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+--- Thread: Top speed calculator (/showthread.php?tid=997)
Top speed calculator - Mike - 09-13-2004
<!-- m --><a class="postlink" href="http://davewin.com/tech/horsepower_calc.shtml">http://davewin.com/tech/horsepower_calc.shtml</a><!-- m -->
You can likely find the information about you car somewhere online... If you can't? Keep trying, it's out there.
My top speed currently should be 145
I think I'm gonna go out and try it 
To reach 200mph I'd need 360hp. Time to start building.
- .RJ - 09-13-2004
1.21 gigawatts!
- BLINGMW - 09-13-2004
shieeet.... finding frontal area isn't easy, only place I found someone listing it was here, and I have no idea if it's accurate:
http://www.carfolio.com/specifications/
seems kinda close though, assuming the calcuator is talking about wheel HP? (seems like they'd make that clear?!) For my E30, I used:
0.33Cd (I saw a lot of .32 and .34, so I went in the middle)
20ft^2 frontal area (converted from 1.86m^2)
2491lbs (with me in it)
116MPH
78HP (104x.75 for drivetrain loss, seems about right)
That's probably not far off?
I've never topped it out. :oops:if it had a cam and exhaust and was well tuned, it might make the near 100whp it would need just to go 10MPH faster. :lol:
- KPWSerpiente - 09-14-2004
Please kids, don't try it on the street. Use the calculator or a handy dandy legal racing track.
As far as I understand, my car is gear limited to 175. TRE makes a few different 5th gears that are either 10% or 25% taller and that can bump you up over the 200 mph mark.
Personally my 4th gear takes me to 140 and I've never tried to shift into 5th at this point (I'm not very brave).
-T
- JohnC - 09-14-2004
0.31Cd (according to the site Chan mentioned)
30ft^2 frontal area (just a wild guess - I really have no idea)
3800lbs (another guess, with 215lbs of me in it. Damn I'm fat)
148.65MPH
225whp (300bhp x .75 for drivetrain loss)
I'd need about 535whp to hit 200mph. But I wouldn't even know it, 'cause the speedo only goes to 160 :twisted:
- white_2kgt - 09-14-2004
don't need no frekin calculator, 155, that's all she will do.
-c
- Mike - 09-14-2004
is the hp # to the wheels or at the crank? i assumed at the crank. i guess i ought to read the site.
if it is at the wheels then i can only go 130? wrong. so it must be at the crank, or i must be making a lot more power than i should be.
- BLINGMW - 09-14-2004
what are the #'s you're using Mike? The site makes no explanation, but I think we can assume it's wheel HP, here's why:
A more basic calculator is here for comparison:
http://www.gtechprosupport.com/support/AeroDragCalc.htm
HP loss due to aero drag = (Cd * Area * Velocity^3)/150000
So in my case, at 116MPH, I'm out 68.7HP due to aero drag alone. I think in this equation, it only makes sense to consider HP at the wheels. So with JUST aero drag, I should be able to go only 121MPH. Obviously the calc you posted Mike takes a bit more into account since it brings in the weight. So it's probably added some stuff onto this basic equation. But if I assume crank HP with the more complex EQ, it says I can go 128MPH! Not likely. At the most, I should be able to go 121. So I think it's wheel HP for the more complex one too. Make sense?
Oh, and this simple calc page has a link to a LOT of front area and Cd info for a bunch of cars! Sweet! (unfortunatly not much within the last 10 years though)
http://www.teknett.com/pwp/drmayf/tbls.htm
As another point of reference, the more complex calc says my E36 could go about 145, which is about right from what I've heard and what I almost saw at Lowes. 8) But if I assumed crank HP? It says about 160. No way. (E36 #'s I used, .32Cd, 21ft^2, 3150LBS)
So Mike, all in all, I call BS. Your hatch can't go 145.
oh, and John! 30ft^2? What, is then when towing? :lol: You should be using ~20 as well. You should be able to go 168. :mrgreen:
- Mike - 09-14-2004
cd = .31
fa = 20.47
weight = 2300lbs
142 (my hp) x .8 (drivetrain loss) = 116hp = 135mph.
the reason i'm not so sure about 135 because i've been 130, car was still accelerating, i'm willing to bet it had more than 5mph left in it.
- ViPER1313 - 09-14-2004
Using stats found from <!-- m --><a class="postlink" href="http://www.geocities.com/autobahnsho/candd6.html">http://www.geocities.com/autobahnsho/candd6.html</a><!-- m --> (Car and Driver Review - actually has frontal area) and a drag coefficient of .33 (saw .32 and .33, went for the higher of the 2) and assuming a 200 pound driver and 100 pounds of fuel, a 89 Taurus SHO would only need 168.7 wheel horsepower to go 143. The cars dyno at 190whp, so I would guess the calc is a little bit off.
- JohnC - 09-14-2004
BLINGMW Wrote:oh, and John! 30ft^2? What, is then when towing? :lol: You should be using ~20 as well. You should be able to go 168. :mrgreen:
You're right. I was playing around with it and left that value in there for the Lightning on accident (and it's probably pretty close to that I would think, maybe even a bit larger). The other values posted earlier were actually for the 300ZX - but obviously frontal area was too large... Using your value of 20 ft^2, I get a top speed of 168.24 mph, assuming 225 whp (300bhp minus 25% drivetrain loss). The 100bhp extra from a JWT ECU plus intake/exhaust would raise the top speed to only ~186 mph.
Of course I'll have to verify these numbers with some real-world testing on residential roads at night in a rainstorm with my lights off.
- BLINGMW - 09-14-2004
mongooze Wrote:....Of course I'll have to verify these numbers with some real-world testing on residential roads at night in a rainstorm with my lights off.
Make sure you get the windows tinted heavily first!
(nice try on the cover up, we know what you really have in mind, a Lightning/300ZX hybrid monstrosity) :lol:
- .RJ - 09-14-2004
Its not cool unless there's children around too
- KPWSerpiente - 09-14-2004
Drag Coefficient - .290
Frontal Area - 20.40
Weight - 3100
Horsepower 320
Top Speed - 194.28.
-T
- Mike - 09-14-2004
do it!