dumb question but what if you were to mix the gasoline a little? i put in premium today and still had a little regular unleaded gasoline still in the car. is that ok?

 

some of my friends were running 87 octane gas with water injection on 20+ psi of boost. and showing no signs of detonation what so ever.. dont know if they are b's ing me but it sounds like it could work

 

only 91 for me....w00t to us!!!!

 

You're fine... There's nothing to worry about.


I use a 2-stage water injection kit on my 600hp 3.2L V6. Water injection does wonders, as long as you know what you're doing with it. You could cause some serious damage if you mess up. Water injection will aid in preventing detonation and pre-ignition. It cools the intake charge, steam cleans your internals, and it slows combustion (simulates higher octane when the fine water mist makes it in the cylinders). I run 91 octane or higher on this motor.

I use 85 octane in my Civic at 5,400 ft above sea level.

 

if 87 octane is the % than how do you get 118 octane? so thats 118%?????

 

Octane is not rated in %. I run 105 on the track.

 

Higher octane fuel burns hotter and cleaner (the lay-person explaination of XCM828's) Lower octane fuel ignites at a lower temperature and pressure. (causing pinging in some vehicles ) Low compression vehicles (such as our Civics and most of the rest of the cars in the world) don't need 91 octane. Higher compression engines (such as boosted and high-performance engines) require 91+ to keep from premature ignition. It may hurt an engine that is supposed to run on 91 octane to drop to 87, but running 91 octane in one that is supposed to run 87 won't hurt... as a matter of fact, it may even increase performance a little bit by running 91 octane. It will also help clean out carbon deposits and whatnot. When I run Fuel system cleaner, I run 91 octane... just to give it that much more..

 

i have a stock civic and i use 93 octane gas and i have no problems.

y do u use less above sea level?

 

If your using 91 octane in a vehicle that does not need it, you'll hurt performance before you will help it. Ideally, you want to run the LOWEST octane you can run without pre-ignition or detonation.

If you want to clean out carbon, run the car hard and it'll work its way out.



Just about anywhere you go is going to be above sea level. The higher you go, the less oxygen you'll find. You lose approximately 3-4% of your power every 1,000 feet you go. With less oxygen, your effective compression will go down. With lowered compression, you do not need higher octane to combat detonation and pre-ignition.

On the flip side, anytime you run boost, you are raising your effective compression, hence why you need higher octane. A hotter running motor, regardless of compression will need higher octane as well.

Running 93 octane in your stock Civic is wasting money...

 

I think that sums everything up. LOL...