Dalerobert
Members
So ive been think ive been putting fuel in from the local garage for the cheapness of it but would it be worth paying that little bit more??
Is certain petrol better then others (local garage fuel vs bp/shellv power fuels)
- Thread starter Dalerobert
- Start date
Jon_G
No Longer Active
I don't think so.
With regard to performance, I'm fairly sure that standard Honda K series engines are unable to take advantage of higher octane fuel, as the timing advance is limited to that suitable with the use of ordinary unleaded (e.g. 95 RON).
With regard to performance, I'm fairly sure that standard Honda K series engines are unable to take advantage of higher octane fuel, as the timing advance is limited to that suitable with the use of ordinary unleaded (e.g. 95 RON).
Dalerobert
Members
surely some will clean the engine better then others?
Jon_G
No Longer Active
That is a common claim. But I've never felt it necessary to put petrol in my Toyota to 'clean' the engine, despite owning it for 11 years.Accord636 said:
Dalerobert
Members
So really unless its a type r dont bother with high octane fuels as they will have no effect
Jon_G
No Longer Active
I don't know if an ATR ECU can advance the timing to take advantage of 95+ RON... but an 8th gen CTR can't.
Higher octane tends to have more detergents in them and can clean the bits in the fuel system and engine, but its unlikely you will feel any difference, but I personally run BP ultimate every 2 months or so, and for me it seems to make the engine a bit revvier and burns more quickly, not sure if its placebo.
BlueVTEC
Members
Pre-Facelift ATR's are mapped to 98. They will run on 95 quite happily but definetely feel more eager with 98.
As for preference or cleaning qualitys, I have none to be honest. However I do avoid supermarket fuel after getting a " bad batch" twice, even with the higher octane fuels.
As for preference or cleaning qualitys, I have none to be honest. However I do avoid supermarket fuel after getting a " bad batch" twice, even with the higher octane fuels.
freddofrog
won 16.4k on Euro lottery :)
exactly, this is the whole point about 98 vs 95.BlueVTEC said:
If an engine is mapped to run on 95, then filling with 98 won't make any difference. However, if an engine is mapped to 98, then it can run on 95 because the ECU will detect the knock (***uming a knock sensor is fitted) and retard the ignition to stop the knock.
As for the cleaning additives in the 98 RON, I don't think that there is any conclusive evidence either way. It does beg the question as to why the additives are in the 98 and not in the 95 .....IMO additives + higher octane = double marketing gimmick which induces some people, whose engines don't benefit from 98, to buy 98 ....."some people" = quite a large percentage of the car-driving population.
jjmartin349571
TA Friends
As somebody who owns older cars the big concern I have with fuel is how much ethanol does it contain. In short ethanol in petrol is bad for the majority of cars unless they are very new and the materials used in their design accounted for fuels containing ethanol. As far as I'm aware the only fuels with minimal amounts of ethanol in are shell and BP super unleaded variants.
As for octane, yep as above the rating is just an indicator of a fuel's resistance to knock. Most European cars are tuned for 95 RON so there's no performance gain to be had using a higher RON fuel. Some performance oriented engines will require higher octane ratings due to higher compression and advanced ignition timing. Putting in fuel which has too low a RON will result in retarded ignition timing where a knock sensor is fitted resulting in less power, or on older engines you'll get knocking/detonation which can damage the engine.
Fwiw my imported Prelude and Legacy are both designed to run on 100 RON fuel which isn't available in the UK, so the ECU will retard the ignition timing when using UK fuels
Anecdotally I tuned the ignition timing on my mk2 Golf using 99 RON fuel, and that knocks like a ****er if you put anything but V power in it now :lol:
As for octane, yep as above the rating is just an indicator of a fuel's resistance to knock. Most European cars are tuned for 95 RON so there's no performance gain to be had using a higher RON fuel. Some performance oriented engines will require higher octane ratings due to higher compression and advanced ignition timing. Putting in fuel which has too low a RON will result in retarded ignition timing where a knock sensor is fitted resulting in less power, or on older engines you'll get knocking/detonation which can damage the engine.
