Honda Power Unit Hardware & Software

[63l8qrrfy6]

Im not sure TC, the K inertia as seen at the crank is 10x the actual rotor inertia assuming a gear ratio of 3.3.

Surely the inertia of a direct drive pancake rotor will be higher but it won't exceed the effective inertia of a geared motor unless you treble the rotor radius.

[godlameroso]

if i were to hazard a few guesses:
i don't think the valve seat is perpendicular to the valve stem due to the need to have a very vertical and straight intake run into the cylinder.
the intake valves in the cylinder are also different sized
the exhaust valves are also different sized.

interesting nugget about the jet combustion going to the walls first before ignition of the lean mixture.

There are different approaches to intake port geometry, depends what type of conditions you're trying to achieve. For example if you are trying to induce tumble to the intake air, you would use more of a "ramp" style intake port, where you increase the surface area of the port floor vs the roof.

A lot of this has to do with the intake system. The air box, the internal geometry of the plennum, geometry of the runners. The plumbing U isn't just good for the exhaust side

[Tommy Cookers]

isn't the present K machine arrangement chosen to optimise the response in shifting ?
didn't they chose gearing rather direct drive for that reason ?

and they don't want a low torque 120000 rpm H machine and a high torque 12000 rpm K machine

[63l8qrrfy6]

From an inertia perspective the best setup would be a very low speed machine turning slower than the crank.

I was not debating the motor performance.

Regarding the previous valvetrain discussions - Honda's 990 cc motogp engine revved to 16000 rpm with single springs and buckets (which are known to have the highest friction compared to roller followers and fingers and up to 30% higher inertia compared to fingers).

I wonder if valve rotation can be achieved with PVRS. Given the durability requirements and the extreme exhaust valve temperatures valve wear must be quite hard to tackle. Maybe there is an advantage to springs after all ?

[PlatinumZealot]

Inertia is a trade off..
Inertia of the geartrain
Inertia of the motor

One will be sacrificed for the other.

If you use a one to one ratio with a pancake motor. That motor will spin slower, down to engine speeds. Slower spining motors require larger magnetic flux that requires bigger ferrite cores Increasing weight and inertia.

It is lighter and i reckon much less inertia to use a geared motor.

[godlameroso]

From an inertia perspective the best setup would be a very low speed machine turning slower than the crank.

I was not debating the motor performance.

Regarding the previous valvetrain discussions - Honda's 990 cc motogp engine revved to 16000 rpm with single springs and buckets (which are known to have the highest friction compared to roller followers and fingers and up to 30% higher inertia compared to fingers).

I wonder if valve rotation can be achieved with PVRS. Given the durability requirements and the extreme exhaust valve temperatures valve wear must be quite hard to tackle. Maybe there is an advantage to springs after all ?

Do you suppose the high exhaust temperatures that produce NOx also contribute to valve seat recession?

[63l8qrrfy6]

Do you suppose the high exhaust temperatures that produce NOx also contribute to valve seat recession?

Absolutely, other than material tribological characteristics valve recession is mainly driven by temperature, seating velocity (it should be kinetic energy at closing really but for reasons unknown seating velocity is still used in the automotive industry) and to a lesser extent seat angle.

Some argue that peak cylinder pressure is also a factor but I'm not so sure.

I'd be very curious to know how they mitigate seat recession since the tradition seat materials used in motorsport have been relatively soft copper beryllium alloys - I imagine they must take quite a beating in an F1 engine.

[Tommy Cookers]

traditionally SI engines have little or no oxygen in the exhaust gas
these engines have lots and so the oxidation potential might seem to be greater than otherwise
but the exhaust gas will be rather cool

high-strength copper beryllium can be quite hard and it could be mechanically hardened in situ
intentionally by use of dedicated rolling equipment and incidentally by valve impact
it would be rather elastically compliant under impact
it can go to 10000 microstrain elastically (at room temperature)
it will run cooler than the usual valve seat insert materials
in typical use it's pretty corrosion resistant

[MrPotatoHead]

traditionally SI engines have little or no oxygen in the exhaust gas
these engines have lots and so the oxidation potential might seem to be greater than otherwise
but the exhaust gas will be rather cool

high-strength copper beryllium can be quite hard and it could be mechanically hardened in situ
intentionally by use of dedicated rolling equipment and incidentally by valve impact
it would be rather elastically compliant under impact
it can go to 10000 microstrain elastically (at room temperature)
it will run cooler than the usual valve seat insert materials
in typical use it's pretty corrosion resistant

If only the rules didn't prohibit Copper Beryllium seats now

[Tommy Cookers]

this would be about 2.5% Beryllium 97.5% Copper

I would have guessed that's permitted
(the rules being written around permitting this material but prohibiting AlBeMet type materials of eg 50% Beryllium ?)

[63l8qrrfy6]

Spot on TC - low Be content makes them legal.

I'm not convinced that the temperatures are as low as you might think though.
I have an article somewhere with a Cosworth study from 2013 that predicted 1050 C valve temperatures. By contrast they said that their 1000 hp V6 from the 80s reached 1100 C. I'll try to find the reference if people are interested.

While the seats can probably be a good 500 C cooler than the valve I still wonder if they are man enough to survive repeated contact/slippage with a valve that has a very high hardness.

[godlameroso]

I'm guessing NHK makes Honda's valves? If someone can make valve springs for these engine speeds they can. And NHK valves are hard as diamonds.

[63l8qrrfy6]

Toyota used Aisan manufactured valves. Other companies that have supplied F1 valves include Del West and Xceldyne.
G&S are also quite popular with british high end racing engine makers.

Honda have made their own valves for the LMP1 V8 but if I had to guess I'd say they are now getting them from Aisan.

[PlatinumZealot]

And here was I thinking that racing valves are "Easy to make" parts.

[Rodak]

Toyota used Aisan manufactured valves. Other companies that have supplied F1 valves include Del West and Xceldyne.
G&S are also quite popular with british high end racing engine makers.

Honda have made their own valves for the LMP1 V8 but if I had to guess I'd say they are now getting them from Aisan.

Are these sodium filled valves for the exhaust?