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Author Topic: Petrol, does it make a difference.  (Read 2149 times)

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Kevin Wood

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Re: Petrol, does it make a difference.
« Reply #15 on: 11 February 2014, 11:58:40 »

Well, I'm going to go against the grain here and state that despite much trying and some dyno testing, I cannot tell the difference.

Each engine will be set up to run on a certain octane of fuel. In the case of Omega B, that's 95RON. Feeding that same engine with 98RON or higher makes no difference except in very extreme circumstances.

sorry

I'd have to agree. Whilst the engine does have knock sensors and the ability to trim timing, I've never seen knock retard active on a non-faulty engine, regardless of fuel, and when it does kick in, it's a limp-home strategy that kills the performance in the event that it finds itself running on weasel-pee. The engine is simply not highly strung enough to suffer any issues on the 95 RON petrol for which it was designed, so it runs with exactly the same ignition advance on that as it does on any high octane petrol. You're never going to get a significant change in performance in that scenario.

My westfield, on the other hand, with 11.5:1 compression and no knock control, really doesn't appreciate 95 RON. (and some petrol marketed as "high octane fuel", for that matter!). So, it does make a difference to the right engine but you need high compression or forced induction, otherwise it's probably a waste of money.
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2woody

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Re: Petrol, does it make a difference.
« Reply #16 on: 11 February 2014, 12:40:32 »

I do use 98RON on trackdays, just to give me that little bit of "overhead" against knock because I know that the engine will get mighty hot on occasion. But it does nothing for the performance at all.
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Rog

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Re: Petrol, does it make a difference.
« Reply #17 on: 11 February 2014, 12:46:55 »

Well . . . . . 

There's no huge difference with my MV6, just a bit

There is a vast and very VERY noticable difference with SWMBOs Volvo 940
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GastronomicKleptomaniac

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Re: Petrol, does it make a difference.
« Reply #18 on: 11 February 2014, 16:33:13 »

I do use 98RON on trackdays, just to give me that little bit of "overhead" against knock because I know that the engine will get mighty hot on occasion. But it does nothing for the performance at all.

Interesting - could it be placebo effect, or perhaps the much-marketed cleaning properties of the fuel making a difference?

 My own unscientific test was to brim the tank of KKP with BP Ultimate, projected range went way higher than it had done in the past, I always suspected the gentle drive to the fuel station would have had a lot more to do with it.
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aaronjb

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Re: Petrol, does it make a difference.
« Reply #19 on: 11 February 2014, 16:40:02 »

My westfield, on the other hand, with 11.5:1 compression and no knock control, really doesn't appreciate 95 RON. (and some petrol marketed as "high octane fuel", for that matter!). So, it does make a difference to the right engine but you need high compression or forced induction, otherwise it's probably a waste of money.

The M3 has a sticker saying "95-98" in the petrol flap door - I've always used V-Power before now, until last night when I was forced to stick regular in (the bingo light was on and the nearest Shell turned out to only have V-Power Diesel and regular UL, which didn't help me much!) .. so far I haven't felt a massive difference, maybe a little flatter at the top end.

The sticker, though, implies the car has a tune for 98 and pulls timing via the knock sensors on anything less - I'm pretty sure both you and Stuart are right for the Omega and it has a tune for 95 and won't add timing over that for 98, just pull timing for fuel worse than 95.. I've never felt any difference in the butt dyno, anyway, and so the Omega gets whatever is cheapest in the area :-[

Well.. I did feel a difference the other week, but that's when it dropped a cylinder or two ;D
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kevinp58

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Re: Petrol, does it make a difference.
« Reply #20 on: 11 February 2014, 20:33:24 »

I only use v-power nitro now as the mig feels so much more responsive and smoother  :y
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2woody

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Re: Petrol, does it make a difference.
« Reply #21 on: 11 February 2014, 20:53:56 »

My own unscientific test was to brim the tank of KKP with BP Ultimate, projected range went way higher than it had done in the past, I always suspected the gentle drive to the fuel station would have had a lot more to do with it.

do you have a "KKP", too ?
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cd 2.2

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Re: Petrol, does it make a difference.
« Reply #22 on: 11 February 2014, 23:21:39 »

This is an age old debate I guess ... My own experience with my shitron Picasso 1.8sx, I found that if I used supermarket fuel I got around 80 miles less to a tank than I did if I was using say BP unleaded (my own personal favourite since I noticed that their unleaded was actually very noticeably green coloured).
The higher octane fuels I see as a waste of money as my right foot is way too heavy at times and I can't justify the higher price. :D
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ajsphead

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Re: Petrol, does it make a difference.
« Reply #23 on: 12 February 2014, 08:29:22 »

With the Mtech chip there's definitely a difference between 95 & 98RON. Not so much with power but the engine runs and pulls more smoothly, Also it stopped the annoying little knock rattle on changing up that he did pre and post chip. Chipping did improve it. Chip & 98 RON gets rid of it completely.
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GastronomicKleptomaniac

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Re: Petrol, does it make a difference.
« Reply #24 on: 12 February 2014, 08:37:58 »

My own unscientific test was to brim the tank of KKP with BP Ultimate, projected range went way higher than it had done in the past, I always suspected the gentle drive to the fuel station would have had a lot more to do with it.

do you have a "KKP", too ?

I did have, you've got him now  ;D It's going to feel strange working on him on Sunday...

It also frightening how easily I slipped into calling the Omegas "him"...
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2woody

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Re: Petrol, does it make a difference.
« Reply #25 on: 12 February 2014, 10:17:41 »

well I never knew that was you......!
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