Fwiw my imported Prelude and Legacy are both designed to run on 100 RON fuel which isn't available in the UK, so the ECU will retard the ignition timing when using UK fuels
Anecdotally I tuned the ignition timing on my mk2 Golf using 99 RON fuel, and that knocks like a ****er if you put anything but V power in it now :lol:
freddofrog
won 16.4k on Euro lottery :)
^ totally agree with all of that.
Just a slight pick on one sentence though ..."the rating is just an indicator of a fuel's resistance to knock"
I would say that the rating is an indicator of the speed of burn ....the lower the rating, the slower the burn ...the slower the burn, the earlier (orretarded) the ignition must be fired ....the earlier the ignition must be fired, the lower the pressure before and during the burn .....the lower the pressure, the lower the power
So if the ignition is not retarded enough for a low rating, then the slow burn can result in auto-ignition in areas in front of the burn
edit: retarded is a retarded typo :lol:
should be advanced (more degrees left to travel before TDC) ....earlier in degrees already travelled (retarded in point of rotation)
Just a slight pick on one sentence though ..."the rating is just an indicator of a fuel's resistance to knock"
I would say that the rating is an indicator of the speed of burn ....the lower the rating, the slower the burn ...the slower the burn, the earlier (or
So if the ignition is not retarded enough for a low rating, then the slow burn can result in auto-ignition in areas in front of the burn
edit: retarded is a retarded typo :lol:
should be advanced (more degrees left to travel before TDC) ....earlier in degrees already travelled (retarded in point of rotation)
Jon_G
No Longer Active
But surely firing the ignition earlier is advancing the timing.freddofrog said:
freddofrog
won 16.4k on Euro lottery :)
by earlier, I meant earlier in degrees, not time, depends which way one is looking, number of degrees left to travel or number of degrees already travelled (so conventionally ....advanced)Jon_G said:
edit: same typo in #9 actually
Jon_G
No Longer Active
Earlier in degrees, so more degrees before top dead centre?
freddofrog
won 16.4k on Euro lottery :)
it really depends on the piece of kit one uses in a lab, on some kit one would dial in the total number of degrees to fire the ignitionJon_G said:
e.g. firing at 355 degrees, then a change to 353 degrees retards the actual number of degrees, which is earlier in the rotation
but in the example, 355 degrees is 5 degrees BTDC, so retarding the degrees to 353 actually increases (or advances) to 7 degrees BTDC
Just the way one thinks about, so semantics of words get lost if one doesn't stick to accepted convention
so my use of the word "earlier" is the problem, "earlier" can imply less degrees ATDC (retarded ATDC) or more degrees BTDC (advanced BTDC)
rather than "earlier" it would be better to put "advance further before TDC" but some people may not still get that, indeed this whole tangent to the discussion may serve as confusion rather than addition.
freddofrog
won 16.4k on Euro lottery :)
I'm not sure whether to start a new thread on this, but no idea where to put the thread. Probably "TypeAccord General Chat" as this is becoming generic to any car, but, a lot of users of this forum don't bother with that section because a large amount is nothing to do with cars (maybe "TA Gen Chat" should split into "TA Gen car chat" and "TA Gen trivia chat").
Anyway, the problem is .... retarding and advancing ignition, and, RON.
Firstly: I'll stick to the convention of degrees BTDC (Before Top Dead Centre, I muddled it in one post with After TDC), and I'll also go over the basics. This is to ensure no confusion up to that point.
Secondly, I'll come to the point about RON, which is not as straightforward as it seems
1. On a car without any form of computerised "map", the timing had two components ...static and dynamic.
As engine RPM increased, the dynamic timing would advance (increase) the number of degrees BTDC when the ignition took place, so that the burn would start earlier (in degrees BTDC), but would always finish at the same point in degrees. In fact, the burn should finish somewhere between 10 to 20 degrees ATDC (depending on what you read).
This dynamic timing was not adjustable on the car without changing the distributor.
But, the static timing was easily adjusted, simply by rotating the distributor body. When leaded petrol was banned in 2000 in the UK, if unleaded 95 RON was going to be used in cars where leaded 4-star petrol had been used, then the distributor body had to be rotated to retard the ignition (move the static timing closer to TDC). IIRC there was an overlap of several years before 2000, when leaded 4-star and unleaded 95 RON were the same price. Note that leaded 4-star was 98 RON, so switching to unleaded 95 RON meant that the petrol was now lower octane, for the same price.
