87, 89, 91, 92 Dyno performance
#11
07-15-2018, 09:37 PM
'
So you run 87 octane in your XL883.. Okay.. I'm not knocking it..
2002 Sportster XLH883 - Hammer 1250, 30 Degree pistons, Impact headwork, Andrews N4, Energy One Clutch, TwinTec 1005S-EX Ignition, 530 Chain (running on 87 octane),,
This is a dumb test. Whatever octane your motor was designed for will perform best. All others will perform lower.
Pro tip, this is all done during powertrain development to a level much much much much higher than you could ever test with out a multi-million dollar R&D facility. Might as well test whether you ride faster after drinking Dasani or Poland Springs. Has about as much relevance.
Pro tip, this is all done during powertrain development to a level much much much much higher than you could ever test with out a multi-million dollar R&D facility. Might as well test whether you ride faster after drinking Dasani or Poland Springs. Has about as much relevance.
2002 Sportster XLH883 - Hammer 1250, 30 Degree pistons, Impact headwork, Andrews N4, Energy One Clutch, TwinTec 1005S-EX Ignition, 530 Chain (running on 87 octane),,
Last edited by 1HD4CJM1X4K; 07-15-2018 at 09:41 PM.
#12
07-15-2018, 09:43 PM
Seasoned HDF Member
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1HD4CJM1X4K (07-15-2018)
#13
07-15-2018, 09:49 PM
This is a dumb test. Whatever octane your motor was designed for will perform best. All others will perform lower.
Pro tip, this is all done during powertrain development to a level much much much much higher than you could ever test with out a multi-million dollar R&D facility. Might as well test whether you ride faster after drinking Dasani or Poland Springs. Has about as much relevance.
Pro tip, this is all done during powertrain development to a level much much much much higher than you could ever test with out a multi-million dollar R&D facility. Might as well test whether you ride faster after drinking Dasani or Poland Springs. Has about as much relevance.
Testing would confirm the figures are accurate.
Proof we are basing our trust on truth in marketing.
#14
07-15-2018, 10:07 PM
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I have. At 8700ft elevation. It ran fine. When it was an XL883 I also ran 87. Throughout the US i've run everything from 85 gasahol to 93 pure.
At sea level, I run 93/91 AKI gas. Why? Because that's what my motor was designed to run. My bike is far from the factory. I'm trusting gas station numbers, which I really shouldn't. They vary so much from pump to pump it's insane. Ever try and run pump ethanol? Better have a tester. If I get knock I just back off and dial down the timing.
As far as your question: my pump gas Sporty won't compare to my buddy's C10 Road King. Because they were designed to make use of it. Run C10 in my bike and it's just expensive noise.
At sea level, I run 93/91 AKI gas. Why? Because that's what my motor was designed to run. My bike is far from the factory. I'm trusting gas station numbers, which I really shouldn't. They vary so much from pump to pump it's insane. Ever try and run pump ethanol? Better have a tester. If I get knock I just back off and dial down the timing.
As far as your question: my pump gas Sporty won't compare to my buddy's C10 Road King. Because they were designed to make use of it. Run C10 in my bike and it's just expensive noise.
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1HD4CJM1X4K (07-16-2018)
#16
07-16-2018, 11:29 AM
Grand HDF Member
It is more than just the compression ratio that determines the Octane requirements.
#17
07-16-2018, 11:50 AM
A couple of SUNOCO race gas tech articles:
Specific Gravity – What Is It And Why Does It Matter?
Beyond Octane
Some of the Sportsters had octane recommendations of 87 others have been 91.
In some years the 883s were 87 and the 1200s were 91.
The S model also recommended 91 octane.
Specific Gravity – What Is It And Why Does It Matter?
Beyond Octane
Some of the Sportsters had octane recommendations of 87 others have been 91.
In some years the 883s were 87 and the 1200s were 91.
The S model also recommended 91 octane.
#18
07-16-2018, 11:54 AM
#19
07-16-2018, 10:00 PM
#20
07-16-2018, 10:24 PM
Learned a LOT about fuel and the requirements.
I have always voiced in the past that it was a waste of money to buy a higher octane fuel when your engine was designed for regular and except for rare cases this holds true.
The comment that a shop should test a plain Jane, stock engine (or a show like Myth Busters} was to show that this was truly a fact.
This thread has run its course, but 50 more Octane threads will pop up over the next year across all of the many internet forums.
We dyno after every slip-on and every air filter, so why not have one shop dyno the fuel we are buying? There is not a single dynamometer run that I have seen that has tested or even challenged the myths that abound. If compression ratios were the only requirement needed to figure out your octane requirements, then no manufacturer would ever have to test ever again. Add a turbo and you would have to re-think that theory.. Or valve timing/overlap. Altitude, temperature, ram air induction..
I never intended for the original post to generate bandwidth and waste so much time. Was just a passing thought that seemed noteworthy,
*Passing thought: Some shop could gain a bit of advertising every time their test results were referenced on a forum.
Last edited by 1HD4CJM1X4K; 07-16-2018 at 10:26 PM.