Fuel Octane

No
Higher octane does not provide any more power for this engine.
 
Octane is a measure of a fuels ability to resist detonation. It is not a measure of how hot the fuel is. Hot meaning, "powerful". If you don't need it, it's a waste of money buying it. As a matter of fact, if you can run the lower octane fuel without detonation, and that's very important, the lower octane fuel will probably give you more power. Thing is, if you get detonation, and you can't always hear it, you would definitely lose power. I always recommend the exhaust gas temperature gauge, (EGT) to detect detonation. When you get detonation, the EGT reading will go down.
 
EGT probes are not approved in the LO206 class.
Now, you can use it on the dyno, but then again you've likely got an A/F ratio meter to monitor things on the dyno.

Jim & Al are correct though in that your higher octane fuel is likely doing more harm (power-wise) than good.



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Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
26 years of service to the karting industry
765-339-4407
bcarlson@CarlsonMotorsports.com
 
CarlsonMotorsports said:
EGT probes are not approved in the LO206 class.
Now, you can use it on the dyno, but then again you've likely got an A/F ratio meter to monitor things on the dyno.
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That's kind of crazy I think. They allow CHT's. The EGT is no more expensive and, in my humble opinion, so much better than a CHT for tuning, I can't understand why they would not allow it. One thing I have discovered with the EGT, after we started using it, we discovered that the CHT tells you little or nothing of any value. On hot days it reads hot and on cold days it reads cold. It tells you almost nothing about what's going on inside the engine.

Few understand how much detonation hurts your horsepower, and the CHT will not detect it, while the EGT does.

Believe me or not, but I have a lot of experience with both, and without question, prefer the EGT. It's a great tuning tool. Asked the people who are using them.
 
Al,
That is the problem some people are having with you on here, you don't understand the class/engine/rules before you make a comment on something. Using EGT is prohibited in this class, and the reason is, the jets are set at a certain size by the rules and can not be adjusted therefore there is no need for EGT. Most if not all tracks also specify a certain octane and/or specific gas station to get gas from. Also, by installing a bung for the EGT probe you are "modifying" the exhaust header which is also prohibited. The rules in this class are VERY strict and they have proven to work to provide a reliable engine that last for several seasons without a rebuild.

Let's say this guy followed your advice and installed an EGT in his header and started changing fuels or jets because he didn't know the rules either, when he got to the track he would not have been allowed to race without changing to a new unmodified header and jets. You could have cost the guy track time and money out of his pocket instead of actually helping him. That's what several people (including myself) are trying to tell you, is just be careful giving advice if you don't know the rules/class you are giving advice on. There are a LOT of guys on here with actual hands on experience (2 have posted above) that can steer this guy and others in the right direction and stay within the rules and save them time and money in the long run.
 
alvin l nunley said:
That's kind of crazy I think. They allow CHT's. The EGT is no more expensive and, in my humble opinion, so much better than a CHT for tuning, I can't understand why they would not allow it. One thing I have discovered with the EGT, after we started using it, we discovered that the CHT tells you little or nothing of any value. On hot days it reads hot and on cold days it reads cold. It tells you almost nothing about what's going on inside the engine.

Few understand how much detonation hurts your horsepower, and the CHT will not detect it, while the EGT does.

Believe me or not, but I have a lot of experience with both, and without question, prefer the EGT. It's a great tuning tool. Asked the people who are using them.
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Alvin,
I agree with everything you said, EXCEPT that it's "crazy." The rules are there for a reason. Jamie's explanation is sufficient.
 
alvin l nunley said:
and what I said was, "kind of crazy". I think there's a difference.
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UGH! Ok, you win. I disagree with it's "kind of crazy."

Rules are there for a reason (whether they are "kind of crazy" to some or not.)
Stable rules are just one strong point to the LO206 engine package.

BTW, Can you define "kind of crazy"? Isn't that akin to "kind of pregnant?" Either someone is crazy or they're not.
Likewise, a rule is either crazy or it is not. Maybe you meant that the rule is just temporarily crazy? ;)

C'mon Al -- it's a great day - let's not bicker over semantics.
 
maybe throwing fuel on the fire here but will follow paulkish and get involved. If EGT is available, would it be possible to put one on and use it for on track testing to adjust those items that are adjustable?? float level for rich or lean?? would more fuel from this process change the detonation?
 
You should be able to use it for testing, no problem. Do you feel you have adetonation problem with your LO206 as it is now?
 
I don't, but then again, may not know what to look for, listen for, in a kart motor... i'm still consider my self new to the sport. but as time permits,.. will do all i can to test and learn. OOPS, looks like we high-jacked the post.
 
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foreverfaster said:
I don't, but then again, may not know what to look for, listen for, in a kart motor... i'm still consider my self new to the sport. but as time permits,.. will do all i can to test and learn. OOPS, looks like we high-jacked the post.
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if you pull the head, and you see something that looks like a light sandblasting around the edge of the piston or head, that's detonation.

I doubt you will see detonation with a stock compression engine, but the engine will slow down if you get too lean. You will lose power if you get too lean, and a drop in the EGT is a good indication that you're too lean.
 
I have never personally seen detonation on any Briggs motor!!
How ever i recently had a customer that kept buying pistons for his 21 cid engine.
He kept burning away the outer edge of the top of the piston.
After a lengthy conversation of trying to convince him to check the ign timing.
He did. It was over 40 degrees.

Note:
Detonation is starting another fire in the combustion chamber after the spark plug fires.
Pre ignition is starting the fire before the spark plug fires.
 
Our regular is 85 octane. Is that too low? Also 10%+ of ethanol in any fuel from a gas station. CO state law that it is at least 10%. Our premium is 91 with mid at 87. Altitude is around 5000 feet above sea level.
 
Dryslick13 said:
Our regular is 85 octane. Is that too low? Also 10%+ of ethanol in any fuel from a gas station. CO state law that it is at least 10%. Our premium is 91 with mid at 87. Altitude is around 5000 feet above sea level.
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if you're not getting detonation, it's not too low. If you pull the head, and you see something that looks like sandblasting around the edges of the piston or head, that's detonation.

Another way to test is; run a a few laps with the 85. Then run a few with the 87. Repeat the test to eliminate the possibility that the track got better or worse. If possible, don't tell the driver which is which. Or............... and this is a big "OR", just take what you hear here as gospel and don't worry about. My vote is for the 87 octane in a stock engine.
 
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