Super Unleaded

[Grim.Badger 15]

I've just checked a pic Rich sent me and as far as I can tell the dizzy is set far to retarded; here is how mine looks:

 

[Anulfo 22]

Personally im a big fan of tesco 99 octane fuel!!!!

[CaptainK 11]

In standard factory format my 1993 L reg original 1.9 CAT engine absolutely hated Super Unleaded with a passion. If I ran it on SUL it would play up and the engine just wasn't happy. But with normal Shell 95 RON petrol is was perfectly happy and quick.

 

BUT, with my GTi6 in the 205 now I run it on Shell V-Power without any problems. I have unfortunately had to run it on 95 when I was in Europe, but it still seemed the same. However, I intend to stick with V-Power as when I get it mapped I want it mapped for the best stuff.

[dcc 855]

I get 250-270 miles to a tank from cheapy tesco fuel - and I get 300-330 from 99. I prefer the 99 because it seems more fun to drive, a little more responsive etc...

[James_R 3]

Down is advanced and up is retarded is that makes sense.

[Tesstuff 222]

I get 250-270 miles to a tank from cheapy tesco fuel - and I get 300-330 from 99. I prefer the 99 because it seems more fun to drive, a little more responsive etc...

 

 

Noway do you get that many miles to a tank if you drive like you did on our 'test drive'

 

I promised not to tell your Mum only

[dcc 855]

welsh autobahns

 

Yerp i get that mileage driving like that! i can get from here to gloucester with atleast 1/4 of a tank left, normally more, after driving like that

Edited May 14, 2009 by dcc

[Tesstuff 222]

welsh autobahns

 

Yerp i get that mileage driving like that! i can get from here to gloucester with atleast 1/4 of a tank left, normally more, after driving like that

 

Obviously a 90 litre tank then

[Rich_p 23]

Right I've turned the dizzy clockwise, it's now over an inch further forward than it was before we did anything to it and it is running so much happier, less kangeroory at low speed too.

 

I still think it's a bit flat though.

 

I put it under load in a high gear and it sounds no different so I guess I could wind it further forward still.

 

That was with the vacuum advance disconnected too.

 

I'm going to change the temp sensor anyway to be on the safe side.

 

It idles fine & doesn't hunt now I've played with the screw on the throttle body.

 

I have no idea what I should be doing with the screw on the afm though, it has been moved so will need adjusting.

 

Does that come into play if I get it tested with a gas anylizer?

 

Rev counter doesn't work now though, bloody french cars

[Maccer 0]

I have been interested about this issue since getting my 205 a while back and hearing many conflicting things about petrol. Many people seem to think that super is the best stuff and we should all be running it in all our 205s, although from the research I've done it seems that it doesn't necessarily work out that way. From what I've read…

RON, or octane rating of fuel is it's resistance to detonation measured in % of a mixture of iso-octane and heptane. So 95RON fuel has the same knocking characteristics as a 95% iso-octane and 5% heptane mix.

The higher the RON, the more compression it can take without spontaneously detonating. High compression engines need higher octane fuel, otherwise they will retard the ignition to compensate for the knock and this will result in a loss of power and efficiency. Either that or ones without sensors will knock, which does the same thing and also knackers the engine very quickly!

The different grades of petrol are very similar in density and hydrocarbon content, so don't burn any more powerfully than another, the extra power comes from the higher compression of the fuel prior to ignition. So putting super in a car that runs without pinking on the bog standard stuff doesn't give you anymore power unless you can advance the ignition more. Similarly it cannot give you any better fuel economy in engines that have mechanical ignition, as the fuel isn't burning any 'better' and nothing happens to the ignition timing and fuelling as a result of putting higher RON fuel in. Apparently it doesn't burn any cleaner either, as the detergents used are the same.

Quote imoc.co.uk "If you are already using the proper octane fuel, you will not obtain more power from higher octane fuels. The engine will be already operating at optimum settings, and a higher octane should have no effect on the management system. Your driveability and fuel economy will remain the same. The higher octane fuel costs more, so you are just throwing money away. If you are already using a fuel with an octane rating slightly below the optimum, then using a higher octane fuel will cause the engine management system to move to the optimum settings, possibly resulting in both increased power and improved fuel economy."

So, it seems from what I've read that unless you are running a 1.9+ or a super-skimmed 1.6 with high compression ratio there really isn't any benefit to using super, so long as its not pinking at your given dizzy setting (and you are happy with your ignition timing setting.

I have run my standard 1.6 with both 95 and 98 and have noticed no difference at all to power or economy with a moderately advanced ignition (about 1cm or so from centre, a fair bit on from factory (or old-adjusted) setting)

So I think in the future I will be saving my 4-5p a litre and sticking with the 95!

 

http://www.imoc.co.uk/technical/article/octane.htm (really detailed!)

http://www.petrolprices.com/about-fuel.html

http://en.wikipedia.org/wiki/Octane_rating

[jackherer 543]

I have run my standard 1.6 with both 95 and 98 and have noticed no difference at all to power or economy with a moderately advanced ignition (about 1cm or so from centre, a fair bit on from factory (or old-adjusted) setting)

So I think in the future I will be saving my 4-5p a litre and sticking with the 95!

