POLL: What do you choose at the pump?
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NastyEvilNinja
4 wheel racer, 2 wheel lunatic
Trinith said:NastyEvilNinja said:
Proved my point perfectly. More octane is not always better. Thanks for that!
Not really - that's why I quoted that bit.
Think of it this way:
You don't want the fuel exploding as the piston is on the upstroke or it can cause catastrophic engine damage with the forces working against each other. Lower RON fuels allow this to happen, whereas higher RON prevent this. By using as low a RON fuel as your engine can run without pinging (which means the fuel is igniting at the wrong point of the piston stroke), you're effectively saying "It's better to have a little bit of catastrophic engine damage rather than have none."
'Tis madness, I tells you! Higher RON fuels may not make a power difference in all cases, but the whole engine runs smoother because it's working as it's designed to. That's something that can't be disputed.
I probably should note as well that my experience of all this is with carbed engines...
CopperHeadpxl
Wannabie Member
I can't even get anything higher then 93 where I live. :C
Mikesmotorbike
Wannabie Member
I just use the regular stuff too. It seems to work fine, and it's cheeper than the premium stuff.
And I'm sure that NastyEvilNinja wasn't trying to be a pain, it's easy to miss a comment if you're joining a thread part way through, unless I reread it, I can't remember what was said on page one either
And I'm sure that NastyEvilNinja wasn't trying to be a pain, it's easy to miss a comment if you're joining a thread part way through, unless I reread it, I can't remember what was said on page one either
Cliff
Wannabie Member
NastyEvilNinja, since we are nothing but faceless a-holes on teh internet, I can't really blame you for not taking the word of people you don't really know as fact. I'm another one of the a-holes who will say you're misinformed, but really, you should go to a track during a race weekend(car, bike, whatever) and have a crew chief or engine tech educate you on fuel octane and it's relationship to ignition timing and compression.
FWIW I use regular(87) on the street and 100 on the track, but I have specific fuel and timing maps for each. :/
FWIW I use regular(87) on the street and 100 on the track, but I have specific fuel and timing maps for each. :/
Sh1ftyClutch
Wannabie Member
Deffintley was very educational. Never learned about octane and its relationship with combustion before.
Trinith
Wannabie Member
Sh1ftyClutch said:
Google around a little, there's a phenomenal amount of information out there for you to soak up. It takes a little time because pretty much everything about a motor is related to everything else. Once you dive in and start learning you'll find all kinds of crazy things.
NastyEvilNinja
4 wheel racer, 2 wheel lunatic
Meh I can't argue with you because I've tested UK fuels. It could be purely that they have 'better' additives in the top brand Super Unleaded fuels, which makes the difference.
I know my old carbed bikes DON'T have knock sensors, and I know they both run much better on the 97-99 RON fuels and I have quantifiable results to verify this. Apparently this is impossible, and yet it's been the same on each of my 10+ bikes. *shrugs*
One thing I did learn is that US fuels are graded differently, and your tests are an average of the RON and MON ratings.
I know my old carbed bikes DON'T have knock sensors, and I know they both run much better on the 97-99 RON fuels and I have quantifiable results to verify this. Apparently this is impossible, and yet it's been the same on each of my 10+ bikes. *shrugs*
One thing I did learn is that US fuels are graded differently, and your tests are an average of the RON and MON ratings.
NastyEvilNinja
4 wheel racer, 2 wheel lunatic
Trinith said:
I think it was aimed at me insinuating I'd ignore all evidence to the contrary in favour of my own opinions - hence why i just ignored it. :roll:
For the record you're still wrong about a more stable combustion leaving more deposits - I don't think you're an a-hole over it, though!
:lol: It's been a discussion - I've found it interesting and entertaining.
Cliff
Wannabie Member
NastyEvilNinja said:Trinith said:
I think it was aimed at me insinuating I'd ignore all evidence to the contrary in favour of my own opinions - hence why i just ignored it. :roll:
For the record you're still wrong about a more stable combustion leaving more deposits - I don't think you're an a-hole over it, though!
