[metromizer]

Originally Posted by JohnAh

@theycallmeebryan: Nice to see that my crazy project can inspire! I did´t think about the possible problem with clean air being pumped and blended with the exhaust. You are probably right about the sensor reading lean mixture making the injectors dumping a lot more fuel than needed in the remaining two cylinders. Dammit! I was hoping to get a some answer about how much of the fuel savings is comming from the harder work in the remaining cylinders and how much is saved by reduced piston friction.

Is there perhaps an easy way to block the intake manifold or to disengage the valves? Don´t remember if I´ve written this before but I want to try removing all push-rods for two cylinders in my old Saab. Removing the push-rods is easy but the question is what will happen when the valve tappets get lose? Removing them is a LOT more work but perhaps they can be lifted up and locked in place by magnets or a thin strip om metal.
Doing the same trick with an OHC-engine demands most likely a destructive operation.

The test is however very interesting. If fuel consumption can be reduced by 5-10% with all piston still in place there may be a way to modify the engine so it can go from standard mode to "split-mode" while driving.

Thanks for posting this, I have a few comments.

only 5-10% reduction in fuel consumption just isn't enough motivation to justify the work, in my mind. By disabling a couple cylinders, but not removing the 'dead cylinder's' friction doesn't seem worth the trouble. If you leave the pistons in, you need to maintain some valve action. If you don't, the piston is compressing air needlessly. Worse, it has no place to go. Ring friction is also a big deal.

Most of the disabling a cylinder or two FE experiments I've read about, have started with a worn out and/or broken engine. I'd like to see someone test a good running engine on a dyno, then remove two pistons and run it.

Pushrod engine: there is a couple ways of dealing with loose lifters after removing pushrods, pistons, permanently disabling a couple cylinders. If you completely remove the lifter, on many engines, you must close off the lifter oiling port or replace the lifter with a plug of somesort. If you remove the camshaft, and precision grind the lobes off round, you can just leave the lifter in place. Another way to remove pistons without having to m9odify the crankshaft, is to modify the connecting rods. Saw the beam and upper end completely off, grind it smooth, and re-install what is left with bearings. That will control the oil leak from that journal. If you don't want it to turn, just add a little .003 shim stock under the bearing shells of the modified rods.