Am I imagining a difference in performance? - Fuel related

[DPS 10]

I alway try to use the high octane (RON) fuel, preferring Tesco or V-power as they are both 99 RON. Yesterday the car was almost on the red having used up a full tank of 99RON Tesco fuel, so I nipped to sainsbury and put in £20 of their "super/premium unleaded" since then my car doesn't feel the same. It's not that the power isn't there I just feel like she's working slightly harder to deliver it, almost as if she's heavier :shrug: I'm going to pop down to Tesco later and top her up with the 'special' stuff again. Maybe I'm imagining it, but it just seems strange that it could cause such a difference in how the car feels. :scratch:

 

Anyone else notice a marked difference when using different fuels?

[nrc 0]

It could have been some dodgy fuel or even dredging up sludge from the bottom of the tank if you let it get really low. I've used Sainsburys super unleaded many times and not noticed any worse performance than V-Power.

[DPS 10]

I had wondered that nrc, I had fuel issues in an old car related to one particular garage on my weekly route so it could have been a crappy batch or as you say crap in my fuel tank.

 

She's an automatic and has just 74k but I think it's time to face an ATF change too. It could be knowing that effecting my perception of her performance. I have to admit I have become a bit paranoid since swapping to an "older" car.

[j_s14a 0]

Mine seems to drive a bit nicer with V-Power in it, though the only other fuel I've tried in mine is BP Ultimate.

[Sean_Jaymo 0]

I opened my fuel tank for what I would have said was the first time in 193k (solid tight/very dirty/original tape holding the wires in place being my clues) and was surprised to see how clean the inside of the tank was. Hardly any crud at all! Maybe it's more of a myth that tanks get dirt in them and I would have thought the the baffle-less (real word?) tank would encourage stuff not to settle on the bottom but in fact be suspended in the fuel during normal driving around and not settle as much on the tank bottom.

[Kevin Bacon 5]

Well the car *is* heavier if you just filled it up :D Topping up won't help. Tesco 99 or V-Power will just dilute down to what's already in the tank.

 

/\ Agreed, the whole "dirt being sucked up" thing is a complete myth. That came from carburettor days where the mechanical pump on the engine pulled fuel out of the tank and through the carbs. Injection pumps push fuel through a filter so no dirt ever gets to the injectors. The only dirt in fuel tanks comes from the fuel itself and injection pumps are designed to run dirty.

 

V-Power is by far the most consistent fuel I've used. Worth paying the extra for. Supermarket stuff is shyte and I avoid Tesco like the plague ever since drawing up a bit of water from their underground tank.

[timmaaah 0]

Regards the whole 'sludge' thing - the pump sucks the fuel from the bottom of the tank anyway - it doesn't suck it from the top ;)

 

I use Tesco fuel all the time - seems fine to me. I rather suspect that it's the same fuels anyway, otherwise BP/Esso/Shell would be making a big song and dance about how their fuel is 'better' than the supermarket stuff, but they don't :)

[Erallus 10]

IS it true premium fuel (ie the more expensive higher octane fuel at petrol stations) can damage an engine if you use it all the time?

 

There's a "mechanic" at work that told me this, not sure if there's any truth in it?

[n3p 3]

Only use V-Power as my car is mapped to it - I'm worried it'll pink if I use 95RON (could just be paranoia!)

 

Re. the crap being at the bottom of a tank myth, Vince @ Stealth told me he took a tank apart before and found a build up of metal filings which he concluded were from petrol nozzles scraping in and out... must have taken a lot of filling up to do that!

[Sean_Jaymo 0]

Regards the whole 'sludge' thing - the pump sucks the fuel from the bottom of the tank anyway - it doesn't suck it from the top ;)

 

Of course, otherwise you wouldn't have any range on your tank?

[Kevin Bacon 5]

Yeah I saw the same metal in my Corrado tank and as a magnet didn't pick them up, I concur with Vince! There's a little disc blocking the hole in some filler necks (some kind of one way valve I assume) which scrapes the nozzle as you withdraw it (oo er!). Those metal flakes would get trapped by the gauze on the pump intake anyway.

