Pumping loss reduction strategies

[cRiPpLe_rOoStEr]

Originally Posted by pgfpro

I'm now working on my eight proto type lean burn pre-chamber(stratified charge). This new pre-chamber I hope will increase flame speed by a hotter kernel that will reach deeper into the combustion chamber.

Prechambers in a spark-ignited engine? That's new to me.

[Ecky]

Originally Posted by cRiPpLe_rOoStEr

Prechambers in a spark-ignited engine? That's new to me.

https://en.wikipedia.org/wiki/CVCC

CVCC is a trademark by the Honda Motor Company for an engine with reduced automotive emissions, which stood for "Compound Vortex Controlled Combustion".[1] The first mention of Honda developed CVCC technology was done by Mr. Soichiro Honda February 12, 1971, at the Federation of Economic Organizations Hall in Otemachi, Chiyoda-ku, Tokyo.[2] Honda's engineers at the time, Mr. Date conferred with Mr. Yagi and Mr. Nakagawa about the possibility of creating lean combustion via a prechamber, which some diesel engines utilized.[3] The first engine to be installed with the CVCC approach for testing was the single-cylinder, 300 cc Honda EA engine used in the Honda N600 hatchback in January 1970.

The volume near the spark plug is contained by a small perforated metal plate. Upon ignition flame fronts emerge from the perforations and ignite the remainder of the air–fuel charge. The remaining engine cycle is as per a standard four-stroke engine.

This combination of a rich mixture near the spark plug, and a lean mixture in the cylinder allowed stable running, yet complete combustion of fuel, thus reducing CO (carbon monoxide) and hydrocarbon emissions. This method allowed the engine to burn less fuel more efficiently without the use of an exhaust gas recirculation valve or a catalytic converter, although those methods were installed later to further improve emission reduction.

Same type of thing?

[cRiPpLe_rOoStEr]

Earlier Honda cars with CVCC engines weren't available in Brazil, so I didn't get used to them, and I'm not sure if the ones available in Uruguay had CVCC.

[oil pan 4]

Besides the most obvious way to reduce pumping losses:
A turbodiesel.

[Frank Lee]

I've got a little Briggs and Stratton gasoline engine from the '30s with a pre-chamber.

[serialk11r]

Originally Posted by Frank Lee

And I wish cylinder deactivation was more effective.

It is effective. 6.2L Chevy engines with it get fairly good mpg. I shudder to think of how much fuel those would burn with all 8 cylinders running at idle.

Back to OP, Honda went for cylinder deactivation because it already has variable timing. The benefit is additive, but you add mechanical complexity.

Lean burn from the factory is not possible with emissions regulations, but we can always trick the ECU with aftermarket parts, and this is the only cost effective pumping loss reduction a DIYer can do unless they were already modifying other parts of the engine for unrelated reasons. Well, I guess a hot air intake works too, but I would worry about the engine knocking from that.

The way you do DIY lean burn is to not be greedy and only go up to 1.1-1.15 lambda using a wideband sensor and narrowband emulator, then richen the fuel map in appropriate areas so it's running at the correct fueling when under load. On the FR-S, before I went on the freeway and triggered the ECU to start correcting the mix, I dropped the idle fuel flow rate 10% by going 15% lean, which is rather incredible. I was able to pick up 1mpg on the freeway by moving the intake cam further, but that was probably not worth the effort.

[oldtamiyaphile]

You can also reduce pumping losses by deleting the throttle plate like Fiat's Multiair engines do.

[oldtamiyaphile]

Originally Posted by serialk11r

It is effective. 6.2L Chevy engines with it get fairly good mpg. I shudder to think of how much fuel those would burn with all 8 cylinders running at idle.

A simple stop/start system would be 100% more effective though.

[cRiPpLe_rOoStEr]

Originally Posted by oldtamiyaphile

A simple stop/start system would be 100% more effective though.

No wonder more vehicles are fitted with idle shut-off than cylinder deactivation. But it might have some effectiveness while cruising.

[ChazInMT]

Annnnd you totally dissed BMW's Valvetronic and some others Variable Valve Lift (VVL) systems which change the displacement of the engine by varying the intake valve to close before BDC on the suck stroke. In fact they keep the throttle plate wide open on those engines using the valves to "Throttle" the engine. It'd be somewhat difficult to retrofit your Geo Metro engines with it. Just sayin. Although I bet that magnificent b@st@rd MPGeo could pull it off....that guys a frickin genius.