Honda Power Unit Hardware & Software

[JuanjoTS]

How can you have a different displacement without changing the displacement?

That's nonsense.

More than 4 disagreements (6 in the case of v6) at the same time....

[Wil992]

No, the displacement mus be between 1590 and 1600 cc, all the time.
that design is not multiple displacements "at the same time". It's multiple displacements one after the other.
And besides...

5.1.7 All engines must have six cylinders arranged in a 90° “V” configuration and the normal section of each cylinder must be circular.
All six cylinders must be of equal capacity.

[Big Mangalhit]

How can you have a different displacement without changing the displacement?

That's nonsense.

I think they mean cylinder shut off so that the effective power outputting displacement would be lowered. If all 6 cylinders had variable volumes there would be an array of combinations of shut off cylinders you could do to have different displacements. But I think that will be all for the commercial department cause in F1 AFAIK bore and stroke are regulated thus all cylinders have the same size. Unless only the bore is regulated and thus some cylinders could have different stroke length (and so different volume) with the total displacement adding to 1600cc. But I doubt it is legal

[Wil992]

How can you have a different displacement without changing the displacement?

That's nonsense.

I think they mean cylinder shut off so that the effective power outputting displacement would be lowered. If all 6 cylinders had variable volumes there would be an array of combinations of shut off cylinders you could do to have different displacements. But I think that will be all for the commercial department cause in F1 AFAIK bore and stroke are regulated thus all cylinders have the same size. Unless only the bore is regulated and thus some cylinders could have different stroke length (and so different volume) with the total displacement adding to 1600cc. But I doubt it is legal

I hear what you're saying, but edited my last post after you submitted this reply.
Yes, you're correct, all cylinders must be same bore and stroke, so it's nonsense.
Regarding the cylinder cutting, I'd say that doesn't affect the capacity of the engine, bore and stroke and therefore swept volume are fixed, but sometimes there's not power from some cylinders. Still same capacity though.

[dren]

Yes, selective firing of cylinders.

[Big Mangalhit]

How can you have a different displacement without changing the displacement?

That's nonsense.

I think they mean cylinder shut off so that the effective power outputting displacement would be lowered. If all 6 cylinders had variable volumes there would be an array of combinations of shut off cylinders you could do to have different displacements. But I think that will be all for the commercial department cause in F1 AFAIK bore and stroke are regulated thus all cylinders have the same size. Unless only the bore is regulated and thus some cylinders could have different stroke length (and so different volume) with the total displacement adding to 1600cc. But I doubt it is legal

I hear what you're saying, but edited my last post after you submitted this reply.
Yes, you're correct, all cylinders must be same bore and stroke, so it's nonsense.
Regarding the cylinder cutting, I'd say that doesn't affect the capacity of the engine, bore and stroke and therefore swept volume are fixed, but sometimes there's not power from some cylinders. Still same capacity though.

Agree 100%. But I still got the impression from the text that the patent was on cylinder with variable volume to shut off some and thus regulate the power outputting deplacement on the fly. Although 1) obviously not for F1 and only for road car. 2) It will not change the displacement per se but I think that is what the author means with variable displacement.

[Wil992]

Not sure what it was for tbh, but you're right, definitely not F1 so not relevant here. Can we put this to bed now and let some of the proper technical people (i.e. Not me) get back to talking about things related to the Honda F1 engine.

[63l8qrrfy6]

That coupled with the 100% torque demand that goes along with most up shifts coupled by an immediate drop in revs. Downshifts requiring far less torque demand or even negative.

More precise control of the other systems (turbine/compressor/K/H) may not be quite to what is required for combustion stability during abrupt changes in operating conditions.

Not quite.
On a downshift you increase the engine speed by a few thousand rpm in about 0.1 sec.
That is a massive angular acceleration.
Torque is then given by the whole engine inertia times that angular acceleration. That's a big number regardless what sign it has ! (It is positive)

No, I was referring to the combustion side, torque demand at the pedal/brake. I'm saying maybe it is an issue of not being able to maintain combustion stability on the upshift, when torque (combustion) is demanded as opposed to braking when downshifting.

If it was a matter of forces between ice/trans, wouldn't you see if on both up and down shifts?

I see, that's actually plausible. Remember a while ago when low speed pre ignition was grenading engines left and right ? It could be an unfortunate speed/load combination. From the little I know about combustion, high performance engines rely on piston motion rather than port geometry to impart kinetic energy to the charge, which means that combustion behaviour is much more sensitive to piston speed.

[godlameroso]

Not quite.
On a downshift you increase the engine speed by a few thousand rpm in about 0.1 sec.
That is a massive angular acceleration.
Torque is then given by the whole engine inertia times that angular acceleration. That's a big number regardless what sign it has ! (It is positive)

No, I was referring to the combustion side, torque demand at the pedal/brake. I'm saying maybe it is an issue of not being able to maintain combustion stability on the upshift, when torque (combustion) is demanded as opposed to braking when downshifting.

