ajcool2

iTrader: (11)

So I did a quick search for a power to weight ratio calculator after a debate with a guy on another forum and came across this site. I used one of their calculators to find my HP using my best 1/4 mile time and it came out to exactly what I dynoed at at FT a few weeks ago. Below is a list of a few of the formulas they use. http://www.ajdesigner.com/phphorsepo...horsepower.php

Estimate of engine horsepower after a quarter mile run using the trap speed method.

Determine the increase in engine horsepower when an after market modification, race or performance part has been installed with trap speed.

Calculate engine horsepower after a quarter mile run using the ET method.

Compute estimated increase in engine horsepower when an after market, racing upgrade or performance part has been installed with ET.

Dyno correction factor. Factor corrects horsepower for normally aspirated internal combustion engine to a standard humidity, pressure and temperature after dynamometer measurement.

Calculate a vehicles power to weight ratio. Acceleration is related to the ratio.

S8ER95Z

Conversions:
weight = 3600 pound = 3600 pound
velocity = 108.59 mile/hour = 108.59 mile/hour

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Solution: horsepower (hp) = 359.7695706769 horsepower


Yeah...not really buying that.

ajcool2

iTrader: (11)

This was the one that I used. My last dyno 257.

Conversions:
weight = 3200 pound = 3200 pound
time = 13.5 second = 13.5 second


--------------------------------------------------------------------------------
Solution:
horsepower (hp) = 257.06115937611 horsepower

03threefiftyz

iTrader: (25)

Well according to the calc you are supposed to inlcude the weight of the driver. I find it fairly accurate. Good find.

ajcool2

iTrader: (11)

Yeah that weight is with me in it beleive it or not lol.

03threefiftyz

iTrader: (25)

What have you taken out? I have about 100 pounds out of my car and it weighed in at 3130 with a 1/3 tank of gas.

ajcool2

iTrader: (11)

Well I'm not a big guy. I weigh about 145 and all I have out is the spare, jack, carpet and board in the trunk. The usual stuff.

03threefiftyz

iTrader: (25)

Interesting.......I am dropping another 50 pounds here with os giken clutch set-up and pc680. That would be about 140-150 out of the car and yours still weighs less. Plus I have about 75 pounds on you.....lol.

S8ER95Z

I was fairly conservative on weight (I'm 155lbs and counted the car at 3445lbs) Just doesn't add up with my car....

03threefiftyz

iTrader: (25)

Is this supposed to be power at the wheels or motor?

scotts300

iTrader: (46)

I agree. The stuff in the back is 60 pounds max, and the curb weight of the car is about 3300 pounds. Take out 60, put in 150, and I'm not computing 3200 pounds.

AJ - did you weigh your car or are you making an educated guess? And yes, I do have a little bit of knowledge in the subject category on a real scale. See attached pic.

scotts300

iTrader: (46)

They typically are the HP value before drivetrain losses.

03threefiftyz

iTrader: (25)

I figure even with the 150+ weight out of my car I still won't be under 3050.....in theory I would be at about ~3080. According to this I should be trapping 108, and I don't (yet )

scotts300

iTrader: (46)

3080 with driver? These calculators are based on the weight with the driver, which will be hard to get down to 3080# without extensive modifications with the driver.

03threefiftyz

iTrader: (25)

No without me.......with me it would be about 3290 ( I am not a small dude )

ajcool2

iTrader: (11)

No I got on the scale at my local track. I just got home and checked the timeslip that I wrote my weight down on and it was actually 3280 with me in it. I also have an aftermarket exhaust so that a little bit there also.

03threefiftyz

iTrader: (25)

That seems more reasonable....3200 had me . Now if I could only get my chubby butt down to 145 like you I would be under 3200.

ajcool2

iTrader: (11)

LOL all my friends joke that im starving myself to help my 1/4 mile time.

03threefiftyz

iTrader: (25)

No one would make that mistake with me , but I have been focusing on taking more weight out of the car this summer (and my gut lol).

Peak350

iTrader: (6)

How do you think I ran such good stock times. Driver weight loss program.