Honda Power Unit Hardware & Software

[Frank_]

praps they vent some of the engine heatsoak at the startline through the turbine ? with a sequential fuelcut rev limiter/launch,
and then utilise that stored K for acceleration instead of dumping it in the coolant when there is no airflow on the rads
same could apply to liftoff near the end of the straight ?

[godlameroso]

The H harvests whenever there's excess boost pressure, such as changing gears, or during flat out sections, under breaking and whenever the driver has to hold part throttle.

You have to waste a little petrol at really low speeds. Imagine you're in a slow turn and you briefly take your foot off the gas, the k goes into regen mode and you get -120 kw in the middle of the turn. How do you stop the car from swapping ends.

I suppose if you were really clever you could have a sort of rear wheel breaking via the k to eliminate understeer. Combined with the electronic differential, and break by wire, you could essentially have a weak version of abs, but full on torque vectoring in the rear.

[Frank_]

if you are utilising heat energy via the turbine that would otherwise be lost in the coolant system it raises the PU efficiency tho eh (during launch and semi-liftoff etc)
staggered 8 stroking or whatever

[hurril]

if you are utilising heat energy via the turbine that would otherwise be lost in the coolant system it raises the PU efficiency tho eh (during launch and semi-liftoff etc)
staggered 8 stroking or whatever

Those are not two alternatives the way you make them out to be. Heat that is not, or would not be, utilized by a turbine would just pass through the exhaust pipe. It would never meet the cooling system.

Heat lost through the cooling system has to do with combustion efficiency itself.

[FW17]

2. ". . . if the turbine is more efficient than the ICE". That is never the case.

Turbines of the turbochargers can run in excess of 75%

[wuzak]

3. Rules allow for 4MJ to be harvest during a lap, but only 2MJ can come from MGU-K.
So, to harvest other 2MJ MGU-H has to harvest somewhere.

That'd be every time the rain light starts flashing at the end of straights. That indicates that the MGUH has stopped pumping electricity straight to the MGUK and is now storing it in the ES.

[Pierce89]

3. Rules allow for 4MJ to be harvest during a lap, but only 2MJ can come from MGU-K.
So, to harvest other 2MJ MGU-H has to harvest somewhere.

That'd be every time the rain light starts flashing at the end of straights. That indicates that the MGUH has stopped pumping electricity straight to the MGUK and is now storing it in the ES.

Nope it denotes that the MGU-K goes from motoring to generating.

[godlameroso]

Magneti Marelli being Honda's DFI and ERS supplier, made this bit of news interesting.

http://www.autoblog.com/2016/08/03/sams ... -from-fca/

[thisisatest]

Regarding cold blowing for regen purposes:
Cold blowing isn't "free" in the sense that it can be used without consequence. You would coasting from a high speed, throttle open, but no fuel or spark, right? The car's momentum is driving the pistons as an air pump, and you would be slowing down because of this. That air goes to the MGU-H and you get electricity.
This has to be weighed against keeping the throttle closed, therefore minimizing pumping drag, and simply slowing down the car with the MGU-K acting as a generator.
Which one is more efficient? The -K. But, can you do both? The -K has a Max recovery rate, but the -H does not, correct?

[godlameroso]

I wouldn't be too sure there's a lot of throttling going on. Probably more efficient to just run leaner, or throttle the compressor itself. That said there are still throttles, but I don't know if they're conventional butterfly valves.

[thisisatest]

Without variable valve lift, I'd say they all have throttles. Renault previously talked about using butterfly throttles for improved part-throttle drivability vs barrel throttles, even at the expense of a few peak HP. That was at the end of the V8 days, but I don't see an alternative.

[gruntguru]

1. "Cold blowing"? If that means using air pumped through the ICE under braking/decel', all the teams would be using it - IF - there is enough energy in that cold air to enable useful power in the turbine.

2. ". . . if the turbine is more efficient than the ICE". That is never the case.

3. "Genset mode" (the efficient alternative to hot blowing) would be enabled whenever the power required to the wheels is less than the maximum output of the ICE but greater than minus-120 kW. (below minus-120 you are in "regen braking mode". There are many seconds per lap when the power requirement falls in this category, so adding the energy available from regen and genset modes, it will always be possible to exceed the per-lap storage limit. So I repeat, hot blowing is an inefficient, unlikely scenario.

first, all you said is true, but...

1. According to my source (for v8) there is still 75% of the exhaust pressure compering to full throttle.

2. Cold blowing is using waste energy

3. Rules allow for 4MJ to be harvest during a lap, but only 2MJ can come from MGU-K.
So, to harvest other 2MJ MGU-H has to harvest somewhere.

1. No chance of back-pressure being 75% with no combustion. Even if the throttles are kept wide open and the fuel cut. All the turbine energy will be consumed by the compressor and even that won't be enough to maintain boost. (Think turbocharged diesel engine at max rpm downhill then cut the fuel - the turbo spools down immediately).

Even if exhaust pressure stays high, that won't provide the same power to the turbine. Most of the turbine power comes from heat (internal energy) in the exhaust.

2. I was responding to a quote from FW17 " Hot Blowing - It the turbine is more efficient that the IC engine why not use hot blowing?"

3. Thanks for clarifying the rule. "Genset mode" will also create additional MGUH energy in some (higher load) conditions. Some tuning of spark advance can increase this proportion at a small cost to efficiency. This is far better than outright "hot blowing" where fuel is burned to generate exhaust energy alone.

[gruntguru]

2. ". . . if the turbine is more efficient than the ICE". That is never the case.

Turbines of the turbochargers can run in excess of 75%

Unfortunately the quoted figure is "percentage of the isentropic efficiency". Isentropic efficiency is the maximum percentage of heat energy in the exhaust that can be converted to work and depends mostly on the turbine inlet temperature (TIT) and pressure ratio (PR). For TIT = 1000*C and PR = 3.5, isentropic efficiency is about 40%, so a 75% efficient turbine will recover 40% x 0.75 = 30%.

[gruntguru]

The H harvests whenever there's excess boost pressure, such as changing gears, or during flat out sections, under breaking and whenever the driver has to hold part throttle.

You have to waste a little petrol at really low speeds. Imagine you're in a slow turn and you briefly take your foot off the gas, the k goes into regen mode and you get -120 kw in the middle of the turn. How do you stop the car from swapping ends.

I suppose if you were really clever you could have a sort of rear wheel breaking via the k to eliminate understeer. Combined with the electronic differential, and break by wire, you could essentially have a weak version of abs, but full on torque vectoring in the rear.

The throttle pedal commands a "torque" level from the PU, with a range from "maximum available" down to some negative value determined by how much "engine braking" (can include MGUK braking) has been included the setup (Map).

So "swapping ends" will happen only if the driver commands too much "negative torque" via the pedal.

[gruntguru]

I wouldn't be too sure there's a lot of throttling going on. Probably more efficient to just run leaner, or throttle the compressor itself. That said there are still throttles, but I don't know if they're conventional butterfly valves.

There are still throttles, but their use is avoided because throttling wastes energy. The preferred methods for reducing output would be
- generate in the MGUK
- reduce RPM
- run leaner
- skip cylinder firings