24 replies to this topic

[IronmanG]

Is there a tool anyone knows of that calculates the acceleration of a car?
So for example your mini has 75 hp, 75 torques and a 3.4 fd. Weight is 750kg.
If you had a 2.9 all other things being equal, how much slower would it accelerate?

[sonscar]

i find there are many variables,changing gear is the main loss.Being able to hold longer/go further before changing is sometimes advantageous.Of course you might only be interested in top gear acceleration.A calculator can only do so much,is the torque/hp peaky?is it flat?does it come in early or only at the top?Curious myself,Steve..

[IronmanG]

i find there are many variables,changing gear is the main loss.Being able to hold longer/go further before changing is sometimes advantageous.Of course you might only be interested in top gear acceleration.A calculator can only do so much,is the torque/hp peaky?is it flat?does it come in early or only at the top?Curious myself,Steve..

Absolutely there are lots of variables. There must be a nerd who has figured it out.
If you have 120 torques with a 2.9 but can only rev to 6000 vs a NA 7500 screamer with 90 torques and a 3.4 which will have the fastest 1/4 mile.

Edited by IronmanG, 31 August 2022 - 03:43 PM.

[stuart bowes]

If you put two 'identical' cars next to each other on the 1/4 mile and race them 10 times, I reckon the outcome would be different each time, driver reaction time off the line, grip, how much you care about your gearbox, how violently and exactly when you change gear...

 

this is why 1/4 mile times and 0-60 are only really vague guidelines, they're never definitive points of comparison

Edited by stuart bowes, 31 August 2022 - 03:56 PM.

[IronmanG]

If you put two 'identical' cars next to each other on the 1/4 mile and race them 10 times, I reckon the outcome would be different each time, driver reaction time off the line, grip, how much you care about your gearbox, how violently and exactly when you change gear...

this is why 1/4 mile times and 0-60 are only really vague guidelines, they're never definitive points of comparison

Again I agree. So it must be assumed that all things other than torques and ratio and rev limit are the same

[PoolGuy]

Courtesy, demo, hire, press cars are always quicker than a car that you own. Joking aside, yes there are calculations that you can do, but you need the coefficient of drag number, which will be almost impossible to find for anything other than a standard car.

[IronmanG]

Courtesy, demo, hire, press cars are always quicker than a car that you own. Joking aside, yes there are calculations that you can do, but you need the coefficient of drag number, which will be almost impossible to find for anything other than a standard car.

Another variable. As long as its the same for both it matters not.

[PoolGuy]

Give this a go https://www.omnicalc...ryday-life/0-60

[IronmanG]

Ye I tried that one. Apparently 150hp is quicker than 100hp 🤔👍😅😅😅
Need one that brings gear ratios and rev limits into but nothing else
Must be a budding mathematician on here

[PoolGuy]

Ye I tried that one. Apparently 150hp is quicker than 100hp
Need one that brings gear ratios and rev limits into but nothing else
Must be a budding mathematician on here

But fwd v rwd doesn't affect things

[IronmanG]

Let's assume you have 2 minis
I has a 2.7fd supercharged and 160 hp under your right foot

Car 2 is 3.1 NA with 120 hp.
Which will get to 100mph quicker.
They both have to change gear the same number of times so its just down to which has the best ability to turn the wheels at that gear ratio they have.
The torque in SC car is massive compared to the NA but does the length of gears make it too slow to accelerate in comparison
And wheelspin, tyre size, drag, colour of paint has no bearing on the outcome! They are assumed to be the same for both cars

Edited by IronmanG, 31 August 2022 - 04:46 PM.

[KTS]

Is there a tool anyone knows of that calculates the acceleration of a car?
So for example your mini has 75 hp, 75 torques and a 3.4 fd. Weight is 750kg.
If you had a 2.9 all other things being equal, how much slower would it accelerate?

 

i'm neither a mathematician nor an engineer (..as i may be about to demonstrate !), but as acceleration is a function of engine torque, and gears/gearboxes are in essence torque multipliers, then, all other things being equal, won't changing from a 3.4 to 2.9 fd result in 15% less torque at the driven wheel ?

[IronmanG]

Is there a tool anyone knows of that calculates the acceleration of a car?
So for example your mini has 75 hp, 75 torques and a 3.4 fd. Weight is 750kg.
If you had a 2.9 all other things being equal, how much slower would it accelerate?

i'm neither a mathematician nor an engineer (..as i may be about to demonstrate !), but as acceleration is a function of engine torque, and gears/gearboxes are in essence torque multipliers, then, all other things being equal, won't changing from a 3.4 to 2.9 fd result in 15% less torque at the driven wheel ?

Ah ok. So as long as the output is more than 15% more on the SC car it will accelerate quicker. In theory

[Turbo Phil]

Torque is not measured in “torques”, but usually in FT/LB or NM.

Phil.

[IronmanG]

Torque is not measured in “torques”, but usually in FT/LB or NM.

Phil.

Yes I know, its my tribute to Jeremy the doughnut Clarkson