Newbie Question: Gas

[Zephyr]

alright, newbie question again, since im learning still. what happens if u put 92 octane in a 89 octane car, or 100 octane or 87, is there a change in milage? performance? and any damage to the condition of the engine? im trying to be more edjumacated one question at a time

[danricenguyen]

I think its ok to put higher octane gas into a car, i was told that it was bad to mix fuels though, I'm not to sure :P

[rice_eater]

:confused: we talked about this over and over... the screen is spinning too hard to be able to axplain....next time i'm in lady! I help you out then...GOOD BYE!

[rice_eater]

Originally posted by danricenguyen
I think its ok to put higher octane gas into a car, i was told that it was bad to mix fuels though, I'm not to sure :P

no it is not bad to mix fuels....you either add or lessen the concentration of octane....so you put 87 with 89 you get 88 or more or less depending if its more of another...:burnout:

[^SkylinE^]

If you put a lower octane in a high performance engine that needs a high octane gas you will begin to get detonation. You will most likely dammage the motor or blow it! High octane gas is more stable than low octane gas.......didn't someone just post this same question and i have already answer this one in more depth in an other thread search for it!

[sin]

but i heard that if you have an engine thats only used a lower grade, and its got a lot of km's, that you shouldnt just switch to a higher octane, cause the car isnt used to it

[treg50]

The owner's manual should tell you what octane the engine is designed to use. Most modern engines are like this. Using a lower octane than specified by the manufacturer can be bad. Using a higher octane when your engine doesn't require it can be bad for the engine. In which case, it's also just a waste of your money, since the engine wasn't designed/optimized to burn that fuel efficiently and you're not getting performance benefits.

[Super_Geo]

Originally posted by rice_eater
:confused: we talked about this over and over... the screen is spinning too hard to be able to axplain....next time i'm in lady! I help you out then...GOOD BYE!


... no more hash for that man... haha ;)

[rice_eater]

Why can't you guys read the other threads??? One last time...higher level octane burns slower...the only reason why you see a "gain" in performance is this:
WHen it's really hot out and your engine is boiling your gasoline will preignite. So say you are using 87 octane...it lights up earlier than it's supposed to and causes knock...your knock sensor picks that up and tells the computer, which automatically retards the timing so that you dont blow up the engine...When in the same condition you use higher octane gas, that mixture will burn slower so your engine won't have to retard the timing as much. When you use a stupid high level of octane it hurts performance because the slower burning mixture will not be able to fully burn by the time the piston starts heading down and the exhaust valves open so you dont make all the power you could have. But there is nothing wrong with putting premium gas in your car the requires lower octane...It burns a bit cleaner and some stations have some special aditives and will get youa slightly better gas mileage. Don't do it for horsepower gains though if your engine is naturally aspirated except in situations like the one i described earlier. Also your engine won't need any time to figure out that it's got higher octane level...you wont damage it. That's whyu you have a computer in there so it can adjust for variations in fuel and airflow.

[Strider]

High compression engines and FI engines require high octane gas because low octance gas will preignite(detonate) before the spark plug fires due to the compression.

In a "regular" engine, preignition will not occur, the air/fuel gets compressed, and the spark plug ignites the mixture. Exactly how it should work.

When you use high octane fuel in a "regular" engine, the air/fuel gets compressed, and the spark plug fires, but the fuel "burns slower," and the piston is already moving down, and the exhasut valves opened before the fuel is completely burned. Therefore, you will get a decrease in performance, and likely an increase in fuel consumption.

The reason high octane fuel "gives better performance" is because it allows higher compression (or boost) before preignition(detonation, knock). Moe air/compression = more power.

[catywampusness]

I always understood that a higher octane fuel will clean out your engine better and get you some power ( a little bit). Hence the octane additives that are sold in car stores and stuff... however, running it on higher octane fuel also seems to kinda hurt your engine if you do it for prolonged periods of time.

[GTS Jeff]

Originally posted by catywampusness
I always understood that a higher octane fuel will clean out your engine better and get you some power ( a little bit). Hence the octane additives that are sold in car stores and stuff... however, running it on higher octane fuel also seems to kinda hurt your engine if you do it for prolonged periods of time. totally wrong. the correct explanation can be found in rice eaters post

[rage2]

Originally posted by catywampusness
I always understood that a higher octane fuel will clean out your engine better and get you some power ( a little bit). Hence the octane additives that are sold in car stores and stuff... however, running it on higher octane fuel also seems to kinda hurt your engine if you do it for prolonged periods of time.
Well at least we know the marketing guys for the oil companies and additives companies are doing their job well! :rofl:

[rice_eater]

Originally posted by GTS Jeff
totally wrong. the correct explanation can be found in rice eaters post

HAHAHA...sweet! This is the first time EVER that we agreed on something man :nut: :D

[2M6]

and the piston is already moving down, and the exhasut valves opened before the fuel is completely burned.

what cam are you running? The exhaust valve shouldn't be opening quite so soon. :dunno:

[mad_psyentist]

Hn. As far as I knew, the engine would just run hotter and you may notice the car idles higher. Gas is gas for a car that wants 87 O's IMO.