It's been a discussion - I've found it interesting and entertaining.
I'm not trying to insinuate you'd ignore anything you hear from us on this forum, just that you can learn a fuckload from someone who works on engines for a living. I know I did.
@ Trinith I wasn't directing that at anyone, I really was just referring to internet users as a whole. Sorry if that came off the wrong way though, I was just being sardonic. :/
P.S. Trin, I think you're first post in any thread should include this v.
Trinith
Wannabie Member
Cliff said:@ Trinith I wasn't directing that at anyone, I really was just referring to internet users as a whole. Sorry if that came off the wrong way though, I was just being sardonic. :/
P.S. Trin, I think you're first post in any thread should include this v.
Makes sense to me, I just wanted to be clear. More often than not I agree too.
As for the pic, that's pretty damn awesome.
Mikesmotorbike
Wannabie Member
a T-rex in a F-14 is definatly awesome
DodgeRider26
PURGE ACCOUNT
I know I have the ability to convey to NastyEvilNinja what we are saying about running the lowest RON possible before getting pinging... however I'm not sure I can do it with text over the internet. 5 minutes face to face with a pen/paper though and you would be in 100% agreement. Here's my last attempt:
Predetonation or pinging is that catastrophic engine damage you mention. In fact, under heavy load if you are getting pinging you usually have about 2-3 seconds to let off the gas before you ventilate your engine block with 2 or 3 broken rods. Predetonation is when the fuel begins combustion and rapid expansion while the piston is still moving upward (compressing).
When this occurs, the use of a slightly higher RON fuel will slow the ignition process down so that the rapid combustion expansion will occur slightly later on that same engine. This will cure the predetonation and make the engine run safely again. The important fact to take away from this is that you can tune where the rapid expansion occurs in your combustion cycle related to the piston movement just by changing RON of the fuel. In effect, a lower RON fuel is the same as advancing the ignition slightly and vice versa. Since running a higher RON fuel effectively retards the ignition (a behavior that is well known to reduce power) you can see the logical jump that using higher RON fuel than necessary will effectively retard your combustion timing causing a loss in power.
The engine was designed for a certain fuel RON and the engine timing map was designed to work with that RON rating of fuel. Assuming an engine is in good working order, running a higher RON fuel will only delay the rapid expansion of the combustion gasses. What this does is cause the majority of the combustion to move the piston, but some of the expansion will continue to occur as the exhaust stroke is occurring. In effect, you will be emitting gas into the exhaust pipe that is still being combusted, if only by a fraction of a second. The loss of this rapidly expanding gas into the exhaust instead of being fully utilized during the power stroke will cause a loss of power and diminished combustion temperatures. Lower temps = more carbon buildup.
In short, using higher RON fuel than recommended by the manufacturer should only be done for 3 reasons.
1. It's all that was available at the time you filled up.
2. You're engine is VERY old and has severe carbon buildup causing predetonation which will be fixed by the higher RON fuel.
3. You are modifying your vehicle timing to advance the ignition some and you need the higher RON fuel to prevent predetonation.
Disclaimer: This information applies only to the Otto type internal combustion engine. Wankels are a whole 'nother ball game.
Predetonation or pinging is that catastrophic engine damage you mention. In fact, under heavy load if you are getting pinging you usually have about 2-3 seconds to let off the gas before you ventilate your engine block with 2 or 3 broken rods. Predetonation is when the fuel begins combustion and rapid expansion while the piston is still moving upward (compressing).
When this occurs, the use of a slightly higher RON fuel will slow the ignition process down so that the rapid combustion expansion will occur slightly later on that same engine. This will cure the predetonation and make the engine run safely again. The important fact to take away from this is that you can tune where the rapid expansion occurs in your combustion cycle related to the piston movement just by changing RON of the fuel. In effect, a lower RON fuel is the same as advancing the ignition slightly and vice versa. Since running a higher RON fuel effectively retards the ignition (a behavior that is well known to reduce power) you can see the logical jump that using higher RON fuel than necessary will effectively retard your combustion timing causing a loss in power.
