Octane Question

[ninjai_ruken]

Originally posted by nine5raptor
Who says it burns cleaner or leaves less residue?

I would expect the 87 to burn cleaner as it is easier to ignite.

There are additives in 87 octane. Basically its a dirty fuel, I had to run a tank of 87 in my car at one time and it ran like shit. Get online and do some research on the difference between 87 and 91 or higher. I don't claim to know more than the next person, just voicing my opinion from past experience. This is one of those subjects that will never come to an agreement unless there is some major research done. Evan then there will always be people who prefer 87 because its cheaper or have some other reasons. The only way I see it. put a tank of 87 in your car see how it runs, then put a tank of 91 or higher. And you pick what you want, me I don't care if it cost a little extra I have a good Job

 

[Raph]

Originally posted by ninjai_ruken
There are additives in 87 octane. Basically its a dirty fuel, I had to run a tank of 87 in my car at one time and it ran like shit. Get online and do some research on the difference between 87 and 91 or higher. I don't claim to know more than the next person, just voicing my opinion from past experience. This is one of those subjects that will never come to an agreement unless there is some major research done. Evan then there will always be people who prefer 87 because its cheaper or have some other reasons. The only way I see it. put a tank of 87 in your car see how it runs, then put a tank of 91 or higher. And you pick what you want, me I don't care if it cost a little extra I have a good Job

exactley,whever i go visit my relatives in france,i fill up and drive down there,when i get there i always have a quarter tank left...then i drive around a bit and the tanks on reserve...when i fill up there,and drive home,the tank is always empty by the time i get back...because of the bad quality fuel....

 

[andymoraitis]

Originally posted by nine5raptor
Who says it burns cleaner or leaves less residue?

I would expect the 87 to burn cleaner as it is easier to ignite.

This is EXACTLY correct. The lower the octane of the fuel being burned, the hotter it ignites in the combustion chamber. As it is, most engines can't combust all the fuel being injected so why add a cooler burning fuel to a non-turbo motor and simply waste money?

As far as the presence of additional gum and additives in lower octane fuel, I'm not sure whether this is true or not, but I run a bottle of fuel injector cleaner every 2500 miles when I change my oil and I have zero problems.

 

[Initial DSM]

This may be a stupid ignorant statement, because im unsure, but NA dsm compression is 9:1 as opposed to 7:8:1 stock turbo cp, and I know when you raise compression on a NA car , you need to run higher octane in order for the car to run right, so wouldnt this apply similiar to a na car with the basic bolt ons ie i/h/e and tb? I do notice my car runs smoother on higher octane, but not 100% sure. been meaing to get a OBD II pocketlogger, that would def answer all these questions on this thread.

 

[andymoraitis]

Originally posted by Initial DSM
This may be a stupid ignorant statement, because im unsure, but NA dsm compression is 9:1 as opposed to 7:8:1 stock turbo cp, and I know when you raise compression on a NA car , you need to run higher octane in order for the car to run right, so wouldnt this apply similiar to a na car with the basic bolt ons ie i/h/e and tb? I do notice my car runs smoother on higher octane, but not 100% sure. been meaing to get a OBD II pocketlogger, that would def answer all these questions on this thread.

That's a pretty good point you bring up. In truth, adding a header, intake and throttle body changes the amount of air being sucked in and forced out of the motor. None of these things actually raise the heat in the combustion chamber and that's where higher octane is needed to keep things cool and detonation at bay. I would agree that if we ran higher compression naturally aspirated motors that high octane would definitely be needed.

 

[Fattie92]

You should run what is recomended by the dealer in your car. The engineers didnt just pick a number out of a hat and said.. "this one needs 87." Iv seen some cases were cars actualy run worse because they opted for the "better" gas. Octane rating has nothing to do at all with the qulity of the gas. Someone also stated that they get better MPG if they get gas in a certian town, compared to another. Well The bigger the city, the worse the gas. Chicago= shit gas. but if you go to the middle of nowhere here in illinois, you will get some good ass gas! You know why? Its because the EPA desided that bigger cities that have poorer air quility need to run more oxygenated gas. the farther out to the middle of nowhere you go, the better the gas is, because the EPA isnt breathing down there neck.

Now for all the cars that run better with higher octane then whats recomended.. OK, cool! If you think your cars running better (heck it might be!), then more power to ya!


PS.. there are also 2 grades of gas. Summer grade, and Winter grade.

also, Winter grade already has HEAT in it! so stop wasting your money on something you dont need!

 

[Initial DSM]

well what about the higher the air flow, the more chance in increase in knock , also hence more of a direction of 'leaning' out the engine which as we know, leads closer to detonation? Hence the need for more fuel or higher grade of fuel to compesate / balance things out?
I do know this...the adjustment of the ecu of lets say (AF/X) clearly states that you SHOULD run 93 octane and nothing lower with the addition of i/h/e. Now why would they say this if theyre assuming youre still running on stock NA cp? Now I know it advances the timing to a degree, but I dont think it would be directly responsible to raising the combustion heat level in the engine, or have the ability to. Throwing out ideas not sure...

 

[Redmachine]

Anyone ever hear of gasahol? My dad used it on his 67 camaro years back and he said the engine ran awesome... way better than any unleaded gas at the time. Just wondering if it was a South Dakota thing or not.

 

[Initial DSM]

Ive heard good things on Methanol/water injection units, allowing you to run higher octane on pump gas...

www.snowperformance.net