Mercedes F1

General engine tech -- Drag Racing to Circle Track

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naukkis79
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Re: Mercedes F1

Post by naukkis79 » Tue Oct 10, 2017 2:56 pm

140Air wrote:
Sat Oct 07, 2017 6:44 pm

At first I thought this was not an effective idea as the engine has to run lean to burn oil in the exhaust, but if it is done during "harvesting" it would be ok to run the engine lean, so this then solves the octane/detonation and oil/fuel mixture problems. It will put a little more energy into the batteries. Good idea!
Fuel limited F1-engine will run lean, target is CO=0 & HC=0. And with very lean mixture excessive oil with intake air is burned in cylinders.

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Re: Mercedes F1

Post by naukkis79 » Tue Oct 10, 2017 3:01 pm

140Air wrote:
Sat Oct 07, 2017 7:44 pm
My guess is that the engine is basically feeding the turbine and a very high share of the total power output is coming off the the turbine's generator with little turbine power going to the compressor and the engine is running at low boost, if any boost, and moderate or low engine power output. So, the 50% efficiency cycle should be a moderate or low cruse cycle with engine running rather slow.
Just a guess.
Nope, 100KG/s gas has energy content about 2000hp, getting 1000hp out from engine means that 50% efficiency is at full power.

And engines are electric turbocompounded, turbine not only provides power to compressor excessive power is then directly added to engines output power.

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Re: Mercedes F1

Post by 140Air » Wed Oct 11, 2017 12:23 pm

naukkis79 wrote:
Tue Oct 10, 2017 2:56 pm
140Air wrote:
Sat Oct 07, 2017 6:44 pm

At first I thought this was not an effective idea as the engine has to run lean to burn oil in the exhaust, but if it is done during "harvesting" it would be ok to run the engine lean, so this then solves the octane/detonation and oil/fuel mixture problems. It will put a little more energy into the batteries. Good idea!
Fuel limited F1-engine will run lean, target is CO=0 & HC=0. And with very lean mixture excessive oil with intake air is burned in cylinders.
Maximum fuel efficiency for the engine should occur at a stoichiometric mixture which would include any oil in the cylinders which will mean maximum heat in the chamber. There will be no lean running desired. But you still have a problem with octane under full boost and highest burn temps, unless you are saying the oil is an octane booster.

Further, we know that the engine itself will hardy exceed 30% efficiency. It means the turbo with its 60%(?) efficiency will have to provide 50% of the output power in order to get the combination to 50% efficiency. That implies the turbo provides ~500hp output power in addition to making boost.

On the other hand, if the engine and all systems can actually reach 50% fuel efficiency under a full power operating condition, what can it do under a maximum economy operating condition, 80%??? You are saying that the parameters for max power and max efficiency are the SAME!

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Re: Mercedes F1

Post by 140Air » Wed Oct 11, 2017 12:27 pm

naukkis79 wrote:
Tue Oct 10, 2017 3:01 pm
140Air wrote:
Sat Oct 07, 2017 7:44 pm
My guess is that the engine is basically feeding the turbine and a very high share of the total power output is coming off the the turbine's generator with little turbine power going to the compressor and the engine is running at low boost, if any boost, and moderate or low engine power output. So, the 50% efficiency cycle should be a moderate or low cruse cycle with engine running rather slow.
Just a guess.
Nope, 100KG/s gas has energy content about 2000hp, getting 1000hp out from engine means that 50% efficiency is at full power.

And engines are electric turbocompounded, turbine not only provides power to compressor excessive power is then directly added to engines output power.
What do you mean by "100KG/s gas"?

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Re: Mercedes F1

Post by Schurkey » Wed Oct 11, 2017 1:49 pm

140Air wrote:
Wed Oct 11, 2017 12:23 pm
Maximum fuel efficiency for the engine should occur at a stoichiometric mixture
Minimum tailpipe emissions happens at stoich. Maximum fuel economy happens when the fuel mix is leaner than stoich, but certain tailpipe emissions increase (NOx).

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Re: Mercedes F1

Post by 140Air » Wed Oct 11, 2017 2:33 pm

Schurkey wrote:
Wed Oct 11, 2017 1:49 pm
140Air wrote:
Wed Oct 11, 2017 12:23 pm
Maximum fuel efficiency for the engine should occur at a stoichiometric mixture
Minimum tailpipe emissions happens at stoich. Maximum fuel economy happens when the fuel mix is leaner than stoich, but certain tailpipe emissions increase (NOx).
The claim is an efficiency of 50% at max power (but, the article only says an engine system on a test bench). You cannot have max power running lean. You are leaving O2 unreacted! However, my assumption is that the engine mode for 50% efficiency is not for max power.

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Re: Mercedes F1

Post by MadBill » Wed Oct 11, 2017 9:30 pm

Given F1's fuel flow limits, it's very possible that the phrase "maximum power" has an asterisk attached that expands it to mean "maximum power possible within the limitations of the rules" and thus very lean of λ. (They do site the plug within a rich mixture pre-chamber and jet the resulting hot gases into the main chamber...)
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Re: Mercedes F1

Post by Schurkey » Wed Oct 11, 2017 10:24 pm

MadBill wrote:
Wed Oct 11, 2017 9:30 pm
(They do site the plug within a rich mixture pre-chamber and jet the resulting hot gases into the main chamber...)
Who knew my '80 Honda Civic CVCC was the precursor to F1 technology. I thought it was just an econobox with a short-lived engine.

