What is octane? KR? Explained here.

**blowfishRus6** · 09-23-2008

there is a difference in the quality of gas. i havent noticed much but my car does run better with better quality gas (bp) i start to have real ruff idels with cheap gas stations.

**01gtprocket** · 05-08-2009

To answser couple of questions..

Here in Ca the highest pump gas you can buy is 91. once in a while i go to sanjose ca and i pump 100 octane race fuel.. I usually get around 94 octane or so. and when i scan the car there and my kr drops..

I no in orgeon and wa they sell 92 octane..

One question a member asked about gas..

Aboubt a week ago I see a no name truck pump gas at the cheveron . the same truck pumped at ampm... Then the very same day see him at the texaco.. I think gas is gas.. If you buy 91 then your find.. the only way i run 87 i take the blower belt off i get 0 kr liek that.. just my to since

If yu are cheap dont want to buy 91.. I would recmmond copper 104-180 tst. and stock pulley.. The way to find out is to scan with 91 then if you see 0 then fill up with 89 and so forth..

**Lincoln** · 06-23-2009

WOW, I am glad I joined this forum, so much useful information. I live in Alberta Canada and I have a 98 gtp and run premium which is usually 91. Car says Premium only so thats all I add, lol. Thank you for the useful info.

**blowfishRus6** · 06-24-2009

my car clearly runs different with diffrent types of gas. no matter where i go its always 93, so i know it cant be the octane. i dont belive that all gas is the same gas.

**TEBO** · 06-26-2009

well i'll throw my 2 cents in on the small gas is gas debate. My dad has a 02 silverado with the 5.3 and he noticed a difference in fuel mileage between Loves and Road Ranger gas. 3+ mpg for Loves. And then i have a question, i have a 98 GP GT and i don't have a book so should i run premium or regular, keep in mind i'm a lowly high school student and can't really aforde premium.
Thank you for this forum o' great GP gods i've learned so much!

**FastKatt** · 06-27-2009

You are fine on 87 oct

**blueguy** · 06-28-2009

Originally Posted by FastKatt

You are fine on 87 oct

X2...you only need premium when you get a tuned PCM and it needs the 91+ for the extra timing...

**FastKatt** · 06-28-2009

Even with a tuned PCM, you'd need a metric f-ton of timing to need premium without a supercharger...

**TEBO** · 06-29-2009

Thank you for the info.

**GeeBee** · 07-03-2009

I am a newbie to modding in general but this should be true.

Primarily Environmental Air Density wasn't mentioned as a contributing factor to ping

Altitude, Temperature, and Humidity are all contributing factors to the air density; Generally speaking the lower the better for those 3, cold air at low altitude with low humidity are the best conditions you can hope for.

Ive also read that aluminum heads can lower pinging since they absorb more heat from the combustion - Generally speaking aluminum heads are more sensitive to heat and are prone to cracking. But i am still looking into the possibility of these for a daily driver (although expensive)

-GeeBee

**Liquifire** · 07-28-2009

Many different gas stations share their gas source, but you never know for sure who does and doesnt and also the storage of the gas once it is pumped into the existing gas holding tanks makes a difference. You don't know if one tank has a foot of water in it and the next one is good...........at the refinery they may be the same, but not necessarily what goes into your gas tank..........fwiw

**cowan1987** · 02-14-2010

Originally Posted by TooMch

I like what you've written Reptile but whenever I've read about the whole 'flame front' thing with regards to KR I'm a little foggy. Another way I think about KR and timing is that fuel takes time to burn in the cylinder. Once combustion begins and starts to spread you will reach a point of peak combustion. Ideally you want this to occur slightly after the cylinder reaches TDC. If peak combustion happens before TDC you get Knock. Imagine your piston racing towards the top of the cylinder and before it gets there it runs into the meat of the fuel burn explosion. All of a sudden the force of peak combustion is trying to force the cylinder down and yet the mechanical makeup of the engine keeps forcing the piston up. At some point things are going to break. Anyway, that is why timing is retarded as one way to combat Knock. You start the combustion later to allow peak combustion to happen after TDC.

That is a picture I can get in my head. It helps me understand timing with relation to what I want to achieve with tuning but also how I would want to use it to battle KR. KR is actually the PCM retarding timing to accomplish this.

