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Thread ID: 70673	2006-07-12 06:04:00	OT - Does US have different octane rating compared to us?	SKT174 (1319)	PC World Chat

Post ID	Timestamp	Content	User
470285	2006-07-13 08:05:00	Running with a higher octane rating than that recommended for the compression ratio and ignition timing does not have any deleterious effects upon an engine at all . I just don't know where Joe gets such an idea from, especially as he is/has been in the trade . All it will do is make your pocket a bit lighter :) I dont know about "modern" engines with computer management/variable valve timing/variable ignition timing, they may well accomodate lower octane ratings without so much 'pinking', but it is running with too low an octane rating that will cause knocking and premature bearing failure . I have noticed a distinct tendency amongst New Zealand drivers to be reluctant to change down gear when low speed cornering around town, creating horrible 'pinking' . Come on up to emissions control equipment with oxygen sensors and catalytic convertors that can't hack higher that required octane and see for yourself . Many cats are cooked and fused together . . . the flatbed types, the monolythic types and the pelletized ones too . . . they just melt down to a non-gas-passing blob that won't let exhaust out of the engine . Stainless steel exhaust components get burnt through, leaving large holes in the system and the owner's pockets . Oxygen sensors melt off, and the "Check Engine" light goes on and the system enters "limp-back" mode to get home at very reduced speeds and performance . On vehicles with dual cats, pre and post cats and the necessary sensors before and after each one of them, the expense of replacing all that can run several thosand dollars . . and it voids the warrantee of 10 years/100,000 miles on emissions-related parts to use higher octane in the vehicle . As far as the exhaust valves . . wel it isn't quite the problem it ustta be with the older sodium-filled stems . The newer alloys on the valves kinda minimize this problem, but it does send a lot of extra heat up the valve stem to the seal and that results in seal failure . The biggest problem as I saw it many times, was the use of higher octane fuels never got the combustion chamber hot enough to purge flyash from inferior lube oil off the piston tops and valve faces . This always resulted in localized hot spots that aggrevaed the preignition by making the fuel fire even earlier because of the glowing enbers that were left behind . Sometimes the result was actually hard pinging . . and downright knocking . . . just the thing higher octane fuel tries to eliminate in the first place . Just as the exhaust temps climb very high in the exhaust system and across the face of the exhaust valve, the dynamic temperature in the combustion chamber never really reaches the high temps necessary to keep emissions to a level set by the AQB . We don't want to exceed stoichemetric temps, but we want to get damned close to it for max efficiency on several fronts: Hydrocarbons generation from cold flamefront propagation get out of sight Killed oxygen sensors from swamping them in unburned or still burning fuel Coked-up catalytic convertors from low pressure continuing fuel burning in the wrong area, ie: the exhaust system Floorboard fires and dry grass/combustable materials fires under a parked car when it is shut off with incandescent cats and related exhaust system Colder than normal combustion chamber temps that leave acids and corrosive agents on the upper cylinder walls and top compression rings Upper cylinder oil contamination from heat related destruction to valve guide seals via conducted heat up the exhaust valve stems from plasma-like flow of still-burning superheated exhaust gasses passing around opened exhaust valves . I am sure you didn't consider the obvious when you stated that you don't think I have the experience of using wrong octane fuels in engines . As to modern engines and the use of inferior grades and wrong (lower than required) octane: Most modern engines (since about 1994 or so) use a "Knock senso" that is just a glorified microphone that screws into the lowest part of the block as is possible according to design, and it "listens" the the engine noises . If it hears a loud sound, and it hjappens a few times or during certain throttle/air mass and air temperature conditions, computing for engine load and coolant values and gear ratios and roadspeed and altitude and air density, then it "tells" the computer that it hears destructive noises and the computer can make one or more or all the following changes to runnability values: Reduce engine load by forcing downshift if the transmission is automatic; Retard ignition timing by packets of 2 1/2 increments until the noisae is either abated or seriously reduced to intermittantly; Eliminate by cylinder-by-cylinder testing of the ignition to try to isolate the offending cylinder and either retard it's timing individually or shut off the fuel injector to that cylinder . Turn on the "Check Engine " light and make it flash at a high speed to warn of imminent catalytic convertor destruction . Some vehicles now use a secomd light with a very stern warning of impending doom! Shut off the engine by turning off the fuel pump . . . to avoid catastrophic engine destruction . All this too can be caused by using the wrong octane . It took me 9 attempts to post this . . time-outs and cannot find server . . . . .	SurferJoe46 (51)
