Mercedes Power Unit Hardware & Software

[Just_a_fan]

I guess the plenum temp rule is an attempt to prevent a spending war on such a limited area. The teams could make a lot of effort and spend a lot of money trying to reduce temps by a few degrees.

[hurril]

Interestingly, this quite specific rule comes in for 2018:

"5.6.8 Engine plenum (as defined in line 4 of Appendix 2 to these regulations) air temperature must be more than ten degrees centigrade above ambient temperature. When assessing compliance, the temperature of the air will be the lap average recorded, by an FIA approved and sealed sensor located in an FIA approved location situated in the engine plenum, during every lap of the race. The first lap of the race, laps carried out whilst the safety car is deployed, pit in and out laps and any laps that are obvious anomalies (as judged by the technical delegate) will not be used to assess the average temperature. The ambient temperature will be that recorded by the FIA appointed weather service provider one hour before any practice session or two hours before the race. This information will also be displayed on the timing monitors."

Weird rule on surface since we don't know what the underlying intention is. Has effect of preventing running wide-open throttle but naturally aspirated (in which case intake plenum air would be = ambient), or running large portions of the lap with throttle closed (this reduces plenum pressure so reduces temp inside it compared to ambient. And yes I know these engines may not have anything that resembles a conventional throttle, or at least not a throttle that responds in a relatively conventional way relative to torque demand.

Maybe engines were using the throttle as a kind of secondary air cooler (intercooler being the first). Or maybe related to the burn-oil-boost-power thing.

How would you run the engine with the throttle closed?

[Tommy Cookers]

preventing 'running large portions of the lap with the throttle etc (nearly) closed'

what you'd want to do using 'flywheel energy transfer' to get 7 MJ/lap ? - apparently all the rage with Honda
(simultaneously low power with low gas load and high rpm on the turbo)

[Facts Only]

I guess the plenum temp rule is an attempt to prevent a spending war on such a limited area. The teams could make a lot of effort and spend a lot of money trying to reduce temps by a few degrees.

Also the teams make their own intercoolers (generally) so it will stop customer teams from havibg to run lower power or higher drag than the works teams if they cant produce as efficient and intercooler.

[AJI]

I guess the plenum temp rule is an attempt to prevent a spending war on such a limited area. The teams could make a lot of effort and spend a lot of money trying to reduce temps by a few degrees.

Also the teams make their own intercoolers (generally) so it will stop customer teams from havibg to run lower power or higher drag than the works teams if they cant produce as efficient and intercooler.

Maybe it's just about preventing teams super-cooling prior to qualy? That would be the only time i could see any benefit, but the question is; how long will dry ice last before a flying lap?

The other sneaky trick that has been used in other categories in the past is to point the fogger of a co2 extinguisher at the intercooler...

[PlatinumZealot]

10 degrees Celsius detla above ambient is extremely good. Not even my processor cooler gets that on a good day! surely cooling 50psi compressed air to within 10 degrees Celcius must be some feat (or cheat!). I think the regs are basically preventing use of ice packs and other "assisted" cooling like they do in drag racing.

[roon]

10 degrees Celsius detla above ambient is extremely good. Not even my processor cooler gets that on a good day! surely cooling 50psi compressed air to within 10 degrees Celcius must be some feat (or cheat!). I think the regs are basically preventing use of ice packs and other "assisted" cooling like they do in drag racing.

7.6 Cooling systems :
The cooling systems of the power unit, including that of the charge air, must not intentionally
make use of the latent heat of vaporisation of any fluid with the exception of fuel for the
normal purpose of combustion in the engine as described in Article 5.14.

Interesting to consider that there are still opportunities for phase-change cooling within this wording. One would be fuel vaporization. Fuel can only be introduced in-cylinder via the direct injectors, but you could still have a fuel line loop through the intercooler to vaporize the fuel without exposing it to the intake/charge air. The vapor would then be reclaimed and sent to the fuel pump for compression back into a liquid for normal use.

