Calculating theoretical 0-60

[eltax91]

Hi guys

I've had a search and found some calculators online, but given its impossible to factor in the aero or grip levels of a car, is it possible to accurately calculate the 0-60 time?

Yes yes, I know I could go and actually do it, but I like both my hands on the wheel and timing the press of the button isn't easy. Plus, it would be nice to have a target.

Take my 'charges mx5 for example. Dyno'd at 206fwbhp and weighs 1050kg. The calculator puts the 0-60 at 5.1 seconds, but surely this cannot be true??

Thoughts??

[StottyEvo]

www.vimulator.com works well. But its only as good as the information that you put in. It also only allows launches from something like 30% of redline so 0-60 times are sometimes a touch slow.

[kambites]

Aero has relatively little effect in anything with "modern" levels of power. Driven wheels, weight distribution and power to weight ratio are probably the three most important factors.

[Krikkit]

kambites said:

Aero has relatively little effect in anything with "modern" levels of power. Driven wheels, weight distribution and power to weight ratio are probably the three most important factors.

Agree, aero means bugger all at these speeds. It's just starting to come into play at 60-80mph (hence pop-up rear wings on some cars)

[kambites]

Krikkit said:

kambites said:

Aero has relatively little effect in anything with "modern" levels of power. Driven wheels, weight distribution and power to weight ratio are probably the three most important factors.

Agree, aero means bugger all at these speeds. It's just starting to come into play at 60-80mph (hence pop-up rear wings on some cars)

If you have more than about 40bhp yes. Increases in aero efficiency will have quite a big effect on the 0-60 time of something like an Austin Seven, since the standard car is aero/power-limited to less than 60.

[kambites]

Even basic calculators like this tend to be reasonably close for cars on normal road tyres: http://www.torquestats.com/

[Fantuzzi]

Surely things like gearing have a bigger affect on 0-60 times rather than just pure power to weight, making any calculation very, very rough?

The modern Elise hits 60mph in 6. but 62 in 6.5 due to the timing of the gear change to third, which is a fair chunk.

[kambites]

Fantuzzi said:

Surely things like gearing have a bigger affect on 0-60 times rather than just pure power to weight, making any calculation very, very rough?

The modern Elise hits 60mph in 6. but 62 in 6.5 due to the timing of the gear change to third, which is a fair chunk.

The change point to third certainly has a big effect, a gear change with a manual box is worth nearly half a second with a good driver who isn't trying to be mechanically sympathetic, closer to a second for an average owner who cares about their car. The huge majority of cars seem to do 100kph in second these days though, probably for exactly that reason.

Edited by kambites on Thursday 11th September 20:01

[Huff]

Can't speak for simulators but my own rough and ready reckoner has long been kerb weight in kilos divided by horsepower. It's a good ballpark and BS-buster.

1050kg/200hp is indeed about 5.1s
My old E34 540 1700Kg/290hp = 5.9s; I got 6.2x a few times, so about right.
Pick something else, say a Saab NG900turbo: 1350kg, 185hp = 7.1s. And that's about right too, they were about 7.2 actual vs 6.9 claimed.
Nissan GTR? 1850Kg and 550hp, suggest 3.4s. Not too far out.


Try it - rarely more than a handful of tenths out, as it should be for cars with about-right gearing, unless the power claim is so ridiculous other things like traction or peaky delivery will get in the way. My Fisher Fury R1 - 505kg with me in it, 165hp, 3.0s suggestd. Not a hope, too difficult to launch, and too peaky.

(And anyway 0-60 is no meaasure of what makes a car 'fast' )

Edited by Huff on Thursday 11th September 20:02

[crazy about cars]

http://www.060calculator.com/


OT: Drunk plus 80s night.... https://www.youtube.com/watch?v=lcOxhH8N3Bo

[Escy]

I'd like to find one that takes into consideration the gearing. My car is RWD weighs about 1000kg and has about 270bhp at the fly. It's geared to top out at only 130mph which I think will make a sizeable difference to the 0-60 time.

[Raman Kandola]

Huff said:

Can't speak for simulators but my own rough and ready reckoner has long been kerb weight in kilos divided by horsepower. It's a good ballpark and BS-buster.

1050kg/200hp is indeed about 5.1s
My old E34 540 1700Kg/290hp = 5.9s; I got 6.2x a few times, so about right.
Pick something else, say a Saab NG900turbo: 1350kg, 185hp = 7.1s. And that's about right too, they were about 7.2 actual vs 6.9 claimed.
Nissan GTR? 1850Kg and 550hp, suggest 3.4s. Not too far out.