The engine was designed for a certain fuel RON and the engine timing map was designed to work with that RON rating of fuel. Assuming an engine is in good working order, running a higher RON fuel will only delay the rapid expansion of the combustion gasses. What this does is cause the majority of the combustion to move the piston, but some of the expansion will continue to occur as the exhaust stroke is occurring. In effect, you will be emitting gas into the exhaust pipe that is still being combusted, if only by a fraction of a second. The loss of this rapidly expanding gas into the exhaust instead of being fully utilized during the power stroke will cause a loss of power and diminished combustion temperatures. Lower temps = more carbon buildup.
In short, using higher RON fuel than recommended by the manufacturer should only be done for 3 reasons.
1. It's all that was available at the time you filled up.
2. You're engine is VERY old and has severe carbon buildup causing predetonation which will be fixed by the higher RON fuel.
3. You are modifying your vehicle timing to advance the ignition some and you need the higher RON fuel to prevent predetonation.
Disclaimer: This information applies only to the Otto type internal combustion engine. Wankels are a whole 'nother ball game.
DoubleT90T
Wannabie Member
I use 91. It's premium where i live.
NastyEvilNinja
4 wheel racer, 2 wheel lunatic
I understand what you're saying DodgeRider26, but that assumes the higher RON delays detonation by a significant ammount over pre-detonation. 97-99 RON (in UK ratings) doesn't.
By being a more stable fuel and being 'harder' to detonate, you're actually creating a bigger bang that, even if you don't think will add power, will ensure a full detonation. Hence why it's cleaner burning and keeps yer lump nice and healthy.
This thread was originally about the reasons why we fill up with different fuels, and that's my main reason. Fuel economy goes up and the engine runs significantly smoother on every bike I've had good quality Super Unleaded in. It's removed flat-spots from the rev range that have been there with lesser fuels, so this is in no way a plecebo effect, and believe me, I would happily use cheaper fuel if I thought it was worth it.
In contrast, in my car.... I THINK I might get better mileage, but haven't tested this yet. The truth is that I can't feel the difference as I can on the bike - but that's little surprise with something 10 times the weight.
Another proven fact I've seen with my own eyes is that car emmissions are lowered with the addition of fuel cleaners and octane boosters such as STP Total Fuel System Cleaner. This stuff is effectively what Shell V-Power has added to their fuel, and before an MOT I run at least a tank of Super through and will add some STP if needed.
So, yes - at both extremes it's a bad thing - but even then it's much better to have an engine breathe a little than it is to suffer from pre-detonation. So which way is best to risk? No brainer for me!
By being a more stable fuel and being 'harder' to detonate, you're actually creating a bigger bang that, even if you don't think will add power, will ensure a full detonation. Hence why it's cleaner burning and keeps yer lump nice and healthy.
This thread was originally about the reasons why we fill up with different fuels, and that's my main reason. Fuel economy goes up and the engine runs significantly smoother on every bike I've had good quality Super Unleaded in. It's removed flat-spots from the rev range that have been there with lesser fuels, so this is in no way a plecebo effect, and believe me, I would happily use cheaper fuel if I thought it was worth it.
In contrast, in my car.... I THINK I might get better mileage, but haven't tested this yet. The truth is that I can't feel the difference as I can on the bike - but that's little surprise with something 10 times the weight.
Another proven fact I've seen with my own eyes is that car emmissions are lowered with the addition of fuel cleaners and octane boosters such as STP Total Fuel System Cleaner. This stuff is effectively what Shell V-Power has added to their fuel, and before an MOT I run at least a tank of Super through and will add some STP if needed.
So, yes - at both extremes it's a bad thing - but even then it's much better to have an engine breathe a little than it is to suffer from pre-detonation. So which way is best to risk? No brainer for me!
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