Octane Booster?

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LoneRonin said:
wow, seafoam thread and right above it octane booster...noobs are out in full force this season.
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Sorry, can`t resist.

Which bike should I get. I am 6`5" 500 lbs. Which oil is best for me to drink and use in my bike. When I get it. Which colour is the fastest? Which Insurance company is best for me? I was caught doing 200 kms on one wheel. On a stolen bike. I am 17 and live alone with myself. Guess that`s 2. Should I wear shorts and a "T' shirt because it gets hot. My Gf the same. Sometimes topless. Wonder why she is followed home? What colour gas is the best? What is this you talk about called a "Sticky "Is it something like a post it note? Can I get a Racing bike to start with? Looks so cool at Timmies.
Can I lane split or if it is too busy there can I use the side walk?
It`s OK I am only joking. I am really confused. I hope to grow up and be a ? That`s another story.
 
cycling said:
Sorry, can`t resist.

Which bike should I get. I am 6`5" 500 lbs. Which oil is best for me to drink and use in my bike. When I get it. Which colour is the fastest? Which Insurance company is best for me? I was caught doing 200 kms on one wheel. On a stolen bike. I am 17 and live alone with myself. Guess that`s 2. Should I wear shorts and a "T' shirt because it gets hot. My Gf the same. Sometimes topless. Wonder why she is followed home? What colour gas is the best? What is this you talk about called a "Sticky "Is it something like a post it note? Can I get a Racing bike to start with? Looks so cool at Timmies.
Can I lane split or if it is too busy there can I use the side walk?
It`s OK I am only joking. I am really confused. I hope to grow up and be a ? That`s another story.
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You had me at topless
 
You forgot to wash your engine out with soap and water. The most important step to long engine life.
 
catzo said:
My bike manual says my bike will take "87 or higher" but its the exact same engine as the r6 which takes premium.
Figure that one out.

I still usually put 87 in because theres no knocking with it.
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Its not just the engine, things like how its tuned and compression ratios make all the difference. I don't know the specific numbers but I can guarantee you the R6 has a higher compression ratio than an FZ6.
 
If I had a big-inch air-cooled thumper or a Harley (e.g.) with huge cylinders & low-revs or if I had a 2-stroke I'd probably opt for higher octane fuel even if the manual stated the engine would be okay with "regular." For higher revving, small-bore multi-cylinder bikes just run what the manual says.

I see no benefit to adding any sort of "octane booster" to a tank of gas that's a few months old and which has been stabilized. First, it's fine, but second, it'll burn off in 200kms and you'll be able to top off with fresh gas then. How long will that take? A couple of hours this coming Saturday should take care of that...
 
Drennan57 said:
You forgot to wash your engine out with soap and water. The most important step to long engine life.
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When you're rebuilding an engine that's been subjected to machining/milling, it is actually.

Buried somewhere I have a photo of me washing out the crankcase and bores on my 6.5 diesel block with hot soapy water.
 
Blackfin said:
If I had a big-inch air-cooled thumper or a Harley (e.g.) with huge cylinders & low-revs or if I had a 2-stroke I'd probably opt for higher octane fuel even if the manual stated the engine would be okay with "regular." For higher revving, small-bore multi-cylinder bikes
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It has nothing to do with big bore, high revving, 2 vs 4 stroke, or anything of the sort – it has everything to do with compression ratios. An engine with very high compression ratios will suffer from detonation (pre ignition) when running on low octane fuel, whereas high-octane fuel removes the issue.

Detonation can physically damage an engine so it's generally a bad idea, however many modern day engines include a knock sensor that will detect detonation and retard the timing to avoid damage. Basically, manufacturers have idiot proofed cars again so that people who buy high performance cars that *require* premium fuel and then get tired of paying for it (and start pumping regular instead) don't all blow up their cars.

Knock sensed timing retardation always comes at a loss of performance, sometimes very drastic, but it beats blowing up your engine.


On a traditional or low compression engine running premium fuel it's nothing more then admitting to believing in the marketing woo suggesting it's somehow better for your engine. Reality is your engine doesn't care.
 
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Well, there is more to it than just the compression ratio. It's a lot more complicated than that.