470286	2006-07-13 08:06:00	Running with a higher octane rating than that recommended for the compression ratio and ignition timing does not have any deleterious effects upon an engine at all . I just don't know where Joe gets such an idea from, especially as he is/has been in the trade . All it will do is make your pocket a bit lighter :) I dont know about "modern" engines with computer management/variable valve timing/variable ignition timing, they may well accomodate lower octane ratings without so much 'pinking', but it is running with too low an octane rating that will cause knocking and premature bearing failure . I have noticed a distinct tendency amongst New Zealand drivers to be reluctant to change down gear when low speed cornering around town, creating horrible 'pinking' . Come on up to emissions control equipment with oxygen sensors and catalytic convertors that can't hack higher that required octane and see for yourself . Many cats are cooked and fused together . . . the flatbed types, the monolythic types and the pelletized ones too . . . they just melt down to a non-gas-passing blob that won't let exhaust out of the engine . Stainless steel exhaust components get burnt through, leaving large holes in the system and the owner's pockets . Oxygen sensors melt off, and the "Check Engine" light goes on and the system enters "limp-back" mode to get home at very reduced speeds and performance . On vehicles with dual cats, pre and post cats and the necessary sensors before and after each one of them, the expense of replacing all that can run several thosand dollars . . and it voids the warrantee of 10 years/100,000 miles on emissions-related parts to use higher octane in the vehicle . As far as the exhaust valves . . wel it isn't quite the problem it ustta be with the older sodium-filled stems . The newer alloys on the valves kinda minimize this problem, but it does send a lot of extra heat up the valve stem to the seal and that results in seal failure . The biggest problem as I saw it many times, was the use of higher octane fuels never got the combustion chamber hot enough to purge flyash from inferior lube oil off the piston tops and valve faces . This always resulted in localized hot spots that aggrevaed the preignition by making the fuel fire even earlier because of the glowing enbers that were left behind . Sometimes the result was actually hard pinging . . and downright knocking . . . just the thing higher octane fuel tries to eliminate in the first place . Just as the exhaust temps climb very high in the exhaust system and across the face of the exhaust valve, the dynamic temperature in the combustion chamber never really reaches the high temps necessary to keep emissions to a level set by the AQB . We don't want to exceed stoichemetric temps, but we want to get damned close to it for max efficiency on several fronts: Hydrocarbons generation from cold flamefront propagation get out of sight Killed oxygen sensors from swamping them in unburned or still burning fuel Coked-up catalytic convertors from low pressure continuing fuel burning in the wrong area, ie: the exhaust system Floorboard fires and dry grass/combustable materials fires under a parked car when it is shut off with incandescent cats and related exhaust system Colder than normal combustion chamber temps that leave acids and corrosive agents on the upper cylinder walls and top compression rings Upper cylinder oil contamination from heat related destruction to valve guide seals via conducted heat up the exhaust valve stems from plasma-like flow of still-burning superheated exhaust gasses passing around opened exhaust valves . I am sure you didn't consider the obvious when you stated that you don't think I have the experience of using wrong octane fuels in engines . As to modern engines and the use of inferior grades and wrong (lower than required) octane: Most modern engines (since about 1994 or so) use a "Knock senso" that is just a glorified microphone that screws into the lowest part of the block as is possible according to design, and it "listens" the the engine noises . If it hears a loud sound, and it hjappens a few times or during certain throttle/air mass and air temperature conditions, computing for engine load and coolant values and gear ratios and roadspeed and altitude and air density, then it "tells" the computer that it hears destructive noises and the computer can make one or more or