Help creating formula for potential laptimes when I go racing

[mabratley]

Hi,

Im after a formula to find out my potential laptimes when i go racing, i know its not perfect because there are many factors, but im jst after a rough figure.


Heres what ive tried so far:
My car has a power to weight ratio of 157.27bhp/tonne (a)
Th leaders car has 164.71bhp/tonne (x)
My laptime was 2.10.3 so 130.3 seconds (b)
His laptime was 1.54.6 so 114.6 seconds (y)

so my equation was:
b/a=1.207 (c)
y/x=1.437 (z)

then:

a/z=109.979 or 1 minute 41 secs roughly
but if i do this:
x/c=137.258 or 2 minutes 17 secs roughly,
which makes no sense as it should be quicker than the time in my car

Any help would be appreciated, thank you

 

[stapel]

Im after a formula to find out my potential laptimes when i go racing....

My car has a power to weight ratio of 157.27bhp/tonne (a)
Th leaders car has 164.71bhp/tonne (x)
My laptime was 2.10.3 so 130.3 seconds (b)
His laptime was 1.54.6 so 114.6 seconds (y)

so my equations were:
b/a=1.207 (c)
y/x=1.437 (z)

then:

a/z=109.979 or 1 minute 41 secs roughly

but if i do this:

x/c=137.258 or 2 minutes 17 secs roughly

What was the logic by which you derived these equations?

 

[mabratley]

I was thinking if the leader is using x amount of bhp/tonne a second, then if i was to do the same i wanted to know my laptime. Its probably completly wrong and stupid idea thinking it could be possible to work it out

 

[stapel]

I was thinking if the leader is using x amount of bhp/tonne a second, then if i was to do the same i wanted to know my laptime. Its probably completly wrong and stupid idea thinking it could be possible to work it out

To have the same brake-horsepower, wouldn't you need to alter your current vehicle, or obtain a different one? I mean, isn't this a property of the actual machines in play?

Also, are you taking torque into account at all? Aficionados seem to consider other factors to be relevant, also.

 

[Ishuda]

Hi,

Im after a formula to find out my potential laptimes when i go racing, i know its not perfect because there are many factors, but im jst after a rough figure.


Heres what ive tried so far:
My car has a power to weight ratio of 157.27bhp/tonne (a)
Th leaders car has 164.71bhp/tonne (x)
My laptime was 2.10.3 so 130.3 seconds (b)
His laptime was 1.54.6 so 114.6 seconds (y)

so my equation was:
b/a=1.207 (c)
y/x=1.437 (z)

then:

a/z=109.979 or 1 minute 41 secs roughly
but if i do this:
x/c=137.258 or 2 minutes 17 secs roughly,
which makes no sense as it should be quicker than the time in my car

Any help would be appreciated, thank you

What were you expecting of your equation [bhp per tonne divided by lap time]. If you were expecting it to be about constant, then what you would be saying is that the more bhp increases the more lap time increases which, as you mention, doesn't make sense. One should expect, I think, that the more bhp increases, the more lap time decreases which might be something like
(1) lap time * bhp ~ constant [maybe just for a and b over a small range]
or maybe
(2) lap time ~ constant1 / bhp + constant2
Formula (2) has the 'advantage' that you could compute both constants [constant1 ~ 54663, constant2 ~ -217.3] to make the formula true for the data you have. Of course that is also true of many other equations you could make up.

 

[Dale10101]

A line of thought

I was thinking if the leader is using x amount of bhp/tonne a second, then if i was to do the same i wanted to know my laptime. Its probably completly wrong and stupid idea thinking it could be possible to work it out

This is a line of thought, am not an expert, someone else might correct my thinking entirely, i.e don’t go investing in hi performance cams and jacking up your compression ratio yet.

His car puts out (164.71)/ 157.27) = 1.047 times more bhp,

and delivers (130.3/114.6) = 1.147 times the performance in lap time, that is to say he is 14.7 % faster.

1.147/1.047 = 1.096 which normalizes his lap performance at your horse power, he is still going to be 9.6 % faster.

Why would that be since you are both putting the same amount of power into the same amount of mass-weight,1 ton? His machine must be more efficient, has fewer retarding forces, wind resistance, internal friction, better tires, gas, etc.

Now if you jacked your engine to match his horsepower you will improve your time but still be 9.6% slower, your time would be:

(his time)(1.096) = (114.6)(1.096) = 125.6 seconds/lap

To equal his time you would need 9.6% more bhp then his, or,

(164.71)(1.096) = 180.5 bph.

(?)

 

[mabratley]

This is a line of thought, am not an expert, someone else might correct my thinking entirely, i.e don’t go investing in hi performance cams and jacking up your compression ratio yet.

His car puts out (164.71)/ 157.27) = 1.047 times more bhp,

and delivers (130.3/114.6) = 1.147 times the performance in lap time, that is to say he is 14.7 % faster.

1.147/1.047 = 1.096 which normalizes his lap performance at your horse power, he is still going to be 9.6 % faster.

Why would that be since you are both putting the same amount of power into the same amount of mass-weight,1 ton? His machine must be more efficient, has fewer retarding forces, wind resistance, internal friction, better tires, gas, etc.

Now if you jacked your engine to match his horsepower you will improve your time but still be 9.6% slower, your time would be:

(his time)(1.096) = (114.6)(1.096) = 125.6 seconds/lap

To equal his time you would need 9.6% more bhp then his, or,

(164.71)(1.096) = 180.5 bph.

(?)

Thats exactly what i was after, thank you. Just so ive got a general idea of what my car is capable of roughly which is 11 secs. Most of which is probably down to me as im a rookie (1 test session, quali and race)

 

[Dale10101]

Thats exactly what i was after, thank you. Just so ive got a general idea of what my car is capable of roughly which is 11 secs. Most of which is probably down to me as im a rookie (1 test session, quali and race)

You're welcome, good luck, stick with race car driving, don't buy one of the new "Hoverboards".