How Octane Works.

I have been reading up on octane boosters and just bought some torco. There are alot of misconceptions about octane.



I was always told that higher octane burns slower and thats where extra power is made. That is not the advantage of higher octane. You wont nessesarily gain power by running higher octane. In some cases it can hurt power.



Octane is not measured by how fast it burns but by its point of ignition. This is where it ties in with the performance of your engine. Modern engines have Knock sensors to help protect itself. Knock is basically early detonation. If the air/fuel mixture ignites to early it obviously will cause damage to your engine. So if your car senses knock it will pull timing and hurt power. The higher the compression of your car the more likely you are to get early detonation. Also, cars that are tuned aggresively with advanced timeing benifit from higher octane. Thats one reason why race cars run really high octane. They advance the timing so as soon as the piston starts it downward motion the spark plug ignites the fuel.



So I know alot of people run higher octane than their car calls for thinking it help the engine. But the truth is, if your car calls for 87 you can safely run it and will see no advantage with a higher octane as long as your car has no knock. Now if you raise the compression of the car and advance the timing then you could befinit from higher octane. In other words....don't waist your money on 93 if your car only calls for 87. You are throwing money away.



I have high compression (11.1:1) so my car calls for 93. When I was tuned my timing was advanced so I am more prone to early detonation. Still I should be safe on 93. When I was on the dyno getting tuned the technition looked to see if I had any knock. He advanced the timing until he saw knock and then backed it off. So I am going to try Torco (octane booster) at the track but unless my car is seeing knock it will do absolutly nothing for me.

We should start having a weekly "how it works" thread.

awesome info. Did not know that.



I will create you a forum for this.

that's pretty sweet. i run 93 because i notice a difference in the mustang and f150. they run more smooth on 93, than they do on 87 when they tend to act like they don't fire all the time when idling.

and i agree, "how it works" thread would be cool

The Forum is up.



Also, We have to run 93 in the solstice because of the tune. Anything else makes it back fire, knock , and run like crap.

One thing to add, the unleaded fuels now-a-days are crap. Some gas stations, no names *cough* *cough*, will advertise a gas to be 89 when it's actually only 87. My truck is most picky with octane. It loves straight 93 and runs similar with a mix of 89 and octane boost.

Also note, read the chemical ingredients. Lead additives will harm your cats if you have them but also if it doesn't have MTBE it's not worth it. General rule of thumb, if it isn't street legal, it's good stuff!

ScottHofferPhotography wrote:

The Forum is up.



Also, We have to run 93 in the solstice because of the tune. Anything else makes it back fire, knock , and run like crap.

I would definitly have someone look at that tune. Normally when you add intake/header like in your case, the adjustment in the tune is for the air/fuel mixture mainly and then they safely advance the timing since it comes extremely safe from the factory. Unless you raised the compression I dont see any reason you shouldnt still be running the the octane the car calls for. If you dont have knock you should run the lowest octane possible. If we can find someone who has HP tuners we can look at your tune and see what its doing. I'm not saying your wrong but if you are knocking on the octane your car calls for with just intake and exhuast you may have a bad tune.



I know a guy who runs 87 in a supercharged C5. A S/C engine creates more heat in the combustion chamber so normally you would need higher octane to avoid pre-detonation. However, he has meth injection to keep it cooler and he found he can run 87 with no knock.

2many2choose wrote:

One thing to add, the unleaded fuels now-a-days are crap. Some gas stations, no names *cough* *cough*, will advertise a gas to be 89 when it's actually only 87. My truck is most picky with octane. It loves straight 93 and runs similar with a mix of 89 and octane boost.

Also note, read the chemical ingredients. Lead additives will harm your cats if you have them but also if it doesn't have MTBE it's not worth it. General rule of thumb, if it isn't street legal, it's good stuff!

I think Shell is one of the only gas stations that garantees octane and puts special additives to help you engine run efficiently.



What type of octane booster do you use if you run 89? This is what started my research on this. I went into advanced auto to see what octane boosters they offer. They had STP, turbo 108, NOS, and Lucus in stock. Then I came home to start reading reviews and studies on them. You can read for hours about it but what I found was they do NOT work like advertized. On average, if they say they raise octane 2 points......they actually only raise it .2.



Some newer cars (like Linsbecks 5.0) can sense which octane it is running and will adjust the timing accordingly. The new 5.0's have 11:1 compression and can still run on 89.



Basically what I am eluding to......if you do not have a high compression motor and doesnt have a ton of timing thrown at it, you should not be benifiting from higher octane. If you are, there are a couple things that could be causeing it.

