Quote from: angelocardoc on October 03, 2011, 09:14:57 PM
Looks like I hit a raw nerve there. 

I'm in Australia and don't vote legitimately (it's a waste of time, my vote makes no difference, can't control them once in), even though voting is compulsory under threat of fine, so the blaming of one pollie over another and all from another country hits no nerve with me.

As burning said: Politics of [insert thing here] are much more complex than simply being an issue of executive privilege or current administration, so it comes off as ill informed and vindictive.

Whether it's Reagan, Bush, Clinton, Dubbya or Barry O what I said stands: If something is Mandated by a pollie, understand it is NOT the pollie mandating it. They are just a Puppet. A convenient person to Blame so those who truly make the decisions remain hidden and blameless.

You might think you Elect a person to lord over you, but you never think about the underlying bureaucracy and lobby groups that run the show, which are entrenched and which you never vote for.

That's all.

Michael

mmm politics .. You know the sayin ' you cant please all the people all the time' ? ... Imo the pollies see that as 'tell the people you will please all of them all the time..... Then be a complete lying bastard and tell them they are pleased anyway .. Cos the latest poll has been spun to prove it'
i still reckon forrest gump shoulda been president! ... And over here in Oz we should have Humphrey B Bear .. Cos after all if the bear cant speak the bear cant lie!
Lol

Quote from: Dr.McNinja on October 04, 2011, 08:51:10 AM

Quote from: angelocardoc on October 02, 2011, 04:36:19 PM

Run your bike on a dyno with 87 and 91 octane. Make sure to drain the tank and the carbs each time.

You'll find your bike produces the same power either way.

Not calling you out on this Doc, but where did you get this info from? Could you post dyno results to prove this? IMHO, there would be far too many variables between engines, gas stations, additives, etc to be conclusive.

This is my ballot paper from the last election... proving once again my vote made absolutely Zero difference to the outcome of the election...



Michael

You rebel mister!!!!!!! I see the Latham effect sits well with you.

I hate to jump on the bash Bush bandwagon, but I still haven't forgiven him the Lincoln Assassination or the Great Chicago fire.

Quote from: aussiegs on October 05, 2011, 01:15:24 AM
You rebel mister!!!!!!! I see the Latham effect sits well with you.

I'm sure I hve the previous election as well where I put Homer as Number 1. I'll post that if I can find it 

Michael

Quote from: burning1 on October 02, 2011, 12:18:58 PM
Royal Purple is good marketing, not good oil.

I should forward your post to my neighbor. He swears that it's the best thing since beer was invented.
I'm using Ipone 10.4 semi-synthetic myself and it seems to work fine.

Quote from: jmelchio on October 05, 2011, 01:22:00 PM

Quote from: burning1 on October 02, 2011, 12:18:58 PM
Royal Purple is good marketing, not good oil.

I should forward your post to my neighbor. He swears that it's the best thing since beer was invented.
I'm using Ipone 10.4 semi-synthetic myself and it seems to work fine.

He probably drinks a lot of bud-wiser. :  

Seriously though, have a look at BobIsTheOilGuy.com. Any mention of Royal Purple will usually be met with ridicule. Favorite brands over there seem to be Mobile 1, Shell Rotella & Amsoil. Redline and Motul also get some good mentions.

Quote from: Big Rich on October 05, 2011, 12:31:56 AM

Quote from: Dr.McNinja on October 04, 2011, 08:51:10 AM

Quote from: angelocardoc on October 02, 2011, 04:36:19 PM

Run your bike on a dyno with 87 and 91 octane. Make sure to drain the tank and the carbs each time.

You'll find your bike produces the same power either way.

Not calling you out on this Doc, but where did you get this info from? Could you post dyno results to prove this? IMHO, there would be far too many variables between engines, gas stations, additives, etc to be conclusive.

Likewise, find me evidence of 91 octane being any more powerful in an engine built for 87. It won't. The only thing that is different is the AKI, which is just some extra stuff added to make the fuel less combustible under pressure. Higher compression engines (which the Gs500 doe NOT have) benefit from it because it prevents predetonation. Interestingly enough the same reason high compression engines need better octane is why diesel engines work.

Anyway, anyone who tells you that it improves engine performance in an engine built for 87 octane is selling you snake oil.

http://www.ftc.gov/bcp/edu/pubs/consumer/autos/aut12.shtm

http://en.wikipedia.org/wiki/Octane_rating#Effects
(see effects of octane rating)

http://www.state.mn.us/mn/externalDocs/Commerce/Gasoline_Octane_Facts_102902052227_OctaneFacts.pdf



The only engines that can take advantage of the 97 octane are highly tuned engines that require it.

