2014-2020 Formula One 1.6l V6 turbo engine formula

[Holm86]

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But 2-4 bars of boost incl atmospheric pressure means 3-5 absolute pressure. So 2-2.5 absolute pressure does not fit in.

I'm afraid you got it a tad confused, Marmorini said "2-4 bar including atmosphere", which means 2-4 bar absolute or 1-3 bar boost.

Sorry yes I got a bit confused

[Holm86]

By fast calculation I get 2.25 bars of boost at 10.500 rpm's with 27,7g/s of fuel at stoichiometric AFR.

Boost would then decrease after 10.500 rpm's to 1.6 bars of boost at 15.000 rpm's.

[xpensive]

By fast calculation I get 2.25 bars of boost at 10.500 rpm's with 27,7g/s of fuel at stoichiometric AFR.

Boost would then decrease after 10.500 rpm's to 1.6 bars of boost at 15.000 rpm's.

2.25 bar boost (3.25 bar absolute) at 10 500 rpm, isn't that a bit on the high side?

[Holm86]

By fast calculation I get 2.25 bars of boost at 10.500 rpm's with 27,7g/s of fuel at stoichiometric AFR.

Boost would then decrease after 10.500 rpm's to 1.6 bars of boost at 15.000 rpm's.

2.25 bar boost (3.25 bar absolute) at 10 500 rpm, isn't that a bit on the high side?

You would need relative high boost when the engine capacity is that small?

EDIT* Again with a bit confusion. Shouldnt do this while at work

The 2,25 and 1,6 bar is absolute pressure.

[munudeges]

When are you going to show it to the public, that Ferrari V6?
Never...

[xpensive]

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EDIT* Again with a bit confusion. Shouldnt do this while at work

The 2,25 and 1,6 bar is absolute pressure.

That is more realistic, considering that Honda's 1988 1.5 turbo V6 was some 675 Hp at 2.5 bar absolute and 12 500 rpm.

[Holm86]

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EDIT* Again with a bit confusion. Shouldnt do this while at work

The 2,25 and 1,6 bar is absolute pressure.

That is more realistic, considering that Honda's 1988 1.5 turbo V6 was some 675 Hp at 2.5 bar absolute and 12 500 rpm.

Yes. But this is at stoichiometric ratio. I feel they will run a bit richer. Which in this case just means less air. No reason to run higher boost than necessary when i doesnt hurt performance.

And its a bit difficult to predict the turbo pressure because it will change according altitude, temperature and intercooler efficiency.

[matt21]

Maybe a diagramm shown a time ago helps here.

I think this image is deliberately misleading, the driven turbine's outlet and the intake-plenum's inlet indicates there will be an intercooler in between, but nobody would place the inlet like that? I believe at this low boost, some 0.7 Bar, there is no need for an intercooler, why we will see the turbo-outlet feeding directly between the two plenums.

1) Why would a low boost engine need such a large turbo spinning at 200,000 rpm?

2) Why is there such a large airbox leading to the turbine inlet?

The engine should be around 600 to 700 mm wide. So the turbo seems not so big to me.

The max fuel flow of 100 kg/hr equals 1470 kg of air per hour with an AFR of 1.
For maximum power you have an AFR of around 0.9, what equals 1323 kg/hr of air.

This is around 1100 m³/hr or 18.4 m³/min. or in other words really a lot at max rpm.

With 1 bar absolute you can do 11.25 m³/min at 15.000 rpm.
So if I calculate 18.4/11.25 I come to around 1.6 bar absolute.

Edit: Please note that this calculation is based on the same charge air temperature for both cases. If you raise the temperature the pressure will also rise.

[Holm86]

That seems to confirm my own calculations of 2.25 bar @ 10.500 rpm and 1.6 bar @ 15.000 rpm.

[xpensive]

Ooops...I guess I was to early to call on the intercooler back then. At a 1.3 Bar boost, they will obviously need one,
but perhaps not of the size Renault have displayed?

I think.

[Tommy Cookers]

aren't all these calculations (of induction pressure) for a simple turbocharged engine ? (no recovery)

the figure of 2.25 bar abs (for a turbocharged engine) demands around 60 hp, this is about the limit of 'free' power
here we are to recover from the exhaust stream substantial power beyond that needed for the supercharging
so the induction pressure would need to be significantly higher than 2.25 bar abs ??

[matt21]

I think, that there is no differnce between for the boost with or without recovery as it is based on the needed air volume for the maximum fuel flow.

The recovery leads to a higher back pressure which is decreasing the power at the crankshaft due to higher work needed for expelling exhaust gases. With a higher boost you can help the engine by pushing exhaust gases out by fresh air during valve overlap by maintaining a positive pressure ratio p2/p3.

[xpensive]

I think, that there is no differnce between for the boost with or without recovery as it is based on the needed air volume for the maximum fuel flow.
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That is indeed a reasonable assumption matt21.

[Holm86]

I think, that there is no differnce between for the boost with or without recovery as it is based on the needed air volume for the maximum fuel flow.

The recovery leads to a higher back pressure which is decreasing the power at the crankshaft due to higher work needed for expelling exhaust gases. With a higher boost you can help the engine by pushing exhaust gases out by fresh air during valve overlap by maintaining a positive pressure ratio p2/p3.

I agree that boost has nothing to do with recovery. The boost is calculated by the air needed to burn the 27.77g/s of fuel @ 10.500 rpm.

Though on an ordinary turbo engine the boost is regulated by a wastegate expelling excess exhaustgasses when the maximum turbo boost is reached. With the MGU-H you are going to slow down the turbine axle with the braking effect caused by the generator instead.

This will cause increased backpressure though. And as you say this can harm engine effect. You suggest using intake air to help remove the exhaust gasses via valve overlap. But this will slightly reduce VE% right?? Which means that the boost need to be slightly higher than without overlap.

And the optimal would be to have this overlap only when maximum boost is reached. Which is why VVT could be usefull in these engines.

[matt21]

I think there is a quite large amount of overlap already in the engines. I looked for a timing diagram but wasn´t sucessful. If anybody could provide this would be helpful.

What I ment was that you could help the engine breathing by maintaining a higer delta p. But this would affect recovery as you have less energy for the generator. So it is little bit of a cat biting in its own tail.
I think they need very clever control strategies for the recovery.

High back pressure leads to high combustion chamber temperature which leeds to higher risk of knocking.

In general, these engines are threatened more by knocking, as they have lower revs.