If you had a car with a known starting bhp and a known 0-60 time, you tuned it and got a faster 0-60. Is there a formula to calculate the power increase?

Eg
200bhp gives 0-60 in 10 seconds
???bhp gives 0-60 in 8.5 seconds (1.5 seconds and 15% quicker)

You’d have to make some assumptions regarding the torque curve of the engine. Peak power only refers to one operating point of the engine which you don’t operate at constantly during a 0-60 sprint

I’m going to go with no. Too many other variables; mainly differing masses of vehicles, differing aerodynamic coefficients, differing transmission losses. Get thee to the rolling road if you’re bothered by figures.

Too many unknowns. The trouble is bhp as a number is just the peak. You could add a load of low down torque which would improve 0 to 60 but have no impact on peak bhp. You could maybe estimate a bit based on a linear power curve but it won’t be accurate.

Could you look at the torque made during the 0-60 sprint and use an average for this in your equation?

Yes.

But for the general public it’d be cheaper and easier to just pay for rolling road time.
It’s about a years work to create the model you need from scratch. Could probably do a half arsed one in 3 months. If you knew exactly what you were doing.

Looking at the interval splits 20-30, 30-40 etc the improvement is pretty even across them suggesting to me that the % increase was spread evenly across the Rev range so I was hoping it would a simpler equation.

Test were actually 20-80mph to avoid wheel spin or overloading the transmission. Private road. About 0.2 of a second improvement for each interval, I little more at higher speeds

Automatic transmission if that affects anything.

Simply put, torque gives acceleration, power gives top speed, so just knowing power won’t help with acceleration times. However power and torque are related, but you would need more info than you have supplied to predict numbers…

Automatic transmission if that affects anything.

😀

Yeah, makes it far harder to calculate!

Though as the simplest possible back-of-envelope scribble (not likely to be strongly linked to reality, just because I thought it was interesting to do):

A 1500kg car doing 60mph has 614328J kinetic energy.

If that accelerates from a standing start in 10s, KE is being increased at a rate of 82.4bhp (61.4kW). In 8.5s, 96.9bhp.

To tell the truth, that’s more efficient that I thought it would be – given these are pretty realistic values for power and car mass etc. Then engine is still doing work to overcome wind resistance, mechanical resistance etc. but more power than I thought is going into accelerating the car.

Unless I’ve messed up a decimal point somewhere, in which case all bets are off.

Edit, as an addendum – the difference in k energy between the car doing 20mph and 80 mph is 1,023,881J. – so you’ll have to scale powers appropriately.

WorldClassAccident – Member

If you had a car with a known starting bhp and a known 0-60 time, you tuned it and got a faster 0-60. Is there a formula to calculate the power increase?

Eg
200bhp gives 0-60 in 10 seconds
???bhp gives 0-60 in 8.5 seconds (1.5 seconds and 15% quicker)

Even if you could what would you gain? (bragging rights?) Peak power isn’t a great indicator of driveability, nor is a 0-60 time. Even a dyno figure is speculative unless it’s an engine dyno. Make a guess, add 10% for your mates, then enjoy your extra power.

What would I gain?

Absolutely nothing, just curious if it could be worked out. This car is about the 200bhp mark so it is my other car with bragging rights.

I have done various tweaks as described in this video : https://www.youtube.com/watch?v=fARuk-nx3Pw

I was wondering if it was possible to calculate anything more meaningful that dropping 1.5 seconds* off the accelerations duration.

*Haven’t a video of the car after swapping inlet manifolds but that took it down to 8:38 so 1.5 seconds near as matters

200bhp gives 0-60 in 10 seconds
???bhp gives 0-60 in 8.5 seconds (1.5 seconds and 15% quicker)

How accurately can you measure your 0-60? For every 0.1s you are out it will screw the calcs up

Check the video. There are several others showing the earlier test runs on a private road.

I calculate the time by creeping the frames forward until the speedo reaches the mark on the dial. I accept the speedo might be wrong but as I am only looking at relative improvement it shouldn’t matter.

I am guessing it might be valid on an electric powered vehicle operating in a vacuum 🙂

otherwise too many variables

You just need to go on to a car forum and ask. They’ll be able to tell you exactly how many bhp you got just by listening to the exhaust note.

😉

How many horse power do you reckon this mod got me?