Think I surprised an M4 driver.......

[techathy]

Yeah and the power gain isn't where the biggest performance differential between dyno & factory published torque curves.

 

[ronk]

Your mixing your data sources and analysis of that "data"

No I'm not. I'm actually ignoring peek torque as it's a useless comparison due to the rev-range differentials of the 35d & 35iS engines. I'm also not look at peek power with much significance as that's more to do with top speed. I'm using a comparison which is the amount of work the engine is capable of doing over the entire rev range. I'm then backing up that theoretical advantage with real-world measured performance.

You can't look at area under a torque curve like that!

 

[techathy]

Your mixing your data sources and analysis of that "data"

No I'm not. I'm actually ignoring peek torque as it's a useless comparison due to the rev-range differentials of the 35d & 35iS engines. I'm also not look at peek power with much significance as that's more to do with top speed. I'm using a comparison which is the amount of work the engine is capable of doing over the entire rev range. I'm then backing up that theoretical advantage with real-world measured performance.

You can't look at area under a torque curve like that!

Yes you can and it's a very useful tool for gauging all round performance. When you get cars that have unexplained performance advantages from peek numbers it becomes clear from such metrics why.

What this does is defines is how much work can be done. Peek power defines the maximum amount of work that can be done.

 

[ronk]

Horse power = work done
Torque = Force

That's a fundamental of mechanics I'm afraid !

 

[techathy]

And... your point is you don't understand what I'm saying?

By using peek numbers all you're doing is saying what the maximum amount of force applied to the gearbox is and the maximum amount of work the engine can do a very particular points in the rev range are. Both completely ignore that acceleration for a prolonged pull is based on how much total thrust is produced at the wheels over a wide speed, thus rpm, range.

 

[ronk]

Torque is a force - it varies as the rpm changes - that is why it is measured along the curve.

Horse power is the amount of work in a period of time.

Those rules cannot be changed to suit the automotive world

 

[Garvin]

Yeah and the power gain isn't where the biggest performance differential between dyno & factory published torque curves.

What engine are these curves for and are the torque/power at wheel or corrected for flywheel?

 

[Axelf]

Wow .... I did not know this post was going to turn like this all I said was I think I surprised an M4 driver

 

[R.E92]

Would be nice to plot the actual wheel torque and horsepower of both the diesel and petrol against each other taking into consideration the road speed just to put the real picture down.

I have a spreadsheet on my other PC of the 7DCT gear ratios and the road speed calc for when I upped my tire sizes but sadly can't get hold of it just now. I'd just need the gear ratios for the 335d and the final drive and I could plot it up pretty quick.

It's hard to explain to diesel users that crank torque is a useless measurement.

 

[R.E92]

Wow .... I did not know this post was going to turn like this all I said was I think I surprised an M4 driver

It's gone off-topic a little but I think it's a good discussion!

 

[ronk]

Wow .... I did not know this post was going to turn like this all I said was I think I surprised an M4 driver

What starts as "send re enforcements we are going to advance ends up as "send three and fourpence we are going to a dance"

 

[Axelf]

cool

 

[ronk]

It's hard to explain to diesel users that crank torque is a useless measurement.

I hope you will try !

When manufacturers publish their figures it's only at the crank numbers they give isn't it?

 

[techathy]

Yeah and the power gain isn't where the biggest performance differential between dyno & factory published torque curves.

What engine are these curves for and are the torque/power at wheel or corrected for flywheel?

The orange graph is wheel torque from my Z4 35iS. The blue one is BMWs graph reduced by the mean estimate rolling resistance from my Z4.

 

[techathy]

Would be nice to plot the actual wheel torque and horsepower of both the diesel and petrol against each other taking into consideration the road speed just to put the real picture down.

I have a spreadsheet on my other PC of the 7DCT gear ratios and the road speed calc for when I upped my tire sizes but sadly can't get hold of it just now. I'd just need the gear ratios for the 335d and the final drive and I could plot it up pretty quick.

It's hard to explain to diesel users that crank torque is a useless measurement.

35iS 3rd vs 335d 4th is a nice one to show the advantage the 35iS holds. The graphs are taken from wheel output.

EDIT: oops! best make the 335d 1705kg not 1507kg

 

[R.E92]

Would be nice to plot the actual wheel torque and horsepower of both the diesel and petrol against each other taking into consideration the road speed just to put the real picture down.

I have a spreadsheet on my other PC of the 7DCT gear ratios and the road speed calc for when I upped my tire sizes but sadly can't get hold of it just now. I'd just need the gear ratios for the 335d and the final drive and I could plot it up pretty quick.

It's hard to explain to diesel users that crank torque is a useless measurement.

35iS 3rd vs 335d 4th is a nice one to show the advantage the 35iS holds. The graphs are taken from wheel output.

EDIT: oops! best make the 335d 1705kg not 1507kg

That perfect!

At 100kph the 335d needs to be in 3rd whereas the 35is is still holding 2nd and producing a shed load more torque to the wheels thanks to the gear ratio.

If that doesn't convince them then there's always the video evidence, albeit against a much slower 335i.

https://www.youtube.com/watch?v=fjKLSBl8CV0

 

[techathy]

And now add over-boost into the equation:

I've only got a partial curve for that because you need an up change with the throttle in kick down.

 

[Garvin]

Yeah and the power gain isn't where the biggest performance differential between dyno & factory published torque curves.

What engine are these curves for and are the torque/power at wheel or corrected for flywheel?

The orange graph is wheel torque from my Z4 35iS. The blue one is BMWs graph reduced by the mean estimate rolling resistance from my Z4.

I was going to query whether this was using over boost but you've answered that in other posts. That is quite a margin over what BMW quote!

 

[stuartinzg]

What engine are these curves for and are the torque/power at wheel or corrected for flywheel?

The orange graph is wheel torque from my Z4 35iS. The blue one is BMWs graph reduced by the mean estimate rolling resistance from my Z4.

I was going to query whether this was using over boost but you've answered that in other posts. That is quite a margin over what BMW quote!

370 is about right, poster above proved it with a real rolling road, mine was a road based rolling road, but spot on 370~

 

[techathy]

Heard once that running 95 unleaded reduces output by 3-4%. That gives an estimated 446Nm +5% (limit of perception) at 1300~4550 on my car. BMW rated it on 95RON?