1) Your engine is running to hot and causing the air/fuel mixture to ignite to early once it is compressed.

2) Your engine has to much timing



The only advantage of higher octane when it relates to performance is its point of ignition. If you are seeing a difference then your engine was detonating to early on the lower octane.

D-Rod wrote:

ScottHofferPhotography wrote:

The Forum is up.



Also, We have to run 93 in the solstice because of the tune. Anything else makes it back fire, knock , and run like crap.

I would definitly have someone look at that tune. Normally when you add intake/header like in your case, the adjustment in the tune is for the air/fuel mixture mainly and then they safely advance the timing since it comes extremely safe from the factory. Unless you raised the compression I dont see any reason you shouldnt still be running the the octane the car calls for. If you dont have knock you should run the lowest octane possible. If we can find someone who has HP tuners we can look at your tune and see what its doing. I'm not saying your wrong but if you are knocking on the octane your car calls for with just intake and exhuast you may have a bad tune.



I know a guy who runs 87 in a supercharged C5. A S/C engine creates more heat in the combustion chamber so normally you would need higher octane to avoid pre-detonation. However, he has meth injection to keep it cooler and he found he can run 87 with no knock.

2many2choose wrote:

One thing to add, the unleaded fuels now-a-days are crap. Some gas stations, no names *cough* *cough*, will advertise a gas to be 89 when it's actually only 87. My truck is most picky with octane. It loves straight 93 and runs similar with a mix of 89 and octane boost.

Also note, read the chemical ingredients. Lead additives will harm your cats if you have them but also if it doesn't have MTBE it's not worth it. General rule of thumb, if it isn't street legal, it's good stuff!

I think Shell is one of the only gas stations that garantees octane and puts special additives to help you engine run efficiently.



What type of octane booster do you use if you run 89? This is what started my research on this. I went into advanced auto to see what octane boosters they offer. They had STP, turbo 108, NOS, and Lucus in stock. Then I came home to start reading reviews and studies on them. You can read for hours about it but what I found was they do NOT work like advertized. On average, if they say they raise octane 2 points......they actually only raise it .2.



Some newer cars (like Linsbecks 5.0) can sense which octane it is running and will adjust the timing accordingly. The new 5.0's have 11:1 compression and can still run on 89.



Basically what I am eluding to......if you do not have a high compression motor and doesnt have a ton of timing thrown at it, you should not be benifiting from higher octane. If you are, there are a couple things that could be causeing it.

1) Your engine is running to hot and causing the air/fuel mixture to ignite to early once it is compressed.

2) Your engine has to much timing



The only advantage of higher octane when it relates to performance is its point of ignition. If you are seeing a difference then your engine was detonating to early on the lower octane.

Even though my car adjusts, it is better to run the higher octane. Especially if you have a 93 ocatane tune in the car. The tune was setup with A/F ratio for best power using 93 octane. They also adjust timing for 93 octane. If it is done right, they go to where they see knock, and then back off a few degrees to be safe. If you run something lower than 93 octane at that point, your going to have knock. If you have a tune specified 93 octane, you need to run that octane level or risk damage.

dlinsbeck wrote:

Even though my car adjusts, it is better to run the higher octane. Especially if you have a 93 ocatane tune in the car. The tune was setup with A/F ratio for best power using 93 octane. They also adjust timing for 93 octane. If it is done right, they go to where they see knock, and then back off a few degrees to be safe. If you run something lower than 93 octane at that point, your going to have knock. If you have a tune specified 93 octane, you need to run that octane level or risk damage.

Right.....it is better for you to run 93 since it keeps the timing advanced which means more power. However, you can safely run 89 in your car with no knock even though it is a high compression engine since it pulls the timing to adjust for it. This is why it concerns me if Scott and Kaleb's cars are running better on higher octane in low compression engines.

The mapping on my fuel trims were set for 93, my car will not adjust its self because the tune will not change in the car. Thats why it does it. He asked me if I was okay with that and I said yea, I would only run 93, so the tune is for that gas only. I get about 35mpg from using 93, I get about 19 from 87.. so I just use the 93 like he said. Jamie put 87 in it once, and it ran like crap, I added an octane booster and its ran good since.

ScottHofferPhotography wrote:

The mapping on my fuel trims were set for 93, my car will not adjust its self because the tune will not change in the car. Thats why it does it. He asked me if I was okay with that and I said yea, I would only run 93, so the tune is for that gas only. I get about 35mpg from using 93, I get about 19 from 87.. so I just use the 93 like he said. Jamie put 87 in it once, and it ran like crap, I added an octane booster and its ran good since.

