neighbors will crap!

Real #'s are 58"x 30" front and the window at 13"x 42"

2150# the weight at 2000 elevation.

Thank you by the way for the #'s
Adam

Barn door? lol
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Skunkworkx
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Location: Harford Co. Maryland
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1968 Chevrolet Camaro

PostPosted: Sat Apr 09, 2011 9:48 am    Post subject: Reply with quote

Tried it and said I needed to pay.....I thought it was a test ? Sad
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