Re: ???Super Fuel???
Re: ???Super Fuel???
IF you have an "older" motor which was designed to run on higher octane fuel, then attempting to raise the octane of the normally available 87 octane fuel MAY be helpful, but I doubt that it would provide DOUBLE the HP gain that your buddy the "snake-oil" believer says...<br /><br />Octane rating is nothing more than a measure of how quickly the fuel will burn... The higher the octane, the slower it burns, thus allowing the motor to be designed to run at higher compressions, and "faster" timing... The slower burn time of the higher octane fuel, allows the piston to reach TDC, or be VERY close to TDC BEFORE the combustion caused peak pressures are reached...<br /><br />HOWEVER... When you set the timing TOO far in advance, then you get "ping" or spark knock, (WHICH FOR ALL PRACTICAL PURPOSES, IS IMPOSSIBLE TO HEAR IN A RUNNING OUTBOARD). Anyway, spark knock, is nothing more than the peak combustion pressures being reached before the piston gets to TDC, resulting in the noise you hear, which is typically, the piston "rattling" in the bore coupled with the "compressive explosion" force of the combustion occurring too soon.<br /><br />Not only do you have these high combustion pressures being reached too soon, you also now add additional heat in the form of the heat of compression (similar to a diesel motor), caused by the additional compression of the combusted gasses, as the piston forces it's way up to and past TDC.<br /><br />These two things are the MAIN reasons motor internal heat damage occurs. What in essence happens is that the piston material begins melting and depositing on the cyl walls, and rings, causing subsequent cylinder wall scoring by the melted remnants of the aluminum piston falling apart under the heat load...<br /><br />Since the higher octane fuels burn more slowly, or to put it more succinctly, in a more controlled manner, this allows you to advance the timing AND/or increase the compression ratios, to take advantage of getting the peak combustion pressures as close as is practical to TDC, thus maximizing the available Power, from the available fuel.<br /><br />In theory, increasing the octane on ANY motor, should allow you to advance the timing a bit, to take advantage of this power gain... In reality, the design considerations of the motor, may actually cause you to do more harm than good, or like was stated before... It may run like a "vampire bat on steroids"... but most likely, only for a short while...<br /><br />My advise, is to do what your motor owners manual (or certified dealer for your brand motor) tells you to do, to not only optimize performance, but maximize longevity...<br /><br />Let the "Snake Oil salesmen", prey on other's motors... you'll be glad in the long run that you did...<br /><br />GOOD LUCK... Obiwan Jeeper
