Mercedes Power Unit Hardware & Software

[roon]

It can probably be roughly calculated from known formulas, but I'm ignorant of them. The Merc compressor does look big in photos, but I think this is at least partly to do with volute design.

A better image of a compact volute. You can see that the diffuser section is contained within the volute.

http://i.imgur.com/CR46bir.jpg

That video clearly shows a compressor housing at the front of the engine. What is especially interesting is the A/R ratio of the compressor housing. It has a very large diameter. The turbine housing is much smaller in comparison . . . .

It is difficult to judge the A/R visually. The reason the Mercedes compressor looks so big is that the diffuser is radial. Most turbocharger compressor housings are "folded (rolled)" to reduce the outside dimension. Mercedes packaging has allowed them to avoid this step. Here is a comparison of the two shapes.

http://i.imgur.com/E5m4esT.png

When Merc said that the diesel guys were involved, I immediately thought they were running a high boost diesel turbo impeller, knowing they were going to bleed off 30% to the hot outlet.

Not familiar with this. Can you post a photo? This variety of compressors has two outlets?

[Zynerji]

When Merc said that the diesel guys were involved, I immediately thought they were running a high boost diesel turbo impeller, knowing they were going to bleed off 30% to the hot outlet.

Not familiar with this. Can you post a photo? This variety of compressors has two outlets?

Theoretical, but what I envisaged was happening the entire time from things that I have read, but apparently, I misunderstood the descriptions. The question is, can you run a high boost turbo (more than you can use), and pump it through a vortex tube and take the 70% that comes out the cold end and run it into the plenum without the need for an intercooler?

[Jejking]

Today I read about Mercs 2018 PU: about 70 per cent new parts.

https://www.motorsport.com/f1/news/merc ... ew-993605/

This source says 'pretty much all new'.

"It's had several phase-ups through the season and we've got ideas to improve the power, the indicated power in the engine.

"We've got ideas to reduce the friction in pretty much every area of the power unit, or the losses in electrical systems." "Some of it is big, fundamental bits of learning, combustion progress, friction reduction, new materials that unlock areas where we've been struggling with reliability. And sometimes it's just a surprise.

"There's still gains to be had [with this formula]. It's a plethora of marginal gains, five millisecond gains.

"Then there's those nice surprises where you thought north would give you 2kW and actually it's south that gives you 2kW.

"It has just been about doing those great experiments and that's where the test facility is important.

"You need to think about what it is you're trying to measure but you need a very impressive dyno with incredible sensors and good test methodology to genuinely detect those gains and to pick them out from the noise of general testing."

[Craigy]

When Merc said that the diesel guys were involved, I immediately thought they were running a high boost diesel turbo impeller, knowing they were going to bleed off 30% to the hot outlet.

Not familiar with this. Can you post a photo? This variety of compressors has two outlets?

Theoretical, but what I envisaged was happening the entire time from things that I have read, but apparently, I misunderstood the descriptions. The question is, can you run a high boost turbo (more than you can use), and pump it through a vortex tube and take the 70% that comes out the cold end and run it into the plenum without the need for an intercooler?

On a very basic level, would you want to use the cold output for engine intake, or would you use it to cool down the fuel or something else in the car?

I've read differing opinions on here about the fuel-limited combustion processes. There are people who think a hotter charge may in fact be more efficient, in light of the fuel flow rate limit - essentially, you're not limited by airflow (so, having cooler, denser air may not be helpful!)

Gruntguru/one of the other gurus, care to weigh in on this point?

[Zynerji]

If it was mixed at 14.7:1, I get that you would run out of fuel quickly. But mixing at 65:1 is far less fuel, even if you stuff 3 times more air into the cylinder.

It matters not, now, as with everything else in F1, they are restricting development to appease cry babies.

[toraabe]

When Merc said that the diesel guys were involved, I immediately thought they were running a high boost diesel turbo impeller, knowing they were going to bleed off 30% to the hot outlet.

Instead of bleed they are controlling the boost by how much they are charging with the mgu-h. Known since long time...

Not familiar with this. Can you post a photo? This variety of compressors has two outlets?

Theoretical, but what I envisaged was happening the entire time from things that I have read, but apparently, I misunderstood the descriptions. The question is, can you run a high boost turbo (more than you can use), and pump it through a vortex tube and take the 70% that comes out the cold end and run it into the plenum without the need for an intercooler?

[Tommy Cookers]

@ Zynerji

an AFR of 65 ? - surely not with gasoline fuel in a spark-ignition piston engine ?
so you're saying it's SACI ?
or fuel boiled at injection ?

how would the PU be more efficient overall at a 65 AFR ?

[hurril]

When Merc said that the diesel guys were involved, I immediately thought they were running a high boost diesel turbo impeller, knowing they were going to bleed off 30% to the hot outlet.

Not familiar with this. Can you post a photo? This variety of compressors has two outlets?

Theoretical, but what I envisaged was happening the entire time from things that I have read, but apparently, I misunderstood the descriptions. The question is, can you run a high boost turbo (more than you can use), and pump it through a vortex tube and take the 70% that comes out the cold end and run it into the plenum without the need for an intercooler?

Where would the other 30% go though?

[Zynerji]

Not familiar with this. Can you post a photo? This variety of compressors has two outlets?

Theoretical, but what I envisaged was happening the entire time from things that I have read, but apparently, I misunderstood the descriptions. The question is, can you run a high boost turbo (more than you can use), and pump it through a vortex tube and take the 70% that comes out the cold end and run it into the plenum without the need for an intercooler?

Where would the other 30% go though?

Wastegate

[Zynerji]

@ Zynerji

an AFR of 65 ? - surely not with gasoline fuel in a spark-ignition piston engine ?
so you're saying it's SACI ?
or fuel boiled at injection ?

how would the PU be more efficient overall at a 65 AFR ?

From what I've read, current engines run at 65:1 AFR in the chamber, and 14.7: only in the pre chamber.

[MrPotatoHead]

Theoretical, but what I envisaged was happening the entire time from things that I have read, but apparently, I misunderstood the descriptions. The question is, can you run a high boost turbo (more than you can use), and pump it through a vortex tube and take the 70% that comes out the cold end and run it into the plenum without the need for an intercooler?

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

[MrPotatoHead]

@ Zynerji

an AFR of 65 ? - surely not with gasoline fuel in a spark-ignition piston engine ?
so you're saying it's SACI ?
or fuel boiled at injection ?

how would the PU be more efficient overall at a 65 AFR ?

From what I've read, current engines run at 65:1 AFR in the chamber, and 14.7: only in the pre chamber.

You are reading the wrong things I think...

[roon]

@ Zynerji

an AFR of 65 ? - surely not with gasoline fuel in a spark-ignition piston engine ?
so you're saying it's SACI ?
or fuel boiled at injection ?

how would the PU be more efficient overall at a 65 AFR ?

From what I've read, current engines run at 65:1 AFR in the chamber, and 14.7: only in the pre chamber.

You are reading the wrong things I think...

What are the actual values?

[MrPotatoHead]

From what I've read, current engines run at 65:1 AFR in the chamber, and 14.7: only in the pre chamber.

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.

[roon]

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.

What are the ballpark values?