Type of fuel

[Lusso916]

Hi all, I have just got a 05 4200 Cambio Corsa, I ran my previous 3200 on premium Shell V Power, hand book states nothing lower than 95 grade, what do you all use.
Cheers Rob.

 

[conaero]

I must confess I don’t see much of a difference between reg and super, either is fine in my book.

I believe the consensus is to avoid high ethanol European fuel.

 

[philgarner]

3200 with turbos 98/99 RON makes sense. 4200 is only mapped for 95 and as far as I understand anything else won't make any performance difference.

 

[Contigo]

3200 only mapped for 95 RON.

 

[lifes2short]

just stay away from supermarket fuels, not all fuels are equal

 

[StuartW]

I must confess I don’t see much of a difference between reg and super, either is fine in my book.

Agreed, it's like many upgrades - you THINK that you are noticing a difference as you have paid more for it but I can't say that I have ever noticed a performance or economy improvement when using super over regular fuels.
I guess that there is some science behind it to prove otherwise but laboratory test conditions can never be matched by real world driving conditions in my experience

 

[CatmanV2]

Science actually pretty much states that it won't make a difference unless the ECU map can take advantage of the increased Octane when modifying the ignition timing.
I confess I did think I notice an improvement once, which was on my old carbed Ducati Monster. Super stopped the carbs from icing in winter....

C

 

[Wack61]

There was definitely a difference in the impreza , ticked over more evenly and faster, I've read turbos run better in general , I use costco 97 ron in the mustang

 

[CatmanV2]

I can imagine the Impreza may well have had a map to take advantage. High compression engines and turbos would probably stand to make the best gains since, well, they are higher compression

C

 

[davy83]

These cars have knock sensors. The ECU tries over several hundred miles to advance the ignition as far as it can without inducing knock. so if you use thr 95 octane it will knock at less ignition advance. Having said all this, the amount of extra power or efficiency you will see in real world conditions will likely be so small to be un-noticable. Because I am not sure I always use 97/99 and quite like V-power I think its good. Either will not hurt your car and you most likely wont notice the difference.

 

[Wanderer]

As I'm now working at Dublin Airport can I use AVGAS? I seem to remember some old Bugatti's running on that?

Dublin is quite literally 'taking off' with Brexit, there's quite literally a railway station under T2 already (quite literally unused and quite literally not connected) and quite literally T3 is on the cards, Aer Lingus Cargo T1 is quite literally going. New runway under construction now not literally. And the AVGAS tanks are going, they will pipe it quite literally in straight from Dublin Port.

Quite literally.

 

[Lusso916]

Thanks everyone.

 

[MRichards]

A few facts need to be realised.

1. Octane rating indicates the ability of the fuel to resist knocking,or,pre-ignition,under high compression. The higher the rating the less likely pre-ignition will occur under most driving conditions.
2. There is absolutely no relation between the octane rating & the power an engine will attain. Power is dependant on the chemistry of the fuel,more specifically it's calorific value.
3. Unless the engine is both constructed & tuned to take advantage of high octane fuel it is wasted. In general terms high octane fuel is used for high compression engines.
4. There are two ways of rating octane ratios. The Research method,abbreviated as RON,is the common way of rating a fuel. RON indicates the ability of the fuel to resist knocking under low engine revolutions. The Motor Octane Rating measures the fuel's ability to resist knocking under high engine revolutions. Both Ron & Mon are measured on all gasoline fuels.
5. You are wasting your money on Avgas which is designed for use in piston engined aircraft which run at low & constant revolutions. It can be used in cars but why bother unless you are stealing it from your employer ?

It was used in the past for old engines which required lead fuel additive.
6. It's probably wise to accept the fuel recommendations of the car's manufacturer but the reality is that regular gasolione usually suffices since the ECU will adjust the timing via the knock sensors. The power developed by the engine will be the same. After all,road cars are tuned for easy driveability,not performance, so discussion around the relative merits of different brands of fuel is futile. However,you have a more important consideration on fuel branding. What you buy at say,a Shell station is not always Shell fuel. Fuel at a station is often bought from another refinery due to distribution difficulties or cost considerations and the mix is further complicated since a lot of fuel is imported from overseas by all companies to augment their supply chain. So what you buy as Shell may have come from a Mobil refinery mixed with imported fuel from China. And,you'll never know the difference !
When you remove all the gimmickry & sales bulls*it from fuels there's little justification for not buying the fuel closest to home at the lowest price,the car will cope just the same.

 

[MRichards]

And that other old chestnut,alcohol addition to gasoline.
The bottom line is that it has no benefit to you the car owner. Why ?
Alcohols can be made from anything lying around which has a bit of carbon in it. Suppose we have a lot of agricultural waste from cropping,that's a very good starting point. The alcohol will then cost about 5 cents/litre to produce. After we pay excise duty on potable spirit & add our profit we sell the stuff to a fuel producer for 20 cents. The fuel company add 10% alcohol to their gasoline & sell it for $1.20 wholesale depending on the current weekly swing in fuel prices. So we get $1.00/litre profit by selling alcohol as gasoline. Not many other places can you get that sort of bonanza.
An average road tanker fuel delivery to a servo is around 35,000 litres so the profit from the alcohol alone is $3,500,that's one **** of a cash cow.
Alcohol is a poor fuel since it burns with a cold flame. As a rule of thumb you need to burn about three times as much alcohol to equal the heat from gasoline. So it's going to wreck your fuel economy.
That cold flame & high latent heat of evaporation isn't good for your car's engine unless it's air cooled. Air cooled two strokes derive benefit from the excessive cooling of alcohol fuel.

