Math wiz help. Horsepower estimate based on speed

Seaz · 05-17-2018, 03:24 PM

So my goal is to figure out my approximate horse power without spending money on a dyno

With mods I've been running the 1/4 mile in 12.5
A stock m40 is suppose to do 13.2

So could we figure out the increase in horsepower to drop 0.7sec?

yllwwgn · 05-17-2018, 03:47 PM

My butt-dyno calculates out roughly another 75HP based on the weight of our cars. But I too await a more analytical and accurate answer rooted in math and not butts....

Seaz · 05-17-2018, 04:08 PM

using this calculator I got 436hp

http://www.dragtimes.com/horsepower-...power+Estimate

Tony · 05-17-2018, 04:20 PM

BMW is lying about the stock HP numbers.

Pray for Mojo · 05-17-2018, 04:28 PM

Quote:

Originally Posted by Tony

BMW is lying about the stock HP numbers.

I'm inclined to believe this as well. Stock m240 xdrive has same 0-60 time with 700lbs less weight.

Tony · 05-17-2018, 05:48 PM

Quote:

Originally Posted by Pray for Mojo

I'm inclined to believe this as well. Stock m240 xdrive has same 0-60 time with 700lbs less weight.

Ford Focus RS has the "Same" HP while being slower and weighing 1000 lbs less.

The Audi SQ5 has similar HP numbers and when I test drove the SQ5 it felt slow. Slower than my prior car the Audi S3 for sure. My X3 M40i feels faster than my S3.

Quick18 · 05-17-2018, 07:19 PM

436 calculated at flywheel x .18 (drivetrain loss) =78.45

Subtract 436-78.45 = 357.55 at the rear wheels.

BMW is just reporting at the rear wheels?

05-17-2018, 03:24 PM	#1
Seaz First Lieutenant 223 Rep 340 Posts Drives: (2018,x3,m40) 2016,x3 2009,335 Join Date: Apr 2012 Location: Montreal, Quebec iTrader: (0)	Math wiz help. Horsepower estimate based on speed So my goal is to figure out my approximate horse power without spending money on a dyno With mods I've been running the 1/4 mile in 12.5 A stock m40 is suppose to do 13.2 So could we figure out the increase in horsepower to drop 0.7sec? __________________ I see normal people , I'm not one of them 2018 X3 M40i - JB4 2016 X3 35i - JB stage 1 2009 335 e92 - JB4
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05-17-2018, 03:47 PM	#2
yllwwgn Lieutenant 170 Rep 445 Posts Drives: 2018 X3 M40i Join Date: Oct 2013 Location: Milky Way, Earth, North America, Arizona more specifically. iTrader: (0)	My butt-dyno calculates out roughly another 75HP based on the weight of our cars. But I too await a more analytical and accurate answer rooted in math and not butts.... __________________ "Since light travels faster than sound, some people appear bright until you hear them speak".
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05-17-2018, 04:08 PM	#3
Seaz First Lieutenant 223 Rep 340 Posts Drives: (2018,x3,m40) 2016,x3 2009,335 Join Date: Apr 2012 Location: Montreal, Quebec iTrader: (0)	using this calculator I got 436hp http://www.dragtimes.com/horsepower-...power+Estimate
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05-17-2018, 04:20 PM	#4
Tony Second Lieutenant 49 Rep 286 Posts Drives: 2018 X3 M40i Join Date: Mar 2005 Location: Rockland County iTrader: (0)	BMW is lying about the stock HP numbers.
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05-17-2018, 07:19 PM	#7
Quick18 Private 29 Rep 52 Posts Drives: X3 M40i Join Date: Feb 2018 Location: North Carolina iTrader: (0)	357 at Rear Wheels? 436 calculated at flywheel x .18 (drivetrain loss) =78.45 Subtract 436-78.45 = 357.55 at the rear wheels. BMW is just reporting at the rear wheels?
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