Would it be in any way advantageous to direct-inject fuel as a vapor instead of, or alongside, its liquid form? Can vaporized gasoline be compressed without it becoming a liquid again? For example, could high heat plus high pump outflow pressure give you, essentially, a vapor injector? This might be a work around for lacking port injectors. Inject vapor only or vapor+liquid fuel in order to assist homogenizing the fuel-air charge, as you'd have if port injectors were legal.

Regarding ice-packs, dry ice would be legal because it is not a fluid and sublimates from solid to gaseous form without entering a liquid phase. Water ice will do the same under low-pressure, low-humidity conditions.

A while back I speculated that sublimated vapors could explain the "smoke" exiting the back of the W08 under certain conditions.

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

Shouldn't exhaust blow out of the exhaust pipes? How does Mercedes manage to blow exhaust under the exhaust?

Source:
https://youtu.be/LGQH3xtoO44?t=26s

The radiator exits are down there, beside and below the crash structure. It could be water vapor or something oil related. Compare to this photo of a Merc engine failure from last year, and notice where the plumes are originating from.

https://s10.postimg.org/t4f1qus89/image.jpg

In the context of the 2017 Barcelona testing video, perhaps there was some small condensation or seal leakage which caused the plume during the start sequence & enging rev-up. Or, maybe some residual dry ice getting sublimated off the radiators.

[bill shoe]

How would you run the engine with the throttle closed?

I meant partial throttle. My comment have probably been superseded by better quality discussion.

[godlameroso]

10 degrees Celsius detla above ambient is extremely good. Not even my processor cooler gets that on a good day! surely cooling 50psi compressed air to within 10 degrees Celcius must be some feat (or cheat!). I think the regs are basically preventing use of ice packs and other "assisted" cooling like they do in drag racing.

7.6 Cooling systems :
The cooling systems of the power unit, including that of the charge air, must not intentionally
make use of the latent heat of vaporisation of any fluid with the exception of fuel for the
normal purpose of combustion in the engine as described in Article 5.14.

Interesting to consider that there are still opportunities for phase-change cooling within this wording. One would be fuel vaporization. Fuel can only be introduced in-cylinder via the direct injectors, but you could still have a fuel line loop through the intercooler to vaporize the fuel without exposing it to the intake/charge air. The vapor would then be reclaimed and sent to the fuel pump for compression back into a liquid for normal use.

Would it be in any way advantageous to direct-inject fuel as a vapor instead of, or alongside, its liquid form? Can vaporized gasoline be compressed without it becoming a liquid again? For example, could high heat plus high pump outflow pressure give you, essentially, a vapor injector? This might be a work around for lacking port injectors. Inject vapor only or vapor+liquid fuel in order to assist homogenizing the fuel-air charge, as you'd have if port injectors were legal.

Regarding ice-packs, dry ice would be legal because it is not a fluid and sublimates from solid to gaseous form without entering a liquid phase. Water ice will do the same under low-pressure, low-humidity conditions.

A while back I speculated that sublimated vapors could explain the "smoke" exiting the back of the W08 under certain conditions.

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

Shouldn't exhaust blow out of the exhaust pipes? How does Mercedes manage to blow exhaust under the exhaust?

Source:
https://youtu.be/LGQH3xtoO44?t=26s

The radiator exits are down there, beside and below the crash structure. It could be water vapor or something oil related. Compare to this photo of a Merc engine failure from last year, and notice where the plumes are originating from.

https://s10.postimg.org/t4f1qus89/image.jpg

In the context of the 2017 Barcelona testing video, perhaps there was some small condensation or seal leakage which caused the plume during the start sequence & enging rev-up. Or, maybe some residual dry ice getting sublimated off the radiators.

For a while I thought they were injecting fuel in a super-critical state, like so http://articles.sae.org/7160/.

[roon]

It seems there's no rule against heating the fuel. Cooling fuel on the other hand...

6.5.2 No fuel intended for immediate use in a car may be more than ten degrees centigrade below
ambient temperature. When assessing compliance, the ambient temperature will be that
recorded by the FIA appointed weather service provider one hour before any practice session
or two hours before the race. This information will also be displayed on the timing monitors.
The temperature of fuel intended for use in a car must be measured via an FIA approved and
sealed sensor.

