Compression vs Ethanol Content | GTAMotorcycle.com

Compression vs Ethanol Content

sinbin

sinbin

Well-known member
So I filled up at Esso and they have the 10% ethanol notice. I noticed a distinct difference (it was worse) compared to Shell (apparently this has no Ethanol).

Does anyone have experience with high compression engines (13:1) and the correlation to the ethanol content in the fuel? Particularly with engines running in warmer climates (30 degrees Celcius + )?

As well how much will the octane booster stuff they sell in CT work in these cases (when experiencing some detonation at low RPM ).

Thanks all!
 
Ethanol tends to increase knock resistance. However, it decreases the amount of energy created during combustion, especially if you have carbs and can't compensate for the lack of energy in ethanol as compared to gas (as engines with o2 sensors can do to some degree). Additionally, higher ambient temperatures will tend to lower power output in general. The octane rating is valid despite ethanol being in the fuel (as a matter of fact, it may be higher BECAUSE it's in the fuel..).
 
If you have an engine with 13/1 you won't need to worry about ethanol in your pump gas.Pump gas won't work with it.You'll be running at least 110 race fuel in it.Reading your sig,your engine is for the most part stock.So just use what the manual suggests.
Canadain Tire booster is just snake oil.Don't waste your money
 
As mentioned, ethanol should increase the knock index. If any fuel should knock, it would be the Shell gas.

But shell makes good gas
 
Thanks to all for the feedback. Apologies but compression is 12:1 atm. The issue i hve is with
 
Revs from a standstill below 2k. I think this may have more to do with air temps. Once i get moving the issue sorts itself out. Time for an airbox or a heat shield methinks.Thanks again all.
 
Invictus43 is 100% accurate.
Both Shell and Esso have up to 10% ethanol in regular grade gas.
Mid-grade may contain up to 5% ethanol.
And their premium gasolines (91 octane) contain no ethanol.
My car, a 1995 fuel-injected V6, hates ethanol and idles like a paint-shaker with regular gas.
Runs much better on Shell Gold, though it doesn't require the octane per se, so it must be the ethanol.
Any detonation/preignition issues will rear their heads during the hot summer weather, but maybe okay in April or October...
But I don't understand - sinbin when you filled up at Esso, of course you bought super gas, so you should have gotten no ethanol at all?
 
sinbin said:
Thanks to all for the feedback. Apologies but compression is 12:1 atm. The issue i hve is with
Click to expand...

Hahaha, I was going to ask what u did to the engine to have 13.1, lol
 
I gather that this is a carb'ed engine. If ethanol-containing fuel is making it act up, it's probably on the hairy edge of being too lean under the circumstances that are making it act up. You might need to tweak the carb settings a little. If it's stumbling on takeoff below 2000 rpm, either next size bigger pilots or a thin washer under the needles (not a full groove position) ought to straighten it out. If it's just a rough idle, give the idle mixture screws another half turn, unless they're already 3+ turns out, in which case you need next size bigger pilot jets and lean out the mixture screws. (Fuel for idling is metered by the pilot jets, and one jet size bigger is probably too much of a change.)
 
Thanks again for the responses. Carbs are mikuni rs flatslides 36. The idle circiut is actually marginally on the rich side, so this behaviour gets worse as the bike warms up. Mostly after fully warmed up and from a standstill. Ive had no lean surge -done high rpm partial throttle openings to test pilots- and the plugs are all tan acrss the board. Idle gets slightly rougher as bike warms. The mains and needle ive set so it is good for both. No lean surging at any point either. Main is also one size on the rich side. Ive tried two sizes up and top end deteriorated after fully warmed. I am still one size up from recommended just in case :)I think i may have to lower floats by an mm?
 
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