Gas octane question – page 4 – toyota nation forum toyota car and truck forums hp gas kushaiguda


i drove an example of a lean burn engine, the 92-95 honda civic vx. they ran ratios of 25 to 1 air to fuel and did so continuously without any of the problems you attribute to those operational parameters. 64 miles per gallon at 64 miles per hour, for 300 miles, but this was a modern design without a carburetor. my pressure washer does not run at a higher speed when it runs out of gas, since it has a load constantly applied if you are pulling the trigger. what killed lean burn engines was not what you described as self destruction, but actually super high nitrous oxide emissions once combustion temperatures passed 3500 degrees.

sure a lean condition in an old tech carbureted engine, causing preignition, will destroy an engine. the other end of the spectrum is HCCI, homogenous charge compression ignition, where no spark is needed, and the mixture is even throughout (homogenous), with the compression igniting the mixture and virtual elimination of any emissions after treatment.

leaner is not more powerful, simply put there is less energy content in a leaner mixture, but when combined with intended turbulence through reduced intake valve lift and only one intake valve opening (of two at lower throttle openings), creating better atomization with that turbulence, and high quantities of exhaust gas recirculation and greater throttle opening with lower pumping losses and you have improved thermal efficiency.

since you were not specific in your "more power" claim for a lean condition, we can either assume you meant more power measured instantly or more power over a long period of time, meaning the same work, produced while consuming less fuel for the same distance traveled, which considering the duration of the scenario would actually be more power measured as the sum of work performed for energy consumed.

controlled lean burn has evolved in the mazda skyactiv engines that run regular fuel at compression ratios of 14.5 to 1. fuel injection consists of 5 individual injections during the power stroke, during combustion to spread out the expansion and provide more of a push versus a slam on the piston top.

neither of these claims had anything to do with the resources you quoted, but like egr, dilution of the mixture with inert gasses allows for greater throttle openings and more efficient power production, not greater power in any instant in time, which i think was your claim "more power" versus reality which is "higher efficiency"

I’m a believer in using premium gas for Toyotas than can run regular. Why? My 1992 Toyota pickup with a 22R-E 4 cylinder fuel injected engine ran flawlessly for 485,000 miles without needing fuel injector cleaners or fuel injector rebuilding or a new fuel pump or any other fuel system componet (except a new fuel filter every 60-100K miles) and still passed California smog tests with lots of room to spare with its factory original catalytic converter. Cylinder compression on all 4 cylinders was still like new.

Here’s similar logic: I’m going to smoke a box of Havatampa cigars, starting when I turn 10 years old, because my grandfather did that and lived into his 90’s. I’m also going to add snuff to my routine, because by great aunt used snuff since she was a child, and she lived to be 102.

Enough detergent in gas is enough, more detergent isn’t necessary better, and too much is, by definition, too much. Detergent % is the only benefit SOME premium gas has (and not all premium gas has a higher % detergent) for an engine system that is designed to on lower octane ratings.