Honda Power Unit Hardware & Software

[gruntguru]

the only real "gain" is being able to run leaner at higher boost levels tho surely ? and all the other tweakings have drawbacks, ie, if they tighten the exhaust volute to increase turbine power/increase compressor size etc, then it costs in terms of ice hp (pumping losses)

There has been a lot of discussion on those same points here previously.

Leaner mix does the following:
1. Up to about lambda 1.2 the percentage of unburned fuel products in the exhaust is reducing so more heat is released.
2. Above 1.2 it seems less heat is lost to the chamber walls due to the lower gas temperature.

On the question of backpressure:
1. Increasing backpressure to facilitate a boost increase of the same magnitude is neutral for pumping loss. (The extra boost creates negative pumping work by pushing the pistons down)
2. Similarly for the turbomachinery, the extra compressor power needed for the boost/massflow increase is about the same as the extra power generated by the turbine - even with the reduction in exhaust temperature resulting from the leaner mix.

[PlatinumZealot]

The ICE will only flow more air if the air density is increased. That means higher pressure, lower temperature or both. Regardless of how it is achieved, the operating point of the compressor will move to the right (and up if the boost is also increased). The probability is the new operating point is no longer in the heart of the efficiency island (peak efficiency contours on the compressor map) so a change to the compressor would be beneficial or even essential.

Regarding the turbine. The new massflow condition will have the same effect here although turbine efficiency is usually "broader", less sensitive to flow changes. Increased massflow will reduce exhaust temperature but exhaust energy will not reduce much, especially if the boost is higher (allowing higher exhaust pressure). OTOH if the more efficient combustion results in a reduced heat content in the exhaust, this would be more problematic. (Increased combustion efficiency must result in a reduction in heat loss to the cylinder, the exhaust gas or both. The reduction is equal to the extra power at the crankshaft)

Regarding the compressor, I agree with what you say, assuming the compressor map is peaky it would not be as versatile across different flow ranges, a different blade design and A/R can be used to get different characteristics, but the original context was the physical size of the compressor within the enginee vee and whether it is limited Honda's horsepower. I think because of the nature of the boost delivery with speed control, I suppose the compressor map is flatter than typical, and I don't believe the compressor size is limited as godlameroso implied.


By the way on the other topic, what lambda ratio do you suppose the Mercedes engines use?

[godlameroso]

I don't doubt that they can generate enough boost pressure, it's just that the compressor does 'weird' things under certain conditions, things that can be much better controlled or mitigated by using an internal geometry and volume not allowed by their current layout. If they were satisfied with the performance of the compressor they wouldn't even bother to change the layout for next year. Maybe they want to get it out because it'll make experimenting next year much easier.

http://www.skysports.com/f1/news/12479/ ... -formula-1

"Honda's power unit currently houses the turbine and the compressor inside the vee of the engine, but it is thought they will switch to the Mercedes layout next year of a compressor at the front and turbine at the rear of the engine, allowing for a bigger turbo.

"It's hard to realise," said Hasegawa. "That is why Ferrari and Renault don't create it. That is why I can't tell if we can realise it."

However, Hasegawa does "believe" that Honda can close the gap to Mercedes no matter what layout they opt for.

"At least I would like to start with the same power level," he added. "That is the first target, even though on the size or weight or centre of gravity, or especially the reliability, it is difficult to achieve the same level.""

[gruntguru]

By the way on the other topic, what lambda ratio do you suppose the Mercedes engines use?

Huge guess here. Somewhere between 1.5 and 1.8

[Brian Coat]

By the way on the other topic, what lambda ratio do you suppose the Mercedes engines use?

Huge guess here. Somewhere between 1.5 and 1.8

What intake air pressure (abs) and temperature do you estimate Lambda 1.5/1.8 equates to (pre-charge cooler)?

[godlameroso]

Ooooh I want to take a stab at this one, given the fuel flow limits of 100kg/hr estimated power from the ICE ~800 hp and 1.7 lambda is right around just under 4 bar or ~58psi of boost for us uncultured Americans. I can't remember where but I saw a graph estimating the different power units and the Mercedes was estimated as using 4.5 bar I assume the real number is somewhere in between.

*Edit, that's a hell of a compressor.

[Abarth]

Deleted...double Post

[Abarth]

[...]estimated power from the ICE ~800 hp [...]

