Fuel octane

Gothy · 11-19-2008, 12:35 PM

Can I ask, what octane you guy's normally run over there in the US.

Its quite a low figure isnt it?

over here (UK) we run 95 octane as a normal fuel
and 97 - 98 for super.

And apparantly our bikes feel like they have more power than yours. According to journalists.

bladeracer · 11-19-2008, 4:13 PM

The fuels are similar they're just measured under two different systems.
Here 91RON is regular, 95 is premium and 98 is the good stuff.
The octane rating makes _zero_ difference in the engine.
The _additives_ in the higher rated fuels can make a difference particularly in fuel economy.

WyoJames · 11-19-2008, 4:34 PM

here it is 91 premium, 87 supreme, 85 normal...but as blade says, there really isn't any difference from country to country, just a different measuring system

Twincam · 11-19-2008, 4:37 PM

I can't remember who tested it, but I believe it was 5th Gear...

They tested the different fuels out (Regular against Peformance (another name for super unleaded) and it showed an increase in BHP...? Probably rigged but was cool to watch.

I think bikes peform best at regular am I right? If you go too high the bikes can start to ping at idle? (Correct me if Im wrong please)

WyoJames · 11-19-2008, 4:39 PM

I've been told by all the dealers out here to run 91 (premium for us)

Evil R · 11-19-2008, 4:50 PM

After 05 ( i think was the transition year, but i could be wrong) all honda's are suppose to run 91. Before that year they were all designed to run on 86. The higher the octane rating the better protection against predetonation in your engine.

WyoJames · 11-19-2008, 5:43 PM

Quote:

Originally Posted by Evil R

After 05 ( i think was the transition year, but i could be wrong) all honda's are suppose to run 91. Before that year they were all designed to run on 86. The higher the octane rating the better protection against predetonation in your engine.

sweet, i got worried there for a sec.

spina220 · 11-19-2008, 6:47 PM

Where I am it is, regular 87, 89 supreme, 93 premium.(NY) I put 93 in the bikes and 87 in the trucks.

edclark99 · 11-19-2008, 7:12 PM

Quote:

Originally Posted by Twincam

I can't remember who tested it, but I believe it was 5th Gear...

They tested the different fuels out (Regular against Peformance (another name for super unleaded) and it showed an increase in BHP...? Probably rigged but was cool to watch.

I think bikes peform best at regular am I right? If you go too high the bikes can start to ping at idle? (Correct me if Im wrong please)

if you tune an engine to give higher output you need to run higher octane, this is to stop pre ignition at high temps, which can cause major damage.
normally to get to this stage you need cams vernier pulley wheels and throttle bodies or carbs in a naturally aspirated engine....

Very few normal engines can benefit from it, but new high power Saab's, subaru imprezas, and some jap big HP cars

edit- forgot the old 5star/100 octaine sold at race tracks mainly for classic tuned motors and formula V etc

bladeracer · 11-19-2008, 10:10 PM

Quote:

Originally Posted by Twincam

They tested the different fuels out (Regular against Peformance (another name for super unleaded) and it showed an increase in BHP...? Probably rigged but was cool to watch.

I think bikes peform best at regular am I right? If you go too high the bikes can start to ping at idle? (Correct me if Im wrong please)

It's certainly possible for the higher octane fuels to provide more horsepower but it's not due to the octane rating at all. To make the higher octane fuels financially viable to a wider demographic they throw in more additives to improve it in other ways. If they only refined it to a higher octane for use in high-compression engines it'd probably be double the price of regular at least because nobody else would buy it. I run 98 in all my vehicles mainly for the extra mileage.

TC: You have it the wrong way around. The _lower_ the rating the more likely it is it to ping or detonate. Pinging is not an idle problem usually and is much more likely under heavy load like full throttle in top gear at 30mph. All engines can perform better on higher octane fuels.
Although it's generally considered that the detonation threshold is determined by the compression ratio of the engine it's actually more dependant on how well the engine breathes and is able to fill the cylinder.

dicknose · 11-20-2008, 3:24 AM

Quote:

Originally Posted by bladeracer

It's certainly possible for the higher octane fuels to provide more horsepower but it's not due to the octane rating at all.