all the following changes to runnability values: Reduce engine load by forcing downshift if the transmission is automatic; Retard ignition timing by packets of 2 1/2 increments until the noisae is either abated or seriously reduced to intermittantly; Eliminate by cylinder-by-cylinder testing of the ignition to try to isolate the offending cylinder and either retard it's timing individually or shut off the fuel injector to that cylinder . Turn on the "Check Engine " light and make it flash at a high speed to warn of imminent catalytic convertor destruction . Some vehicles now use a secomd light with a very stern warning of impending doom! Shut off the engine by turning off the fuel pump . . . to avoid catastrophic engine destruction . All this too can be caused by using the wrong octane . It took me 9 attempts to post this . . time-outs 11 attempts now	SurferJoe46 (51)
470287	2006-07-13 08:08:00	Running with a higher octane rating than that recommended for the compression ratio and ignition timing does not have any deleterious effects upon an engine at all . I just don't know where Joe gets such an idea from, especially as he is/has been in the trade . All it will do is make your pocket a bit lighter :) I dont know about "modern" engines with computer management/variable valve timing/variable ignition timing, they may well accomodate lower octane ratings without so much 'pinking', but it is running with too low an octane rating that will cause knocking and premature bearing failure . I have noticed a distinct tendency amongst New Zealand drivers to be reluctant to change down gear when low speed cornering around town, creating horrible 'pinking' . Come on up to emissions control equipment with oxygen sensors and catalytic convertors that can't hack higher that required octane and see for yourself . Many cats are cooked and fused together . . . the flatbed types, the monolythic types and the pelletized ones too . . . they just melt down to a non-gas-passing blob that won't let exhaust out of the engine . Stainless steel exhaust components get burnt through, leaving large holes in the system and the owner's pockets . Oxygen sensors melt off, and the "Check Engine" light goes on and the system enters "limp-back" mode to get home at very reduced speeds and performance . On vehicles with dual cats, pre and post cats and the necessary sensors before and after each one of them, the expense of replacing all that can run several thosand dollars . . and it voids the warrantee of 10 years/100,000 miles on emissions-related parts to use higher octane in the vehicle . As far as the exhaust valves . . wel it isn't quite the problem it ustta be with the older sodium-filled stems . The newer alloys on the valves kinda minimize this problem, but it does send a lot of extra heat up the valve stem to the seal and that results in seal failure . The biggest problem as I saw it many times, was the use of higher octane fuels never got the combustion chamber hot enough to purge flyash from inferior lube oil off the piston tops and valve faces . This always resulted in localized hot spots that aggrevaed the preignition by making the fuel fire even earlier because of the glowing enbers that were left behind . Sometimes the result was actually hard pinging . . and downright knocking . . . just the thing higher octane fuel tries to eliminate in the first place . Just as the exhaust temps climb very high in the exhaust system and across the face of the exhaust valve, the dynamic temperature in the combustion chamber never really reaches the high temps necessary to keep emissions to a level set by the AQB . We don't want to exceed stoichemetric temps, but we want to get damned close to it for max efficiency on several fronts: Hydrocarbons generation from cold flamefront propagation get out of sight Killed oxygen sensors from swamping them in unburned or still burning fuel Coked-up catalytic convertors from low pressure continuing fuel burning in the wrong area, ie: the exhaust system Floorboard fires and dry grass/combustable materials fires under a parked car when it is shut off with incandescent cats and related exhaust system Colder than normal combustion chamber temps that leave acids and corrosive agents on the upper cylinder walls and top compression rings Upper cylinder oil contamination from heat related destruction to valve guide seals via conducted heat up the exhaust valve stems from plasma-like flow of still-burning superheated exhaust gasses passing around opened exhaust valves . I am sure you didn't consider the obvious when you stated that you don't think I have the experience of using wrong octane fuels in engines . As to modern engines and the use of inferior grades and wrong (lower than required) octane: Most modern engines (since about 1994 or so) use a "Knock senso" that is just a glorified microphone that screws into the lowest part of the block as is possible according to design, and it "listens" the the engine noises . If