New Thread; DPFI Economy Enhancement

[Gary Palmer]

All: I have several ideas which I have not been able to get to, but which I think migh have some merit. I want to post a description/explanation, for everyone to be aware of, consider, brainstorm or so forth.

I have a 89 DPFI Honda. One feature of this is that the fuel is injected at the throttle body, so that a "mixed" gas is in the intake to all of the cylinders. Now it seems too me like at any given speed, say 2500 rpm, that if I call the amount of mix going into one cylinder, 100%, that some percentage of that, say 25%, is utilized just to spin the engine, at that rpm.

However, my thought was what if I had a throttle control device on a cylinder, couldn't I reduce the amount of A/F gas going into, say 2 cylinder's, just giving them the 25% they need to spin? If I could do that, then the other 2 cylinder's would get more A/F, enhancing the "swirl", allowing a lean mixture to burn more efficiently. Consequently, it would seem to me I ought to be able to get some better efficiencies out of the A/F going into the engine, maybe making functionally more similar to a 3 cylinder engine.

Any thought's, ideas, suggestions?

p.s. I have several more ideas, but I figured it would be better to take them one at a time.

[Gary Palmer]

Woop's. I stepped on metro's thread, which I didn't mean to do.

I have a 89 Honda DPFI. One feature of this car is the A/F get's mixed at the throttle body, so that the "mix" is in all of the intake tube's.

However, my thought was that at any given rpm, say 2500, it takes some percentage of the A/F just to spin the engine, say 25%. Therefore, if we restricted the flow into 2 cylinder's, to just the 25%, then that ought to make the "swirl" efficiencies higher in the other two cylinder's. This should be somewhat similar to the HF engine, where they restrict the flow to one intake valve, instead of two, to create the higher swirl.

I have not had a chance to try or test this idea, but I thought I'd put it on here, to get some other thought's or perspective's.

Please let me know what you think! Thanks, Gary Palmer

[95metro]

I answered anyway...:

It's a novel idea. My very first thought is engine balance. But it sounds like it could be worth testing. However, it seems like you could achieve the same effect on an MPFI and just place smaller injectors on the cylinders that are going to receive less fuel.

But, I really don't know if that would work either...

[Gary Palmer]

95 metro: I don't think that would work the same way, because you wouldn't have any way to know, for sure, how much less air those cylinders were getting. I can't think of a "easy" way to do this on a MPFI system, because I think you'd have to do a efi setup with a separate Oxygen sensor on each exhaust, uniquely.

Anybody else have any idea's?

[SVOboy]

I sense that you'll get terrible misfire from the off balanceness of the combustion and the terrible airflow after it hits whatev you're sticking in the runner.

[BuffaloChips]

On multiport injection systems the PCM controls the spark timing, duration and voltage to each cylinder. It will also adjust the amount of fuel to each cylinder also. If knock is detected in a particular cylinder the PCM can adjust accordingly. So, I would venture to say that you would have to know how to hack the PCM to make such a thing work properly.

[omgwtfbyobbq]

I'd think efficiency would be about the same, and the engine would run very rough. Since pumping losses are proportional to the intake charge. If you toss a larger charge into one cylinder, and a smaller charge into another, then any gain in efficiency via the larger charge will be wiped out by the drop in efficiency of the smaller charge. Adding swirl is usually done via shaped intake ports, cylinder heads, and piston tops. If you really want to run lean/more efficiently I'd guess your best bet would be going with some sort of SAFI and ITBs.

[onegammyleg]

It could be Mercedies Benz that has an engine that drops cylinder to increase FE on the cruise ,ime not sure.
Ime not sure how that system works either.(slightly off thread here)

It is possible to do it if you are prepeared for the vibrations.
Just prevent one or more of the intake valves from opening.
This can be done the most easiest in a head that has hydraulic lifters.

Reroute the oil supply lines to the intake lifters to a bypass solenoid valve.
Have that switched when high vacuum conditions exist in the intake manifold.

Vibrations would be less depending upon the style of engine and how many cylinders you deactivate.

EG . a V8 with 2 or 4 cylinders stopped may be quite smooth still., but a 4 cylinder with 1 cylinder stopped miight be prety rough indeed.