Tesco Super 99 or 97 Octane

[pyaap]

Hi Guys,

Any idea what`s gone on here then?

http://www.volvoforums.org.uk/showthread.php?t=42525

If I`ve read it right, the only thing which is noticeably different is 95 RON fuel was being used at the time, instead of 99 / 98 RON

[pyaap]

Hi Engineer,

Thanks for your input as well; I appreciate that you too are very well versed with the issues surrounding modern day engines. However, would you yourself fill your tank with 95RON before going for a track day (e.g. Marham), where there will be sustained full throttle running?

I think part of the problem here is I don`t currently see any tuner(s) guaranteeing that their ECU upgrades will run safely on 95RON fuel under all circumstances / situations (including "hard" / track usage). On the contrary, most tend to suggest using Super Unleaded (or a higher octane fuel anyway); one has gone so far as to have supposedly developed a `special` map for 95RON fuel. As a lay person in this field, I just can`t help but wonder why there is all this bother if tuned cars can run on any grade of fuel that is out there?

[pigapumbu]

Originally Posted by Engineer

Fair enough but IMHO nothings ever black & white when it comes to vehicle technology despite peoples habit of pigeon holing it for convenience sake and as Matt said it’s not good posting info quoted off the internet or stuff you think is right if you don’t know it’s actually factually based and up to date, this is just miss-information and causes confusion. By the way including bioethenol it’s 5% and for what it's worth it’s not the only anti-knock additive which affects the cylinder flame path timing.

But if you’re happy recommending that people pay more for fuels their particular engine may not need then so be it

Cheers

I posted the links and referred to them so that everyone can have a read and make their own minds up. There are tons of info with real tests done and it can be cross referenced anytime if one thinks its now accurate. I don't tell anyone they are right or wrong because I know it all. Far from it, I like to be fair and discuss. Let the individual make up their minds.

Thanks for reminding me about the percent mix. Saved me the trouble of looking up my bookmarks. (Lazy to do it) I knew it was a small amount. Wonder what happens when they put more though. Hmm..!

Anyway, my point on using higher RON is (a) my car is modified and (b) I want to give it good fuel. If someone is driving a 1.6i car and hardly goes beyond 4000revs, i would hardly say use 99RON. Judging from another member here, 91RON will do just fine.

Cheers.

[pigapumbu]

Originally Posted by bobcat

it isnt really the same stuff going around, im just answering your questions.

however ive got to ask, in regards to copying and pasting info - why have you given an example (the powerchip bit above) that uses a NA car (bmw)? as NA engines have completely different ignition maps.

this term run it hard seems to keep coming up, you seem to be implying that if running on 95 ron the engine will not last long, but chnage to 98+ ron and you wont have a problem.

you can still get knock on 98+ ron.

I think we are getting to the end of this post now, but to sum up: higher octane fuel will give better performance and economy if you car is mapped\supports it as i will advance the timing. however if you want to run on lower ron fuel the car will adapt its timing to suit. and if on that hot day when running even 95 or 98+ your engine starts to knock it will full the timing back.

so there you go, use what fuel you like. I run my car on asda fuel as its convenient and have not had any problems over the last 70,000 miles ive done using it.

All well and good. Lets put it all aside the technical mumbo jumbo. If you really want to answer my question...Would you as a tuner guarantee running a car you modified to use Asda 95RON be it on track or town? No point going on in circles if one is not willing to put the money on what the advice is !!

As you say, this thread is coming to the end. But for all those going to read it at a later time, ask yourself this.. you got the car modified, but do you run it with 95 or higher. Choice is yours. It could be ok or you could be facing a situation where the bottom line would be something like this. see here..

If any tuner you use tells you 95RON is a-okay (even for track days),.. as the saying goes, get it in black and white.

BobCat, I think most people will know what run hard means. And yes NA cars use different timing but the principle is the same. In turbo cars, we force feed petrol/air into the cambers and pressure/heat plays more. All the more reason I see the importance to use a higher RON. Or maybe Volvo cars build the engines so well and the ECU so good, that their cars never pink with any given fuel.

cheers all. The common consensus is out there whether one needs to use a higher RON in a modified car. The choice is yours.

[pigapumbu]

Originally Posted by pyaap

Hi Guys,

Any idea what`s gone on here then?

http://www.volvoforums.org.uk/showthread.php?t=42525

If I`ve read it right, the only thing which is noticeably different is 95 RON fuel was being used at the time, instead of 99 / 98 RON

Yes I have been reading that same thread and asking the same thing. Why? Answer could be that owner was not using ASDA 95RON.

cheers

[st5ve]

Just had a look at my owners manaul re specifications Engine:
Engine type B5202S 10 valve, B5252S 10 valve, B5204S 20 valve, B5254S 20 valve Volvo recomends 95 RON min 91 octane.
Engine type B5204T 20 valve, B5234T 20 valve, Volvo recomends 95 RON min 91 - 98 octane.