it hears a loud sound, and it hjappens a few times or during certain throttle/air mass and air temperature conditions, computing for engine load and coolant values and gear ratios and roadspeed and altitude and air density, then it "tells" the computer that it hears destructive noises and the computer can make one or more or all the following changes to runnability values: Reduce engine load by forcing downshift if the transmission is automatic; Retard ignition timing by packets of 2 1/2 increments until the noisae is either abated or seriously reduced to intermittantly; Eliminate by cylinder-by-cylinder testing of the ignition to try to isolate the offending cylinder and either retard it's timing individually or shut off the fuel injector to that cylinder . Turn on the "Check Engine " light and make it flash at a high speed to warn of imminent catalytic convertor destruction . Some vehicles now use a secomd light with a very stern warning of impending doom! Shut off the engine by turning off the fuel pump . . . to avoid catastrophic engine destruction . All this too can be caused by using the wrong octane . It's taken me 9 attempts to post this . . time-outs 11 attempts now 13 attempts . . tested my speed . . . it's 4133/944 15 attempts	SurferJoe46 (51)
470288	2006-07-13 08:45:00	Great posts Joe, speshly the last three ;-) Tip to overcome time outs. If yer gonna write a thesis and we do love your work (speshly the early stuff) try writing it in wordpad or somthing then cut and paste to the reply box, works for me.	JackStraw (6573)
470289	2006-07-13 09:44:00	I didn't understand much of that at all :) If you're telling me all that can happen just because someone fills up with a slightly higher octane rating, then you lot must make pretty crap cars! I must have a word with my son who is pretty high up in Chrysler north of the border and get the real gen. We had 104 octane in UK around 1960, and engines that normally took premium grade didn't fall apart. What you are describing sounds like a dose of overly retarded ignition, with burnt out valves etc. When unleaded juice was introduced, there was misinformation about retarding ignition in high compression engines to compensate for the lower octane. A wee bit of retardation maybe, but reducing compression ratio was the only proper advice to take if alternatative non-lead high octane ie 100 RON was not available.	Terry Porritt (14)
470290	2006-07-13 10:28:00	When car engines did start blowing up, from memory in the early 60s was when Shell introduced Shell X100 detergent motor oil. They made a mistake and had too much detergent, the result was that all the varnish coatings that had built up over the years in older engines was suddenly purged, and engines seized up left right and centre. At about the same time Shell made the same error with their range of turbine oils like Shell Turbo 27, which was used in power station steam turbine generating sets. The result was foaming oil everywhere, and loss of hydrodynamic bearing load carrying capacity due to bubbly aerated oil. It was a serious problem, but it gave us work analysing the theory and behaviour of bubbly oil in bearings :) The week the M1 motorway in the UK opened I filled up my at that time bog standard Vincent 998cc Rapide V twin with 100 octane and took it down there ,averaged 90mph from the centre of Birmingham to Watford and back to Brum, just stopping to fill the tank at the Watford end. Full throttle at 110-112mph all along the motorway, both ways. This was with an engine war-time designed to run on 72 octane Pool petrol, and with the standard Specialoid 6.5:1 compression ratio pistons. No catastrophe for running with higher octane.	Terry Porritt (14)
470291	2006-07-13 10:59:00	sodium-filled stems. ???? in top end sports cars mayby! for quite some time they where F1 cars only. certainly afaik never in a ordnary car. EGR devices are a good thing...they really work and are not detrimental to the engine at all. LMAO. when they first came out they where often ripped out and replaced with (even the fuel injection systems) carbys and dissys.....they made more power and in a lot of cases where better emmisions wise ! unforuntly EGR causes poor performance which is why its turned off at full throttle. very comman here to disable it as it often causes problems. high octane causeing problems ?? yeah right. plenty of people here have used high octane in low compression vechiles. more likly is they used high octane and wound the ignition and fuel right up to get more power out of the underpowered slug. they proberly over did it. cat converters, they clog up with normall fuel and exspecialy if they use LEADED high octane fuel ;)	tweak'e (69)
