Carb tuning with ethanol gas

gallegosmike · Apr 13, 2009

I need help with carb tuning with ethanol gasoline @ 10%. I can not buy straight gasoline anymore! :cry:

I was thinking about going 200 to 250 rpm less then what factory suggests. Yes, I know that tuning rich kills some hp. But I need get around the fact that ethanol gasoline burns hotter. All my saws are stock for now!

372xp/Univent 13250
Rancher 455 12250
336 12250 -

I have a tach and tuned both univent and 336. The both were tuned way low.
I live around 7500ft and cut wood above 9000ft.

Any sugestions with high adjustment on carb? Go lower, tune to stock rpm or?

:cheers:

Lakeside53 · Apr 13, 2009

The E10 doesn't burn materially hotter - it's running leaner so you just need to adjust the mixture slightly richer to get back to the stock numbers.

I'd tune by ear, then make sure I was reasonably close to stock numbers.

Erick · Apr 13, 2009

Lakeside53 said:
The E10 doesn't burn materially hotter - it's running leaner so you just need to adjust the mixture slightly richer to get back to the stock numbers.

I'd tune by ear, then make sure I was reasonably close to stock numbers.

:agree2:

oldsaw · Apr 13, 2009

Lakeside53 said:
The E10 doesn't burn materially hotter - it's running leaner so you just need to adjust the mixture slightly richer to get back to the stock numbers.

I just got some 100LL for the saws and noticed that the 066 was way rich without the ethanol. I generally run it a bit rich for mill duty, so it kind of "crossed the line". Amazed at the difference, will have to work on the tuning a bit when I get it out.

Mark

gallegosmike · Apr 13, 2009

Lakeside53 said:
The E10 doesn't burn materially hotter - it's running leaner so you just need to adjust the mixture slightly richer to get back to the stock numbers.

I'd tune by ear, then make sure I was reasonably close to stock numbers.

Thought that ethanol was a oxygenation agent causing the fuel air mixture to burn hotter?

ShoerFast · Apr 13, 2009

gallegosmike said:
Thought that ethanol was a oxygenation agent causing the fuel air mixture to burn hotter?

Yes and no,,,,

It dose oxygenate, but it has fewer BTU's per pound of fuel then pure gas.

A monkey wrench in tuning just richer/leaner, ethanol gas is also lighter/thinner and will flow more freely then pure gas past the carb's metering.

Again, fastest timed cut,,, or a burble out of a cut that clears in a cut.