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Re: Mercedes F1

Post by 140Air » Thu Oct 12, 2017 2:01 am

MadBill wrote:
Wed Oct 11, 2017 9:30 pm
Given F1's fuel flow limits, it's very possible that the phrase "maximum power" has an asterisk attached that expands it to mean "maximum power possible within the limitations of the rules" and thus very lean of λ. (They do site the plug within a rich mixture pre-chamber and jet the resulting hot gases into the main chamber...)
This is true Bill, max power under a fuel flow limit does mean the maximum completeness of fuel burned is the goal rather than the maximum completeness of O2 reacted where lean of stoich may be beneficial rather than rich of stoich as when you have an air flow limit as is most commonly the case. But the issue is 50% efficiency with a second issue, how do or did they use oil?

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Re: Mercedes F1

Post by peejay » Thu Oct 12, 2017 2:59 am

140Air wrote:
Wed Oct 11, 2017 2:33 pm
Schurkey wrote:
Wed Oct 11, 2017 1:49 pm
140Air wrote:
Wed Oct 11, 2017 12:23 pm
Maximum fuel efficiency for the engine should occur at a stoichiometric mixture
Minimum tailpipe emissions happens at stoich. Maximum fuel economy happens when the fuel mix is leaner than stoich, but certain tailpipe emissions increase (NOx).
The claim is an efficiency of 50% at max power (but, the article only says an engine system on a test bench). You cannot have max power running lean. You are leaving O2 unreacted! However, my assumption is that the engine mode for 50% efficiency is not for max power.
"Max power" meaning not maximum potential power, but the highest output that engine is producing in its particular state of tune.

You may be surprised how many production engines are running stoich at WOT, even turbo ones.

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Re: Mercedes F1

Post by 140Air » Thu Oct 12, 2017 12:39 pm

peejay wrote:
Thu Oct 12, 2017 2:59 am
140Air wrote:
Wed Oct 11, 2017 2:33 pm
Schurkey wrote:
Wed Oct 11, 2017 1:49 pm

Minimum tailpipe emissions happens at stoich. Maximum fuel economy happens when the fuel mix is leaner than stoich, but certain tailpipe emissions increase (NOx).
The claim is an efficiency of 50% at max power (but, the article only says an engine system on a test bench). You cannot have max power running lean. You are leaving O2 unreacted! However, my assumption is that the engine mode for 50% efficiency is not for max power.
"Max power" meaning not maximum potential power, but the highest output that engine is producing in its particular state of tune.
The problem with designing an engine to not give the all-out max power it could conceivably make comes when trying to pass a car in front, out-pacing it on the straight with DRS or out-accelerating it out of a turn. This is most of the time the difference between winning and second place. In theory, they are at the fuel flow limit when at max power on the straight, but have to throttle back elsewhere to meet the total fuel limit.
The engines are tuned on the fly, from the cockpit and apparently from the pit. I remember a couple years ago the engineer telling Hamilton, who was in second place, "...it's ok to use more rpm...". The only reason he would not already be using more rpm would have to be for efficiency. Apparently there was more power available at higher rpms and he was not already running at the fuel flow limit, even n a desperate chase.

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Re: Mercedes F1

Post by n2xlr8n » Thu Oct 12, 2017 1:49 pm

peejay wrote:
Thu Oct 12, 2017 2:59 am
You may be surprised how many production engines are running stoich at WOT, even turbo ones.
Yes, I would be surprised. Which manufacturers?
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Re: Mercedes F1

Post by 140Air » Thu Oct 12, 2017 1:57 pm

n2xlr8n wrote:
Thu Oct 12, 2017 1:49 pm
peejay wrote:
Thu Oct 12, 2017 2:59 am
You may be surprised how many production engines are running stoich at WOT, even turbo ones.
Yes, I would be surprised. Which manufacturers?
I would be very surprised too, especially since they can do what they want at WOT, with no concern for emissions or fuel economy. Why not use good old fashion rich mixtures for lower chamber heat and lower exhaust temps? It's easier on the equipment and gives more power.

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Re: Mercedes F1

Post by peejay » Thu Oct 12, 2017 5:54 pm

n2xlr8n wrote:
Thu Oct 12, 2017 1:49 pm
peejay wrote:
Thu Oct 12, 2017 2:59 am
You may be surprised how many production engines are running stoich at WOT, even turbo ones.
Yes, I would be surprised. Which manufacturers?
Time-dependent, some/most will run stoich until the computer determines that they need to cool the catalyst. For 2-10 seconds you get stoich at WOT.

And then there's the 1.0 Ecoboost, which will run stoich under almost all conditions with no enrichments at all.

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Re: Mercedes F1

Post by MadBill » Thu Oct 12, 2017 9:40 pm

When I was working on gas-CNG truck fuel systems in the late nineties, they ran λ for ~ 15 sec. at WOT, then went into rich cat protection mode. On CNG, protection mode was lean rather than rich...
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