For the B5234T5 Volvo recommends 98 RON lead-free petrol for the best performance, but will run on any fuel with an octane rating of 91-98. This is with a standard ECU, when the ECU is modified with either a chip or remap bobcat states that the ECU will still recognise the octane rating and will adjust the timming, but I assume there is limitations, with 95 RON in a modified car it is safe to use as long as you don't floor it or take the rev's over 4k as this may produce knock?
However if you want to eliminate knock when you floor it or take the engine over 4k rpm then a higher octane rating is needed to prevent knocking?

As Volvo already recommend 98 RON in the B5234T5, it would therfore make sense to use nothing less than 98 RON in a modified car.

If a remaped or chipped ECU can still make adjustments to the timing etc and detect what octane rating the fuel being used, (as the same way a standard ECU would) then in theory anyway you could use 95 RON fuel. That is unless the ECU has been chipped or remapped wrongly then using a higher octane rating will cover up/help hide any issues with the ECU that has been chipped or remapped. Is this a fair assumption?

[bobcat]

Originally Posted by pigapumbu

All well and good. Lets put it all aside the technical mumbo jumbo. If you really want to answer my question...Would you as a tuner guarantee running a car you modified to use Asda 95RON be it on track or town? No point going on in circles if one is not willing to put the money on what the advice is !!

As you say, this thread is coming to the end. But for all those going to read it at a later time, ask yourself this.. you got the car modified, but do you run it with 95 or higher. Choice is yours. It could be ok or you could be facing a situation where the bottom line would be something like this. see here..

If any tuner you use tells you 95RON is a-okay (even for track days),.. as the saying goes, get it in black and white.

BobCat, I think most people will know what run hard means. And yes NA cars use different timing but the principle is the same. In turbo cars, we force feed petrol/air into the cambers and pressure/heat plays more. All the more reason I see the importance to use a higher RON. Or maybe Volvo cars build the engines so well and the ECU so good, that their cars never pink with any given fuel.

cheers all. The common consensus is out there whether one needs to use a higher RON in a modified car. The choice is yours.

yes lets put all the technical mumbo jumbo aside, not sure if i want to read through any more copy and pasted text.

Would i recomend 95 ron to people with cars running maps ive made? yes i would, and do. i run my car on supermarket 95 ron and boost past 1 bar daily.

I also do alot of driving off boost where higher ron\more knock resistant fuel isnt needed due to the lower compression, cylinder pressure and even with pretty advanced timing.

However i have a question which i would like to ask pigapumbu.

so far we have determined from vary posts and the wiki that you kindly copy and pasted for us that ron only affects the abilty of the fuel to resist knock\autoignite. we have agreed that it does not relate to the fuels energy.

so i would like ask at what conditions will an 850 t5 engine knock with 95 ron fuel? and therefore this will allow us to know what point we need the knock resistance of the 98 ron fuel. I ask this as your main issue seems to be that "running it hard" on less than 98 ron will damage the engine. however as we have agreed unless the fuel is knocking higher ron fuel isnt needed. Im asking you this as you state that you should run on 98+ when running hard, so that means you must know why?

please can you clarify what running it hard means?

I would also like to ask this an an open question, if you have been told only to run 98+ ron are you not worried that the variable ignition timing that volvo built into the ecu has been disabled? so come that hot day, lean mixture, or other factor that would cause more stress in the cylinder chamber ---- booooom!!! or even worse have you knock sensors been disabled?

Im sure some people reading this are running standalone ecu's, and know for a fact that most of them will have igntion retard maps - meaning when the car see's knock it pulls out timing even if running on the holy grail that is 98+ ron!!!

[bobcat]

Originally Posted by ttacornwall

Just had a look at my owners manaul re specifications Engine:
Engine type B5202S 10 valve, B5252S 10 valve, B5204S 20 valve, B5254S 20 valve Volvo recomends 95 RON min 91 octane.
Engine type B5204T 20 valve, B5234T 20 valve, Volvo recomends 95 RON min 91 - 98 octane.

For the B5234T5 Volvo recommends 98 RON lead-free petrol for the best performance, but will run on any fuel with an octane rating of 91-98. This is with a standard ECU, when the ECU is modified with either a chip or remap bobcat states that the ECU will still recognise the octane rating and will adjust the timming, but I assume there is limitations, with 95 RON in a modified car it is safe to use as long as you don't floor it or take the rev's over 4k as this may produce knock?
However if you want to eliminate knock when you floor it or take the engine over 4k rpm then a higher octane rating is needed to prevent knocking?

As Volvo already recommend 98 RON in the B5234T5, it would therfore make sense to use nothing less than 98 RON in a modified car.