If it was a matter of forces between ice/trans, wouldn't you see if on both up and down shifts?

I see, that's actually plausible. Remember a while ago when low speed pre ignition was grenading engines left and right ? It could be an unfortunate speed/load combination. From the little I know about combustion, high performance engines rely on piston motion rather than port geometry to impart kinetic energy to the charge, which means that combustion behaviour is much more sensitive to piston speed.

Increased piston speed actually improves mixing because of increased turbulence. When a car upshifts, the throttle is reduced, revs drop and some pressure charging is lost, and I think we're seeing the results of a band aid fix that results from combustion instability during a transient condition.

[garrett]

Wild speculation mode:
What if, ultrasonic vibrations caused by the pre-chamber resonance are vaporizing gasoline much like high frequency oscillators are used in humidifiers to vaporize water. This in turn causes combustion instabilities at a certain rpm range, in other words, combustion happens at a nice normal predictable level until you get to a certain RPM range where combustion happens faster because of the fuel vapors caused by the frequency.

Very interesting idea! Could it be that Honda retries ultrasonic fuel atomizing like they reportedly did with the RA168E ?

[63l8qrrfy6]

No, I was referring to the combustion side, torque demand at the pedal/brake. I'm saying maybe it is an issue of not being able to maintain combustion stability on the upshift, when torque (combustion) is demanded as opposed to braking when downshifting.

If it was a matter of forces between ice/trans, wouldn't you see if on both up and down shifts?

I see, that's actually plausible. Remember a while ago when low speed pre ignition was grenading engines left and right ? It could be an unfortunate speed/load combination. From the little I know about combustion, high performance engines rely on piston motion rather than port geometry to impart kinetic energy to the charge, which means that combustion behaviour is much more sensitive to piston speed.

Increased piston speed actually improves mixing because of increased turbulence. When a car upshifts, the throttle is reduced, revs drop and some pressure charging is lost, and I think we're seeing the results of a band aid fix that results from combustion instability during a transient condition.

That's what I think dren was suggesting which is why I brought up piston speed. As someone pointed up Honda upshifts at higher revs maybe to avoid dropping to a funny engine speed. I'm not convinced the throttle moves at all during upshifts though..

[PlatinumZealot]

it could be that at those piston speeds the aerodynamic effects in the combustion chamber is not conducive to stable combustion even after dumping in fuel. Honda was very well dumping in fuel the whole race and that would explain their poor fuel mileage.

[diffuser]

it could be that at those piston speeds the aerodynamic effects in the combustion chamber is not conducive to stable combustion even after dumping in fuel. Honda was very well dumping in fuel the whole race and that would explain their poor fuel mileage.

Dumping in fuel ? Running rich ?

[glenntws]

Well, after arguing about combustion vibrations affecting engine stability, I have a idea which could explain the poor fuel mileage.

What if the ICE isn't able to feed the pre-chamber with a good enough air/fuel mixture? It's possible that the valve motion profile makes up for a weird charging motion at the rev range of approx. 9k-10k rpm, where it could become a conflict with high loads. The turbulence in the chamber could get to the wrong form so that the pre-chamber isn't flooded with the right air-fuel mixture anymore. What could happen are very weak jets out of the pre-chamber, which don't ignite the fuel as wished, which in turn could lead to higher peak pressures then calculated.

While in a normal engine you just want the biggest charge motion possible over the whole chamber, for TJI it is better if you generate a tumble effect which supports the "cleaning" of the pre-chamber. Also, you would want the right tumble/swirl motion to bring the fuel as closely as possible to the pre-chamber (if they didn't put the injector into the chamber which is a very possible thing).

The solution could be:
- different port shape
- rearrangement of pre-chamber and/or injector
- different cam profile
- different pre-chamber and/or piston shape
- different connector type (don't know how to say) between main and pre chamber

Overall: If this is the problem, Honda Needs to go fast because this has to be fixed by combining different solutions in all these places

A temporary fix for this problem however is the method of pouring more fuel in than needed. You get a richer mixture in the chamber, but the chamber in the pre chamber also get's richer which improves jet Quality if it was running to lean before.

Either they used that or they didn't use TJI in Melbourne. Either way, the engine ran smoother which could also be a result of the better Jet Quality. I'm sorry if this may Sound so idiotically to you Mudflap but I'm sure it's possible to hear a difference in the engine sound. Either I can hear and Interpret the engine sound correctly or I'm just hypnotising like you said. It's left to you, what's right...

[dren]

it could be that at those piston speeds the aerodynamic effects in the combustion chamber is not conducive to stable combustion even after dumping in fuel. Honda was very well dumping in fuel the whole race and that would explain their poor fuel mileage.

Suppose they were running the PU rich, or the team short filled the tanks to take advantage of a lighter car? I'm sure there's an optimum medium with all the variables at play over a race distance. But is it safe to say the PU was running rich? I don't know. Just a thought.