Honda Power Unit Hardware & Software

[Tommy Cookers]

Didn't xactly get the logic of the above, but fact of the matter is that the max output of the PU is the ICE plus the MGU-K,
regardless how you slice or dice it. The MGU-K is limited to 160 Hp and the ICE fuel flow is limited, why any increase in
maximum horsepower must at the end of the day come from an increase in efficiency in the ICE.

.... To all intents and purposes you have more power over the whole lap instead of only part of the lap.

concaptually the 160 hp can be used for every second of the lap (if most of the electricity is used immediately, not stored)
about 130 hp from mgu-h generation gives (including 30 hp stored ie mgu-k recovery less spoolup) 160 hp mgu-k motoring
whenever wanted

generating 130 hp from the mgu-h is a easy
what is not easy is generating this 130 hp without costing crankshaft power and/or package disadvantages
that's why Ferrari and Renault seem to have settled for less than the conceptual 160 hp mu-k at WOT
not so far from a turbocharged engine (as the Mercedes is ?)

the 160 hp (120 kW) is limited by electrical power rules assuming 95% efficiency
so sometimes maybe 163-5 hp mechanical power can be realised legally

[xpensive]

Thanx TC, good xplanation of the given limitations.

[gruntguru]

MGUH output will always cost something in terms of crankshaft power. All the engine designers would be smart enough to maximise total power output - crankshaft + turbine, certainly with a discount applied to the MGUH number since at best it will suffer about 5% loss at each of the MGUH and the MGUK and more if it goes to the ES for a while.

[dren]

The Honda unit is matching Merc's output on the test rig.

[dren]

MGUH output will always cost something in terms of crankshaft power. All the engine designers would be smart enough to maximise total power output - crankshaft + turbine, certainly with a discount applied to the MGUH number since at best it will suffer about 5% loss at each of the MGUH and the MGUK and more if it goes to the ES for a while.

I thought one of the papers floating around on here showed a certain percent of power taken at the turbine was "free".

[Sasha]

The Honda unit is matching Merc's output on the test rig, right Sasha?

That was the major reason why Honda waited until 2015 to race their PU.They knew Mercedes was going to have the best PU and thru Mclaren was going to know it's performance numbers.Honda's problems in the past was under estimating it's comp and producing under performing engines.

That will not happen this time! Plan is to meet 2014 Mercedes PU by early test and beat it by Feb 2015.
So sould be equal to the 2015 Mercedes PU.

[mikeerfol]

I don't think the engines were the problem for Honda, it's not like the cars were competitive regarding the aero in an aero-dominated F1..

Anyway the thing is, how different are the performance numbers of the McLaren Mercedes PU vs the factory Mercedes AMG engine?

[Holm86]

The Honda unit is matching Merc's output on the test rig.

People, please add sources to your claims.

[trinidefender]

If Honda and McLaren do make a test rig to run this year during a test then I wouldn't try to make any direct comparisons between it (the Honda) and the Mercedes engined cars simply because none of us will know how hard the engines were being run etc. my understanding is that the testing, if it is done, would be more for reliability trials than outright power trials.

What I will be paying close attention to would be:
1. The exhaust note at various stages. On throttle, off throttle, low rpm, high etc etc.
2. The sidepod size. If the test rig has the same radiator layout then we should be able to get a view of the sidepods and hopefully inside them to see if the radiators/oil radiators/intercooler(s) are smaller, bigger or the same as the merc unit. This might give us fans some insight into the thermal efficiency of the engine. A less thermally efficient engine will generally require more cooling as more of the fuels energy goes into cooling the engine.
3. Any pictures of the engine. This one is the obvious thing to look for but will probably be kept covered more than anything else while the car is stripped. Layout of the ancillaries. Intercooler positioning (if running an air/water intercooler), turbo layout and maybe compressor/turbine sizing, heat shielding. MGU-H location, exhaust manifold design and basically anything outside the block and head of the engine.

A question for those who are following this more closely than me. Is Honda building the gearbox themselves or leaving that to McLaren? Any ideas on particulars of the gearbox? All the talk has been on the engine and next to nothing on the gearbox.

