I have a civic SI well sort of. It says to use 91 octane or higher, a guy i know says that it really doesn't matter what you use. As long as it's clean it should work, he says.

So my question is this, is he wrong?

I beleive you should use what it says for gas.

Now my car has a swaped b18c so I don't need to use the higher octane in that guy do I?

Thanks guys you are all the best

 

unless urboosted i wouldnt worry aobut running 87,89,91 or 93 octane, they arent to much of a difference in octane

 

tell that to your Ecu.

my 99 si says premium fuel only.. so what do i put in it? 93 all the time. i put 92 in it and it gets all kinda pissed

 

any science behind any of these two responses? I'm trying to learn the whole deal with octane, not just a simple yes or no answer, i'd kinda like to hear the logic behind both of your guys' (or gals') responses...

 

so 1 octane makes that big of a deal?? i never heard of that but i could be wrong and if i am i apologize

 

I didn't know that si's need premium but I do know that jdm engines have to have 91 or higher octane because that's japans normal octane rating like 89 is here for us. The cars were made to run on it so thats what you need to use.

 

so do b18c's need to use the higher octane? or can they run whatever is cheap??

 

I need some more info to tell you. Is it a JDM engine orUSDM?

 

how would i tell if it's jdm or usdm? lol
I need more information to tell you lol...

 

Octane is a rating of the compression needed to ignite the fuel in the combustion chamber. The higher the octane the higher the compression that can be run in an engine along with the more timing that can also be advanced.

Common Honda engines such as the high comp B16 and B18C engines need at the very least 91 octane to keep from detonating, if 91 is not available use 92-93. Honda had to use a lot of timing on these engines in order to produce the horsepower that they do produce, so running 87 will cause the car to knock. The knock sensor will then tell the ECU to back the timing out to keep the engine from ruining itself but will cause a dramatic loss in power from your vehicle.

Your common SOHC and LS integra (B18B1) engines are a much lower comp and can safely use 87 octane.

All turbocharged engines should be tuned and driven on the highest octane that you can get from the majority of local pumps.

Answer your questions?