Mercedes Power Unit Hardware & Software

[wuzak]

You are reading the wrong things I think...

What are the actual values?

If I knew the actual values I wouldn't be able to tell you... but as it is I don't know for sure (but I know the ballpark) - but I know 65:1 is fantasy.

Wasn't the theory in here that the alpha (?) value is somewhere between 1.5 and 2?

Which would mean an AFR of between 22:1 and 29.4:1.

And the pre-chamber is probably richer than 14.7:1.

[MrPotatoHead]

That would be a lot closer to reality.
And the pre Chamber is richer for sure.

[tok-tokkie]

Why did the FIA place the restriction that there may be only 1 injector per cylinder?
It makes it very difficult to have different A/F ratios in the pre-chamber and the combustion chamber. To what purpose? Where is the injector - in the pre-chamber or in the combustion chamber? Do you believe all four manufacturers have the injector similarly positioned?

[Zynerji]

Where would the other 30% go though?

Wastegate

I think you are mixing up the hot and cold side. And your idea is very odd

Lots of ideas are very odd at first... rear mounted engine, wings, sculpted floor, DDD, tuned mass dampers, hydraulic assist suspension...

Doesn't mean that they don't have merit.

[godlameroso]

Why did the FIA place the restriction that there may be only 1 injector per cylinder?
It makes it very difficult to have different A/F ratios in the pre-chamber and the combustion chamber. To what purpose? Where is the injector - in the pre-chamber or in the combustion chamber? Do you believe all four manufacturers have the injector similarly positioned?

If it was easy everyone would do it, f1 is about pushing engineering to the limits.

I can't think of a bigger challenge than designing one direct injector that does the job of both port and DI. Not to mention the combustion chamber to go along with it.

As far as using springs over pneumatic system, it may add more friction, but @13,000rpm max, valve float shouldn't be an issue. Not to mention the pneumatic system adds weight and complexity, and is less reliable than a properly matched spring.

[MrPotatoHead]

Why did the FIA place the restriction that there may be only 1 injector per cylinder?
It makes it very difficult to have different A/F ratios in the pre-chamber and the combustion chamber. To what purpose? Where is the injector - in the pre-chamber or in the combustion chamber? Do you believe all four manufacturers have the injector similarly positioned?

Because they weren't planning around TJI. TJI was just the answerThey were trying to push F1 closer to road car tech which is DI right now.
F1 teams were already planning on switching to DI anyway back in the Port Injection days but the FIA put a limit on fuel pressure which stopped that.

[MrPotatoHead]

Why did the FIA place the restriction that there may be only 1 injector per cylinder?
It makes it very difficult to have different A/F ratios in the pre-chamber and the combustion chamber. To what purpose? Where is the injector - in the pre-chamber or in the combustion chamber? Do you believe all four manufacturers have the injector similarly positioned?

If it was easy everyone would do it, f1 is about pushing engineering to the limits.

I can't think of a bigger challenge than designing one direct injector that does the job of both port and DI. Not to mention the combustion chamber to go along with it.

As far as using springs over pneumatic system, it may add more friction, but @13,000rpm max, valve float shouldn't be an issue. Not to mention the pneumatic system adds weight and complexity, and is less reliable than a properly matched spring.

Pneumatic springs are still the answer because of valve dynamics especially Jerk.

[MrPotatoHead]

Getting back to AFR... AFR is not what we should be discussing here. Lambda is all anyone involved with serious calibration and discussions will use.
AFR is meaningless without knowing the exact fuel makeup.

[wuzak]

Why did the FIA place the restriction that there may be only 1 injector per cylinder?
It makes it very difficult to have different A/F ratios in the pre-chamber and the combustion chamber. To what purpose? Where is the injector - in the pre-chamber or in the combustion chamber? Do you believe all four manufacturers have the injector similarly positioned?

