Honda Power Unit Hardware & Software

[roon]

Conical lobes aren't unique to BMW. Look at Brian.G's threads on this forum. I'm not sure this is the valve detail he's referring to.

BMW had asymmetrical cam lobes at one time. Asymmetrical in the sense of timing i.e. indexing of the lobe apexes relative to each other. However, this may also not be unique to BMW.





Keep in mind the "complex" runner reference. It could be that, due to runner shape, a follower or rocker is used on one of the valves which contacts the camshaft at an atypical location i.e. not beneath the camshaft, but at the side or top. If there was no space available directly beneath the camshaft for a traditional bucket and spring arrangement, due to runner shape, such components could be relocated to the side of, or on top of, the camshaft. This would require 'asymmetrical' or out-of-phase lobes.

Another interpretation may be rocker arms, generally. Both valves operated by rockers; no asymmetry. BMW have used cam operated rockers on motorcycle heads before. Again, not unique to them.







This potentially frees up space underneath the camshafts and can permit greater valve inclination angles. There is precedent elsewhere:

Injectors on the exhaust side is nothing strange. The injector merely sits on the cylinderbank together with the exhaust valves instead of with the intake valves.

I always thought that the injector is placed in the top of prechamber, but If injector is in exhaust side (as motor fan pic. indicates) how do they have rich mixture in the prechamber? there might be multiple injection first one when piston is near tdc to mainly fill prechamber?
https://drive.google.com/open?id=1tpCUl ... SY3ZJV5gNa

I know, right? I've wondered that from the start and the only thing that seems possible is for the injector to create a denser cloud close to the holes in the pre-chamber and then hope that enough of it gets sucked/ pushed in there by the compression. (The pressure gradient is evened out/ lowered so that it is equal on both sides of the "membrane" that the holes form, thereby pulling the fuel with it.)

There seem to be so many concurrently active factors that go in to this though and it's not that easy to form a working picture of all of them I think.

The piston crown could either partially form the prechamber or contain an internal passage that aligns with the injector at TDC. Either way, the injector would spray into the piston/combustion chamber prior to TDC. At and near TDC, the piston geometry ensures that only a small volume is available for the injector to spray into: the prechamber.

[godlameroso]

Point to ponder: think BMW motorcycle engine camshafts.

Wazari, do you refer to the 1200cc boxer camshafts? The ones with the conical profile and ~20deg valve angle?

http://articles.sae.org/8444/
http://images.motorcycle-usa.com/PhotoG ... Boxer-.jpg

Notice they have one camshaft that has a lobe for both the intake and exhaust valve, otherwise they'd have to use a side exhaust. F1 has to use side exhaust, so unless you have some intricate port channels you'd just have the intake valves facing the V, and exhaust valves on the outside.

Could this mean Honda is doing something as outlandish as having the intake and exhaust valves running perpendicular instead of parallel to the length of the block?

[roon]

Notice they have one camshaft that has a lobe for both the intake and exhaust valve...

Good catch. Pair the runners fore-to-aft, rather than side-to-side, and stack them vertically instead of horizontally. Might explain the 'taller' head reference.

Could this mean Honda is doing something as outlandish as having the intake and exhaust valves running perpendicular instead of parallel to the length of the block?

When are valves ever oriented "parallel to the length of the block?"

[godlameroso]

Take a 4 cylinder all 8 intake valves run parallel to the length of the block.

[roon]

Thought you meant the valves themselves i.e. stem centerline.

[godlameroso]

Sorry I should have been more clear.

[Wazari]

Yes I meant the "boxer" engine camshafts. Some of you are spot on on your assumptions.

I hear that dyno testing is going well in terms of reliability and efficiency. After accomplishing those targets comes power. The baseline for the 618 is done and running. They are many more innovations in the pipeline which I highly doubt the other manufacturers will have in 2018 or ever for that matter, that Honda will try and fully incorporate by mid-season.

I would like to see the fuel flow limit go away and allow refueling during a race. This is racing....????

[iichel]

This is racing....????

Almost. It is formula racing. Part of the formula is no refueling.
On the one side, I'd love to see smaller, lighter cars with a lot of power.
But I think if the fuel strategy will come back, it will make the racing a bit more boring since all the passes can be on pit lane.

[hurril]

Yes I meant the "boxer" engine camshafts. Some of you are spot on on your assumptions.

I hear that dyno testing is going well in terms of reliability and efficiency. After accomplishing those targets comes power. The baseline for the 618 is done and running. They are many more innovations in the pipeline which I highly doubt the other manufacturers will have in 2018 or ever for that matter, that Honda will try and fully incorporate by mid-season.

I would like to see the fuel flow limit go away and allow refueling during a race. This is racing....????

Do you think that there would be a place for an MGU-h (or -k for that matter) in such a formula?

[1158]

If the intake/exhaust valves were laid out perpendicular to the length of the block I imagine you could get away with 1 cam per side. It would allow any easy way to get different valve timing for each valve. Not variable timing but different timing. The question is can that be of any use?

[Frank_]

it would allow the ports to be stacked vertically (taller head) and allow more room for injector/sparkplug assy ?

[roon]

Yes I meant the "boxer" engine camshafts. Some of you are spot on on your assumptions.

The BMW boxer engine spans many decades and its features discussed in this thread so far include: lobe phasing, lobe shape, runner placement, cam followers, rockers, and bevel drives. Can you say which relates to the Honda PU?

If the intake/exhaust valves were laid out perpendicular to the length of the block I imagine you could get away with 1 cam per side. It would allow any easy way to get different valve timing for each valve. Not variable timing but different timing. The question is can that be of any use?

Photos all suggest DOHC:

https://i.imgur.com/RIsna31.jpg

Note that the "tall" head variant seems to be the 2015 engine.

[godlameroso]

Think of flow characteristics into and out of the engine such a setup would induce? In a typical setup the main intake port splits into a path for each individual valve, they open roughly at the same time at the same rate, the air tumbles into the CC, and leaves roughly the same way. With this unique setup depending on how the ports are designed you can have a strong swirl effect in the CC, and if the ports are variable then you can tune it to promote either tumble or swirl type flow depending on the load/engine speed, or some combination of the two.

[1158]

I'm probably way off on the different valve timing idea and I wonder if there is enough scope to do anything before P2V issues but if there were slightly different timing events for each valve could that promote swirl in the chamber and give you more individual (albeit smaller) exhaust pulses hitting the turbine blades?

[roon]

If each runner (per-cylinder) is individually throttled as part of a VIM system, then you could indeed effectively have variable flow properties without variable valve timing. Call it variable flow timing. One valve can actuate earlier than another via asymmetrical cam lobe phasing. The throttles would be used preference flow into one runner or the other, which in turn determines when the bulk of the intake flow enters the cylinder.

To eliminate flow restriction trade-offs, you oversize the runners. Which might explain a taller head.