800 HP pure ICE Power @ 100 kg/h @ 46 MJ/kg fuel means:
46% efficiency when 0% compounding
51% efficiency when 50% of max. allowed 160HP of MGU-K are compounded power = 880 HP self sustained power.
55% efficiency when 100% of max. allowed 160HP of MGU-K are compounded power = 960 HP self sustained power

If we assume that when compounding the added power will be closer to about 60kW/80HP than to 0 kW, we are in slow running 2 Stroke Naval Diesel Territory.....
Is that really a realistic number with a 10'000+ rpm engine??

[Pierce89]

This article puts them in the range of 1000bhp in qualifying mode based on sonic analysis.

http://www.motorsport.com/f1/news/analy ... 29341/?s=1

[motobaleno]

This article puts them in the range of 1000bhp in qualifying mode based on sonic analysis.

http://www.motorsport.com/f1/news/analy ... 29341/?s=1

total power not ICE alone

the same source says 750 bhp in race trim from ICE alone

[Joseki]

[...]estimated power from the ICE ~800 hp [...]

800 HP pure ICE Power @ 100 kg/h @ 46 MJ/kg fuel means:
46% efficiency when 0% compounding
51% efficiency when 50% of max. allowed 160HP of MGU-K are compounded power = 880 HP self sustained power.
55% efficiency when 100% of max. allowed 160HP of MGU-K are compounded power = 960 HP self sustained power

If we assume that when compounding the added power will be closer to about 60kW/80HP than to 0 kW, we are in slow running 2 Stroke Naval Diesel Territory.....
Is that really a realistic number with a 10'000+ rpm engine??

Is the 46 MJKg value a close estimation to reality?

[PlatinumZealot]

On the compressor..

1.5 Lambda is 1.5 x Soichiometric of 14.7:1 = 22.05 kg of Air to 1 kg of fuel.
@ 100kg/hr fuel flow, air flow @ 1.5 lambda= 2205 kg/hr or 80 lb/minute
@ 1.8 lambda it is 96lb/min

Depending on whole bunch of engine characteristics the volume flow rate will vary based on the boost pressure. Unless we know how good the engine flows and the compression ratio etc.. it is hard to estimate how much boost the engine uses.

But let us assume that the compressor is similar to your typical mega-sized high performance racing compressor:

Seems like these maps would work for my estimates...Let's just pretend the map is a little flatter than this.. I assume the F1-compressors are more versatile??




So a pressure ratio of 2.2 and 80lb/min to 96lb/min air flow will land you close the middle of the efficiency Island with these compressors. We can then suppose that not that much boost is needed. If these sort of compressors are used... However a smaller turbo for packing's sake might have to deliver more boost to get the same air-flow. Remember F1 engines are high flow engines they don't need a lot of boost to multiply their horsepower... so.. what do you guys think?


How do you think the Electrical energy generation coincide with these purported shaft speeds?

[hurril]

This article puts them in the range of 1000bhp in qualifying mode based on sonic analysis.

http://www.motorsport.com/f1/news/analy ... 29341/?s=1

What sort of sound analysis is this? What are they looking for? Can you hear (a machine that is) the cylinder pressure?

Also: I must have missed that fuel thing that Ferrari supposedly did? Can I read about that somewhere?

[godlameroso]

That's essentially been the point all along, I can't for the life of me understand why we're even arguing. A smaller turbo will have much narrower islands, and be less efficient overall. Honda believed as you did that a small turbo would suffice, that not much boost is needed. Then reality came to odds with theory. I remember mentioning several times to people's disgust that I could hear compressor stall.

Again I give Honda massive respect for developing the turbo to the extent they did. And there might have been good lessons. Maybe the increased combustion efficiency let's the turbo get away with slightly more inefficiency, and it works because they can run the compressor a little harder and the increase in temperature is balanced by the lower combustion temperature resulting in a net gain.

[gruntguru]

Ooooh I want to take a stab at this one, given the fuel flow limits of 100kg/hr estimated power from the ICE ~800 hp and 1.7 lambda is right around just under 4 bar or ~58psi of boost for us uncultured Americans. I can't remember where but I saw a graph estimating the different power units and the Mercedes was estimated as using 4.5 bar I assume the real number is somewhere in between.

The last estimates I heard were around 3.5 bar but I wouldn't be surprised if Mercedes is higher. The numbers are absolute pressure btw not gauge so 4 bar is ~44psi.