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Tommy Cookers wrote:what I always feel like saying seeing the topic (or myth ?), regarding the implied substantial loss of heat energy through the exhaust piping is .....

the exhaust gas is at a mean pressure of 5 bar, moving at a mean velocity of 300 mph in a plain pipe
if this situation has significant heat loss why do we ever need 'radiators' ?
ie devices whose surface area/transit time product is several orders of magnitude greater

my gut guesstimate is that the energy loss preventable by insulation is less than 1%
energy is wasted by irreversibity of (supersonic) port blowdown and manifold transition processes - this cannot be saved even by infinite insulation
if insulation significantly reduced energy loss why would we do it in an NA race application ?
exhaust energy loss and consequent pressure loss would be beneficial to NA

just saying .......

Agree with you somewhat. The speed of the gases doesn't really give much contact time for the gases to exchange much heat with the pipe. The pipe will be accumulating heat rapidly; however the opposite for each gram of gas passing though at 300mph.
I can't think of much enhancements to the exhaust, so this theory may in fact be a myth; thought its fun to consider the possibilities.

On a different note, does anyone have details on the MGUH arrangement inside the V for the Merc engine?
It is different than the others because its a hollow shaft motor. I would like know how it is clutched, mechanisms for deactivation activation etc.

How do you know that it is a hollow shaft engine?

Journal bearings would be lighter and control axial movement better than roller bearings for such a long shaft, so it's assumed that they're using journal bearings instead of roller bearings. We don't really know for sure, in fact I don't even know if that's exactly what we're talking about.

ringo wrote:On a different note, does anyone have details on the MGUH arrangement inside the V for the Merc engine?
It is different than the others because its a hollow shaft motor. I would like know how it is clutched, mechanisms for deactivation activation etc.

Assuming it is clutched at all.

The rules allow clutches, but they do not require them.

hurril wrote:How do you know that it is a hollow shaft engine?

If the motor is geared/clutched to the turbine it likely has a hollow shaft to enable the shaft connecting the turbine and compressor to pass through.

wuzak wrote:

hurril wrote:How do you know that it is a hollow shaft engine?

If the motor is geared/clutched to the turbine it likely has a hollow shaft to enable the shaft connecting the turbine and compressor to pass through.

Fair enough! So that would apply to Honda too then I suppose. You could clutch the turbine instead though unless my grasp of the rules is bad?

hurril wrote:

wuzak wrote:

hurril wrote:How do you know that it is a hollow shaft engine?

If the motor is geared/clutched to the turbine it likely has a hollow shaft to enable the shaft connecting the turbine and compressor to pass through.

Fair enough! So that would apply to Honda too then I suppose. You could clutch the turbine instead though unless my grasp of the rules is bad?

Quite possibly it would also apply for Honda.

The motor can be clutched to the turbine, but the turbine and compressor must always be connected and rotate at the same speed.

So it depends on Honda's layout - it is quite possible that the MGUH is not geared (ie it spins at the same rate as the turbine/compressor) and not clutched, which would enable it to be fixed to the compressor and turbine with no other shaft.

Another reason a shaft may be hollow is that the centre part of the shaft doesn't do much for transmitting torque.

Hollow shaft motors are those where the rotor is hollow straight through to allow a drive shaft to pass through completely.
The drive shaft is free to rotate unless it has a coupling or some mechanical means, such as a clutch to lock it with the rotor.

this is a good example;


So imagine this being the MGUH generator/motor, and the turbine-compressor shaft passing through completely.
The turbo shaft passes through that hollow shaft or quill, if you may call it that, and the quill only rotates with the turbo shaft when the clutches are engaged.

I think most of the MGUH if not all are clutched. This provides better energy management and allows faster acceleration of the turbo as it avoids eddy currents and back emf etc. The MGUH can also be allowed to spin at a different speed from the turbo when the clutch is disengaged then it can be engaged for rapid acceleration of the turbine. So there are a range of possibilities when there is more freedom between mguh and turbo.

ringo wrote:I think most of the MGUH if not all are clutched.

3 MGUs are not clutched. Maybe even 4, I have not seen details of the 4th.

3 teams or 3 engine manufacturers? Are they geared to operate at a different speed than the turbine, or just one shaft connecting TC, and MGUH?

noname wrote:

ringo wrote:I think most of the MGUH if not all are clutched.

3 MGUs are not clutched. Maybe even 4, I have not seen details of the 4th.

Clutching would just add more mass. As reliant as these PUs are on the MGUH, I don't see much need for clutching. Eliminating the field in the generator would have a similar effect if it was wanted.

godlameroso wrote:3 teams or 3 engine manufacturers? Are they geared to operate at a different speed than the turbine, or just one shaft connecting TC, and MGUH?

3 PUs manufacturers.
None is geared. Amongst companies I know were/are working on F1 PU, only 1 more-or-less seriously considered gearing.

On a different topic.
Do teams coat the exhaust ports and turbines innards withe heat resistant materials such as YSZ? And what is the risk of the coating flaking off into the turbine? Correct me i missunderstand it, these materials tend to have high thermal expansions compared to inconel and low expansion compared to aluminum? How is this managed?

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