HeatRaveR Posted February 18, 2005 Share Posted February 18, 2005 Currently in CA, our pump gas is available in 87, 89, and 91. Has it always been this way, or was it different 20-30 years ago? Did our "Regular" used to be "Premium" back then? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted February 18, 2005 Share Posted February 18, 2005 It was different a little as 3 years ago when 93 was available. The octane was changed to 91 as the 93 CA spec formula was privately held and for cost savings it was dropped to 91 to avoid paying the cost of the 93 octane formula. As fo 30 years ago.....I was still messing my diapers Tim Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted February 18, 2005 Share Posted February 18, 2005 If I remember right in teh 60s the best gas was Cheveron Custom Supreem @ 120 octane, blue in color. Used to use it our race bikes. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 18, 2005 Share Posted February 18, 2005 You can still buy 100 octane unleaded at some Unocal stations. Quote Link to comment Share on other sites More sharing options...
Guest 81na ZX Posted February 18, 2005 Share Posted February 18, 2005 If I remember right in teh 60s the best gas was Cheveron Custom Supreem @ 120 octane, blue in color. Used to use it our race bikes. Cause lead is a knock detterant, which is what octane measures I don't know if "regular" pump gas octane went down, or manufacturing costs to get that octane went up. Today, ALL gas with an octane over ~106 is leaded Quote Link to comment Share on other sites More sharing options...
Guest tony78_280z Posted February 18, 2005 Share Posted February 18, 2005 Tim, from what I heard you are still messing in your diapers. Ok, that was lame. I still owe you for that dent in the Z comment. http://forums.hybridz.org/showthread.php?t=98809 Quote Link to comment Share on other sites More sharing options...
dot Posted February 22, 2005 Share Posted February 22, 2005 Up here in the sixties we had "Sunoco 260" that was 104 octane and purple in colour. With lots of carcinogenic power inducing lead! Quote Link to comment Share on other sites More sharing options...
Tim240z Posted February 22, 2005 Share Posted February 22, 2005 Tim' date=' from what I heard you are still messing in your diapers. Ok, that was lame. I still owe you for that dent in the Z comment. http://forums.hybridz.org/showthread.php?t=98809[/quote'] Well now...that all 'DEPENDS' Quote Link to comment Share on other sites More sharing options...
2126 Posted February 28, 2005 Share Posted February 28, 2005 Just a little info to share with you all about gasoline and the different octane ratings. I received this information from a fellow named Jim Fueling (don't laugh) who was the engine wizard behind the successful Nissan IMPSA effort back when. Anyway, according to Jim gasoline has X amount of BTU capacity and infact regular gasoline has the highest BTU capacity! Here's where it gets interesting. It has to do with controlling the ignition of the fuel/air mixture. We all know the a higher compression engine generally makes more HP. Thats why we have turbos and supercharges as well. So inorder to keep the fuel/air mix from lighting off before the desired time, anti-knock (lead and what ever they use now) additives are added to prevent the unwanted detenation. Hence we have the higher octane rating intended for the higher output engine. Of course this was more applicable back in the 60's and 70's when engines were less efficient than they are now. Better combustion chamber designs, better ignition systems, and better induction systems have made engines more efficient now days and do have an effect at better controlling detenation. So, again according to Jim, theretically speaking...if an engine could be made that was 100% efficient you would not need the anti-knock additives. Is this making any sences to anyone? Quote Link to comment Share on other sites More sharing options...
Moridin Posted March 16, 2005 Share Posted March 16, 2005 Just a little info to share with you all about gasoline and the different octane ratings. I received this information from a fellow named Jim Fueling (don't laugh) who was the engine wizard behind the successful Nissan IMPSA effort back when. Anyway, according to Jim gasoline has X amount of BTU capacity and infact regular gasoline has the highest BTU capacity! Here's where it gets interesting. It has to do with controlling the ignition of the fuel/air mixture. We all know the a higher compression engine generally makes more HP. Thats why we have turbos and supercharges as well. So inorder to keep the fuel/air mix from lighting off before the desired time, anti-knock (lead and what ever they use now) additives are added to prevent the unwanted detenation. Hence we have the higher octane rating intended for the higher output engine. Of course this was more applicable back in the 60's and 70's when engines were less efficient than they are now. Better combustion chamber designs, better ignition systems, and better induction systems have made engines more efficient now days and do have an effect at better controlling detenation. So, again according to Jim, theretically speaking...if an engine could be made that was 100% efficient you would not need the anti-knock additives. Is this making any sences to anyone? Octane number, if I remember correctly, is the percent Octane in the gasoline. 87 Octane has 87% 8 Carbon chains and 13% 7 Carbon chains (Heptane). Octane itself has a high resistance to compression before spontaneous combustion, where Heptane does not. According to this, a higher Octane should have more chemical power, because it has more Carbon bonds to break up. Anyway, it basically comes down to the more the Octane the more controlled the burn. I'm not sure where they come up with 106 Octane, etc... or how that relates to percent Octane in the fuel. Quote Link to comment Share on other sites More sharing options...
