OIL spewed out the breather all over the motor!!!! WHY?

[OTIS RX-1]

So his wideband was reading within the desired range of operation and this was 100% caused by bad or low octane fuel at high boost???

 

[KnappAttack]

Yep, not enough octane and to greedy with the boost tends to do that.

 

[wheeline]

I'd say no to the knock-box , but yes, to boost 101 schooling. You are now going through the school of hard knocks, no pun intended, And that my friend, is an expensive education.

Why do you say no to the knock box?

 

['DEEZ NUTZ']

Heres mine!!

 

['DEEZ NUTZ']

I have heard the knock boxes are hard to dial in as far as sensitivity. Then they can change, they are hard to trust. Just what I have heard.

 

[BigDog05]

I apologize for being dumb, but in otherwords A/F ratio is independent of detonation?

Example: I go to a gas station and think I bought 93 octane. But I actually get 87 octane, because its old or whatever. My low boost setting is 6lbs, which should be good for 93 at 2800ft where I ride.

I could actually do damage even though the A/F is showing OK? I guess I expected to see a lean A/F Number.

Sorry if I'm beating a dead horse here.

 

[wheeline]

You're right on BigDog. Octane is the measurement of gasoline's resistance to knock. So when your turbo starts stuffing more air into the cylinder it raises your compression ratio and requires a higher octane to resist pre-ignition or knock. You will still have unburnt fuel in the exhaust and your AFR gauge will look ok.

I'm not an expert but would say that a hole in the piston = not enough octane and a seized cylinder = not enough fuel.

 

[sledheadgeorge]

Too bad they don't have a portable octaine tester we can carry with us. Or even a slim strip tester like they use for measuring ph.

 

[Master of Faster]

Too bad they don't have a portable octaine tester we can carry with us. Or even a slim strip tester like they use for measuring ph.

That would be nice, maybe you could even get them custom calibrated for your sled, just dip it in and have it say "You can apply "x" lbs of boost before you blow your sled up today" LOL

Seriously though, something like that would be nice so you could be confident in the fuel you're running.

 

['DEEZ NUTZ']

Would a egt gauge read hotter when engine is knocking????

 

[Thomas800]

No actually the opposite. When detonation starts the observed EGT will drop, sometimes dramatically. Unfortunatly the heat that is absent from the exhaust gases is being pushed into the piston and the combustion chamber by the kaotic happenings in the chamber.

 

[Maddog]

ok, I'm now confused. Everyone says a wideband is a must with boosted sleds(either turbo or sc). If they do not help determine if detonation is occuring, then what good are they?

 

[KnappAttack]

The Wideband only helps to dial in the fuel mixture. I don't thing they are needed on a carbed machine as long as you have a good baseline. In fact you don't need one on the efi if you have a good baseline either. The problem is everyone changes things up so much, i.e. multiple headgaskets, low comp pistons, boost level, altitude, cam tweaks, ect.ect. that the need for fuel mixture changes. The wideband allows you to make those tweak to fuel mixture with better accuracy, thats all.

 

[Maddog]

Thanks

 

[Srxspec]

Your Air/Fuel ratio gauge does not know how much boost or what octane you are running. It tells you where your fuel mixture is at. It is up to you to make sure that there is enough octane for the amount of boost you are running!