A boosted engine does not have the same fuel needs as a high compression engine. Please spend some time reading about it. Anybody that reads about will learn a great deal.

 

You've said that a few times (for us to read more).

Judging by your comments, it seems that you could do well to read a lil more yourself. Start with cams, and how they effect compression due to different intake closings. Then spend a little more time with the effects of timing, detonation and how octane plays into that.

Not everyone here is as stupid as you imply they are.


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I understand what everyone is saying.....
As I only have a stage 1 - air and pipes on my bike (thundermax).

but I did run 100 octane on my bike before, and I felt an increase in power (compaired to 91)...
My bike even sounded louder...

My question is: Is it safe to run higher octane (100 unleaded, or higher) on a bike that hasn't had
engine work... ?

 

I doubt that it can hurt anything other than your wallet.
You might want to try a small amount of octane boost with your 91 octane (instead of the 100) just to see if it will help as much.

BP 93 is available in my area and my bike loves it. But when I went to Sturgis all they had was crappy gas. Small amounts of octane booster helped me a lot until I got back to better fuel.

Stay away from noname gas and look for Shell or BP if you can find it. You might not need any additives at all! There is some real crap fuel sold at some stations. I'm thinking you have some of the bad fuel because 91 should be plenty for your bike.

 

"Keep talking its not often you get to listen to a genious."


Its alot more than intake closing times. Try port volume, port length, dia, t body or carb dia, valve face dia, valve face angle, seat angle, dome shape, chamber shape, valve shrouding, chamber scavange, header dia, and a multitude of other factors.



Compression is cylinder volume divided by compression chamber volume.
example 100 cc cylinder volume divided by 10 cc compression chamber volume = 10-1. And this is at it optimum so cam overlap or closing times can only detract from from its optimum.

Maybe you should read about engines and how they work. Smokey Yunick has some fantastic reading material.

Also dyno tests around the world have proven the facts about race gas.

Man just think how fast NASCAR would be with 200 octane.

 

one thing was not mentioned. Stock spark plugs. They supposedly work in conjunction with bike to retard timing if detonation occurs. Could be his canned map that causes detonation with the 93 fuel he normally runs(like faast ed pointed out the timing is too advanced). the increase in octane stops the detonation and advances the curve back to it's settings. Hence the power increase. Anyways I agree with faast ed. He feels a power increase cause of the way his bike has been tuned. I bet he could get a nice performance boost by having an expert properly tune his bike on a dyno as opposed to his current canned map. In that case, he most likely will not gain anything from increased octane.

 

I assume you are talking about the ION Spark Detector system that takes it's 'reading' directly from the spark plug gap.

The problem is that the tables used by the system to detect 'knock' and retard the timing if needed are set up assuming you use factory recommended plugs, wires, etc... If you use anything other than factory ignition components the 'tables' can give false readings.

Here is a little additional information;

"Detection is dependent on the values calibrated in the software that represent knock, and are based on a stock engine (or a known modified engine such as the STAGE I,II) with a GIVEN set of production intent parts such as spark plugs, wires, and even the compression ratio can and does change the resistance at the coil. So once folks start changing wires, plugs (to non-factory specs) and modifying the engine cams, compression ratio etc,(and even expected A/F ratios, and therefore combustion temperature) the values derived form a production engine are no longer valid and may cause the software to "determine" that knock is present when it's not or fail to detect knock when it is."

 

yes that is what I was referring to...

 

It's optimum? Bwaha!
It's "optimum" compression was engineered around a stock cam. The Dynamic compression is much lower (than static compression) while running a stock cam.
It's "optimum" compression is easily raised from that point with a cam that has the later intake close.
So your statement is obviously very wrong. Cam closing times do not "only detract" from optimal.

You described static compression. Dynamic compression with a stock cam compared to a cam with a later intake close (same static compression) - are two very much different animals.
Who cares if the cam don't put you above Static compression?
If the late intake close puts you above an optimal CCP, what's it matter what your static compression was? It's still high compression as far as the motor function is concerned.

Of course you new that, but chose not to mention it for some reason.

Not clear what your post had to do with the OP's noticable difference in performance with higher octane.


Yes, indeed they have! Ever notice how no one runs 87 octane at the race track?




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YOUR RIGHT IM WRONG. I GIVE UP. I guess you know everything and your bike goes a million mph with 700 octane fuel. You fricken moron.


"Yes, indeed they have! Ever notice how no one runs 87 octane at the race track?"

So you think everybody at the race track runs low compression? Dude go pull your head out of your azz.


You really should do some reading about internal combustion engines.