306 2.0Litre 16v Compression Ratio

T

The Pupat

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Fellow Frogger
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Hi my parents have a 306 2.0litre 16v auto sedan. I was wondering if anyone knows the compression ratio of the motor...and how much difference running on premium or Optimax (98RON) would make.
Currently only gets the regular most of the time... I still don't think dad understands that high comp motors need good fuel.
 
the XU10J4R (late model 2.0 16v) has 10.4:1 compression. I'm not sure whether or not it has a knock sensor etc. to take advantage of better quality fuel.. (I'm sure someone here will know though!)

AFAIK it requires premium (95 RON) fuel; there should be a sticker inside the fuel filler cap. I do recall from some reviews that you can get it de-tuned from the dealer to run on standard unleaded fuel (though those reviews were old and might only be talking about the older 8 valve engine)

As for 95 vs 98 RON fuel, my GTi6 (XU10J4RS engine) gets about 10% better fuel economy using Optimax/Synergy 8000, over the older 'normal' premium 95 RON fuel. Ends up being cheaper to use the 98 RON stuff!
 
May I suggest you try BP Ultimate if you have it where you live. Apparently its a better quality fuel than Optimax as it is refined at 98RON as opposed to having an additive mixed to bring it up to 98RON.

I likewise get 'about' 50-60kms more on 98RON, but if you were to fill my car using either i'd be buggered picking the difference.

I do believe the engines have a knock sensor. I put 91RON (ULP) in once and to me there was no difference. No knocking at all.
 
Yeah I was just wondering about performance. It's my parents car so I don't really give a shit about economy...just performance.
 
I certainly notice a difference between Premium 95 RON and the 98 RON petrols.

I tend to prefer Optimax in the car compared to BP Ultimate. I think I've been pretty objective on this whole fuel matter, and personally the car is more lively with the Optimax. Whether or not this is because some batches of fuel are different to others, who knows, but Optimax seems to have been more consistent for me.

I have, however, been told BP Ultimate and Shell are pretty well the same thing refined at the same place. That Optimax enhanced out of additives story sounds like a tall one Phasis, where'd you hear that?

Regarding other fuels, I noticed substantial pinging at low revs under load in 1st, 2nd and 3rd gears (didn't go any higher than that) when I put in standard unleaded (I had no other choice at the time.)

I would strongly recommend against standard unleaded if it specifies on your vehicle not to use it.

The knock sensors will retard the timing to a certain point if there are inconsistencies in the fuel, however they don't allow enough 'room' for 91 RON if the car was designed for a minimum of 95 RON. At least that is how it seems to me - my car pinged like a bastard and I cringed every time it happened.

At high revs, you probably can't hear it... and the higher engine loads experienced in highway driving would overheat the pistons rather quickly, I'd say.

These are the reasons why your car says 'minimum 95 RON' near the fuel cap.
 
Originally posted by ntrx:
<strong>I certainly notice a difference between That Optimax enhanced out of additives story sounds like a tall one Phasis, where'd you hear that?
</strong><hr></blockquote>

It was brought up in here a while back on another thread of similar discussion.
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Just to throw some interest into the discussion, I know for sure there are only two refineries in Sydney, Caltex and Shell. I can't believe that it is possible to meet Sydney supply demands or cost effective, for BP to transport fuel down from Brisbane. I'd like to be proved wrong on this one, but I'm confident that there aren't that many 98 octane fuels around. Likewise with Shell PULP. It's the only one at 96 octane. The rest are 95.
 
I suspect that there might be quite a bit of variability in the comparative quality of different fuels in different places.

In Victoria , for example, Shell have the most modern refinery and , were, for example, the only refinery which was capable of continuously producing unleaded and leaded in conmpletely seperate lines. The older Mobil refinery had to do occasional runs of super through its unleaded lines for technical reasons and they certainly used additives to get their old 95RON pulp. (My father in law was an engineer with Mobil at the refinery until retiring)

I suspect that this is part of the reason that Shell were first on the market down here with 98 octane and "lead replacement" fuel, and for the hideous problems that mobil pulp fuel caused some users (myself included) for a while.

I'm pretty sure that in Victoria the new Mobil, BP, Ampol and Caltex 98 RON fuels in Victoria are all sourced from the same refinery (the Caltex Sydney refinery I think). They all ran out of it when there were problems at the Caltex refinery a few weeks back.

In other states the situation may well be very different.