Higher octane kicks in around 9:1 compression ratio. That is, in theory, only those engines with higher compression ratios will benefit. The GS is right on the line. And seeing as some lower octane fuels are ethanol based, it is quite possible better performance is obtained from a higher octane fuel in a GS.

I don't think any scientific evidence is available to satisfy your request - I assume anecdotal evidence is not true evidence, right?

Looks like you'll both just have to butt heads some more...



Michael

Quote from: mister on October 05, 2011, 09:46:47 PM
Higher octane kicks in around 9:1 compression ratio. That is, in theory, only those engines with higher compression ratios will benefit. The GS is right on the line. And seeing as some lower octane fuels are ethanol based, it is quite possible better performance is obtained from a higher octane fuel in a GS.

I don't think any scientific evidence is available to satisfy your request - I assume anecdotal evidence is not true evidence, right?

Looks like you'll both just have to butt heads some more...



Michael

The least you could've done is used an image that didn't emasculate us

Very mature the both of you lol. I do however like the gorilla picture better. 

Quote from: mister on October 05, 2011, 09:46:47 PM
Higher octane kicks in around 9:1 compression ratio. That is, in theory, only those engines with higher compression ratios will benefit. The GS is right on the line. And seeing as some lower octane fuels are ethanol based, it is quite possible better performance is obtained from a higher octane fuel in a GS.

This isn't true at all. My 04 GSX-R 600 had a 12.5:1 compression ratio, and ran just fine on 87 (as per manual, and 35K of riding experience.) Octane requirements are significantly more complex than a simple statement about the compression ratio. Operating temperature of the engine, temperature of hot-spots, spark plug heat range, displacement, operating conditions, altitude, ignition timing, engine speed and volumetric efficiency all have a huge impact on what fuel is required.

Of those things, effective compression ratio is one of the most important; CR*VE.

Quote from: burning1 on October 05, 2011, 11:34:22 PM

Quote from: mister on October 05, 2011, 09:46:47 PM
Higher octane kicks in around 9:1 compression ratio. That is, in theory, only those engines with higher compression ratios will benefit. The GS is right on the line. And seeing as some lower octane fuels are ethanol based, it is quite possible better performance is obtained from a higher octane fuel in a GS.

This isn't true at all. My 04 GSX-R 600 had a 12.5:1 compression ratio, and ran just fine on 87 (as per manual, and 35K of riding experience.) Octane requirements are significantly more complex than a simple statement about the compression ratio. Operating temperature of the engine, temperature of hot-spots, spark plug heat range, displacement, operating conditions, altitude, ignition timing, engine speed and volumetric efficiency all have a huge impact on what fuel is required.

Of those things, effective compression ratio is one of the most important; CR*VE.

I'm confused, I wrote, "In Theory" which you disagree with - disagree with the Theory that higher compression engines are more likely to have pre ignition - but then finish that one of the most important aspects of pre ignition is infact, compression ratio which you disagree with. 

We're not gonna get all scientific manual on this again are we? Sprockets and HP and Power and sh!t?

If so, instead of spending time here with it all, better head on over to Wikipedia and correct their information: "The higher the octane number, the more compression the fuel can withstand before detonating." Here's the link to their page http://en.wikipedia.org/wiki/Octane_rating so you can go fix it.

Michael

Quote from: mister on October 05, 2011, 12:59:01 AM
This is my ballot paper from the last election... proving once again my vote made absolutely Zero difference to the outcome of the election...



Michael

For future reference mister. Darth Vader should  be voted number 1

Quote from: mister on October 06, 2011, 02:34:23 AMI'm confused, I wrote, "In Theory" which you disagree with - disagree with the Theory that higher compression engines are more likely to have pre ignition - but then finish that one of the most important aspects of pre ignition is infact, compression ratio which you disagree with. 

Effective compression ratio is very different than the compression ration number quoted on the specifications.

The mechanical (or manufacturer specified) compression ratio is pretty simple; take the displacement of the cylinder, and divide that by the size of the combustion chamber. With the GS500's 9:1 compression ratio, the GS500's 243.4 cc displacement per cylinder is compressed into a combustion chamber 27cc in size.