 

http://www.imoc.co.uk/technical/article/octane.htm (really detailed!)

http://www.petrolprices.com/about-fuel.html

http://en.wikipedia.org/wiki/Octane_rating

 

The point is you can advance the ignition further and get more power if you use super but with the timing that far advanced it will pink like mad on 95. This is much more pronounced on the 1.9 than the 1.6 which is why Peugeot said the 1.6 was suitable for unleaded with timing adjustment and the 1.9 wasn't, the power loss on the 1.9 would have been too much and customers wouldn't have accepted it.

 

As an aside, if you can't dial in enough ignition timing on your 1.6 to make it pink on 95 ron maybe your distributor is a bit tired?

[taylorspug 7]

As an aside, if you can't dial in enough ignition timing on your 1.6 to make it pink on 95 ron maybe your distributor is a bit tired?

 

Just what I was thinking, it should definately be able to pink on 95 RON if you give it enough advance.

[Maccer 0]

Very true guys, my dizzy isn't advanced as far as it would go, (it has about a 1cm ish to go before it is fully advanced) and I'm sure it would pink if I gave it more of a twist. Mine was set where it is by the guy who did my valve stem seals a while back who said that about 10mm twist clockwise from the centre is usually about right and I've not had a play with it since. Although I'm tempted now to throw a bit of super in and have a fiddle - just to see if I can set it 'better' on super and then see if it pinks on 95 the next time - not sure that there will be much in it with my 1.6 lump!

 

I thought it was worth making the point though that putting super in doesn't do anything for power or fuel economy unless there is a corresponding ignition adjustment - either a physical one on the distibutor or via engine management on engines that need super. Any perceived increase in power/economy from sticking super in without changing anything else is just a placebo, and a waste of money!

Edited May 19, 2009 by Maccer

[bales 1]

Very true guys, my dizzy isn't advanced as far as it would go, (it has about a 1cm ish to go before it is fully advanced) and I'm sure it would pink if I gave it more of a twist. Mine was set where it is by the guy who did my valve stem seals a while back who said that about 10mm twist clockwise from the centre is usually about right and I've not had a play with it since. Although I'm tempted now to throw a bit of super in and have a fiddle - just to see if I can set it 'better' on super and then see if it pinks on 95 the next time - not sure that there will be much in it with my 1.6 lump!

 

I thought it was worth making the point though that putting super in doesn't do anything for power or fuel economy unless there is a corresponding ignition adjustment - either a physical one on the distibutor or via engine management on engines that need super. Any perceived increase in power/economy from sticking super in without changing anything else is just a placebo, and a waste of money!

 

But without wanting to sound rude that is exactly what has been said from the very start of the thread. Nobody is suggesting that you gain massive amounts of power, but with the timing being adjustable on the 1.9/1.6 and them being originally set up to run on higher octane fuel - then you will get a difference from either advancing to suit SUL or by noticing pinking on normal 95RON if it is set up for SUL.

 

Also as was mentioned, cars with knock sensors - like my XU10cjt2e - do respond to different octanes of fuel because they will retard the ignition if they detect knock which affects performance.

My car does go noticabley better and is smoother with SUL, and of course Optimax or V-Power as it is now is designed to keep the combustion chambers free of crap etc...

[welshpug 1,622]

When I had a new dizzy on mine it was set pretty central in the slot, that was on VPower on a 1.9.

[SurGie 54]

I thought it was worth making the point though that putting super in doesn't do anything for power or fuel economy unless there is a corresponding ignition adjustment - either a physical one on the distibutor or via engine management on engines that need super. Any perceived increase in power/economy from sticking super in without changing anything else is just a placebo, and a waste of money!

 

 

I would have to disagree on that one, my GTI 6 does much better per tank than using watered down stuff, also

using V-power will make the inside of engine much cleaner so would be more efficient...

Edited May 19, 2009 by SurGie

[Grim.Badger 15]

Very true guys, my dizzy isn't advanced as far as it would go, (it has about a 1cm ish to go before it is fully advanced) and I'm sure it would pink if I gave it more of a twist. Mine was set where it is by the guy who did my valve stem seals a while back who said that about 10mm twist clockwise from the centre is usually about right and I've not had a play with it since. Although I'm tempted now to throw a bit of super in and have a fiddle - just to see if I can set it 'better' on super and then see if it pinks on 95 the next time - not sure that there will be much in it with my 1.6 lump!

 

I thought it was worth making the point though that putting super in doesn't do anything for power or fuel economy unless there is a corresponding ignition adjustment - either a physical one on the distibutor or via engine management on engines that need super. Any perceived increase in power/economy from sticking super in without changing anything else is just a placebo, and a waste of money!

 

You probably won't hear it pink on 95 if it's set to 97, but you're plugs will get knackered very quickly. The white bit on the plug discolours and gets pit marks on it You also get a lot of sooty buildup.

But the point you are making is right, your average chavmobile wont have any benefit from SUL, but if you adjust the timing on a 1.9 to 95 the spark will be igniting the fuel with the piston way too far down the cylinder and you will lose power.