OIC....I wonder why he did a 93 tune on the car? Did he say why? I would like to know the advantage of running a higher octane in your application. This is going to cause me to do another 5 hours of research on the subject. lol

He said he could lower my fuel trims or something like that without getting knock if I used higher octane, he said this would give me alot more mpg and it raised if almost 20mpg with the tune. He said the bad is, that its so low it wont run right off 87, so make sure you use 93. He said he has tuned tahoes to get 38 mpg.

Ok found out a little bit more and some things I was wrong about.....



Ignition occurs before TDC (top dead center) on the upward stroke and not after TDC on the downward stroke. So fuel is ignited while the fuel is still being compressed. The reason he probably had you run higher octane was because he put in ALOT of spark advance.....which means you have a very aggressive tune. Thats why I dont understand why he would do that in your application unless he thought it was going to be a racecar and you wanted maximum performance out of it.



20 mpg out of a tune sounds like alot. If what he told you is true and it can be done safely, everyone should be getting a tune and running 93. I will do some research on this too to see how advancing timing can add that many MPG.



Is it wrong that I get off on learning this stuff?

D-Rod wrote:

Is it wrong that I get off on learning this stuff?

It is wrong the way you get off when you see me after a few days or me being gone.

ScottHofferPhotography wrote:

D-Rod wrote:

Is it wrong that I get off on learning this stuff?

It is wrong the way you get off when you see me after a few days or me being gone.

VERY WRONG! But at least you know he was happy to see you!

No matter what dave thinks.



I do not like to sword fight with other men in the shower.

yep, this thread took a 180 lol

91foxbody wrote:

yep, this thread took a 180 lol

:aggreed:

Just wanted to throw this out for anyone wondering: There is a downside to running higher octane if you don't need it. It causes buildup in your engine faster than lower octanes. If you really put your foot down a lot that may not apply to you since that tends to remove deposits. Also as octane increases, basically the resilience of the fuel, you get less detonation from compression, but also less from hot spots that may form in older engines, which is why a lot of older engines get less rattle or knocking from higher octane.

I know some of the gas stations around here are getting lax with fuel, our supercharged Xterra takes premium, and a couple places, when I put in 93, it gets all jerky and nasty under boost, especially under a lot of load, like 4th or 5th gear up a hill. But then I refill at a different place and the problem goes away. Although it does have a small pulley on it and goes at 8lbs boost@2k rpm, 17lbs boost @5k, so I need the good stuff or else damage, makes me pretty angry when I don't get whats advertised. So you gotta be cautious, you don't always get what it says, and I've heard horror stories about the octane booster making combustion so hot it melts pistons... so just be careful out there. Hope this helps some people.

Tygur wrote:

Just wanted to throw this out for anyone wondering: There is a downside to running higher octane if you don't need it. It causes buildup in your engine faster than lower octanes. If you really put your foot down a lot that may not apply to you since that tends to remove deposits. Also as octane increases, basically the resilience of the fuel, you get less detonation from compression, but also less from hot spots that may form in older engines, which is why a lot of older engines get less rattle or knocking from higher octane.

I know some of the gas stations around here are getting lax with fuel, our supercharged Xterra takes premium, and a couple places, when I put in 93, it gets all jerky and nasty under boost, especially under a lot of load, like 4th or 5th gear up a hill. But then I refill at a different place and the problem goes away. Although it does have a small pulley on it and goes at 8lbs boost@2k rpm, 17lbs boost @5k, so I need the good stuff or else damage, makes me pretty angry when I don't get whats advertised. So you gotta be cautious, you don't always get what it says, and I've heard horror stories about the octane booster making combustion so hot it melts pistons... so just be careful out there. Hope this helps some people.

That's a common problem. Some stations have terrible winter blends that don't meet the advertised octane. They have trouble with the anti-gel in Diesel over the winter as well. They add either too much or too little at the terminal.

I won't run the Sky on winter gas, because it's not tolerant at all to dropped Octane. The Evo I have a 91 tune on in the winter, but I still strive to find "93".

tkromer wrote:

I won't run the Sky on winter gas, because it's not tolerant at all to dropped Octane. The Evo I have a 91 tune on in the winter, but I still strive to find "93".

The nice thing about owning HP tuners (or whichever tuning SW you use) is you can see if you are getting knock whenever you want to check it. I have a good bit of timing thrown at my car. I really need to invest in HP tuners to see if I ever get any knock on 93. Or I can see which gas stations to avoid if one shows knock on 93.

I have HPTuners, I'm just lazy about changing timing. I don't drive the Sky unless roads are dry anyway.

If you need work done on the vette I can do it. I think additional credits are only like $99.