what happens when you gas up a 93 octane on your jeep?

lesterjanpearson

lesterjanpearson

New member
The dealer said we need to put 95 octane gas or else.

I didnt get much explaination.

also had a friend who keeps putting 93 octane on his jeep because it was cheaper, it got overhaul.

I'm also wondering if the octane rating in US is same with PH. cause I see people in jeep forums saying on 89 octane.

I'm very lost.
 
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Ddays

Ddays

Hooked
You only need to run the lower octane in JK's. As long as you have no detonation (pinging sound) the fuel you are running is sufficient. If you get occasional light detonation while lugging the engine (going up a long hill at low rpm's is where this usually occurs) you don't really have to worry much as long as its only occasional. If its under acceleration from a stop or happens frequently try a higher octane rating. Google "detonation" and a you'll find lengthy explanations on what's happening in the engine when this happens...
 
lesterjanpearson

lesterjanpearson

New member
what is the short term and long term damage when using lower than required octane?

I actually am sticking with 95 octane, since the shop said it is. we mostly have just 95 and 93 for like 90% of the gas stations.

we have 97 and 91, very rare.
 
Kilroy

Kilroy

New member
87 is recommended by manufacture running hirer octane is only need really if chipped supercharged or it does help pinging at hire altitude is sometimes beneficial running it in a stock jeep will do nothing as far as damage to the engine. Unless you vehicle is tuned and or blowen in some way is really the only reason to do it. Pump fuel is crap anyway the octane numbers are really different when compared to Europe. I used to race cars and road bikes with 110 to 125 leaded and if they used the same way they calculate octane levels as gas pumps it would be like 125 and 145 octane lol. But as you can't run leaded it's a mute point[emoji57]

Also race fuel has no ethnol in it. Look up the shitty ethnol and what it does to motors. that's why you can buy none ethnol gas for your say 2 stroke motors they rally don't like ethnol[emoji23]
 
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zimm

zimm

Caught the Bug
To really answer your question- octane is resistance to pre-detonation. That means the fuel/air mixture ignites before the piston is at top dead center, so it hammers down on the piston while it's still rising. That results in "pinging" and can break stuff. The higher the compression ratio (the more volume is squeezed), the higher octane required to keep the mixture stable before it ignites. That's why high performance engines need higher octane. There's no advantage to running higher octane in an engine designed for lower. Modern engines have knock sensors that can tell when pre-detonation is happening and it retards timing on the motor so the spark happens later- this results in no pinging, but lower horsepower. Again, only in higher compression motors like BMW's. So, use whatever is the equivalent to US 87 octane, which is "regular" in your jeep. No need to waste money on higher octane.
 
lesterjanpearson

lesterjanpearson

New member
I may have to rephrase my question to "what happens when you gas up with a lower than required octane".

thanks guys, really good input from everyone.
 
D

DKjeep

New member
When mine was stock even with a tuneup and fresh air filter I would get detonation easily with 87 ocatane. If I ran 89 or better it was gone. Now that I am under boost I have to run 93.
 
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