 

[CatmanV2]

These cars have knock sensors. The ECU tries over several hundred miles to advance the ignition as far as it can without inducing knock. so if you use thr 95 octane it will knock at less ignition advance. Having said all this, the amount of extra power or efficiency you will see in real world conditions will likely be so small to be un-noticable. Because I am not sure I always use 97/99 and quite like V-power I think its good. Either will not hurt your car and you most likely wont notice the difference.

I've heard this before. My understanding is the process of adjusting the timing is pretty much real time though.

C

 

[davy83]

Retarding the ignition is real time and will occur on a combustion by combustion basis. However It is my understanding that the base ignition timing map is not changed cycle by cycle but it updated on a much slower basis. So if you change from low octane petrol to higher this will knock less but the ECU will take some time to alter the base timing map to suit the fuel (i.e. more timing advance). If you change from higher octane to lower the real time knock prevention will retard the ignition timing immediately to prevent knock (if knock occurs), but will not retard the base timing map until the onset of knock has been happening for some time. I may be wrong here but that is my understanding of how this works. I helped develop some of the first knock-adaptive ECU units back in the 70's so my detailed knowledge of these systems may well be out of date.

As for the calorific value in the fuel I think as far as I know the ignition timing advance you get with higher octane fuel is where the additional power and fuel burn efficiency come from and not the calorific value of the fuel as you quite rightly state. I believe earlier ignition starts the burn earlier and can give more complete combustion of the fuel, it also alters the peak expansion from the burn to match the position of the piston more accurately, and all of this requires a lot of time on a dyno, and much tweaking.

I have some photos some where of flame fronts developing in a quartz walled piston where you can see the combustion process occurring, step by step, its quite fascinating, used high speed phase contrast photography to pick out density changes in the gases as opposed to just colour. Sorry drifting there.

I've heard this before. My understanding is the process of adjusting the timing is pretty much real time though.

C

 

[CatmanV2]

Retarding the ignition is real time and will occur on a combustion by combustion basis. However It is my understanding that the base ignition timing map is not changed cycle by cycle but it updated on a much slower basis.

You may be correct however my understanding is the map provides a series of ranges and is not in fact updated. But what do I know
C

 

[cheshiremaserati]

A few facts need to be realised.

1. Octane rating indicates the ability of the fuel to resist knocking,or,pre-ignition,under high compression. The higher the rating the less likely pre-ignition will occur under most driving conditions.
2. There is absolutely no relation between the octane rating & the power an engine will attain. Power is dependant on the chemistry of the fuel,more specifically it's calorific value.
3. Unless the engine is both constructed & tuned to take advantage of high octane fuel it is wasted. In general terms high octane fuel is used for high compression engines.
4. There are two ways of rating octane ratios. The Research method,abbreviated as RON,is the common way of rating a fuel. RON indicates the ability of the fuel to resist knocking under low engine revolutions. The Motor Octane Rating measures the fuel's ability to resist knocking under high engine revolutions. Both Ron & Mon are measured on all gasoline fuels.
5. You are wasting your money on Avgas which is designed for use in piston engined aircraft which run at low & constant revolutions. It can be used in cars but why bother unless you are stealing it from your employer ?

It was used in the past for old engines which required lead fuel additive.
6. It's probably wise to accept the fuel recommendations of the car's manufacturer but the reality is that regular gasolione usually suffices since the ECU will adjust the timing via the knock sensors. The power developed by the engine will be the same. After all,road cars are tuned for easy driveability,not performance, so discussion around the relative merits of different brands of fuel is futile. However,you have a more important consideration on fuel branding. What you buy at say,a Shell station is not always Shell fuel. Fuel at a station is often bought from another refinery due to distribution difficulties or cost considerations and the mix is further complicated since a lot of fuel is imported from overseas by all companies to augment their supply chain. So what you buy as Shell may have come from a Mobil refinery mixed with imported fuel from China. And,you'll never know the difference !
When you remove all the gimmickry & sales bulls*it from fuels there's little justification for not buying the fuel closest to home at the lowest price,the car will cope just the same.

Spot-on. You must be in the petroleum industry as you are the only one who has made reference to RON and MON.
I have so many people who tell me supermarket fuel is bad and use V-Power instead. I use Teco 99 Momentum in the Porsche and never had any issues. The ECU adjusts for 95 RON if I use that in the event that I cannot get to Tesco. The other three cars - one diesel runs fine on supermarket diesel and the two petrol cars run fine on 95 RON unleaded from supermarkets or wherever I happen to fill up.

The only consideration is the detergents that Shell add to V-Power after they sell wholesale to Tesco, Sainsbury, Morrison etc. But each of these also adds their own detergents after loading the tanker from a Shell or BP or Esso refinery.

 

[Koz]

I run the 4200 on Sainsbury’s Super. Car seems to respond well to it and it’s a decent price.

 

[lifes2short]

some good points there from the people in the know, but supermarket stuff just makes me nervous for any high performance motors, might be unfounded but just how I feel about it, for the extra pennies i'd rather use V Power