2. If one continued to run a car on unleaded 95 RON without retarding the ignition (moving the static timing closer to TDC), then one would get knock, which eventually ruins the engine. But, if lower octane burns more slowly, then surely the static timing would have to be advanced (increased further BTDC) to give the fuel more time to burn. On that basis it would seem that RON is not related to speed of burn after all, although some say it is. Indeed if it is related to speed of burn then it can be implied that lower RON burns faster.
Apparently it is actually related to the quality of the burn i.e lower octane petrol does not burn as evenly as higher octane petrol, so with lower octane petrol, if you retard the ignition (move the ignition closer to TDC), then the burn pressure is delayed and will be less so that the likelihood of "knock" is reduced.
Thus, depending on how the ECU is engineered to react to the knock-sensor, it is very possible that higher octane fuel will result in timing advance (further BTDC) resulting in higher pressure, resulting in higher power.
As for additives, without reading anything about it, I would expect that they are there to ensure smoother burn (as well as cleaning etc).
So, if you know that your engine will advance the ignition (move further BTDC) with higher octane, then you can argue in favour of using it ....unless I'm mistaken (if you plough your way throw these links you might come to a different conclusion)
http://en.wikipedia.org/wiki/Gasoline
http://en.wikipedia.org/wiki/Talk%3AOctane_rating
http://www.chemistryexplained.com/Ny-Pi/Petroleum.html
Anyway, the problem is .... retarding and advancing ignition, and, RON.
Firstly: I'll stick to the convention of degrees BTDC (Before Top Dead Centre, I muddled it in one post with After TDC), and I'll also go over the basics. This is to ensure no confusion up to that point.
Secondly, I'll come to the point about RON, which is not as straightforward as it seems
1. On a car without any form of computerised "map", the timing had two components ...static and dynamic.
As engine RPM increased, the dynamic timing would advance (increase) the number of degrees BTDC when the ignition took place, so that the burn would start earlier (in degrees BTDC), but would always finish at the same point in degrees. In fact, the burn should finish somewhere between 10 to 20 degrees ATDC (depending on what you read).
This dynamic timing was not adjustable on the car without changing the distributor.
But, the static timing was easily adjusted, simply by rotating the distributor body. When leaded petrol was banned in 2000 in the UK, if unleaded 95 RON was going to be used in cars where leaded 4-star petrol had been used, then the distributor body had to be rotated to retard the ignition (move the static timing closer to TDC). IIRC there was an overlap of several years before 2000, when leaded 4-star and unleaded 95 RON were the same price. Note that leaded 4-star was 98 RON, so switching to unleaded 95 RON meant that the petrol was now lower octane, for the same price.
2. If one continued to run a car on unleaded 95 RON without retarding the ignition (moving the static timing closer to TDC), then one would get knock, which eventually ruins the engine. But, if lower octane burns more slowly, then surely the static timing would have to be advanced (increased further BTDC) to give the fuel more time to burn. On that basis it would seem that RON is not related to speed of burn after all, although some say it is. Indeed if it is related to speed of burn then it can be implied that lower RON burns faster.
Apparently it is actually related to the quality of the burn i.e lower octane petrol does not burn as evenly as higher octane petrol, so with lower octane petrol, if you retard the ignition (move the ignition closer to TDC), then the burn pressure is delayed and will be less so that the likelihood of "knock" is reduced.
Thus, depending on how the ECU is engineered to react to the knock-sensor, it is very possible that higher octane fuel will result in timing advance (further BTDC) resulting in higher pressure, resulting in higher power.
As for additives, without reading anything about it, I would expect that they are there to ensure smoother burn (as well as cleaning etc).
So, if you know that your engine will advance the ignition (move further BTDC) with higher octane, then you can argue in favour of using it ....unless I'm mistaken (if you plough your way throw these links you might come to a different conclusion)
http://en.wikipedia.org/wiki/Gasoline
http://en.wikipedia.org/wiki/Talk%3AOctane_rating
http://www.chemistryexplained.com/Ny-Pi/Petroleum.html