1/4 mile runs: Horsepower Calculations

[bernmc]

Following our recent jaunt to Silverstone and WRC's surprise dyno figure of 200BHP for Jane's unmodified post-facelift VR4, I've been having a look at calculationg horsepower from quarter mile figures.

I've found a really useful page with a bunch of equations and calculators (click on the equation to go to the calculator) here.

Using figures from our very own CVR4 League Table, a vehicle + driver weight (non-wouter) of 1600Kg, and the 'Elapsed Time (ET)' method, I get figures like this for engine HP (Sorry Zentac - I don't know how much that teensy tiny FTO weighs!):

SGHOM the Mad (quoted 450BHP) - 358
Valmes The Ruski (Quoted 246BHP) - 281
Naughty Nick Mann (quoted ???BHP) - 265
Sneaky like Snake Spirit (quoted 318BHP) - 238
Heavy H.7 (??std car) - 228
Shy Shooter (??std car 174.5 WHP) - 204

I know there are lots of factors that the equation doesn't take into account, but it makes interesting reading, and suggests that the WRC dyno is probably correct...

Figures are quite different using trap speed though. Whadayathink eh?

[Wouter]

Bern.... are calling me fat??

[Nick Mann]

Do you mean power at the wheels there, Bern? Because they look far too low for flywheel figures. Probably good at the wheels numbers though!

Or maybe your weight figures are out? I weighed Kierans VR4 (Legnum, type S, leather, tiptronic) at 1660 with no-one inside. So I would allow a minimum of 1750 for my car with me in it, possibly 1800.

[bradc]

Yeah I think those figures are at the wheels too.

[lo-fasty]

I put my figures. Weight 1750kg best quarter mile time of 14.20606 at Avon Park ( sorry shakespeare county raceway) and I have 265.9 galloping horses 265BHP

[SGHOM]

SGHOM the Mad (quoted 450BHP) - 358
Valmes The Ruski (Quoted 246BHP) - 281
Naughty Nick Mann (quoted ???BHP) - 265
Sneaky like Snake Spirit (quoted 318BHP) - 238
Heavy H.7 (??std car) - 228
Shy Shooter (??std car 174.5 WHP) - 204

It's nice to see my mad -mobile still way out in front !!
come on someone ?? take my title !! [ VR4's only need apply ! ]

[zentac]

hmmm - rubish ! it recons mine is 271bhp

[bradc]

271hp at the wheels would be beleivable for you though Richard

[bernmc]

Do you mean power at the wheels there, Bern? Because they look far too low for flywheel figures. Probably good at the wheels numbers though!

Or maybe your weight figures are out? I weighed Kierans VR4 (Legnum, type S, leather, tiptronic) at 1660 with no-one inside. So I would allow a minimum of 1750 for my car with me in it, possibly 1800.

Dunno - the page just says 'engine horsepower'. I based weight on the spec in the club resources - is that for the galant then? Is the leggie realy 140kg fatter

[Kenneth]

Is the leggie realy 140kg fatter

I would say that depends on who is driving Bern! (and passengers)

[richy rich]

ive weighed mine and it came in at 1600 i think it was and that was with me in it.

[bernmc]

ive weighed mine and it came in at 1600 i think it was and that was with me in it.

That tallies with the spec - 1520 for car + 80ish for you.

[richy rich]

yep......

[Nick Mann]

I put mine (now Kierans) on a calibrated weighbridge. With 1/4ish of a tank of fuel, a handful of tools in the boot and my jacket on the passenger seat. There was no-one in the car. It came in at 1660 kg. I will get my latest one on there too for comparison and let you all know the result.

[Wodjno]

try here.. good site and info and it list our car

http://www.letstorquebhp.com/4wd.asp

[zentac]

271hp at the wheels would be beleivable for you though Richard

I had it dyno'd at 280 at the hubs on 0.8 bar, when I ran my 12.44 1/4 I was running 1.2 bar and 100bhp nos so theres no way 271 is correct!

[valmes]

Ok. Here are the results from CarTest2000. I think they are by far more accurate than those in the link provided by Bernmc - "The Angliskii"...

Well just take a look.

Keep in mind that it has a lot more parameters hidden in the parameters screen.

Lets start with stock setup:




And here are the results in Metric system:




And in English:




Note that -206 kw - 276 bhp - 280 PS

Also another thing to note is the difference in 0-60 mph and 0-100 kph...
Having to change at 97 kph to 4th gear takes some time away... and 0-60 is just under those 97 kph.

[valmes]

Now lets see how much BHP would drive me into 13,54




And here are the results in Metric system:




And in English:



Note that -246 kw - 330 bhp - 335 PS

One more thing to note is the difference in ¼ mile and 400 meters times. Last is slightly shorter distance, hence slightly better time...

[bernmc]

Nice software - must find it and have a play!

[bradc]

That is amazing software Valmes, is it freeware?