Air-cooled engines tend to run at much higher cylinder head temperatures than liquid-cooled engines, and that tends to promote detonation.

Small-bore engines are less prone to detonation than large-bore engines. Doesn't matter number of cylinders, the bore size is what counts. With small diameter cylinders, there is a shorter distance from the spark plug to the furthest reaches of the combustion chamber. Within the engine, if you burn the mixture via the flame front before it has a chance to detonate, it doesn't detonate. Modern 600cc sport bike engines commonly have compression ratio in the 13:1 range nowadays. Don't try that on a Chevrolet V8 if you want to fill it up at the corner gas station.

High-revving engines are less prone to detonation. If the piston goes down the cylinder quickly enough, the cylinder pressure drops fast enough that the end gas doesn't reach detonation conditions. Also there is a time-lag before self-ignition occurs, and these engines again want to burn the mixture via the flame front before that time lag happens.

The design of the combustion chamber matters. 4-valve DOHC with spark plug dead center minimizes the distance the flame front has to travel.

The design of the intake runners matter. Some modern engines promote high "tumble" charge motion which helps the mixture burn normally via the (turbulent) flame front before detonation can occur. Case study: the new Chrysler Pentastar "upgrade" (3.6 litre DOHC-4v, 11.3:1 compression http://www.allpar.com/mopar/V6/PUG-2015.php and also the Renault TCe90 https://www.youtube.com/watch?v=XNvRhWL1stQ

The cam timing matters. Long-duration intake cams let some of the charge back out of the cylinder which reduces cylinder pressure which makes the engine "think" it has lower compression than it actually is. The Atkinson-cycle engines in many of the newer hybrid cars (notably, Prius, but it's not the only one) takes advantage of this. But if you just simply sacrifice low-end torque by using long-duration cams, the same thing happens. The aforementioned 600cc sport bikes are doing this.

(yes, I'm a mechanical engineer; yes, I'm a powertrain junkie. I don't actually work in powertrain engineering myself, but I have a friend who spent way too much time in postgraduate studies and now works in powertrain engineering and knows way too much about all this stuff)
 
side note: I put Wossner 13.5:1 pistons in my ZX10R at the time of overhaul and select-fit the head gasket to get the race-manual-recommended 0.65mm piston-to-head clearance (quite a bit tighter than stock). The tight squish clearance helps with charge turbulence and that reduces detonation. It runs fine on premium pump gas. I wouldn't chance running 87 octane in it (No knock sensor) and if I were to do a track day or top-speed run in it, I'd use race fuel for insurance. But for day-to-day riding, pump premium is fine.
 
The OP needs a brain boost. Enough with the annoying threads. ?

via Tapatalk
 
Brian P said:
Well, there is more to it than just the compression ratio. It's a lot more complicated than that.
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Fair enough, I'll consider myself educated. ;)

I'll stand fast on the (perhaps simplistic in comparison, now, but still factual) viewpoint that burning a higher octane fuel than what the engine calls for, however, provides little to no net benefit other than to line the pockets of the oil companies a little more.

So, if your bike calls for 87 octane, burn 87. If it requires 90 or above, chances are there's a good reason for it, so one best follow the advice. Personally, my bike calls for 87, I burn 87 - I just finished off a tank of 91 today (my december fillup of no-ethanol) and noticed zero difference - some with many more miles on VTX's than myself report that their bikes run worse on premium.
 
LoneRonin said:
Its not just the engine, things like how its tuned and compression ratios make all the difference. I don't know the specific numbers but I can guarantee you the R6 has a higher compression ratio than an FZ6.
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Yes, it does, but BARELY. 12.2:1 for the fz6 and 12.4:1 for the r6.
12.2:1 is a plenty high compression ratio and normally an engine like that would use premium.

For comparison, the cbr 600rr also has a 12.2:1 compression ratio and obviously takes only premium.

Ive debated this a lot of the fz6 forums lol. I know there are lots of other factors than compression ratio, but it is too similiar to the engine in the r6. I'm pretty sure that yamaha only stated 87 to make the bike seem more affordable. Still, it seems to work fine. There are lots of owners of my bike that swear on 91 tho.
 
