Honda Power Unit Hardware & Software

[Richard]

Au contraire, it has everything to do with their superiority, I'm still certain that they have a clutch, which the spannerman (Whiting) mindlessly approved upon some years back. This way they can disconnect the turbine to reduce inertia and speed up the compressor with the MGU-H only, which in turn allows the use of log-xhausts, all in all dramatically improving throttle-response and packaging.

We can have a new thread if you like so you can humour us with your imagination. How is this configured and how is it justified to meet the regs?

[MOWOG]

humour us with your imagination

OOooohh, the gauntlet has been well and truly flung!

[xpensive]

...
How is this configured and how is it justified to meet the regs?

I'm afraid you wouldn't understand, this is engineering stuff esteemed moderator.

[Richard]

I wouldn't but I'm sure others would. Or is this a bout of handwavy hyperbole?

[xpensive]

It's the only xplanation for how they get away with log-xhausts, while retaining throttle response, nobody has used that for decades.

Ooops, there goes another vote for having an opinion contradicting the moderator's...

[hurril]

It's the only xplanation for how they get away with log-xhausts, while retaining throttle response, nobody has used that for decades.

Ooops, there goes another vote for having an opinion contradicting the moderator's...

The only? Surely the MGU-H-motor could ramp up the whole turbo to "retain throttle response" too albeit probably less energy efficient than what you propose. So it would actually not be the only explanation... since there is this one too. My guess is that working against turbine inertia isn't as "taxing" to the ES as the actual work having to be done by the compressor either.

[mrluke]

It's the only xplanation for how they get away with log-xhausts, while retaining throttle response, nobody has used that for decades.

Ooops, there goes another vote for having an opinion contradicting the moderator's...

Not really.

Turbo cars are less sensitive to exhaust design than an NA. There are lots of examples of big power turbo cars running log manifolds. Its clearly not ideal but it works and in Mercedes case allows them a packaging advantage that outweighs the power loss.

[toraabe]

In term of log exhaust, you are loosing on volume efficiency, but gaining more on turbo efficiency because of shorter piping and higher temperature. So i think that all team will run lo style manifold in 2015. Another big benefit is aero package, and less cooling requirements. The PU106A uses the turbo efficiency better than the other two, and is able to harvest more energy from the MGU-H and power the MGU-K direct.

[PlatinumZealot]

Honda's engine sounds damn good If i do say so myself. Nice Metallic sound to it..

[xpensive]

The truth shall set you free, I'm certain it will all come out in the end, I might be wrong though, but I don't think so.

[Ciro Pabón]

Well, I think it has been said several times in different articles, or am I wrong?

The MGU-H serves two purposes: it's used in place of a waste gate because it slows the speed of the turbo OR it's also used to accelerate it to compensate turbo lag, according to the amount of air the engine needs. Ergo, exhaust length is not that important.

I believe that's why MGU-H actually makes sense.

I'm not sure if I understand the point, X. Could you elaborate a lagom, kompis?

[xpensive]

If you can disconnect the turbine at MGU-H spool up of the compressor, you will lose both turbine inertia and windage.

Windage as the turbine would otherwise have to momentarily spin faster than the xhaust gases moves.

That is my home-spun theory anyways.

[Tommy Cookers]

what you see as windage is using stored electrical energy to lower mean exhaust pressure, raising crankshaft power and massflow
at this point an allround help to the supercharging
quite a useful thing to be doing with stored electrical power

EDITediting this post crossed with Xs post
the word I was looking for was invalidate
ie rather neutral to the clutch idea, does not necessarily invalidate it

[xpensive]

...
not gainsaying the clutch idea, though

Thanks TC.

See that Richard?

[Blanchimont]

5.1.6 Pressure charging may only be effected by the use of a sole single stage compressor linked to a sole single stage exhaust turbine by a shaft assembly parallel to the engine crankshaft and within 25mm of the car centre line. The shaft must be designed so as to ensure that the shaft assembly, the compressor and the turbine always rotate about a common axis and at the same angular velocity, an electrical motor generator (MGU-H) may be directly coupled to it.

5.2.4 The MGU-H must be solely mechanically linked to the exhaust turbine of a pressure charging system. This mechanical link must be of fixed speed ratio to the exhaust turbine and may be clutched.

So, yes, it is possible to use a clutch to disengage the mguh from the shaft, but the turbine and the compressor have to stay connected all the time.