Because they weren't planning around TJI. TJI was just the answerThey were trying to push F1 closer to road car tech which is DI right now.
F1 teams were already planning on switching to DI anyway back in the Port Injection days but the FIA put a limit on fuel pressure which stopped that.

They flat out banned it!

Rule from 2011 Tech Regs
5.8.2 Only one fuel injector per cylinder is permitted which must inject directly into the side or the top of the inlet
port.

[hurril]

Wastegate

I think you are mixing up the hot and cold side. And your idea is very odd

Lots of ideas are very odd at first... rear mounted engine, wings, sculpted floor, DDD, tuned mass dampers, hydraulic assist suspension...

Doesn't mean that they don't have merit.

Well the wastegate sits on the exhaust so it cannot release hot air from the compressor.

[MrPotatoHead]

Why did the FIA place the restriction that there may be only 1 injector per cylinder?
It makes it very difficult to have different A/F ratios in the pre-chamber and the combustion chamber. To what purpose? Where is the injector - in the pre-chamber or in the combustion chamber? Do you believe all four manufacturers have the injector similarly positioned?

Because they weren't planning around TJI. TJI was just the answerThey were trying to push F1 closer to road car tech which is DI right now.
F1 teams were already planning on switching to DI anyway back in the Port Injection days but the FIA put a limit on fuel pressure which stopped that.

They flat out banned it!

Rule from 2011 Tech Regs
5.8.2 Only one fuel injector per cylinder is permitted which must inject directly into the side or the top of the inlet
port.

But before that (~2005) they limited the pressure which killed the idea.

[Tommy Cookers]

F1 teams were planning on switching to DI .......

of course
Mercedes-Benz won the WDC in 1954 and 1955 with Bosch DI and Ferrari won the F1 WDC in 1964 with Bosch DI
though Vanwall's 1958 WCC win etc used Bosch PI
(and thousands of 1950s road cars used Bosch DI)

[Zynerji]

I think you are mixing up the hot and cold side. And your idea is very odd

Lots of ideas are very odd at first... rear mounted engine, wings, sculpted floor, DDD, tuned mass dampers, hydraulic assist suspension...

Doesn't mean that they don't have merit.

Well the wastegate sits on the exhaust so it cannot release hot air from the compressor.

That's fine, it can vent to atmo. It's just hot air.

[hurril]

Lots of ideas are very odd at first... rear mounted engine, wings, sculpted floor, DDD, tuned mass dampers, hydraulic assist suspension...

Doesn't mean that they don't have merit.

Well the wastegate sits on the exhaust so it cannot release hot air from the compressor.

That's fine, it can vent to atmo. It's just hot air.

Right but there are rules here. I might be misunderstanding something but I _think_ that expelled air will have to be ducted into the intake before the turbo. This is probably an attempt at doing away with creative "blown aero" but I have probably just misstaken something. But I wonder if the rules don't state something along the lines of: air entering the compressor must only ever be expelled through the exhaust. Now, having the compressor ingesting that 30% amount of hot air again nullifies this business of bleeding the hot air with fancy tubes.

[PlatinumZealot]

What are the actual values?

If I knew the actual values I wouldn't be able to tell you... but as it is I don't know for sure (but I know the ballpark) - but I know 65:1 is fantasy.

Wasn't the theory in here that the alpha (?) value is somewhere between 1.5 and 2?

Which would mean an AFR of between 22:1 and 29.4:1.

And the pre-chamber is probably richer than 14.7:1.

Yup. This range is about where i have the numbers too. 21 AFR and slightly higher. 65 afr is just unchecked famtasy.

That vortex cooling thing looks too lossy. And why whould you do that and the rules say you have to send all the air from the compressor into the engine?

There is still a great advantage from running cooler air into th engine. More oxygen and easier compression. No reason to run hot air when you have direct injection. Besides, the better your intercooler is, the smaller you can make it. The teams always struggle with cooling on the edge to get the best aerodynamics.