BUT quite a bit of fuel is now imported directly in refined state from Singapore. This is certainly true, for example, of the fuel sold in the growing number of Safeway / Woolworths outlets. In my experience their 'regular" unleaded (in Victoria) is probably a bit higher octane than the stuff you get out of regular unleaded bowsers from other sources. I'd guess that their premium is probably about 96 octane. Its certainly better than the "old" premium unleaded fuels from Mobil / Ampol etc, but may not be quite as good as the "new generation" ones. Still, at the price its well worth trying. My wifes SEAT (which is very "fuel sensitive") runs fine on it, as does my 505 XN6 wagon.

Its good to see improvements from all of the leading brands though. A year ago the only fuel that I could happily use was Optimax. Now at least there is a bit of competition again.

Cheers

Rod
 
I try to pour shell optimax all the time but the other week i tried some BP ultimate. I must say i thought i noticed a little difference (for the better) than when i poured optimax. BUT maybe i'm just thinking i felt an improvement. I've also read how some people really hate the stuff, so i guess it depends on the servo you go to. I don't think all shell or BP stations are created equal
 
Has anyone used the new "g" high octane unleaded found at the smaller chains. I put some in today in the Pug and it felt great. Felt great while driving, but sitting at lights the car was idling very roughly. Its called "Trafigura" or something, 98 octane.

Will see what it's like on the way home....

[ 11 March 2002: Message edited by: YEL020 ]</p>
 
somebody might have already said this, so i am sorry about that i say it again...
these cars need to run on high octane fuel not just for peromance resons.. if used as a shopping tolley, it stops them pinking all the time tooif you want to run then on low rating fuel you need timing retarded...
:D :D
regards paul.
 
I put BP premium in 2 days ago, it had to run the worst out of all the premium fuel that I have used. Don't know why but the shell optimax seems ten times better.
As my car has 4000rpm at 110 (or there abouts) when going up the freeway from sydney to newcastle and when I hit a hill the bp premium made my car pink like crazy ( the same as normal unleaded.) where the shell premium always made it run fine and never pink.

Hell maybe my car is just old and cranky.

Jono
 
Originally posted by crosspug:
<strong>I put BP premium in 2 days ago, it had to run the worst out of all the premium fuel that I have used. Don't know why but the shell optimax seems ten times better.
As my car has 4000rpm at 110 (or there abouts) when going up the freeway from sydney to newcastle and when I hit a hill the bp premium made my car pink like crazy ( the same as normal unleaded.) where the shell premium always made it run fine and never pink.

Hell maybe my car is just old and cranky.

Jono</strong><hr></blockquote>

Jono,

I flatly refuse to use BP products of any sort in any of my cars. The worse case of problems with contaminated fuel I ever saw was c/o BP where it was suspected the fuel had been contaminated with Turps. 4 am on a busy Highway full of overnight semis. :eek:
I was told by someone in the oil industry at that time that if I didn't know the garage well to always buy from Mobil as they are charged for their petrol based on the reading of the totals at the bowsers rather than what's put in the underground tanks which gives them no incentive to buy fuel from "other" sources.
Also after the scam BP tried to pull on Citroen owners with increasing the price of base LHM by over 100% for some very dubious reasons including the cost of production. We now buy LHM plus (the dearer stuff) from another supplier for less than BP used to charge for the cheaper old stuff before the price hike.
It's no use complaining to BP either, as when we did regarding the LHM fiasco they are so full of themselves they can't believe anyone has the right to question their actions.
Easiest way is to do as I do & not deal with them in the first place. :p :p :p :mad:

Alan S
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Cant use high RON rated fuel in my 405. The Weber guy where I used to live was convinced the horrific smoke from my car after the rebuild was because of these fuels. My father who drives my car time to time back in NZ now runs low RON Challenge fuel with 5 litres of av gas per tank. No smoke !
BP was shit in NZ aswell.
 
I don't think the motor is pinging then. I was sure that the dealer (city peugeot) said to run it on half a tank of premium to half a tank of regular...so my dad just alternates. though the dealer repair book has the engine rated to run 95 RON.
 
Originally posted by The Pupat:
<strong>what's pinging actually sound like?</strong><hr></blockquote>

Hard to describe, but the things that come to mind are the sound of water bubbles popping in hot oil; a light , slightly eratic, metallic rapping; a demented click beetle - Its a metallic clicky, pingy, ticky sound - significantly higher in pitch than a noisy tappet and less regular.

You will usually only hear it when the engine is under some stress - accelerating up a hill in top gear, or taking off from a standing start in second gear, will usually produce it if your engine is close to the margins.

Cheers

Rod
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