I need to try to get my head around the part about higher octane not burning slower, though. My understanding has always been that higher octane fuel has a more controlled (hence slower) combustion. That's why it helps combat knock. It allows the peak combustion to occur after TDC. Just a different method to get to the same place as retarding timing. I'll need to re-read your section on octane and burn rates and why higher octane reduces Knock a few more times.

Thanks for doing this.

Its not a slower burn . its a more complete burn

**TheOtherNick** · 02-14-2010

Higher octane does burn slower.

**sinceregtp** · 03-25-2010

Not to mention winter blend suckey gas! So would adding Octaine boosters help with the gas quality? If so which one?

**FastKatt** · 03-25-2010

I can't remember where,...
Maybe on ClubGayPride...
There's a thread about Octane Boosters
Talks about what they put in them, good ones & bad ones...

I don't use any of them, but I do use Lucas Fuel Additive
LucasOil.com I buy the big bottle, get like 32oz or more (Like 5-6 tanks worth)

**RegalGS98s** · 03-25-2011

Originally Posted by FastKatt

I can't remember where,...
Maybe on ClubGayPride...
There's a thread about Octane Boosters
Talks about what they put in them, good ones & bad ones...

I don't use any of them, but I do use Lucas Fuel Additive
LucasOil.com I buy the big bottle, get like 32oz or more (Like 5-6 tanks worth)

I used the Lucas fuel additive also. Usually just under $10 a bottle. It claims you can use it with regular gas on a vehicle requiring premium. Would like to know if this is true, but it seemed to be from me running 87 octane with my setup. I ran it on my mostly stock Regal GS at the time with short air intake, 180 tstat, and custom tune. It seemed to run good for about 6 months. This was during the time when gas was peaking $4.50 a gal and hardly anyone was buying premium so figured premium was loosing octane from sitting.

I had an issue, but I don't know if it was related where the engine would just randomly turn off, and I wouldn't be able to restart for about 10 minutes. I thought the injectors were clogging from the Lucas additive so I swapped them and did so other replacements. I cleaned the crank position sensor with brake clean and I don't recall it happening again after that, but the car didn't run much longer due to an unrelated issue so I only got about 2 weeks of testing done. Engine shutting off was happening almost daily so I thought it was the CPS. When disassembling the engine, the cylinder walls were smooth and there was no mechanical damage except bearings from a different issue and I didn't notice any knock when it ran.

**Bio248** · 03-25-2011

you have to add a whole **** ton of those octane booster things in order to actually get anything out of it. best off just running premium anyway.

**RegalGS98s** · 03-25-2011

Originally Posted by Bio248

you have to add a whole **** ton of those octane booster things in order to actually get anything out of it. best off just running premium anyway.

I know what you're saying about the boosters. The Lucas fuel treatment is a fuel additive lubricant though. Somehow I guess from it making the fuel slippier, it's supposed to allow for a lower octane. When the premium fuel sits from slower sales, figure it's losing octane and is about the same as regular at that point so have to add something.

**Bio248** · 03-25-2011

that doesnt make any sense. the fuel additives are like heet. they are meant to break down the water in the tank so that you dont screw anything up.

**Iceman6669** · 07-17-2011

Originally Posted by TheOtherNick

Higher octane does burn slower.

Originally Posted by Reptile

There's always a lot of confusion regarding octane, octane-boosters and how they work. Typical misconceptions are evident in blank-statements like:

"Higher octane fuels burn slower, thus their higher octane number"
"Higher octane fuels burn hotter, therefore more power is generated"
"Higher octane fuels explodes with more force, thus their higher power"

All three of which are untrue and are coincidental in effect,

Some racers think that they need a slow burning gasoline to make good horsepower. This is far form the truth. What we need is a good fast burn gasoline to be able to complete the burn in the time available.

Keep in mind that at 6000 RPM, each spark plug fires 50 times per second. At this rate, there is very little time to draw the intake charge into the cylinder, compress it, burn it, expand it, and exhaust it. A good fast burn gasoline is very important in making as much horsepower as possible at this engine speed. The most horsepower is developed when the gasoline is burned completely.

So who's right????

Thread: What is octane? KR? Explained here.

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