Page 140 of 216
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 04:27
by godlameroso
MrPotatoHead wrote: ↑19 Apr 2018, 03:46
godlameroso wrote: ↑19 Apr 2018, 00:35
MrPotatoHead wrote: ↑18 Apr 2018, 21:26
Peak torque is unlikely to happen under 10,500 because of the fuel flow limitations.
Most cars I tune peak torque happens long before the injectors reach peak duty cycle(~85%), I'm not saying that peak torque is at 7k rpm but not at exactly 10,500, maybe ~9,200k rpm.
But remember this is not a fuel flow unlimited engine.
There is a linear fuel ramp up until you hit 10,500 then it’s flat right?
Yes this is true, the fuel curve ramps up with RPM. Even then as these cars exceed the lean limit by default and highest power is still somewhere near theoretical lambda 1, I thought that max fuel flow wouldn't necessarily coincide with max power. I could be mistaken, but it was just a hunch I've had for a few years.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 04:29
by MrPotatoHead
godlameroso wrote: ↑19 Apr 2018, 04:27
MrPotatoHead wrote: ↑19 Apr 2018, 03:46
godlameroso wrote: ↑19 Apr 2018, 00:35
Most cars I tune peak torque happens long before the injectors reach peak duty cycle(~85%), I'm not saying that peak torque is at 7k rpm but not at exactly 10,500, maybe ~9,200k rpm.
But remember this is not a fuel flow unlimited engine.
There is a linear fuel ramp up until you hit 10,500 then it’s flat right?
Yes this is true, the fuel curve ramps up with RPM. Even then as these cars exceed the lean limit by default and highest power is still somewhere near theoretical lambda 1, I thought that max fuel flow wouldn't necessarily coincide with max power. I could be mistaken, but it was just a hunch I've had for a few years.
It is a complex formula especially if you take into account the combined ICE + ERS Power... the KERS could very well be doing torque fill to any degree under max flow and thus it’s teally hard to predict.
It would make a good discussion over beer for sure
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 04:32
by godlameroso
MrPotatoHead wrote: ↑19 Apr 2018, 04:29
godlameroso wrote: ↑19 Apr 2018, 04:27
MrPotatoHead wrote: ↑19 Apr 2018, 03:46
But remember this is not a fuel flow unlimited engine.
There is a linear fuel ramp up until you hit 10,500 then it’s flat right?
Yes this is true, the fuel curve ramps up with RPM. Even then as these cars exceed the lean limit by default and highest power is still somewhere near theoretical lambda 1, I thought that max fuel flow wouldn't necessarily coincide with max power. I could be mistaken, but it was just a hunch I've had for a few years.
It is a complex formula especially if you take into account the combined ICE + ERS Power... the KERS could very well be doing torque fill to any degree under max flow and thus it’s teally hard to predict.
It would make a good discussion over beer for sure
I hadn't even considered the darn ERS, that opens up another can of worms entirely for sure.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 04:34
by MrPotatoHead
Indeed. This is why I keep reminding people how complex and interesting these engines are.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 04:51
by MrPotatoHead
As a reminder this is what Cosworth predicted the power and torque curves to look like in 2014:
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 05:55
by johnny comelately
That is a very telling graph.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 06:44
by godlameroso
It is, it's just off by about 230hp.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 07:32
by gruntguru
If fuel efficiency was constant throughout the operating range, injector duty cycle (which is proportional to fuel flow) would be proportional to power. Torque would be proportional to fuel flow per cycle ie injector pulsewidth.
The fuel flow formula for F1 (if efficiency was constant) would produce constant maximum power from 10,500 to 15,000 rpm. Torque would be falling rapidly in this region ie the red curve in the chart below would be power and green would be torque.
Below 10,500 the formula is 0.009 x rpm + 5 kg.hr which will obviously produce rising power but again falling torque due to the "+5" term which means that even at zero rpm, the engine can consume 5 kg/hr and produce infinite torque.
Obviously the assumptions are not valid but the point is that torque is likely to be maximum at around 10,500 and is very flat and probably slightly higher below this speed.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 07:35
by gruntguru
There is no torque curve there.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 07:37
by NL_Fer
MrPotatoHead wrote: ↑19 Apr 2018, 04:34
Indeed. This is why I keep reminding people how complex and interesting these engines are.
Still funny allot of people talk about the bhp as a static number. Team A is 25bhp down on B. When in reality, team A could find some energy and let the MGU-K start earlier on, they would still have the same peak bhp, but be faster on track.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 10:41
by henry
Having previously calculated a power curve for the Ferrari ICE so I calculated a torque curve.
It rises by about 5% from 10600 rpm to 11200 rpm and then falls away reducing by 15% by 11900.
The torque and power peaks pretty much coincide at 11200 rpm.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 11:37
by johnny comelately
henry wrote: ↑19 Apr 2018, 10:41
Having previously calculated a power curve for the Ferrari ICE so I calculated a torque curve.
It rises by about 5% from 10600 rpm to 11200 rpm and then falls away reducing by 15% by 11900.
The torque and power peaks pretty much coincide at 11200 rpm.
Is that in the ferrari thread or could you pop that up?
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 12:18
by henry
johnny comelately wrote: ↑19 Apr 2018, 11:37
henry wrote: ↑19 Apr 2018, 10:41
Having previously calculated a power curve for the Ferrari ICE so I calculated a torque curve.
It rises by about 5% from 10600 rpm to 11200 rpm and then falls away reducing by 15% by 11900.
The torque and power peaks pretty much coincide at 11200 rpm.
Is that in the ferrari thread or could you pop that up?
It starts here
viewtopic.php?f=4&t=9259&start=9015
There are a few discussion points over the next few pages. For instance refinement to use rotational inertia as well as mass in the calculations.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 12:30
by johnny comelately
henry wrote: ↑19 Apr 2018, 12:18
johnny comelately wrote: ↑19 Apr 2018, 11:37
henry wrote: ↑19 Apr 2018, 10:41
Having previously calculated a power curve for the Ferrari ICE so I calculated a torque curve.
It rises by about 5% from 10600 rpm to 11200 rpm and then falls away reducing by 15% by 11900.
The torque and power peaks pretty much coincide at 11200 rpm.
Is that in the ferrari thread or could you pop that up?
It starts here
viewtopic.php?f=4&t=9259&start=9015
There are a few discussion points over the next few pages. For instance refinement to use rotational inertia as well as mass in the calculations.
OK, thank you, I see its the previous discussion we had about this matter.
Re: Renault V6 Power Unit
Posted: 19 Apr 2018, 12:40
by johnny comelately
gruntguru wrote: ↑19 Apr 2018, 07:32
If fuel efficiency was constant throughout the operating range, injector duty cycle (which is proportional to fuel flow) would be proportional to power. Torque would be proportional to fuel flow per cycle ie injector pulsewidth.
The fuel flow formula for F1 (if efficiency was constant) would produce constant maximum power from 10,500 to 15,000 rpm. Torque would be falling rapidly in this region ie the red curve in the chart below would be power and green would be torque.
Below 10,500 the formula is 0.009 x rpm + 5 kg.hr which will obviously produce rising power but again falling torque due to the "+5" term which means that even at zero rpm, the engine can consume 5 kg/hr and produce infinite torque.
Obviously the assumptions are not valid but the point is that torque is likely to be maximum at around 10,500 and is very flat and probably slightly higher below this speed.
https://i.imgur.com/Bcf2EzO.png
Right up front I have to apologise for this but I am struggling with the graph.
using the diesel line can you covert or add a lambda line, partic for the lower revs, i get the go leaner at 10.5K+ rpm by max allowed?