 

I've cut open 20K old fuel filters in my Corrado and my R32 and they were just totally black with lots of fine 'dirt' collected into clumps.

 

As for the fuel qualities, it's true that there are only so many refineries in the world, but Supermarkets just buy what ever is cheapest, so you get inconsistent supplies. I believe the Tesco 99 is refined especially for them though, but the 95 stuff could be anything. V-Power is also unique to Shell and no, constant use of it does no harm to engines what so ever :) The tall tales some mechanics come out with are just ridiculous!

[DriverVR6 11]

In the old days (good and better old days as far as I'm concerned!) the majority of fuel tanks were mounted externally and were made of steel. So they used to rust on the outside and rust on the inside. So dirt (rust) clogging up the fuel lines, filters and carb jets could be a problem.

 

With the Corrado having a plastic fuel tank, it's not and never has been an issue. You'll get ordinary "dirt" particles in there, but not of a size that will cause any issues.

 

As for "performance" fuels, you'll not notice the difference on a standard car, so imho it's a complete myth generated by clever marketing people to get your cash.

Edited June 11, 2014 by DriverVR6

[Kevin Bacon 5]

My MK1 Golf and Jetta had that problem. The filler necks rusted through and let all manner of rust and road grime into their tanks!. Good old Autocavan (remember them??!) had a stainless replacement thankfully.

[DriverVR6 11]

Autocavan...yes I remember them. I had one of their modified brake linkages on my Scirocco GTX to improve the appalling brake pedal feel. Still miss that car, even with its crap brakes!

[Kevin Bacon 5]

Lol, yep, I had one of those too, and the clutch cable repair plate......and a little air scoop to let more air into my MK2's air box. Like you say, they were the good and better old days!

[Ray1965 10]

I;ve switched to Shell V power, so judging from your comments it's a good move?

 

Talking about Tesco i have seen on Facebook twice in recent months people filling up with their Diesel and having major problems with cars packing in and numerous engine running issues.

Maybe it is down to the state of the actual filling stations supply tanks or is it the quality of the fuel? Correct me if i'm wrong to me this has to be wrong as all the supermarkets buy from the same supplier and fill the tankers with the same fuel.

I've been on the M180 motorway going over to Grimsby and all you see on there is Morrison, Tesco etc tankers going to the immingham refinery to fill up.

[Liam20vT 10]

I've only used Tesco's 99Ron fuel in my 20vt rado once and never again! Car ran like poo, had issues starting in the morning - would cut out if i wouldnt give it a little rev - just felt really underpowered. Whenever I get the opportunity to run shell V power the difference is day and night (There are no Shell garages in my local area) Feels alot smoother/faster. I only get to use Esso premium, which to be honest for the price i pay (£1.32) a litre its pretty good stuff.

[sexybourbon 0]

As for "performance" fuels, you'll not notice the difference on a standard car, so imho it's a complete myth generated by clever marketing people to get your cash.

 

I'm not entirely sure I agree with that , although not arguing about it I'd say it's pointless on a smaller car ... Let's say my 1.2 clio as it's just plain and simple not a fast car , but I'd say the corrado with a big 2.9 lump it does make a slight difference ! Mine runs a bit smoother and seems to pick up that bit better on acceleration and compared it in a turbo car I'd say it makes a big difference other wise people like Vince at stealth wouldn't push all people who turbo vr's and stuff to run it

 

And an other point that race cars wouldn't use higher octane race designed fuel if it didn't work , they would just use 95 Ron like everyone else

[Jamie 1]

I normally only use V - Power in mine but when we were in Austria I was just putting the local 98 in as it was 20c a litre cheaper and was convenient, switched back to Shell Super Racing/V-Power on the way back and noticed no difference whatsoever other than in my wallet...

