Great Q&A Forum on your website www.masterautotech.com , Thanks.
Two questions: What affect does Ethanol have on internal components of today’s automobile engines?
I have GM's Power Mgmt (V8) where 4 cylinders are not firing when a certain speed/RPM are reached. Seems to be a good system and you do not notice as they cycle off and on. But what about wear and tear on the firing cylinders? According to GM it is always the same cylinders that are shut down. In this day of electronic superiority I would think the cylinders could be alternated which would produce equal wear and tear on all. Thank you.
I asked Mark Sarlo an automotive engineer who calls into my radio show every Saturday at 10:30 what problems ethanol might cause on an internals of a combustion engine. Mark stated that ethanol (alcohol) is a great engine solvent and will cause the engine oil to become dirtier a little faster. In our part of the country we don’t have E85 ethanol fuel; we only have 10% or less in our fuel. According to Mark 10% may cause problems on some older vehicles that have carburetors and/or older model fuel injection systems. Ethanol is not very kind to the soft rubber components such as rubber hoses as well as “o” rings and paper gaskets that are found in most fuel delivery systems. Vehicles built prior to 1999 seem to have a higher sensitivity to ethanol induced problems. Your newer model GM is not so sensitive and can handle up to 10% with no problems. Even on today’s newer vehicles once you get over the 10% of ethanol things can go down hill very rapidly. Only if your car was designed for higher amounts of ethanol (E85), then no problems with the amount of ethanol in your fuel is expected. Just change your oil every 3 to 5 thousand miles depending on your driving habits is still a good rule of thumb.
Now to the other question about alternating cylinders by disabling the SAME cylinders when the computer determines it does not need the extra power.
In a perfect world this would make a lot of sense to alternate the cylinders to minimize wear and tear on the engine cylinder walls and valves. In reality the cylinders the computer disables are the one’s that allow the engine to remain smooth with no noticeable vibration. If you disabled other cylinders the engine would vibrate and not run very smoothly. What the computer does is send a command to the certain valves in the cylinder head to stay open. This allows a smooth operation of the engine that is now running on 4 cylinders. This electronically controlled system is a much better system than the early 80’s system that Cadillac experimented with. With today’s electronic superiority things can be done that seemed impossible 20 years ago. Maybe in the future automotive engineers will be able to design a vehicle engine so that it is mechanically and electronically capable to “alternate” disabling cylinders under “no load” conditions, and still remain smooth and vibration free to the operator of the vehicle.
Have a Very Merry Christmas,
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