More dyno action. 100 octane vs 92 octane

[chadihman]

Finally got my new larger displacement pump and fittings installed on the dyno. I like the change because now it pulls the saw down much easier and the flow control is not as touchy to set at a loaded rpm.

I filled the tank on my stock oem 460 with 92 octane mixed 40:1 with stihl hp. I ran the saw and recorded the #'s. I emptied the tank and filled it with 100 octane mixed 40:1 with stihl hp. I ran the saw for a little to make sure all the 92 was run through the carb. I tested and scribbled the #'s for the 100 octane.

92 wins by .15 hp over 100. Not much but it proves that its not worth paying extra for high octane in a stock saw. The next test will be on a ported 460 blowing 210 psi. with an ignition advance. I'm sure the 100 will win in that test.

 

[ndlawrence]

Finally got my new larger displacement pump and fittings installed on the dyno. I like the change because now it pulls the saw down much easier and the flow control is not as touchy to set at a loaded rpm.

I filled the tank on my stock oem 460 with 92 octane mixed 40:1 with stihl hp. I ran the saw and recorded the #'s. I emptied the tank and filled it with 100 octane mixed 40:1 with stihl hp. I ran the saw for a little to make sure all the 92 was run through the carb. I tested and scribbled the #'s for the 100 octane.

92 wins by .15 hp over 100. Not much but it proves that its not worth paying extra for high octane in a stock saw. The next test will be on a ported 460 blowing 210 psi. with an ignition advance. I'm sure the 100 will win in that test.

Higher octane is used mainly to be able to run higher compression without detonation right?:msp_confused:


BTW awesome dyno

 

[Homelite410]

I am in love with your work. Simply awesomeness at its best!!

 

[albert]

Was the 92 E10? Even if not, AV fuel is formulated much differently than pump fuel. I would think AV would require leaning the carb.

 

[moody]

Like I said before your best performance will be with 89 low ethanol fuel. But I like the way you're testing myths and theories.

 

[blsnelling]

Awesome stuff here. It shows what we believed to be true, but also shows that it would be imperceptible to the user, which was also expected. It's been said many times, that perception is far more powerful than you can imagine. The proof's in the pudding here

How are you handling tuning differences between fuels?

 

[chadihman]

Was the 92 E10? Even if not, AV fuel is formulated much differently than pump fuel. I would think AV would require leaning the carb.

Yes it was 92 E10

How are you handling tuning differences between fuels?

Same tune no change. The saw idles a little different and seems maybe a tad more fat on the tune with the 100. The 100 smells much different and I think that might be from un burnt fuel.

 

[yakcatr]

On a stock engine. (No additional timing or compression) for pump fuel lowest octane is generally better. Ping or detonation is what happens when fuel ignites too soon. Higher octane resists detonation.
I run premium in all my small engines because premium is no ethanol here.

Try some 100 octane race fuel or even some 97 octane oxygenated and you will see a bump in power but you will have to add more fuel.
Fuel is not just about octane. I can post more if you like but don't want to derail your thread.

 

[struggle]

to be directly apples to apples the saw would have to be leaned out. 100LL A/V will run noticably richer without a retune. Which I would suspect would improve numbers a little on the stock saw class

 

[Nitroman]

Yes it was 92 E10


Same tune no change. The saw idles a little different and seems maybe a tad more fat on the tune with the 100. The 100 smells much different and I think that might be from un burnt fuel.

Without going into the expense of an O2 sensor, you can make the tune the same by tuning one saw to ear, then noting the EGT while under load. While the other saw is under load, tune to that EGT and you'll be the same. The challenge here will be to make sure your thermocouple probe is at exactly the same position relative to the exhaust port. It wouldn't be too hard.

Go to Westach for a 3" gauge (nicely visible), for $78.00 and a thermocouple for $40.00; you want the fast response thermocouple. You can also pick them up on eBay.