 

Incidentally I remember Autocavan very well - had loads of their bits on my cars over the years. Geoff Thomas was an absolutely brilliant engineer. One of my friends was the branch manager of the Farnham branch and ended up being given Geoffs MKII that was used as his test bed and had pretty much every item he designed on it, including an early remote damping coilover setup. Always wondered what happened to that car

[DriverVR6 11]

And an other point that race cars wouldn't use higher octane race designed fuel if it didn't work , they would just use 95 Ron like everyone else

 

Race engines are designed to make full use of high octane fuels.

 

Ordinary road going cars which are designed to run on a specific octane of fuel will give no noticeable effect. If you ran a standard VR6 on Asda fuel and then one "performance" fuel like Shell or BP's, you'd see maybe 3 or 4 bhp difference on a dyno. On the road, you would not notice a 3 or 4 bhp difference, not unless you have the senses and feel that Ayrton Senna or Alain Prost had/have.

 

And lets be honest, most of the Corrado's out there are losing 10 to 15 bhp just by being poorly maintained and in a bad state of tune.

Edited June 11, 2014 by DriverVR6

[Kevin Bacon 5]

Yeah you can see on the petrol flap sticker it was mapped for 98 RON at the factory and whilst 95 is OK to use, you will get a reduction in performance. I'm sure it states that in the manual somewhere?

 

So in other words, if you use V power, the chance of pinking is virtually zero (unless carrying 20 bags of cement in the boot) and therefore you get peak performance at all times. I

 

If you use 95, the chance of pinking greatly increases, so the knock sensors pull the timing and your power drops. So as ever, you gotta pay to play.

 

Talking about Tesco i have seen on Facebook twice in recent months people filling up with their Diesel and having major problems with cars packing in and numerous engine running issues.

Maybe it is down to the state of the actual filling stations supply tanks or is it the quality of the fuel?

 

As far as I understand it, underground tanks at filling stations build up condensation water at the bottom (heavier than fuel) which needs periodic syphoning. I guess some stations are hot on that and others aren't. I've picked up a tank of water from Tesco in my R32, which resulted in a 30 second misfiring coughing fit. Haven't touched it since and no reoccurrence.

[Dox 22]

I normally only use V - Power in mine but when we were in Austria I was just putting the local 98 in as it was 20c a litre cheaper and was convenient, switched back to Shell Super Racing/V-Power on the way back and noticed no difference whatsoever other than in my wallet...

 

Incidentally I remember Autocavan very well - had loads of their bits on my cars over the years. Geoff Thomas was an absolutely brilliant engineer. One of my friends was the branch manager of the Farnham branch and ended up being given Geoffs MKII that was used as his test bed and had pretty much every item he designed on it, including an early remote damping coilover setup. Always wondered what happened to that car

 

Geoff Thomas pops up on cgti every now and again talking of day of old racing etc, he's had an interesting life and tells great stories of past racers and their antics :)

[timmaaah 0]

Of course, otherwise you wouldn't have any range on your tank?

 

Indeed, so running a tank dry will not suck in more sludge/muck as it is already sucked from the bottom of the tank ;)

[Sean_Jaymo 0]

Yeah, that's what I said in not so many words?

[DPS 10]

Interesting reading the comments, I didn't know the tank was plastic! I may geek up on various fuel reviews and perhaps try not to use sainsburies muggle-fuel again haha! She now has about 40% sainsburies 97RON and 60% tesco 99RON so I reckon the fuel could now be 98Ron (I'm making a complete guess that 'RONs' work that way :D) but I ended up working from home so didn't get chance to see if she's back to normal today, if indeed she was ever not normal. There are no Shell garages near where I live which is a shame, they seem to be the rarest. I always try to use high octane because it says to under the petrol flap.

 

I have had a few intermittent lumpy running issues which I finally narrowed down to corrossion in the MAF sensor plug. There's a small crack in the housing that was letting in water. Contact cleaner and insulation tape has resolved the problem. My intermittent ABS sensor fault has been almost completely cured since the car has been garaged (I did notice it was worse after a wash) so I wouldn't dismiss the fact that now she's running fine I'm possibly inventing things that are wrong :bonk: or maybe not ;)