gas types

so whats the difference between unleaded gas and premium gas? i have been wondering this for a while since u can put both in regular engines correct? also what types of gas do you guys use (mainly)?

The difference in gas types mainly is the RON level.

In the UK regular petrol is 94 or 95 RON depending on the supplier. Premium is 97 to 99 RON.

RON is the level of some chemical or other that is in petrol which effects the level at which the petrol combusts, 94 RON fuel ignites easyer than 99 RON fuels, and can lead to pre-detination in performance engines from the heat in the cylinders, also there are many other factors like amount of detergant in the fuel etc.
Personally I have to use 99RON fuel which is only available from Shell (Optimax) as the GT4 is an import and designed to run on Jap fuel which is 100RON. Its more expensive but gets better milage, not that that matters in a performance car, if your gonna worry about milage, get a Honda Civic.
Most modern cars run on regular petrol, no problem.

RON has different values in the States than it has here so I`m not sure what the values are for reg/premium over there. It should say on the petrol pumps.

so whats the difference between unleaded gas and premium gas? i have been wondering this for a while since u can put both in regular engines correct? also what types of gas do you guys use (mainly)?

The only gas you can buy now is unleaded gas. All grades from all brands are unleaded because lead will deactivate your catalyst in your cat. converter. Premium is just the highest octane gas at the station. Low octane gas pings more easily than high octane gas. The higher your compression ratio (everything else being equal) the higher octane gas your car needs.

Modern engines adapt to whatever octane gas you put in them. Use the lowest octane gas that Toyota recommends for your engine. You can try higher octane gas and see if it makes your car more powerful and gives you better mileage. If is does, then it is worth it to consider using the higher octane gas. If is doesn't, then you are just wasting money using higher octane gas than your car will burn efficiently.

alright, thanks for the input guys.

true but higher ocatane gas wont give you more hp unless you re tune your ecu...granted if you use race gas (101) instead of 87 octane gas you will see a slight inporvement in HP but between 87 and 91 you wont even feel a difference...

the reason why gas pings is because 87 octane has a lower flash point than 91 octane...the higher tha flahs point the hotter and faster it burns...to reduce pining you just retard your timing...im planning on using 87 octane and retard my timing when i put the 4agze in (better to use a higher octane gas to reduce ping and the chances of pre detonation)

Nialusa`s little Petrol chart -

RON..MON..PON
90.....83....86.6
92.....85....88.5
95.... 87....91
96.....88....92
98.....90....94
100...91.5..95.8
105...95 ...100
110...99....104.5

Research Octane Number (RON) is an indicator of the fuel's anti-knock performance at lower engine speed and typical acceleration conditions.

Motor Octane Number (MON) reflects the anti-knock performance of a fuel under high engine speed and higher load conditions

Pump Octane Number (PON) -Reflects what you actually get at the pump. - This is what you Yanks use to measure your octane, us Limeys use RON as do the Japs. I use 98RON in my car as thats the highest we can get, its the same as your 94 RON, I just wish I could get propper 101RON racing fuel that would be to us the same as 106RON (which we cant get) If you want to run a higher octane fuel, just by a JDM engine management system.

Higher octane gas will give you more hp if your car pings with lower octane gas. The ECM will retard the timing to get rid of the ping if you use the lower octane gas and not retard it if you use the higher octane gas. More advance = more hp.

for sure....i see a lil flaw in my last post LOWER ocvtane hgas has a HIGHEr flash point...that means the loweer the octane # the easier it is to ignite, thats why you get pre-dentonation with lower octane gases

think of it this way, at 87 octane when the cylendar fires it burns up all the gas immidatly pushing the piston REALLY hard downward

with 91 octane it burns slower so it burns the whole time the piston is on the way day, basically its pushing the pisoton down the whole time instead of one massive blow that forces it down...this is better for HP becuase it has a constant rat eof burn

the bad thing (and why you dont just put race gas in ur car for no reason) is that the gas can actaulyl continue to burn on a n upstroke resulting in a loss of Hp and burning of your valves...this is why retardation is such a bad thing

for sure....i see a lil flaw in my last post LOWER ocvtane hgas has a HIGHEr flash point

No, you were right the first time, low octane = Low flash point ie it takes less temp to ignite the fuel.
High octane fuel has a high flash point so that the fuel dosnt pre ignite when it comes into contact with the hot internals of the piston chamber or get pre-ignited by anything other than the spark.

I have an 04' GTS it requires 93 octane b/c its compression ratio is 11.5:1. I used Shell for a long time now I go to the Marathon around the corner from my house b/c its premium is only $.10 cents higher instead of $.20 cents higher like everryone elses.

87 octane can pre ignite i.e. pre dentonation becuase it has a highgher flash point it ignites esasyer than 91, thats why 91 is able to burn almost the whole stroke and 87 just makes a big boom and gives it one big push andwhy do you say 93, they dont sell 93 at the pump

Flash point is the lowest temperature at which a liquid can form an ignitable mixture in air near the surface of the liquid. The lower the flash point, the easier it is to ignite the material - cut and paste directly from the Encyclopedia Britanica, are you gonna tell me they are wrong aswell???
You do like to argue stuff alot 91celicast, perhaps just maybe there are people in this world that know a little more than you do bud?????

hey 91 ST you're mixing up your words low flash point = lower temp that it ignites, a higher flash point means it ignites at a higher temp which means its harder to ignite...and they do sell 93 at the pump..that's all my car takes and all i ever buy...in some areas they don't though, which is probably why you haven't seen it.

<---confuses himself...haha ...yeha i had that wrong then, i really need to think before i type cuz i even said 87 ignited easyer but i said it had a high flash point....gotta love typing on the internet