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Brian P said:
Well, there is more to it than just the compression ratio. It's a lot more complicated than that.
Click to expand...

Glad you touched on a number of the points I was thinking of. Hadn't thought of cam timing and its effect on the effective compression ratio (vs the mechanical one) and had forgotten about chamber turbulence.

I mentioned two strokes because they burn oil and it's my understanding that oil tends to "dilute" the octane rating which makes the fuel more likely to autoignite. Subaru tuners are big on air/oil separators in the crankcase ventilation systems to keep oil vapour out of the intake tract for the same reason; on the EJ257 detonation can break piston ringlands. I've a got a piston from my 1980 RM125 I replaced back in the early 80s. Its crown is pitted with detonation damage. That was an air-cooled and likely ran very hot...
 
PrivatePilot said:
I'll stand fast on the (perhaps simplistic in comparison, now, but still factual) viewpoint that burning a higher octane fuel than what the engine calls for, however, provides little to no net benefit other than to line the pockets of the oil companies a little more.
Click to expand...

No argument from me there. Unless your bike has an engine with higher compression than stock, just do what the manual says.
 
Brian P said:
Well, there is more to it than just the compression ratio. It's a lot more complicated than that.

Air-cooled engines tend to run at much higher cylinder head temperatures than liquid-cooled engines, and that tends to promote detonation.

Small-bore engines are less prone to detonation than large-bore engines. Doesn't matter number of cylinders, the bore size is what counts. With small diameter cylinders, there is a shorter distance from the spark plug to the furthest reaches of the combustion chamber. Within the engine, if you burn the mixture via the flame front before it has a chance to detonate, it doesn't detonate. Modern 600cc sport bike engines commonly have compression ratio in the 13:1 range nowadays. Don't try that on a Chevrolet V8 if you want to fill it up at the corner gas station.

High-revving engines are less prone to detonation. If the piston goes down the cylinder quickly enough, the cylinder pressure drops fast enough that the end gas doesn't reach detonation conditions. Also there is a time-lag before self-ignition occurs, and these engines again want to burn the mixture via the flame front before that time lag happens.

The design of the combustion chamber matters. 4-valve DOHC with spark plug dead center minimizes the distance the flame front has to travel.

The design of the intake runners matter. Some modern engines promote high "tumble" charge motion which helps the mixture burn normally via the (turbulent) flame front before detonation can occur. Case study: the new Chrysler Pentastar "upgrade" (3.6 litre DOHC-4v, 11.3:1 compression http://www.allpar.com/mopar/V6/PUG-2015.php and also the Renault TCe90 https://www.youtube.com/watch?v=XNvRhWL1stQ

The cam timing matters. Long-duration intake cams let some of the charge back out of the cylinder which reduces cylinder pressure which makes the engine "think" it has lower compression than it actually is. The Atkinson-cycle engines in many of the newer hybrid cars (notably, Prius, but it's not the only one) takes advantage of this. But if you just simply sacrifice low-end torque by using long-duration cams, the same thing happens. The aforementioned 600cc sport bikes are doing this.

(yes, I'm a mechanical engineer; yes, I'm a powertrain junkie. I don't actually work in powertrain engineering myself, but I have a friend who spent way too much time in postgraduate studies and now works in powertrain engineering and knows way too much about all this stuff)
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What about load on the engine?
Bikes have less load, that's why they can run higher compression ratio with the same octane fuel
 
Don't think "load". Think "pressure". The engineering term is BMEP "brake mean effective pressure". This takes out the effect of "scale", i.e. allows differently sized engines to be compared on equalized terms. Modern sport bike engines have among the highest BMEP of normally-aspirated production 4 stroke spark ignition engines.
 
and this is why Brian is an engineer...I just threw out compression ratios, he comes back in such depth and detail you'd think he read it out a textbook.
 
Brian P said:
Don't think "load". Think "pressure". The engineering term is BMEP "brake mean effective pressure". This takes out the effect of "scale", i.e. allows differently sized engines to be compared on equalized terms. Modern sport bike engines have among the highest BMEP of normally-aspirated production 4 stroke spark ignition engines.
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Ok I'll settle with that
 
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