Its Just 89oct! Or is it?

Posted: April 4, 2011 by kemist88 in Tech
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Hey im sure we all have experimented with gas to see if the extra 20-30cents/gal are worth going from 87-93oct. You’ll here everything thing from 93 oct adds power to your car, it gives it better milage, its a cleaner gas, ect ect. THIS IS NOT 100% wrong nor is it right. If you understand firstly what an octane level is then it give you and idea on how on some cars the above can be true. Octane is the unit they measure gasoline/fuel ability to resist pinging/pre-detonation/knock. Some of you are wondering now whats pingin/knock? Its pre-detonation usualy cause by lean afrs, excessive boost, or too high of compression or overly advanced ignition timing. So how do they all tie in? Well if you have your mothers corrola or camry made in 1993 you realy dont need 93 or even 91 oct. because its a low compression N/A car its made to be economical and take cheap gas.  Now wether it will preffer 87 or 89 or 83oct (if they still have 83) you will have to experiment and see how the car responds. Now boosted cars and performance-based cars example evo, acura -r/gsr, honda si ,rsx-s any high compression car 91 octane minimum! “But i put 91 oct in my sti and then 93 after it was on empty and it feels totaly diffrent so how does it not add power” . Well simple the car was made to best respond to 93oct or higher. Try putting 110oct in it you will gain no substantial power, unless you tune for it. Running the car on 91 octane over 93oct may not cause any damage worth you selling your car or moving to a state/county were they have it availible because the ecu accounts for this. But many many num-nut will turn up the boost on a car it may feel faster and then blow up the ecu can only pull so much timing and richen up the afrs(air:fuel ratio) to stop excessive knock.  now this leads to the 2nd half of the topic wich is gas milage and cleaner  fuel. If you have exsive knock on a ecu that will try to compensate its tune to stop it you will get a richer burn (more fuel) . More fuel=less mpg, itpulling timing produces less efficent combustion, less efficient cumbustion= less tq . so you using more gas , to make less tq , so intern your loosing mpg. A leaner burn will also lessen emmisions . Now rember a factor that causes knock. lean burns! “omg it all makes sensce now” high octane alows for a leaner burn!

Every car is difrent! not all will benifit from higher octane from the factory nor will all thrive on low octane in its factory form! thats why its important to do research and read your car manual haha. There all no links because this is all from me



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