peter030371
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| posted on 4/1/18 at 02:11 PM |
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Super vs Regular unleaded
Had a quick search and can't find this already on here which surprises me a little.
Has anyone done any proper back to back tests of Super Unleaded vs Regular Unleaded? Sort of thing I am on about is a modern FI engine with maps
optimised for both fuel types. What did difference do you get on the rolling road and the real road?
When AT Speed mapped my Duratec (Omex 600, 2lt, RB throttle bodies, light flywheel, rest standard) they asked what fuel I had in it (regular) and then
why did I only put regular in it (I hadn't thought about doing anything else). I asked what difference would it make and they said
'some' but would say no more!
At some point its sure to end up back on the rolling road so is it worth switching to Super for a car that is has a heavy track bias?
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ttalps2000
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| posted on 4/1/18 at 02:14 PM |
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When I asked my rolling road guy the same question, he said it makes very little if any difference from his experience and findings. If running big HP
with turbo's etc then it would make a little difference.
However if the fuel has been left in the tanks on the forecourt for a period of time, due to the amount that they actually shift, from what I have
read, it usually comes down to about 95 ron rating anyway. So if you do use it, get it as soon as its gone in the tanks at the forecourt!
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theduck
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| posted on 4/1/18 at 02:47 PM |
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Personally I see no need for it in most NA setups, unless VERY high conpression (arbitary 11:1 or higher) because for most NA engines your power
won’t be knock limited until they are running very high compression
For boosted engines, where generally you are knock limited, then the higher octane fuel can help significantly as it will allow you to safely run more
timing before encountering knock, it is part of the reason that E85 is so popular in places where it is readily available.
[Edited on 4/1/18 by theduck]
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jossey
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| posted on 4/1/18 at 02:50 PM |
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My car runs crap on normal fuel much better on super. It's a 300 hp turbo. Also after almost 5000 miles the pistons and valve stems looked clean
which was a surprise.
I've only run the car on normal fuel twice due to being stuck on middle of no where without super available.
[Edited on 4/1/18 by jossey]
Thanks
David Johnson
Building my tiger avon slowly but surely.
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gremlin1234
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| posted on 4/1/18 at 03:30 PM |
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it can certainly be worth using the more expensive fuel...
I recommend the esso super, because it doesn't (usually) have ethanol in it.
standard unleaded has 5% ethonol
https://www.esso.co.uk/fuels-faqs
quote:
What is the ethanol content of your fuels?
The majority of unleaded 95 Octane petrol sold in the UK contains up to 5% ethanol as required under the Government’s Renewable Transport Fuels
Obligation (RTFO).
There is currently no requirement for renewable fuel (such as ethanol) to be present in super unleaded (97 grade petrol).
Esso super unleaded petrol (Synergy Supreme+ Unleaded 97) is ethanol free (except in Devon, Cornwall, the Teesside area and Scotland).
We would therefore advise anyone who has concerns about the presence of ethanol in petrol to use Synergy Supreme+ – providing they do not fill up in
Devon or Cornwall, the Teesside area or Scotland.
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ian locostzx9rc2
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| posted on 4/1/18 at 03:40 PM |
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Many years ago I ran a seat Ibiza gti as a track car not big horsepower but it did make a difference could get 5mph extra on the main straight I did a
few years ago see a test back to back with 4 300+ hp cars and the gain range was 6 to 18bhp more !!
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loggyboy
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| posted on 4/1/18 at 04:58 PM |
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Only real world test I did was in my old redtopped nova. used to vary between tesco 99 and regular. Religiously along the same stretch of (private)
road the car would top out between 137 and 139mph on GPS using regular. With 99 it would raise to 142-143. Tested this about 6-8 times with consistent
results.
Considering its a big jump in BHP it takes make a difference in top speed I suspected a 10+bhp gain.
These test back up similar results - on SOME cars.
https://www.youtube.com/watch?v=gQghB4asSnI
https://www.youtube.com/watch?v=d8L-X89duEs
[Edited on 4-1-18 by loggyboy]
Mistral Motorsport
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CosKev3
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| posted on 4/1/18 at 05:32 PM |
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All cars I've ever tried it in have definitely ran smoother/better/more responsive.
It's very noticeable in my kit car with the R1 engine.
I've had it mapped on 95 now it's charged,but run super in it for some protection and at least I know it's safe to put 95 in it if I
end up at a station with no super somewhere 
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mark chandler
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| posted on 4/1/18 at 08:31 PM |
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I ran a MR2 turbo for a year or so, the ECU controlled the boost on knock running optimax it would add a couple more PSI than standard which made a
big difference.
On a n/a engine unless you have pretty wild cams and are running on the edge probally not worth much.
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peter030371
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| posted on 4/1/18 at 09:35 PM |
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Some interesting answers. My engine may not benefit now but in the future once I have tweaked it a bit it is probably worth the change.
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907
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| posted on 4/1/18 at 10:12 PM |
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I'm the first to admit I'm no expert, but when two star; whoops, unleaded, first came out did we not have to retard timing settings?
Does it then follow that if you use, lets say Momentum (99 oct from Tesco) you could advance timing back towards where we were in the days of leaded
petrol, and regain some of the loss that came with unleaded?
Like i said, I don't know, which is why I'm asking.
Paul G
p.s.
I do rightly or wrongly, use Momentum in my Lotus 907 as it's a 1976 engine and would have been made to run 4*
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ReMan
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| posted on 4/1/18 at 10:34 PM |
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The Porsche gets upset if it detects knock from 95, retards ignition,powers down etc and then stays like that for "a long time" even when
back on 98"
Others may do similar
www.plusnine.co.uk
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froggy
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| posted on 5/1/18 at 11:16 AM |
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I tune on 97 and run on 99 for trouble free track abuse in my turbo car , might lose a few hp but I’m not worried about fuel quality or having to keep
an eye on gauges for the sake of a few pence per litre
[IMG]http://i144.photobucket.com/albums/r187/froggy_0[IMG]
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Oddified
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| posted on 5/1/18 at 11:13 PM |
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When my car was nasp, i mapped it on 97 and if i used 95 to get me home it was ok, just a minor tinkle now and again if worked. Now it's
supercharged and again mapped on 97, putting 95 is a no go area!. I would guess it would need 5 - 10deg timing taking out and/or much lower boost.
If the engine isn't being pushed/on the edge then 97/95 won't make much difference, turbo/supercharger/nitrous and being pushed a bit, it
does make a difference.
Ian
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