6.5.3 The use of any device on board the car to decrease the temperature of the fuel is forbidden.

I take it this is about limiting the evaporative cooling effect the fuel has when injected in the cylinder. Or maybe the fuel flow sensor has a temperature operating window i.e. if the fuel were chilled too much, the sensor might not read properly, leading to fuel mass flow beyond 100 kg/hr.

[zibby43]

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

Mercedes' 2018 F1 engine will be "pretty much all new"

Excerpt:

"Mercedes is pushing on all fronts to maintain its advantage and is planning extensive updates to the engine.

'Pretty much all new,' Cowell told Motorsport.com regarding the expectations for this year's engine.

'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.'

Although F1 is entering its fifth year with the current engine formula, Cowell believes there is still more to come in terms of pure performance gains."

[wuzak]

Regarding intercooling, I would think that manufacturers would be aiming to minimise the cooling achieved.

The higher they can run the intake temperature, the more power they can get from the fixed fuel flow, theoretically. So long as they can run without detonation, higher temperatures should be better.

More cooling in conventional turbo systems allows more fuel to be used to gain more power. But this is not the case in the current regulations.

[Zynerji]

I guess I had thought they had 2 ranque-hilsch vortex tubes built into the compressor housing of the turbo to output super cooled air to the engine, dumping the hot air out the wastegate.Obviously, you would need to over-boost to compensate for the loss, but that is what I though the huge compressor wheels confirmed. I would expect this type of system to be able to completely eliminate intercooling with enough development.

https://s3.wp.wsu.edu/uploads/sites/44/ ... nomena.pdf

The work necessary to compress the cylinder is directly proportional to the temperature of the incoming air, so with confirmation that the teams use 2 fuel feeds (cold and hot) and they mix them before injection to hit a target temperature, I always thought this was done as a way to dynamically increase the compression ratio, as with running 65:1 AFR would not be as dramatic increase in fuel usage as 14.7:1.

[roon]

Regarding intercooling, I would think that manufacturers would be aiming to minimise the cooling achieved.

The higher they can run the intake temperature, the more power they can get from the fixed fuel flow, theoretically. So long as they can run without detonation, higher temperatures should be better.

More cooling in conventional turbo systems allows more fuel to be used to gain more power. But this is not the case in the current regulations.

Where can development go in terms of intake temperature? Elimination of charge cooling? As in, further optimized combustion can cope with uncooled supercharger output.

I guess I had thought they had 2 ranque-hilsch vortex tubes built into the compressor housing of the turbo to output super cooled air to the engine, dumping the hot air out the wastegate.Obviously, you would need to over-boost to compensate for the loss, but that is what I though the huge compressor wheels confirmed. I would expect this type of system to be able to completely eliminate intercooling with enough development.

https://s3.wp.wsu.edu/uploads/sites/44/ ... nomena.pdf

The work necessary to compress the cylinder is directly proportional to the temperature of the incoming air, so with confirmation that the teams use 2 fuel feeds (cold and hot) and they mix them before injection to hit a target temperature, I always thought this was done as a way to dynamically increase the compression ratio, as with running 65:1 AFR would not be as dramatic increase in fuel usage as 14.7:1.

I remember reading about these during the vortex-exhaust rumors. Perhaps there was a mistranslation somewhere and what was meant was "compressor exhaust" i.e. the BOV/compressor bypass; and not the engine exhaust. Would be interesting to compare the efficiency of such a "charge segregator" to a traditional intercooler. How would one go about calculating this?

[Zynerji]

A 3d model, and someone to run the CFD I guess. Honestly, I can see 2 1.25 inch tubes in the outside scroll with the orifice and reflecting cone to do this pretty easily. Also, you can expect about 70% volume to come out the cold side, so that can set your sizing a bit easier.

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.

It would simplify the design enormously if it could remove the need for intercooling. I hope someone here has the CAD skills and are intrigued enough to check it out.