Honda Cackle theory

[Zynerji]

So, we got lots of info from Honda about the changes over time in their engine, and something just jumped out at me concerning their revelations. They claimed that a large part of unlocking performance from the VLIM was being able to actually close the intake completely on demand. At first that didn't make sense to me, then I had an idea about what they may be doing.

The whole point would be to operate in this order:

approachingTDC->IntakeValveOpen->VLIMopen->PistonDownIntake->(possibly light fuel injection on intake)->BDC->VLIMclose->PistonUp->IntakeValveClose(after PistonUp pressurizes the intake runner of the VLIM)->TJIignite->PistonDownPower->ExhaustValveOpen->PistonUp->IntakeValveOpen/VLIMclosed(secondary pulse to ExhaustValveOpen, possible second ignition, during valve overlap)->ExhaustValveClose, VLIMopen-PistonDownIntake...

I am interested in anyone's thoughts concerning this idea. Using the VLIM as a pressurised pre-chamber to cause an afterburn after the exhaust valves open could potentially help the spooling of the turbo, and also cause the cackle that only the Honda has. This is all based upon the interviews buried the Honda Engine/Preseason/STR threads, and I couldn't find their direct links anymore, but im sure others here have them bookmarked...

Thanks!

[Big Tea]

So, we got lots of info from Honda about the changes over time in their engine, and something just jumped out at me concerning their revelations. They claimed that a large part of unlocking performance from the VLIM was being able to actually close the intake completely on demand. At first that didn't make sense to me, then I had an idea about what they may be doing.

The whole point would be to operate in this manner:

TDC->IntakeValveOpen->VLIMopen->PistonDownIntake->(possibly light fuel injection on intake)->BDC->VLIMclose->PistonUp->IntakeValveClose(after PistonUp pressurizes the intake runner of the VLIM)->TJIignite->PistonDownPower->ExhaustValveOpen->IntakeValveOpen/VLIMclosed(secondary pulse to ExhaustValveOpen, possible second ignition)->PistonUp->ExhaustValveClose, VLIMopen-PistonDownIntake...

I am interested in anyone's thoughts concerning this idea. Using the VLIM as a pressurised pre-chamber to cause an afterburn after the exhaust valves open could potentially help the spooling of the turbo, and also cause the cackle that only the Honda has. This is all based upon the interviews buried the Honda Engine/Preseason/STR threads, and I couldn't find their direct links anymore, but im sure others here have them bookmarked...

Thanks!

Not sure I completely follow you, but could not the same be achieved with just some sort of control of the inlet valve?
Don't know if this is possible, via switchable cam followers or what ever?

[godlameroso]

There's no variable cams, or valves, and variable intake timing would have to be carried out in the plenum, it's an interesting idea. But I like the out there stuff, it shows creativity and imagination, which most people never got to develop as children.

[Zynerji]

You would need the VLIM to close to have the intake runner volume be pressurisable.

[Zynerji]

There's no variable cams, or valves, and variable intake timing would have to be carried out in the plenum, it's an interesting idea. But I like the out there stuff, it shows creativity and imagination, which most people never got to develop as children.

This could also simulate a variable intake valve, as you could just leave the valve partially open, and fully control the flow through the VLIM.

[godlameroso]

There's no variable cams, or valves, and variable intake timing would have to be carried out in the plenum, it's an interesting idea. But I like the out there stuff, it shows creativity and imagination, which most people never got to develop as children.

This could also simulate a variable intake valve, as you could just leave the valve partially open, and fully control the flow through the VLIM.

Yes that's my guess as well, that Honda uses clever intake ports along with the VLIR, and the airbox/plenum to adjust the timing of airflow despite fixed valve timing.

[63l8qrrfy6]

They claimed that a large part of unlocking performance from the VLIM was being able to actually close the intake completely on demand

Where did they say that ? Sounds like they meant closing the turbo inlet vanes at partial loads - someone has posted a picture of the pre whirl mechanism a while ago.

Really now, why would they keep the intake valve open - it would go through the piston !
Secondly, if you want to block flow after the turbo you can just close the throttles - that's what they are there for!

[Zynerji]

They claimed that a large part of unlocking performance from the VLIM was being able to actually close the intake completely on demand

Where did they say that ? Sounds like they meant closing the turbo inlet vanes at partial loads - someone has posted a picture of the pre whirl mechanism a while ago.

Really now, why would they keep the intake valve open - it would go through the piston !
Secondly, if you want to block flow after the turbo you can just close the throttles - that's what they are there for!

One of the Honda interviews. Whichever one was about the VLIM evolution. And I'm pretty sure someone also posted the Honda Patent that does the same thing.

[Big Tea]

There's no variable cams, or valves, and variable intake timing would have to be carried out in the plenum, it's an interesting idea. But I like the out there stuff, it shows creativity and imagination, which most people never got to develop as children.

Not that its viable, but could it not be done by lifting the fulcrum bar of the rocker arms? (I know rocker arms went out with Noah's Ark, but just asking?)

[godlameroso]

Not allowed, valve timing must be fixed. Who knows how many cam grinds Honda has tried.

[Zynerji]

I still think there may be something to running a pressurized VLIM pre-chamber. If its pressurized with a slight amount of fuel, and opens into a closing exhaust cylinder cycle (lower volume) that has an open exhaust port, you would be able to evacuate residual exhaust gasses from the space by blasting in the fresh air from the VLIM, and if that were to ignite due to the presence of fuel in the pressure chamber, it would probably ignite in the exhaust port directly, causing a heat spike to go to the turbo to be harvested. I imagine the entrainment of the incoming air that is acted upon when there is a timed opening of the pressurized VLIM chamber would be worth investigating as well. If the IntakeValve opens 1 degree before the VLIM opens at the other end, the pulse may be helping with cylinder filling as well. It would also allow for variable compression as the VLIM could always vent back to the plenum, possibly introducing a partial air\fuel mixture there as well.

My ideas, not an engineer.

It would be great to hear from some of the engine gurus on this one. I wish we could tag users in posts...

[hurril]

I still think there may be something to running a pressurized VLIM pre-chamber. If its pressurized with a slight amount of fuel, and opens into a closing exhaust cylinder cycle (lower volume) that has an open exhaust port, you would be able to evacuate residual exhaust gasses from the space by blasting in the fresh air from the VLIM, and if that were to ignite due to the presence of fuel in the pressure chamber, it would probably ignite in the exhaust port directly, causing a heat spike to go to the turbo to be harvested. I imagine the entrainment of the incoming air that is acted upon when there is a timed opening of the pressurized VLIM chamber would be worth investigating as well. If the IntakeValve opens 1 degree before the VLIM opens at the other end, the pulse may be helping with cylinder filling as well. It would also allow for variable compression as the VLIM could always vent back to the plenum, possibly introducing a partial air\fuel mixture there as well.

My ideas, not an engineer.

It would be great to hear from some of the engine gurus on this one. I wish we could tag users in posts...

But the VLIM:s are not opening/ closing on a per cycle basis.

[Zynerji]

But the VLIM:s are not opening/ closing on a per cycle basis.

Is this written somewhere in the Honda tech interviews? Or is it just more speculation presented as truth?

[63l8qrrfy6]

Speculation ? Dear lord..
It's how they work. They adjust to an optimal length for any engine speed.

[hurril]

But the VLIM:s are not opening/ closing on a per cycle basis.

Is this written somewhere in the Honda tech interviews? Or is it just more speculation presented as truth?

Have you ever heard of a VLIM even being able to do that?