Honda Power Unit Hardware & Software

[gruntguru]

Facts

Honda's TC now is too small to get full benefits of Jet Injection/pre-chamber CC.That is why their ICE is so down on power.With the new CC and injectors the performance envelope is much larger with better effiency!
That is why they are moving the TC out of the V in 2017. The only question is the MB layout or the Ferrari/Renault layout.(Mclaren wants MB layout)

But they are getting max ER from this PU design.

Sasha, and anybody else who may be able to answer, does the lower combustion efficiency (and resulting ICE power) mean that the exhaust has more potential energy in it allowing for greater turbine and therefore MGUH recovery?

Yes and No. The lower combustion efficiency mostly results in increased heat loss to the cylinder but some heat may go to the exhaust where a fraction can be harvested.

[Mansell89]

Facts

Honda's TC now is too small to get full benefits of Jet Injection/pre-chamber CC.That is why their ICE is so down on power.With the new CC and injectors the performance envelope is much larger with better effiency!
That is why they are moving the TC out of the V in 2017. The only question is the MB layout or the Ferrari/Renault layout.(Mclaren wants MB layout)

But they are getting max ER from this PU design.

Is this where Button gets his "we probably have the best deployment on the grid" comment from?

Is it very likely therefore that ICE output (assuming they go follow the Mercedes Benz layout) can get somewhere closer to on par with the front runners or are there still other factors that can limit their PU progress?

[Pany]

Billion dollars question!!!!!

[godlameroso]

A bigger question is layout, Honda layout is close to Mercedes. They need a longer shaft and a few other changes to move the compressor and turbine slightly outboard of the V. This makes it easier as far as chassis design is concerned yet limits and makes more difficult to upgrade the power unit. The turbo sizing has to be very close from the get go.

On the other hand moving things to a more conventional layout makes changes much easier but harder for the chassis team. So it's a question of convenience, and compromise. In other words both engine and chassis are important, either Honda or McLaren is going to have to work harder than the other depending on the layout.

It all depends on what kind of packaging wizardry the two can come up with. This decision is critical and the longer it takes the harder it's going to be to implement, so this needs to get sorted. It's hard to weigh all the pros and cons without an ego.

[Chicane]

http://www.autosport.com/news/report.ph ... et-penalty

[Alonsofor2017]

It's a difficult situation because if they copy Mercedes they can become competitive but it would be almost impossible to overtake Mercedes, is it 100% the best direction, the Mercedes one

[Paul]

Blindly copying will hamper them. Realising it's the best solution as part of their development road-map will not.

[godlameroso]

It's a difficult situation because if they copy Mercedes they can become competitive but it would be almost impossible to overtake Mercedes, is it 100% the best direction, the Mercedes one

Well technically they're not copying Mercedes layout, they're already half way there. The only difference between Honda and Mercedes layout is how far the compressor is spaced from the turbine. Granted it's not so simple as I make it, as the devil is in the details.

[Tommy Cookers]

Under normal full power conditions, this pressure is probably 3 bar or more - maximising turbine power for mguh recovery. This 3 bar is a work penalty on the engine - the pistons have to use some crankshaft power to pump the exhaust out. Reducing this to 1 bar will improve the BMEP by about 2 bar - almost 6% improvement on a 35 bar engine.

BMEP is calculated from actual output predominantly occuring 'per active rev' ie during compression and expansion strokes (that's why the calculation of BMEP from measured power differs according to whether the engine is a 2 stroke or a 4 stroke) but the notional '3 bar exhaust' pumping loss as described by gg occurs over a half rev ie 1 stroke only (exhaust) so a 35 bar BMEP engine with 3 bar exhaust pressure reduced to 1 bar will improve the BMEP by about 1 bar (averaged over the 2 strokes) about a 3% BMEP and power improvement

If that were the case, a change to the cylinder pressure during the power stroke of say 1 bar would only change the BMEP by half a bar (which is not the case). If you check the calculation of BMEP from brake output you will find a term "number of revolutions per power stroke" so a four stroke engine has double the BMEP of a two stroke at the same rpm and power.

RETRO-EDIT - I was wrong (as quoted above)
and now 22nd Sept accept GG's position on this power improvement % - apologies all round !!

note to self .....
BMEP is the steady fictitious pressure applying through 1/2 rev (ie 1 stroke), every other revolution in a 4 stroke

btw
wastegating and electric supercharging gives less direct benefits in addition to the above, allowing ......
greater charge and power for given combustion peak T & P conditions (also a feature in Ricardo Hyboost)
and possible over-scavenge, for extra exhaust valve cooling

[PhillipM]

Interesting to see a quote on AS today stating they won't introduce the new combustion concept even though they could because it would take them too long to get it dialled in properly.

[CLKGTR]

Why Honda uses so much more revs than Mercedes (around 1000 rpm), visible from onboard footages, even in qualy where fuel consumption isn't important?

[godlameroso]

Two reasons, more harvesting, and the small compressor needs more shaft speed to produce enough pressure.

[godlameroso]

it would be interesting to see a textbook expression for power loss on the exhaust stroke due to exhaust pressure

Difficult when CFD is the only tool that can examine this in the proper temporal scales. And combustion CFD is still very immature. At best we can make calculated guesses based on flow benches and dynos. Suppose you use a probe and get very accurate measurements, it still doesn't give you an apples to apples relationship that you can apply across the board. It's still very dependent on the geometries and timings of events as opposed to a rigid axiomatic formula. We're getting there though, the industry is making big strides with meshes every year. Which means the equations and the processes are becoming more accurate. Even though a lot of the software is proprietary, there's still a substantial amount floating the public domain. In fact there's a lot of code "borrowing" going on in both directions.

[hurril]

Two reasons, more harvesting, and the small compressor needs more shaft speed to produce enough pressure.

This looks like it is conflating the TC shaft with the ICE one. You seem very knowledgable though so I'm going to ask if the revs are there simply to produce more gas for the turbine?

[PlatinumZealot]

The ICE is really honda's problem. Turbo is soo... soo.. they can easily fix that to get a good qualifying, but since the race is where you score points, they sized the turbo for the race. Small power from the ICE means a small turbo for the race. So what we do know is that the ICE is the weakness. Combustion rather. It is too easy to fit a big ass turbo in dyno (or run the engine on compressed air) and fix the power issue (on the dyno to verify things).. so someone with half a brain know it's the ICE that the major weakness.