470292	2006-07-14 06:00:00	???? in top end sports cars mayby! for quite some time they where F1 cars only . certainly afaik never in a ordnary car . LMAO . when they first came out they where often ripped out and replaced with (even the fuel injection systems) carbys and dissys . . . . . they made more power and in a lot of cases where better emmisions wise ! unforuntly EGR causes poor performance which is why its turned off at full throttle . very comman here to disable it as it often causes problems . high octane causeing problems ?? yeah right . plenty of people here have used high octane in low compression vechiles . more likly is they used high octane and wound the ignition and fuel right up to get more power out of the underpowered slug . they proberly over did it . cat converters, they clog up with normall fuel and exspecialy if they use LEADED high octane fuel ;) Got a bunch of hardheads here . . . hmm . . OK . . leaded gasoline has been forbidden since 1974 in the US, since 1972 in California . So there! Sodium filled valves were standard on Fords, Chevys (All of GM actually), including Cadillacs, Lincolns, Buicks, Oldsmobiles, however Chrysler abstained for a while, offering sodium in their 440's and HP 383's . Many engines still use them here in the US . I know . . . the warnings about cutting the ends too short while machining the valves is in every box that contains a new valve . They are also declared "Haz-Mat" and must be so disposed . So there! Cats typically last 200,000 miles although engines that burn oil or if they can even find leaded fuel (Mexico maybe) will find them contaminated and the core melted into a puddle . So there! EGR reduces the stoichemetric tendencies of engines running lean (17:1 AFR's) and the possibility of fusing nitrogen to oxygen molecules making nitrous oxide . . . the eye burning nitric acid forming emission . So there! EGR's only operate at cruise if engine temp is normal (above 185 F) and power demand is just to maintain speed without hills or strong headwinds . So there! EGR's lower fuel octane requirements, reducing knock and ping and improve fuel mileage . So there! EGR's are installed on all US multi-fuel military vehicles that don't run diesel as an economy device to improve fuel mileage . So there! There were a lot of shadetree mechanics here that also resisted the EGR's, Cats, lead-free fuels, fuel injection, oxygen sensors, feedback carburetors and NOx devices . They put ball bearings in hoses to block signals to them; they re-routed vacuum lines to suit their old fashioned ideas, they removed 195 F thermostats because everybody "knows" and engine cannot run that hot and live . They by-passed every emission device they thought was bad ju-ju because they didn't understand what was going on . They poked holes in monolythic catalytic barriers, and poured out the pellets on the bed type because they were ignorant . I remember when alternators first showed up under the hood/bonnet, and the old-timers said they'd never work, but what they were really saying was that they could not understand HOW they worked! Diodes were just too "whiz-bang" and incomprehensible to them . Sounds like you've got a few people there who also think evil spirits are at work in the automobile engine and they are afraid of or totally shy away from technology completely because it ain't the way it was in the olde days or it's too mysterious . That's sad . Roilling on the floor laughing will not make technology stand still or go away either .	SurferJoe46 (51)
470293	2006-07-14 06:04:00	But that's there and we are here, Joe. The most common cars in the US would be fairly uncommon here. So there!	Graham L (2)
470294	2006-07-14 06:27:00	But that's there and we are here, Joe . The most common cars in the US would be fairly uncommon here . So there! That's not a good way to think Graham . . . . . unfortunately, the US auto designs and emission control stuff is being passed out pretty uiniversally nowadays . Given that there is a great difference in driving styles and needs versus what one can get away with in your area . . . that's just not going to be what the future is bringing . Pragmatic denial of technological advances in design and construction of engines dictates that at least some vehicles in NZ will have the newer gizmos, and you're going to be forced to move into the new stuff anyway as the older cars die a natural death from wearing out, or unnaturally by accident . It's not uncommon for me to drive about 20,000 miles a year in my Blazer, another 30,000 in my Amigo, and my wife gets another 40,000+ in her van . (That's about 144,840 . 60+ kilometers per year if my calculator is correct) . The US just drives long distances . . . that's all . I used to drive 160 miles (260 Kilometers) to work daily . Others drive longer than that . Speeds on the freeways are 75 MPH (120 . 70 KPH) in some areas, 70 MPH (112 . 65 KPH) in others . Some states have no set speed limit . It is not uncommon to have 200,000 miles on a car before it is sold or traded in for a newer model . My Amigo right now has 264,899 miles (429,531 . 24 Kilometers) on the original clutch, water pump and engine . I am keeping it forever .	SurferJoe46 (51)
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