8 cut to 4

mrvette

Phantom of the Opera
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Mar 24, 2008
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I had a loose wire come apart long time ago on my DPFI batch fire 350, and so the effect was the car ran fairly decently at freeway speeds...but raggedy as hell, even worse than it was normally .....

well now that all the crap is sorted out and I"m getting decent enough fuel economy...I wonder about an experiment of wiring the injectors to fire the original Bendix pattern of 7218 and then 3465 and so to even out the thrust on the crank....maybe re do it to 7834 and so forth....

what I"m trying to do is save gas......but not damage the engine....

one of the tricks to get fuel economy is to alternate fire injectors under light load cruise, or even moderate acceleration...

so IF, I can put in a kill switch for FOUR of the cylinders in my batch fire system, and externally trigger it off say manifold pressure and a comparator circuit...(electronic switch to enable or kill the cylinders) I wonder about that as being effective for fuel economy without killing the engine mechanically....

now I know the O2 sensor is in the pass side only....so maybe I have to kill only the driver's bank, and see what happens.....that way the O2 is happy....

any thoughts??? wonder about just faking the O2 input to the computer?? assuming the engine really objects to killing the driver's bank injectors???
 
got thinking a bit further 72184365 firing order...so we eliminate the odd numbers on the drivers side....we have left to be working.....7x1xx3x5 so that means really the harmonicas are the same on the crank....NO?? one end, the other end then the two in the middle??

that would even it out pretty well, no??

I gotta try this, but if you all think of some really risky hazard why not.....

I won't , obviously.....
 
If it were me I would arrange your batches and what cylinders you cut off by your firing order.
 
Cadillac did a 8-6-4 firing order thing about 1983. Try looking that up and seeing which cylinders they cut and what order. The fix for the Caddy's was to cut the wire that told it the tranny was in 4th and locked. About 90% of the Caddy's would shake like a dog passing a peach seed.
 
Cadillac did a 8-6-4 firing order thing about 1983. Try looking that up and seeing which cylinders they cut and what order. The fix for the Caddy's was to cut the wire that told it the tranny was in 4th and locked. About 90% of the Caddy's would shake like a dog passing a peach seed.

I had an 81 Caddy. HT4100 POS. Glad it wasn't the 8-6-4, a bigger POS. It operated by solenoids on the rockers to disable cylinders.

The newer GM cars just shut off the appropriate injectors. Much better deal.
 
The newer GM cars just shut off the appropriate injectors. Much better deal.

I stand corrected. They use solenoids to shut off the appropriate cylinder lifter.
http://en.wikipedia.org/wiki/Active_Fuel_Management

Well, since I obviously can't get special lifters and all that crap....I wonder what if anything could be done with just cutting one bank of injectors..??

AND more importantly, what happens to the crank loading when I do that???

tear up the bottom end??

:flash:
 
Cutting back on just two cylinders would be a savings. Have you searched the net, to see if there is some one else doing this mod?
 
You would have to be able to cut out certain cylinders that are evenly spread in combustion as not to put to much stress and unbalance in the engine. You can leave the rockers doing their work. It will cost some extra fuel but that is it.

Basically i would think you can only do this with a sequential system. Megasquirt is getting ready with one of these. You can retrofit any chevy with this system. Gets expensive though.
 
You would have to be able to cut out certain cylinders that are evenly spread in combustion as not to put to much stress and unbalance in the engine. You can leave the rockers doing their work. It will cost some extra fuel but that is it.

Basically i would think you can only do this with a sequential system. Megasquirt is getting ready with one of these. You can retrofit any chevy with this system. Gets expensive though.

LONG time ago, I remember talking to Bruce Bowling about DPFI, back before the computer daze yet....I was doing the DPFI on my Pontiac 455.....

anyway that MSquirt system is fine, but hard to find a computer that can take an old serial D, then deal with all the file transmittals, etc....

I had some 4-5 computers trying to handle all that crap, and gave up, sold the computer off, and sold the laptops....

went back to stock system...
 
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