91 RON vs 95 RON fuel, my experience this week
11-24-2005, 01:18 AM
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91 RON vs 95 RON fuel, my experience this week
A bit long but....., sorry!
After reading a thread here on the 964 being optimized for 95 octane, and having had to fill a very empty car with fuel, I decided to do a little experiment. I put about 40 litres of "regular unleaded", 91 RON in mine on Saturday. I know this is not very scientific but here's a few strange (subjective off course) observations. Firstly, whilst the car didn't have any trouble running on it, it was noticeably down on power. Maybe not outright power, but it seemed to have lost that slight edge. Under hard acceleration it revved out cleanly but almost felt like the engine was adjusting itself throughout the rev range. Hard to explain but small little steps in output as you accelerate through the rev range. Another curious thing, maybe completely unrelated, is that the gearchange seems to have become more sticky on part throttle. Now, before you call me whacky let me explain. Sometimes when driving on part throttle in traffic and going on the overrun as you approach the traffic lights, the gear becomes "sticky" as you gear back through the gears. It easily slips into gear on upchanges, but kind of jumps out on downchanges, especially when you change to neutral. Does this make sense? I think its got something to do with the torque on the overrun that sort of locks in the gears. Well, this was noticeably more pronounced in the last few days. To the point where I became a bit concerned and the car really became a handfull in traffic. Initially I didn't make the connection with the fuel, that is until I filled up the (empty) tank this morning with 95 RON. This car didn't immediately feel faster, just "happier". It revved smoother, felt more together and hey presto, the gearbox felt slicker?? Strange I know but I've just come back from another long drive in traffic and it still feels great. Symptoms gone! Just for info, the weather has been quite stable as well as the amount of traffic on my route to work, so no big difference in temperatures or driving patterns. Anybody care to venture an opinion?
Frans
After reading a thread here on the 964 being optimized for 95 octane, and having had to fill a very empty car with fuel, I decided to do a little experiment. I put about 40 litres of "regular unleaded", 91 RON in mine on Saturday. I know this is not very scientific but here's a few strange (subjective off course) observations. Firstly, whilst the car didn't have any trouble running on it, it was noticeably down on power. Maybe not outright power, but it seemed to have lost that slight edge. Under hard acceleration it revved out cleanly but almost felt like the engine was adjusting itself throughout the rev range. Hard to explain but small little steps in output as you accelerate through the rev range. Another curious thing, maybe completely unrelated, is that the gearchange seems to have become more sticky on part throttle. Now, before you call me whacky let me explain. Sometimes when driving on part throttle in traffic and going on the overrun as you approach the traffic lights, the gear becomes "sticky" as you gear back through the gears. It easily slips into gear on upchanges, but kind of jumps out on downchanges, especially when you change to neutral. Does this make sense? I think its got something to do with the torque on the overrun that sort of locks in the gears. Well, this was noticeably more pronounced in the last few days. To the point where I became a bit concerned and the car really became a handfull in traffic. Initially I didn't make the connection with the fuel, that is until I filled up the (empty) tank this morning with 95 RON. This car didn't immediately feel faster, just "happier". It revved smoother, felt more together and hey presto, the gearbox felt slicker?? Strange I know but I've just come back from another long drive in traffic and it still feels great. Symptoms gone! Just for info, the weather has been quite stable as well as the amount of traffic on my route to work, so no big difference in temperatures or driving patterns. Anybody care to venture an opinion?
Frans