[gruntguru]

MGUH output will always cost something in terms of crankshaft power. All the engine designers would be smart enough to maximise total power output - crankshaft + turbine, certainly with a discount applied to the MGUH number since at best it will suffer about 5% loss at each of the MGUH and the MGUK and more if it goes to the ES for a while.

I thought one of the papers floating around on here showed a certain percent of power taken at the turbine was "free".

That is correct. However there is a range of outcomes from "Maximise ICE crankshaft power regardless of turbine output" through to "Maximise turbine output regardless of crank output". Somewhere between these two is a sweet spot where total output is maximised. ICE crankshaft power will not be maximal at this sweet spot.

[Wayne DR]

That is correct. However there is a range of outcomes from "Maximise ICE crankshaft power regardless of turbine output" through to "Maximise turbine output regardless of crank output". Somewhere between these two is a sweet spot where total output is maximised. ICE crankshaft power will not be maximal at this sweet spot.

Looking at the diagram on page 87 of the Technical Regulations, it shows "Max +/-120kW" from the MGU-K to the Engine. I agree that you will lose energy/power from the internal losses within the electric motor/generator, but I don't see anywhere the requirement to deduct these from the 120kW allowance. So could you not have a 125kW motor/generator which (via efficiency losses) puts out 120kW?

There is also an unlimited draw from the MGU-H and MGU-K to "Other Ancillaries". If you have a constant ancillaries draw of 5kW, could you not add this on too?

The limit is "Max +/-120kW" to the engine, so a 130-140kW motor/generator could be used with smart electronic limits to produce 120kW after internal losses + ancillary loads when maximum power is required. This may only be 10kW, but it is still something. I also understand that "there are no free lunches", so this energy is still lost (i.e. it is not used to directly accelerate the car).

[trinidefender]

That is correct. However there is a range of outcomes from "Maximise ICE crankshaft power regardless of turbine output" through to "Maximise turbine output regardless of crank output". Somewhere between these two is a sweet spot where total output is maximised. ICE crankshaft power will not be maximal at this sweet spot.

Looking at the diagram on page 87 of the Technical Regulations, it shows "Max +/-120kW" from the MGU-K to the Engine. I agree that you will lose energy/power from the internal losses within the electric motor/generator, but I don't see anywhere the requirement to deduct these from the 120kW allowance. So could you not have a 125kW motor/generator which (via efficiency losses) puts out 120kW?

There is also an unlimited draw from the MGU-H and MGU-K to "Other Ancillaries". If you have a constant ancillaries draw of 5kW, could you not add this on too?

The limit is "Max +/-120kW" to the engine, so a 130-140kW motor/generator could be used with smart electronic limits to produce 120kW after internal losses + ancillary loads when maximum power is required. This may only be 10kW, but it is still something. I also understand that "there are no free lunches", so this energy is still lost (i.e. it is not used to directly accelerate the car).

Think of it this way. Currently the MGU-K is limited to 120 kW. As per the regulations (the regulations limit the energy sent between the battery and the MGU-K) at this power limit there would per lap time limit of just over 33 seconds for the MGU-K to produce 120 kW.

Now if a team decides to run the MGU-K at 60 kW then they can run it for over 66 seconds. If the MGU-H can always put out the other 60 kW then the MGU-K is still running at its limit of 120 kW, subtracting mechanical inefficiencies.

Basically the more energy the MGU-H can send directly to the MGU-K, the longer the battery is able to power it because it will provide less energy per second.

[wuzak]

There is an efficiency factor for the MGU-K. IIRC it is 95%. So if you can make yours have more than 95% efficiency you will get a gain.

[Tommy Cookers]

MGUH output will always cost something in terms of crankshaft power. All the engine designers would be smart enough to maximise total power output - crankshaft + turbine, certainly with a discount applied to the MGUH number since at best it will suffer about 5% loss at each of the MGUH and the MGUK and more if it goes to the ES for a while.

I thought one of the papers floating around on here showed a certain percent of power taken at the turbine was "free".