Sort of right - but missing the point.

There isnt any more energy in the higher octane fuels.

But the higher octane allows you to do other things that get you more power. Running higher compression, more boost, adjust timing.

So the extra power would only be available from a higher octane fuel.
Ok - so the fuel doesnt have the extra power in it, but the effect if that by running higher octane fuel your engine may generate more power. So where did the power come from? Its not actually the fuel, but that looks like the only thing that changed - so its not unreasonable to say "higher octane fuel provides more power".

Quote:

All engines can perform better on higher octane fuels.
Although it's generally considered that the detonation threshold is determined by the compression ratio of the engine it's actually more dependant on how well the engine breathes and is able to fill the cylinder.

Again - I think thats a bit misleading.
There are plenty of engines that will not perform better with a higher octane.
If they arent pinging on normal octane (or the engine adjusting timing to stop pinging) then higher octane wont give much of a benefit. You are likely to get no more power or fuel economy. Sure it depends on whats added, but in general you wont get more power from higher octane unless your engine has spare "capacity" (boost, timing etc) that is being held back by pinging.

bladeracer · 11-20-2008, 3:26 AM

As I stated - no engine will perform better _at all_ due to higher octane alone.
It is _only_ the additives in the higher octane fuels that allow more power and or economy.
I really don't think I could have stated it any more clearly...

bladeracer · 11-20-2008, 3:44 AM

And, just to clarify I'm not talking about making _any_ alteration to the engine at all.

jazzy · 11-20-2008, 5:16 AM

Its 95 and 98 here...When I first bought the bike I put 98 in...she started pinging and making all manner of strange annoying noises.
So I changed to 95 and within a tank full it all stopped.

spina220 · 11-20-2008, 5:45 AM

higher octane fuel is supposed to be cleaner also, no?

jazzy · 11-20-2008, 5:50 AM

depend s on filtration at the pump...so i've been told

bladeracer · 11-20-2008, 5:52 AM

It would depend on the specifics of the particular brand I think.
This is what I generally use - Products and services - BP Ultimate - New improved BP Ultimate Unleaded
Haven't tried this stuff yet though - Shell in Australia - Shell V-Power

spina220 · 11-20-2008, 5:58 AM

I have used 93 in every bike I have ever owned, and that is quite a few, and never had any problem with pings or anything. I used it in practice in all my race bikes too and just can not see putting in 87.

jazzy · 11-20-2008, 5:58 AM

Like you say Blade when its produced at source thats basically whaqt you get. There are a couple of garages here that have Extra filters either at the nozzle or just after the tanks(of course they charge a little extra for this!) whether it makes any extra diff or not i dont know.
Evening Blade

spina220 · 11-20-2008, 6:01 AM

Different strokes for different folks I guess.

jazzy · 11-20-2008, 6:04 AM

Bladeracer, just read ya BP link...I was getting detonation/pinking on the higher produced octane??? Would this lead to say that possibly ny mixture was out???
This bike is from new, do they make mistakes ike that out of the factory??

dicknose · 11-20-2008, 6:18 AM

Quote:

Originally Posted by bladeracer

As I stated - no engine will perform better _at all_ due to higher octane alone.
It is _only_ the additives in the higher octane fuels that allow more power and or economy.

Well thats not correct.

It not just about the additives, its also about the octane.
A modern high performance engine run on a low octane fuel will detect this with a knock detector and will do things to reduce this knocking - and in doing so will reduce power. This is most noticable on a turbo engine where the engines computer can limit boost (and hence power)

In these cases the extra power you get with a higher octane fuel is not just due to additives, its due to be able to use the engine to its full ability.
Octane rating - Wikipedia, the free encyclopedia

If you prefer to word it another way...
high octane doesnt give you more power, but lower octane can cause you to have less!
So high octane fuel doesnt get more power than "optimum conditions", but it is more power than lower octane fuel which means you are running at less than optimum.
Either way you word it - on some high performance engines you will get more power due to octane rating of the fuel. Its not due to any additives, its due to the octane letting the engine work to its full design spec.