Try it - rarely more than a handful of tenths out, as it should be for cars with about-right gearing, unless the power claim is so ridiculous other things like traction or peaky delivery will get in the way. My Fisher Fury R1 - 505kg with me in it, 165hp, 3.0s suggestd. Not a hope, too difficult to launch, and too peaky.

(And anyway 0-60 is no meaasure of what makes a car 'fast' )

Edited by Huff on Thursday 11th September 20:02

That formula works better on petrol cars as opposed to diesals due to torque etc

[xRIEx]

eltax91 said:

Take my 'charges mx5 for example. Dyno'd at 206fwbhp

fwbhp?

[Krikkit]

kambites said:

Krikkit said:

kambites said:

Aero has relatively little effect in anything with "modern" levels of power. Driven wheels, weight distribution and power to weight ratio are probably the three most important factors.

Agree, aero means bugger all at these speeds. It's just starting to come into play at 60-80mph (hence pop-up rear wings on some cars)

If you have more than about 40bhp yes. Increases in aero efficiency will have quite a big effect on the 0-60 time of something like an Austin Seven, since the standard car is aero/power-limited to less than 60.

I wasn't really thinking of something with so little aerodynamic efficiency.

[Lawbags]

All those calculators are rubbish.

Apparently, I'll do 0-60 in 3.497 seconds. Maybe on the speedo with silly amounts of wheel spin, but in real life- no chance.

[Lawbags]

Huff said:

Can't speak for simulators but my own rough and ready reckoner has long been kerb weight in kilos divided by horsepower. It's a good ballpark and BS-buster.

1050kg/200hp is indeed about 5.1s
My old E34 540 1700Kg/290hp = 5.9s; I got 6.2x a few times, so about right.
Pick something else, say a Saab NG900turbo: 1350kg, 185hp = 7.1s. And that's about right too, they were about 7.2 actual vs 6.9 claimed.
Nissan GTR? 1850Kg and 550hp, suggest 3.4s. Not too far out.


Try it - rarely more than a handful of tenths out, as it should be for cars with about-right gearing, unless the power claim is so ridiculous other things like traction or peaky delivery will get in the way. My Fisher Fury R1 - 505kg with me in it, 165hp, 3.0s suggestd. Not a hope, too difficult to launch, and too peaky.

(And anyway 0-60 is no meaasure of what makes a car 'fast' )

Edited by Huff on Thursday 11th September 20:02

Using your method, I'll get 2.75 seconds!

[eltax91]

xRIEx said:

fwbhp?

Flywheel

[Lawbags]

swerni said:

Lawbags said:

Huff said:

Can't speak for simulators but my own rough and ready reckoner has long been kerb weight in kilos divided by horsepower. It's a good ballpark and BS-buster.

1050kg/200hp is indeed about 5.1s
My old E34 540 1700Kg/290hp = 5.9s; I got 6.2x a few times, so about right.
Pick something else, say a Saab NG900turbo: 1350kg, 185hp = 7.1s. And that's about right too, they were about 7.2 actual vs 6.9 claimed.
Nissan GTR? 1850Kg and 550hp, suggest 3.4s. Not too far out.


Try it - rarely more than a handful of tenths out, as it should be for cars with about-right gearing, unless the power claim is so ridiculous other things like traction or peaky delivery will get in the way. My Fisher Fury R1 - 505kg with me in it, 165hp, 3.0s suggestd. Not a hope, too difficult to launch, and too peaky.

(And anyway 0-60 is no meaasure of what makes a car 'fast' )

Edited by Huff on Thursday 11th September 20:02

Using your method, I'll get 2.75 seconds!

2.47 for me. Maybe we can't use a calculator

The other huge factor that these don't take into account is grip/tyres and the type of diff. Open, viscus, plated, helical or even welded.
I've just looked at one of my vids when I was dialing in launch control and yes, the speedo might hit 60 in 3 seconds or so, but the cars actual speed is no where near 60.

Has anyone actually done a GPS tested 0-60? Be good to know some real life figures compared to these calculated stats.

[Lawbags]

swerni said:

eltax91 said:

Flywheel

Good point
RWD and yes, using power at wheels it increased to 3.1 so closer.

Law bags your maths have your car weighing circa 880kg, is it stripped out!

I use 900kg. I had it on the scales at 910kg with the standard seats and I'm now running light weight buckets, so guess I'm down another 10 kg. But yes, totally stripped.

[Lawbags]

Here's it mid paint...