That is correct. However there is a range of outcomes from "Maximise ICE crankshaft power regardless of turbine output" through to "Maximise turbine output regardless of crank output". Somewhere between these two is a sweet spot where total output is maximised. ICE crankshaft power will not be maximal at this sweet spot.

but in principle we are not designing an engine around this sweet spot
we are designing around another spot
because in principle the rules do not allow free choice of turbine power
we are designing an engine to work around mean turbine power dictated by the 120 kW mu-k limit

the mean turbine power required depends on how much mean mu-k power comes from braking recovery (minus spoolup) energy
brake recovery is kept quite low by a torque limit rule (though BR is very circuit-specific)
so about 90 kW seems to be needed from the turbine (90 kW mean throughout WOT time)
this seems to match the iirc 80 kW (presumably continuous rating?) stated for the MM unit

precedent shows axial turbine power adds up to 18% to crank power essentially 'free' ie with negligible loss of crankshaft power
this is what blowdown running is all about (exhaust pressure not significantly above ambient after exhaust BDC)
our mep and CR suggest we can have around 12-15% 'free'
but to have 120 kW mu-k freely available we need more turbine power than this

dictating a design that has raised exhaust pressure aka 'backpressure' (significantly above ambient throughout)
other precedent shows this is competitive (backpressure with boost raised may cost no crankshaft power and increase turbine power)
Merc exhaust suggests this (pressure running of the turbine), but F's and R's is compatible with this (an element of pressure)

so the Honda exhaust system should tell us something

btw 120 kW assumes 95% efficiency at the motor (of electrical power to crankshaft by coupling gear) - so we might get 122 kW

[gruntguru]

That is correct. However there is a range of outcomes from "Maximise ICE crankshaft power regardless of turbine output" through to "Maximise turbine output regardless of crank output". Somewhere between these two is a sweet spot where total output is maximised. ICE crankshaft power will not be maximal at this sweet spot.

but in principle we are not designing an engine around this sweet spot, we are designing around another spot because in principle the rules do not allow free choice of turbine power we are designing an engine to work around mean turbine power dictated by the 120 kW mu-k limit the mean turbine power required depends on how much mean mu-k power comes from braking recovery (minus spoolup) energy brake recovery is kept quite low by a torque limit rule (though BR is very circuit-specific) so about 90 kW seems to be needed from the turbine (90 kW mean throughout WOT time) this seems to match the iirc 80 kW (presumably continuous rating?) stated for the MM unit precedent shows axial turbine power adds up to 18% to crank power essentially 'free' ie with negligible loss of crankshaft power this is what blowdown running is all about (exhaust pressure not significantly above ambient after exhaust BDC) our mep and CR suggest we can have around 12-15% 'free' but to have 120 kW mu-k freely available we need more turbine power than this dictating a design that has raised exhaust pressure aka 'backpressure' (significantly above ambient throughout) other precedent shows this is competitive (backpressure with boost raised may cost no crankshaft power and increase turbine power) Merc exhaust suggests this (pressure running of the turbine), but F's and R's is compatible with this (an element of pressure)

so the Honda exhaust system should tell us something

btw 120 kW assumes 95% efficiency at the motor (of electrical power to crankshaft by coupling gear) - so we might get 122 kW

I disagree - we are almost certainly designing around the "sweet spot".

With electrical efficiency of 95% for both MGUK and MGUH, nett turbine power would need to be 133 kW to supply 120 kW of work at the MGUH.

For 3.5 bar MAP, 3.0 bar exhAP, MAF = 0.56 kg/s, Exh MF = 0.59 kg/s, EGT = 800*C, turb & comp efficiencies = 0.8 :-

Compressor power = 90kW
Turbine power = 137kW
Nett power = 47kW

These numbers are steady flow (pressure turbine) so the turbine power will be higher courtesy of blowdown energy - say another 50kW, for a total Nett power of 97 kW. We are still 36kW short of the 133 required to drive the MGUK at 120kW continuously - the question is - is enough braking energy harvested to make up the shortfall (and provide some spare energy for spool up and emergency power techniques (where the compressor andthe MGUK ar both driven from the ES to maximise crankshaft power)). The answer is almost certainly no. Assuming (generously) that time under brakes is 25% of time under full throttle, and that harvesting is 120 kW throughout braking events, there will be 30kW available during full throttle events from braking regen'.

Even without the above analysis, it is known that the cars deplete the ES while running at race speed, so clearly any extra power from the MGUH would be useable.

EDITED to correct MAF and Exh MF from 0.056 and 0.059 to 0.56 and 0.59