High Test and Carbon deposits

Wacko Wally /

I have always put high test gas in my ped thinking that it would run cleaner but I was surfing the forums and found a comment, in passing, suggesting that the opposite might be true. Yes, I know that higher octane has a higher resistance to preignition but was always told that high test contained less "impurities". Does anyone have a definitive answer or a link to a page with such?

Re: High Test and Carbon deposits

High Test to my knowledge has no less impurities than lower octane fuel. I've never seen it foul anything up, but it isn't usually needed in stock moped engines. I use it in my Polini kitted Sebring,but not necessarily in my other `peds. Some companies USED to seem like they had a purer gas years ago when you bought Hi-Test,but now I don't think so. If you're fouling out plugs and carbonning up engines and such, blame the oil or oil ratio or low compression or timing could be off.

Re: High Test and Carbon deposits

Leaded gas WILL leave more deposits (cant say they are 'carbon').. on valves of 4 strokes... that is well proven... especially by 4 stroke aircraft engines that still use leaded gas (low-lead).

But those are 4 stroke valves.

And I don't think there is any proof that high octane has less impurities than low octane... (hell.. its the same stuff basically... it is a small quantity of additives that makes the octane difference)

I also don't think there is any proof that high octane has any kind of.. 'cleaning properties'.. that many people seem to think it does.

You don't need high octane in any stock ped... they are low performance motors with low compression ratios.

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