HeatRaveR Posted March 17, 2005 Author Share Posted March 17, 2005 The octane # in the US isn't a percentage, but rather the average of the MON and RON #'s (there's stickers posted on gas pumps showing this). I forget what they stand for, but they're some other numbers rating. Anywho, the reason I asked what was available that long ago is I'm wondering what type of gas the engineers back then designed the engines to run on. Because, if I can get away with regular 87 octane in my stock 280ZX turbo, I'd be that much happier (I'd read in a book that it ran on "regular unleaded"). Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted March 18, 2005 Share Posted March 18, 2005 I think the octane ratings of gas took a plunge when lead was outlawed. I know it was being phased out about the time the catalytic converter was introduced (73?). So I would guess if your car came out anytime after 76 then it should run on the modern day definition of regular unleaded. The owners manual for my 1970 240 says to use (i think) 95 octane gas. Once I upgraded the leaky, worn out SU's to dual Webers it runs fine on modern day regular. Best way to find out is put in a tank of regular and see if it pings under hard acceleration on a hot day. If it doesn't, your fine. If it does, you need higher octane or a different engine tune. Quote Link to comment Share on other sites More sharing options...
bjhines Posted March 18, 2005 Share Posted March 18, 2005 There is a neat program about the history of gasoline....on History channel...I think.... Moridin has the closest correct answer.... Heptane = 0 octane rating Octane = 100 rating. This is only the basis for our "octane rating". It has nothing whatsoever to do with the actual compounds in the fuels we call gasoline. gasoline contains many diffent carbon chains.... In fact current day gasoline may contain varying quantities of compounds anywhere from 6 to 10 carbon chains long. These compounds have been "cracked" from longer molecules during the refining process using heat and catalysts.... In fact there may have been several cycles of cracking and recombining of these molecules to get the mix we call gasoline. The cracking process was developed to get more "gasoline" grade fuel out of each barrel of oil. It has been modified to get not only more gas...but better gas for high performance engines. The actual "octane" rating for these compounds has been further modified by a process that "joins" the loose end of the carbon chains in a RING shaped molecule that turns out to have enormously higher octain ratings than the linear chains.....although it is the same chemical. Additives like Tetra-Ethyl-Lead further improved octane ratings as the need for detonation resistant fuels increased with high performance aviation engines in WW2. Countless other compounds have been developed since then to replace lead with less hazardous substances. Other additives help stabilize fuel, clean the engine, and reduce emissions. Most importantly.... ALL FUEL OF A GIVEN RATING IS THE SAME....NO MATTER WHERE YOU BUY IT IN THE USA. All the distribution companies use the same infrastructure to pipe the same fuel as everyone else. Ahhh....but you say that Amoco fuel "smells" better....or soandso fuel burns better...Yea Yea Yea...There is a difference at the pump....but the only real difference is in the ADDITIVES that the individual fuel companies put in their alotment of gasoline...that is done locally at the depot where the gas company fills it's trucks.... Quote Link to comment Share on other sites More sharing options...
bjhines Posted March 18, 2005 Share Posted March 18, 2005 Ohh....My manual for my 1972 240Z says to use 93 or 95 octane fuel. I imagine the 1970-71 models would require 95 octane...as they had the highest compression of any Z car ever. High octane fuels have been around since WW2... Consumer grade gas was lower octane in the 40s and 50s because the average Joe's car had a very unsophisticated motor. Folks who drove high performance cars went to the airport for gas. High octane consumer gas became more expensive and harder to find after lead was banned... You can purchase gas at your local airport and pump it directly into your car IF.... you have no restrictor plate in your filler tube.... The rule is...you can only pump avgas into a vehicle that can use the large sized filler tube. No gas cans...no funnels allowed... If your local airport operator says no...just mention that you can actually fit their large sized filler into your antique car...with no funnels or other aids. Be careful when you pump from avgas pumps....they flow about 5 times the rate of a consumer filling station... Quote Link to comment Share on other sites More sharing options...
Michael Posted March 22, 2005 Share Posted March 22, 2005 I remember that in the 1980's 87-octane gasoline was marketed as "unleaded", 89-octane gasoline was "regular" (meaning, leaded), and 91 or 92-octane gasoline was "premium", with the lead content ambiguous (probably it was unleaded). The 89-octane leaded gas was the cheapest. I cheerfully used it in my first car, a 1974 Toyota Corona (which went FWD and became the Camry in 1983). Sometime around the late 80's-early 90's leaded gasoline pretty much disappeared. The 87-89-91/92/93 ratings remained, but the 89-octane gasoline, having become unleaded, increased in price, so that now the cost per gallon progressed monotonically with increase in octane rating. My 1992 BMW 325is is supposed to be filled up exclusively with premium unleaded (91 or better); at least, that's what the owner's manual claims. However, I have been using 87-octane regular gasoline for several months, with no discernable ill effects. The same trick didn't work on my 1987 Toyota Supra turbo. When running on 87-octane, especially when the engine was still cold, it would very noticeably pull out the timing to reduce risk of detonation, with a very noticeably decline in acceleration. Quote Link to comment Share on other sites More sharing options...
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