My car (Forester XT) is quite noticable for this. You can see it in the computer logs - put the wrong fuel in and the computer starts to reduce max boost. You can then actually fill up with high octane fuel and you dont instantly get any more power. Reset the computer and bingo - instant power gain. That instant gain is due to octane letting the engine run different settings.

dicknose · 11-20-2008, 6:23 AM

Quote:

Originally Posted by jazzy

Bladeracer, just read ya BP link...I was getting detonation/pinking on the higher produced octane??? Would this lead to say that possibly ny mixture was out???
This bike is from new, do they make mistakes ike that out of the factory??

Its just as likely to be bad fuel.

I know that here in Australia there was a bit of scandal when some service stations were selling the wrong octane fuel - basically charging extra for the same stuff. Lots of people complained about their cars running badly and I think it finally took one of the tv "current affairs" shows to prove it.

I also know that here some brands had a bad reputation for poor consistency on their high octane - one week it was great, the next it was poor. And even then it depended greatly on where you were as the same brand could be sourced differently in different cities.

My suggestion - try another brand first and see if that helps.

jazzy · 11-20-2008, 6:27 AM

Good point..this garage was the one with the extra filtration...only put 98ron in at this garage. Will try somewhere else.

bladeracer · 11-20-2008, 6:40 AM

Quote:

Originally Posted by dicknose

You can then actually fill up with high octane fuel and you dont instantly get any more power. Reset the computer and bingo - instant power gain. That instant gain is due to octane letting the engine run different settings.

I'm not aware of any manufacturer that produces higher octane fuel that doesn't also have enhancing additives.
Unless you are able to do this test with two identical fuels except for their octane rating I'm not sure you can make such a comparison.
I agree that if you are running an engine on lower-than-required octane such that it isn't combusting properly then an increased octane with no other additives would see an improvement. In a case where the engine has a computer that can alter the way it burns the fuel then you'd probably see a difference but I'm talking about _not_ changing the engine characteristics at all.

bladeracer · 11-20-2008, 7:35 AM

Quote:

Originally Posted by jazzy

Bladeracer, just read ya BP link...I was getting detonation/pinking on the higher produced octane??? Would this lead to say that possibly ny mixture was out???
This bike is from new, do they make mistakes ike that out of the factory??

I can't think of any way you'd get detonation from a higher octane fuel but not a lower one _if_ the ratings are accurate. If there was something wrong with carburation, timing or mechanicals then the problem would get worse on a lower octane fuel.
All I can think is that the 98 you ran was either incorrectly labelled, contaminated in some way or very stale.
I have often wondered but have never investigated how quickly the RON degrades over time when unconfined.
I've read that blending ethanol speeds up the degradation of fuel but I've never seen actual figures for how long it takes 98RON to degrade to 91RON and such.

jazzy · 11-20-2008, 7:37 AM

Quote:

Originally Posted by bladeracer

I can't think of any way you'd get detonation from a higher octane fuel but not a lower one _if_ the ratings are accurate. If there was something wrong with carburation, timing or mechanicals then the problem would get worse on a lower octane fuel.
All I can think is that the 98 you ran was either incorrectly labelled, contaminated in some way or very stale.
I have often wondered but have never investigated how quickly the RON degrades over time when unconfined.
I've read that blending ethanol speeds up the degradation of fuel but I've never seen actual figures for how long it takes 98RON to degrade to 91RON and such.

Thanks, thats a LOT clearer

exit90a · 11-20-2008, 7:40 AM

This link explains the different rating numbers by region and clears up exactly why higher octane is required. Octane rating - Wikipedia, the free encyclopedia Most vehicles will have an octane rating specified by the MFG near the fuel hole and in the manual if you are not sure what is needed.

jazzy · 11-20-2008, 7:43 AM

exit90a already had that link, my question wasn't about WHICH fuel grade, but about the problems I was having with differeent fuel grades...its all in this thread.....

Gothy · 11-20-2008, 8:19 AM

wow i really didnt expect this many posts so soon. lol.

I went through a stage of only using 98, in my 400.
Its amazing the difference it makes to pulling power, but i stoped using it when the fuel prices rocketed upwards.

But in my car it doesn't really make any difference.

so i guess it depends on the particular engine.

also why do your numbers get lower for higher octane ratings?