 

[chadihman]

to be directly apples to apples the saw would have to be leaned out. 100LL A/V will run noticably richer without a retune. Which I would suspect would improve numbers a little on the stock saw class

I wanted this test to be just as it was. I think lots of people think race fuel will instantly give them power without changing the tune.

I'll have more results with my o2 sensor hooked up. I plan on testing the 100 in a ported saw with high compression and I'm going to test the ignition advance from stock to 6 or 7 deg advanced. Winter will bring more time to test more

 

[leeha]

Yes it was 92 E10


Same tune no change. The saw idles a little different and seems maybe a tad more fat on the tune with the 100. The 100 smells much different and I think that might be from un burnt fuel.

If the saw is running a tad fat with 100 it will loose power.
You should retune with 100 fuel to get the most out of it.

Awsome dyno.





Lee

 

[blsnelling]

You cannot change fuels without tuning. Some fuels tune entirely different than others. Most race gas will run WAY richer than pump gas. I recommend that you tune the saw by ear, then duplicate that RPM with the other fuels. I don't mean to sound as harsh as it probably is, but the results are meaningless without corrective tuning.

 

[chadihman]

I wanted this test to be just as it was. I think lots of people think race fuel will instantly give them power without changing the tune.

I'll have more results with my o2 sensor hooked up. I plan on testing the 100 in a ported saw with high compression and I'm going to test the ignition advance from stock to 6 or 7 deg advanced. Winter will bring more time to test more

Did you read this Brad?:hmm3grin2orange:

I know its not apples to apples but it sure did prove one theory. I used to dump octane booster in my truck when I was younger thinking it would have to make more power. I'll retest asap with retuning. My brothers 460 was squish cut and ported. I'll test that saw with 92 and 100. That's my best 460 so far. This video was taken with a tank trough it. It's much stronger now as it's been broken in.[video=youtube_share;DWVvPa5XmRE]http://youtu.be/DWVvPa5XmRE[/video]

 

[blsnelling]

Gotcha I'll make a prediction that the difference will again be minimal. If your test show otherwise, I may be spending more money on fuel in the future This is good stuff. Thanks for doing it and sharing it!

 

[sunfish]

Good stuff man!

I've tried 100 and tuned for it. All my saws feel stronger on 91 non-eth.

 

[Duane(Pa)]

Chad, first off, thanks for doing this and sharing it !!! Question: is the 100 some kind of pump gas unleaded, or are you using 100LL Avgas? I have no source of non E fuel from any pumps around here. I can get canned fuel and avgas. I know you will try all kinds of stuff, really looking forward to Stihl MotoFuel supposedly Non E, long shelf life, pre-mixed with Ultra, and a decent octane rating can't remember the number. Thanks again, DW

 

[wyk]

Yes it was 92 E10


Same tune no change. The saw idles a little different and seems maybe a tad more fat on the tune with the 100. The 100 smells much different and I think that might be from un burnt fuel.

Great work, mang.

Doesn't Ethanol have less BTU's per volume VS Gasoline? And did you test to see if it was 10% Ethanol by volume? Some places that have advertised 10% have tested up to 20%. Do they even regulate the amount of ethanol in fuel by testing for it at the state level? If your sample had a large amount of ethanol in it, then those results are skewed on the basis of octane.

 

[Trx250r180]

have you checked the exhaust temps with the race fuel vs pump gas ,a few timber fallers i know say they are lower with the race gas

 

[bcaarms]

Chain speed vs cardinal direction

With the dyno you could tell if running the chain pointing to the East improved chainspeed with less load due to earth rotation, or if the same results were achieved pointing the saw to the North. Or maybe it didnt matter because the chain running opposite direction on bottom of bar. But if you rand it on its side would it matter Northern Hemispere vs Southern Hemisphere.

I used to have a lot of spare time, but this move to the Country has me covered up for now. I'm grateful there are still folks with time to investigate these things. :msp_sleep: