95 or 98 fuel?
Discussion
JW1 said:
Hi,
Are there any benefits to using 98 over 95 fuel in a 987 3.4, such as noticeably improved performance and better MPG?
James.
Yes, but the change will be gradual unless you fill it with 99 (may as well use Shell Vpower as it is priced the same as other brands 97/98 fuels) and then have the adaptions reset. The car will then be expecting the best fuel and perform accordingly straight away.Are there any benefits to using 98 over 95 fuel in a 987 3.4, such as noticeably improved performance and better MPG?
James.
thegoose said:
Yes, but the change will be gradual unless you fill it with 99 (may as well use Shell Vpower as it is priced the same as other brands 97/98 fuels) and then have the adaptions reset. The car will then be expecting the best fuel and perform accordingly straight away.
Goose - I never have understood what needs to adapt (but I am a doctor not a mechanic!).If the ECU is set to work with 95 - 98 RON fuel, don't the knock sensors just allow ignition to advance to farthest edge of envelope and retard as necessary? And they sample thousands of times a minute so is adaption not instant?
Or am I being daft?
The ECU tries to use its higher octane settings and then backs off when it detects knock. It keeps a memory of this amount of retard and is programmed to stick to that for quite a time. It doesn't try to revise its plan very often and be all accounts will only give the extra timing back bit by bit.
Magic919 said:
The ECU tries to use its higher octane settings and then backs off when it detects knock. It keeps a memory of this amount of retard and is programmed to stick to that for quite a time. It doesn't try to revise its plan very often and be all accounts will only give the extra timing back bit by bit.
That's kind of how I understood it. Basically, the car is very quick to turn the wick down when it gets low grade fuel but turns it back up again rather slowly and cautiously, hence you will eventually get full performance but you won't notice the difference as it's gradual.Conversely, putting super diesel in a car that's previously been run on cheap stuff can have instant benefits - I watched a rolling road test on tv (5th Gear maybe?) and normal hatchbacks were showing gains of 10bhp or more immediately when switched over.
I used to only put VPower in my 986 but then started to experiment with the standard stuff. If it wasn't for the massive premium they put on high RON, I'd still use it but given the car appears totally happy, even on track, with yer bog-standard stuff, that's what I use nearly all the time now.
My understanding is that you get a slight performance increase, say 5%, and that some of the extra cost is offset by improved efficiency and therefore mpg.
It's probably marginal stuff, but why not optimise your cars engine performance? Why did you buy a Porsche?
Buy a 100k 991 and then reduce its power to save a few pence? This is the actions of a madman.
MTR
It's probably marginal stuff, but why not optimise your cars engine performance? Why did you buy a Porsche?
Buy a 100k 991 and then reduce its power to save a few pence? This is the actions of a madman.
MTR
I tried a test in my GT2 once on a private track - 1/8 tank of V power and did various test runs from zero to 160mph, recorded data on vbox and then went to fill up with 95 and redid the test. Didnt see any noticeable difference in the times recorded. You could argue that launch times account for the difference, but I specifically looked at the 60-100mph data which was in third gear to remove the gear change element. Ok so I didnt drain the tank so the test on 95 was done with some 99 left in the tank but still the difference was practically nil (i.e. not even 1/10 of a second over 60-130mph). Anybody else done this?
jonamv8 said:
95 in my 6TT. Think 98 making a difference is similar to placebo effect IMO
Have a rolling road power run done, then have the adaptions reset when you're on your second tank of Vpower and have another power run done and let us know what the difference is.I think it's daft for an OPC to say they use cheap stuff, it's hardly creating the right picture for the customer. Imagine if they said " yeah, well, the car's designed to run on N rated tyres, but we use LingLong Ditchfinder Specials and the cars still seem to make it down the road and back"....
GT2CS said:
I tried a test in my GT2 once on a private track - 1/8 tank of V power and did various test runs from zero to 160mph, recorded data on vbox and then went to fill up with 95 and redid the test. Didnt see any noticeable difference in the times recorded. You could argue that launch times account for the difference, but I specifically looked at the 60-100mph data which was in third gear to remove the gear change element. Ok so I didnt drain the tank so the test on 95 was done with some 99 left in the tank but still the difference was practically nil (i.e. not even 1/10 of a second over 60-130mph). Anybody else done this?
Did you run it far enough to drain the 98 from the fuel lines and filters? Must be about 5 or 10 miles worth?Gassing Station | Porsche General | Top of Page | What's New | My Stuff