If a remaped or chipped ECU can still make adjustments to the timing etc and detect what octane rating the fuel being used, (as the same way a standard ECU would) then in theory anyway you could use 95 RON fuel. That is unless the ECU has been chipped or remapped wrongly then using a higher octane rating will cover up/help hide any issues with the ECU that has been chipped or remapped. Is this a fair assumption?

thankyou for that post ttacornwall.

so as you can even volvo recomend 98 ron on their turbo cars, but their ecu's can allow the car to pretty much run on anything.

and also look at what volvo recomend for non turbo cars!!!!!!!!!!!!!!!!!!!!!!!!!!

i would like to ask an open question of why that is?

and that is one of the reasons why i run 95 ron.

[gettingolg]

I've a sore head now!

We've seen a lot of local forecourts ( and a shed load of other local shops and businesses ) close round here and I dont like being surrounded by a 'ring' of Tesco stores and forecourts. We have 3 within 4 miles, 2 within 10mins drive from here, a 4th planned within another 10 mins. Throw in a couple of Asda's for good measure. We go out of our way to support local retailers as much as we can - this includes buying fuel.
We currently have an old 740 turbo estate. Ive read most of the posts on this subject and though our car isnt modded, has a similar management system to Noah's Ark and is driven by someone who's clearly neither a mechanic or a chemist - she doesnt like supermarket grog.
Ive used V-power and I was surprised at the difference. Ever since then Ive filled up with branded and the old girl clearly prefers this to Asda or Tesco's brew.
My main point anyway is this - I fill up at one of our VERY few remaining locals - 92.9p for Total's 95 yesterday. Regardless of opinion I suggest everyone uses a local forecourt at least occasionally.
Otherwise one day you'll wonder why all the petrol stations have been replaced by showhouses and why the good lady thought it was fine to run your Volvo down past the red.......oh - and then after a hike with a plastic can why the local supermarket wants over a quid a litre!!!

Love the forums! Great to see plenty of opinion AND getb the chance to gain a little knowledge from all of you! Im on here more than Im on eBay now. Missus cant decide if its good or not so good....
Cheers!

[Conehead]

Originally Posted by ttacornwall

Just had a look at my owners manaul re specifications Engine:
Engine type B5202S 10 valve, B5252S 10 valve, B5204S 20 valve, B5254S 20 valve Volvo recomends 95 RON min 91 octane.
Engine type B5204T 20 valve, B5234T 20 valve, Volvo recomends 95 RON min 91 - 98 octane.

For the B5234T5 Volvo recommends 98 RON lead-free petrol for the best performance, but will run on any fuel with an octane rating of 91-98. This is with a standard ECU, when the ECU is modified with either a chip or remap bobcat states that the ECU will still recognise the octane rating and will adjust the timming, but I assume there is limitations, with 95 RON in a modified car it is safe to use as long as you don't floor it or take the rev's over 4k as this may produce knock?
However if you want to eliminate knock when you floor it or take the engine over 4k rpm then a higher octane rating is needed to prevent knocking?

As Volvo already recommend 98 RON in the B5234T5, it would therfore make sense to use nothing less than 98 RON in a modified car.

If a remaped or chipped ECU can still make adjustments to the timing etc and detect what octane rating the fuel being used, (as the same way a standard ECU would) then in theory anyway you could use 95 RON fuel. That is unless the ECU has been chipped or remapped wrongly then using a higher octane rating will cover up/help hide any issues with the ECU that has been chipped or remapped. Is this a fair assumption?

You forget to mention that on the T5, Volvo state in the handbook that they recommend using 97RON and above for MAXIMUM performance. It states that (in mine anyway) that you can use 95 RON but performance will be reduced. It does not however say it will cause a problem.
The ECU self learning theory is a Fallacy with respect to the sensors will determine the outer limits of combustion, and tell the ECU which changes the ignition and injection points to suit. i.e. it reads the knock and detonation sensors and adjusts to keep the engine within safe tolerances.( in Layman terms)
If you change the fuel you change when these sensors act because of different properties of the fuel detonating and knocking at different points. This is what is being referred to when you say the ECU adjusts, for different fuel.

This is also why different tests behave differently on different cars, because ECU's trely on other readings depending on the car, so yes a bmw M5 would behave differently to a Volvo.

This is why you use 99 Ron fuels, because you are using all the power, and why remap if you don't want more power.

There will be no problem also using 95 ron, especially for everyday use, but if an engine is making less power then you are more likely to drive it harder, if you like to drive fast, than when using 99 ron.

I tend to use whatever fuel I fancy ans whatever station I pass, and the only thing I definitley notice is it is slower on 95 ron, but as I commute a lot this is not a problem, and I know it won't reduce the engine life, regardless of what fuel I use.