Premium fuel or not?
10-16-2002, 08:44 PM
#2
RL Technical Advisor
[quote]Originally posted by bship:
<strong>My mercedes recommends premium and I could tell a difference when it wasnt used. Any recommendations on my 83 911 SC?</strong><hr></blockquote>
Bship:
Just my opinion based on experiences, but I'd strongly recommend premium fuel in ANY 911.
Due to the amount of mechanical noises that these engines make, one cannot hear the kind of detonation that damages pistons & rings. By the time you actually hear something, the damage is done.
<strong>My mercedes recommends premium and I could tell a difference when it wasnt used. Any recommendations on my 83 911 SC?</strong><hr></blockquote>
Bship:
Just my opinion based on experiences, but I'd strongly recommend premium fuel in ANY 911.
Due to the amount of mechanical noises that these engines make, one cannot hear the kind of detonation that damages pistons & rings. By the time you actually hear something, the damage is done.
10-16-2002, 08:50 PM
#3
Technical Specialist
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Assuming your 1983SC is an American model, it was meant to run regular unleaded. On my 81SC, regular unleaded was used unless I was at the track, where premium unleaded was used. That was to prevent pre-ignition under very hot track conditions, which are different than what you see on the street.
10-17-2002, 12:15 AM
#4
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I have always run Premium unleaded, Chevron if at all possible, Shell otherwise.The book claims regular but gas is not consistant, use Premium and have it tuned porperly with a 4 gas analizer.I use Premium in my 83SC and get an average of 400 miles a tank.I have 244,000 miles on a daily driver.
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10-17-2002, 09:23 PM
#8
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If you can get the Sunoco Ultra - 94 octane - then use it. It's definitely the way to go, especially in the summer. 911 motors do their detonating at the bmep peak, which is the same as the torque peak, which is around 5,000 rpm in your late US SC, I believe. I have heard frightening detonation noises when I gunned it after coming off a crowded, slow highway in mid summer, when the engine gets really hot. With my old US '83, nothing would cure it completely (especially if I was silly enough to try to run the A/C), but the Sunoco definitely helped. With my '83 Euro, which I now own, the Sunoco completely fixes it. It's my guess that this is the cause of the broken ring lands that you hear about, and the reason why Porsche went to forged pistons for the Carrera 3.2. Also, the Carrera type oil cooler made a difference in my US car, and my Euro car has the 28 tube type, which seems to do a good job.
10-28-2002, 09:37 PM
#9
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Fine...
'cept in our area..Sunoco blends their fuels with 10% ethynol..known to severely damage the rubber fuel lines of German cars' engines <img src="graemlins/crying.gif" border="0" alt="[crying]" />
---Wil Ferch
'cept in our area..Sunoco blends their fuels with 10% ethynol..known to severely damage the rubber fuel lines of German cars' engines <img src="graemlins/crying.gif" border="0" alt="[crying]" />
---Wil Ferch
10-29-2002, 08:13 AM
#10
Rennlist Member
Ouch! Wil, do you know whether Sunoco has alcohol in Mass.? I also wonder how true these stories of hose melt downs are. Anyone know for sure? Also, what about the alcohol as a promoter of water contamination problem in our CIS cars? Is this a thing of the past with the modern blends? I probably need to think about this with the reformulated gas due to make its appearance in Mass. in the near future. Anyone know the anticipated arrival date?
11-03-2002, 11:51 AM
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Tom:
All I can say is that Sunoco ( in our area) suddenly had gas prices that were 2-5cents cheaper than other name brands....and then I saw the (required?) disclaimer label on the fuel pump, about the 10% minimum ethynol content. Call Sunoco's 800 number ( don't have it now...but I called before and this was confirmed).
---Wil Ferch
All I can say is that Sunoco ( in our area) suddenly had gas prices that were 2-5cents cheaper than other name brands....and then I saw the (required?) disclaimer label on the fuel pump, about the 10% minimum ethynol content. Call Sunoco's 800 number ( don't have it now...but I called before and this was confirmed).
---Wil Ferch
11-03-2002, 03:38 PM
#12
RL Technical Advisor
Gentlemen:
Couple things,......
While I am unfamiliar with the EPA status of your location, many cities are required to use oxygenated fuels during the winter months; Nov to March, and you will find gasolines containing Ethanol up to 10% by volume. Some oil companies use that compound all year around and some switch back to MTBE; April to Oct.
Ethanol is a fine octane booster but it has three drawbacks:
1) Ethanol absorbs water and will pick up any water or moisture in the fuel system. Metal parts that are not stainless steel are very prone to rust-corrosion and this is a serious issue. Keep the tank full in your car to minimize moisture absorption.
2) Ethanol is a fine solvent. Any dirt, rust particles or any crud in the tank will be loosened and sent off to quickly clog fuel filters. I strongly,.....strongly recommend changing fuel filters twice a year where & when Ethanol is used. Once in the Fall and once in the Spring keeps the fuel system happy.
3) Ethanol attacks all the elastomers in the fuel system and will soften & eventually dissolve those rubber parts. Only the few items made from Viton rubber are unaffected. Not much anyone can do about that. Thank the EPA for adopting ethanol as the main approved oxygenate (might be some political overtones here).
Couple things,......
While I am unfamiliar with the EPA status of your location, many cities are required to use oxygenated fuels during the winter months; Nov to March, and you will find gasolines containing Ethanol up to 10% by volume. Some oil companies use that compound all year around and some switch back to MTBE; April to Oct.
Ethanol is a fine octane booster but it has three drawbacks:
1) Ethanol absorbs water and will pick up any water or moisture in the fuel system. Metal parts that are not stainless steel are very prone to rust-corrosion and this is a serious issue. Keep the tank full in your car to minimize moisture absorption.
2) Ethanol is a fine solvent. Any dirt, rust particles or any crud in the tank will be loosened and sent off to quickly clog fuel filters. I strongly,.....strongly recommend changing fuel filters twice a year where & when Ethanol is used. Once in the Fall and once in the Spring keeps the fuel system happy.
3) Ethanol attacks all the elastomers in the fuel system and will soften & eventually dissolve those rubber parts. Only the few items made from Viton rubber are unaffected. Not much anyone can do about that. Thank the EPA for adopting ethanol as the main approved oxygenate (might be some political overtones here).