However, this doesn't take into account how effective the engine is at filling the engine with air. E.g. A engine that's really bad at filling the engine with air won't have as much pressure in the cylinder at TDC as an engine that's very good at filling the cylinder with air. The engine's ability to fill the cylinder is usually described as the volumetric efficiency, which is affected by a huge number of factors, including the cam profile, valve timing, intake tract length, head flow characteristics, efficiency of the exhaust, back-pressure, and resistance of the air filter.  Volumetric efficiency varies by RPM, but is always at it's greatest at torque peak.

Unfortunately, I don't happen to know the VE of the GS500 offhand... However, motorcycles don't typically tend to have the best VE in the world. Some cars manage to achieve a VE above 100% without using turbocharging. Turbo charged cars force air into the engine, and easily achieve VE's well in excess of 100% (A VE in excess of 125% is trivial and common with a turbo, and 200% is doable with some mods.)

Effective compression ratio takes VE into account, but almost never appears on the manufacturer spec sheets - most list the mechanical VE, as mentioned above. For that reason, mechanical compression ratio alone is not a good measure of octane requirements, especially when applied to bikes.

There's other things that you can't really apply directly from cars as well. Just today, I was reading an article stating that average piston speeds in excess of 4000FPM are very dangerous for an engine, however, doing the math showed that the redline of a modern literbike had the pistons traveling nearly 5000FPM.

Quote from: burning1 on October 06, 2011, 03:45:11 AM

Quote from: mister on October 06, 2011, 02:34:23 AMI'm confused, I wrote, "In Theory" which you disagree with - disagree with the Theory that higher compression engines are more likely to have pre ignition - but then finish that one of the most important aspects of pre ignition is infact, compression ratio which you disagree with. 

Effective compression ratio is very different than the compression ration number quoted on the specifications.

The mechanical (or manufacturer specified) compression ratio is pretty simple; take the displacement of the cylinder, and divide that by the size of the combustion chamber. With the GS500's 9:1 compression ratio, the GS500's 243.4 cc displacement per cylinder is compressed into a combustion chamber 27cc in size.

However, this doesn't take into account how effective the engine is at filling the engine with air. E.g. A engine that's really bad at filling the engine with air won't have as much pressure in the cylinder at TDC as an engine that's very good at filling the cylinder with air. The engine's ability to fill the cylinder is usually described as the volumetric efficiency, which is affected by a huge number of factors, including the cam profile, valve timing, intake tract length, head flow characteristics, efficiency of the exhaust, back-pressure, and resistance of the air filter.  Volumetric efficiency varies by RPM, but is always at it's greatest at torque peak.

Unfortunately, I don't happen to know the VE of the GS500 offhand... However, motorcycles don't typically tend to have the best VE in the world. Some cars manage to achieve a VE above 100% without using turbocharging. Turbo charged cars force air into the engine, and easily achieve VE's well in excess of 100% (A VE in excess of 125% is trivial and common with a turbo, and 200% is doable with some mods.)

Effective compression ratio takes VE into account, but almost never appears on the manufacturer spec sheets - most list the mechanical VE, as mentioned above. For that reason, mechanical compression ratio alone is not a good measure of octane requirements, especially when applied to bikes.

There's other things that you can't really apply directly from cars as well. Just today, I was reading an article stating that average piston speeds in excess of 4000FPM are very dangerous for an engine, however, doing the math showed that the redline of a modern literbike had the pistons traveling nearly 5000FPM.

Uh ha. So, after all is said and done... what I said still stands... higher octane is designed to stop pre ignition (auto detonation or knocking whichever term you choose to use). In an ideal world, the GS500 does NOT benefit from higher octane fuels. BUT, like all things, your results may vary. So try them out for yourself and go by your own results.

Michael

I agree with most of what you said. Just pointing out that you can't determine the required octane rating by looking at the manufacturer specified compression numbers.  If in doubt, open the owners manual.

FWIW: I raced the GS on regular whenever it was available (though most tracks only sell fuel 91 octane and above.) 3000+ track miles, and the plugs showed no signs of pre-ignition damage.

fwiw .. When i bought mine i ran it on 98 for ages .. Then after reading the various threads about fuel went down to 95 for a few tanks .. Now Theres always various climate conditions on different days ... But .. While i didnt really notice any change to overall power .. On 95 the midrange seems to lag a little .. The hills seem a little longer .. On 98 again now and the bike hauls my heavy butt along nicer .. Maybe just my perception/expectations .. Maybe Age of fuel .. But i fill up at high use stations .. It just feels crisper thru the mid range acceleration?