Ok, here it goes...

Would running a few ounces of premix per tank reduce the chance of flooding? As I understand it, our flooding issues are just the gas washing away the lubricating oil from the seal, so would premix not help prevent this?

I did search a lot on this but I didn't really find an answer to my question.


thanks.

 

Well.. thats not exactly the correct answer on flooding... it can be ONE reason, but there are others, like injector leakdown, that must be fixed by actual mechanical exploration!!!

Running an ounce of premix in your tank is not going to HURT anything, so go ahead and give it a shot.

just don't put more than an ounce or two in a full tank. You're still running the regular oil injection, and too much oil in the motor is not good either!!

 

actually with the stock MOP working you could run up to 200:1 ratio (gas : premix oz) and not have problems.

Remember though that premix will also lower the octane, and while that is generally good for a non turbo, lower octane could be disasterous for a Turbo motor.

 

You mean raise the octane, Mark, not lower...The oil itself does not combust (although does "burn"), and anything added to the gas that doesn't itself combust will raise the compression and heat levels at which it combusts, or raise the octane, if you will...

Lower octane- easier to combust (and more apt to pre-detonate)

Higher octane- exactly the opposite...

 

No, you don't understand octanes ratings...

Higher octane burns faster, lower octane burns longer

Oil (as pre-mix is) will lower the octane, forcing the burn to be longer.

Octane ratings are not how easy it is to ignite.

Petrol distillates (like premix) burn, so they do not lower combustion temp, or raise compression. There is no oil left after the combustion cycle.

 

I always thought that the Higher the octane the slower the burn, which then translates into greater detonation resistance? Which is why Higher Octane is not as good for N/A cars, because the higher octane is sacrificing a little bit of punch to resist the chance of detonation that is not there. But I very well could be wrong =)

And to my original question, I know a little premix won't hurt anything, and infact might help a little bit if my MOP is a fucked, or some oil injectors are not spraying....but will it reduce the chance of flooding?

I am mainly asking this for my '88 GXL, not my T2 sorry

 

no premixing probably will not help the flooding at all.


mark, if you say lower octane burns longer, how would that be more prone to detonation when compared to petrol of a higher octane rating?

 

Higher octane doesn not necessarily burn faster, it burns more smoothly. In fact, lower octane gas has more small, straight chained hydrocarbons in it, which will contribute to rapid combustion (and detonation)

Octane ratings are relative to the tendency of gasoline to detonate/knock/ping under compression as compared to Iso-Octane. Iso octane is a branched-chain hydrocarbon, meaning that instead of having its carbons linked in a straight line, there are several branches with the branches linked together by a central carbon. Having the carbons linked at a central point makes the molecule more compact and thus less likely to produce a broken piece or, end vapor, that will ignite at those temperatures (thats REALLY simplified)

Straight chained hydrocarbons are obviously longer and more succeptable to "breakage" of the chain, resulting in smaller, end vapor, hydrocarbons which are more likely to ignite during compression. This is kinda like playing "crack the whip" as a kid, the longer the chain is, the easier it becomes to break off a link!!

ANYWAY... Iso-Octane is given the rating of 100 in its ability to resist detonation from compression. Just compressing the a/f mixture can result in temperatures of over 700 Degrees F., as a gas is compressed, it becomes hot. Anything that is less resistant is given a number lower than 100 any thing more resistan is given a number higher than 100. Commonly, Mixtures of gasoline are put through two basic tests to determine their octane rating and then those test results are averaged. Ever see R+M/2 on the octane sticker.. thats what it means.


Circular shaped molecules Toluenes and Xylenes are even more resistant to detonation during compression, thus, you hear about people adding toluene to their gas to increase the octane rating of the gas.

NOW THEN... the two stroke oils that we add to our gas, along with most other lubricants, are comprised largely of long, straight chained hydrocarbons. We know that long, straight chains are easier to break.

THEREFORE, adding two stroke oil to your gas will result in the formation of more small pieces, or end vapors, that can ignite during compression, thus lowering the octane rating of the gas. However, at 100-1 mix ratios, this lowering effect is going to be WAAAYYYYY less than even a point, especially if you are using a high grade lubricant.

Also.. You will not, with any noticeable effect, raise the compression of a motor by adding something to the gas. At least not by adding anything that will burn. Yes, oil vapor will have a different compression factor per given volume than gasoline vapor, however, the biggest fraction of what is being compressed inside the housing is air, the gasoline/oil mixture makes up such a small fraction of the actual cylinder charge that changes to it are not going to have any significant change in the amount of compression created as the rotor squeezes the mixture before ignition.

 

My question here is, does the change in octane running 100:1 premix really make a difference?

 

Thanks for the further details and correction of some of my terms!

 

Should rename this thread "Screw Premix & flooding....Octane breakdown!"

Though I thought the octane rating was a ratio of Octane to another similar hydrocarbon such as Heptane or something....