Compression Ratio and fuel

[rsfruitbat]

Hi All

What compression ratio do you run in your competition boxer engines and what fuel do you run them on.

In my 1400 I am running 11.1:1 and using tesco 99 or shell super unleaded.

I am looking to up mine and trying to get an idea of where others have gone.

rsfruitbat

[BS25]

As our PM conversation, 12.0:1 on fuel injection and Shell Nitro (Super Unleaded).

[Veesix75]

I'm pretty much the same as you rsfruitbat. I use sainsbury's super unleaded.

I have occasionally dropped in some millers cvl, but never noticed a difference.

[PETROLHEAD]

I use sainsbury's super unleaded.

Forgive me, but i really wasnt expecting that!


Do you know something we don't Tim?

[Veesix75]

Nope!

Never had an issue, car runs fine, fueling, spark, air all good on sensors when on rollers.

I've never worked in the petro industry, but I doubt there are that many different refineries in the world......similar to baked beans, lots of brands, only a couple of bean factories.

Perhaps my car will start f@rting after this post! Or maybe someone will tell my valves are about to break in half?

I don't have a shell station near me.

[PETROLHEAD]

="Veesix75"

Perhaps my car will start f@rting after this post! Or maybe someone will tell my valves are about to break in half?

Oh gosh i hope not Tim!


My stand point isnt really a criticism of the fuel, or its manufacturer, and I'm not saying that its not any good either. You're likely correct. The saino's petrol is very likely sourced from the same barrel as their competitors, but, where they are often found deserving of criticism is in their delivery and consistency.

I've heard many tales of diluted higher octane fuels from being mixed with regular ron in order to use up whats in the delivery tanker. Or. That all the petrols are in fact the same in the tanker, until a booster additive is included at the forecourt. And errors in this arrangement can lead to many variations and discrepancies.


In this world, its not going to make or break a race hopefully, but add some forced induction into the mix and it can be catastrophic!

Shell as you correctly suspect is the the favoured fuel, but not from an outright octane rating, but because it is what it says it is much more reliably.


Have i explained that correctly? Sounds a bit waffly! Lol!

[rsfruitbat]

I was told that Sainsbury's fuel is provided by Shell. If I cant get Tesco 99 then I use Sainsburys's

tesco is the preference as its 24hrs pay at pump and sainsburys wont sell me more than 2 gallons at a time so when you are filling 3 jerry cans for a rally its a lot of trips and aggro.

On a rally forum I have asked the same question and the numbers I am being told is in the range 12.5 - 13 CR. They are also talking about dynamic CR as well. Swept volume after the inlet valve has closed?

Anyone used this measure?

So to get me up to 12:1 I need to take 0.6mm off the block so the piston will be almost 1mm proud of the block. This is less than a compressed head gasket and I still need to work out piston to valve clearances etc. Has anyone else had this situation?
I guess I am going to need oversize tensioner pulleys aswell as mine are already on top limit? Or does anyone know of a shorter belt?

rsfruitbat

[PETROLHEAD]

Hmmm, getting rather technical now mate!


It wouldn't surprise me about Saino's fuel being a major brand, Shell etc, they aren't going to make their own are they, but i'll repeat what i learnt some time ago whilst i was doing japanaese imports for a living.

The subaru lads, loving modifying as they do, knew they had essentially strong motors by design, and we all know how some rudimentary tuning can vastly improve a forced induction motor, so they were starting to explore why so many were losing motors at relatively mild tunes.

in short this is what they did, under as controlled circumstances as they can produce on the road.

The knock sensor on this motor is converted to a knock counter, with digital readout, and the results were published following some control testing over a month of committed driving styles and journies.

The Shell V power came out way ahead of the rest, BP ultimate was 2nd but by some margin, and Tesco whilst promising the highest octane actually proved to be terribly inconsistent. One day it would be good, although still knock, or detonate, marginally more than Shell V power, but then most of the time it would knock like a Gardner diesel on easy start! proving it to be far from the octane it claimed, unless you caught a very lucky delivery.


I have to add that these were clever chaps who knew what they were doing, not your Car Park Doughnut crew types at all, but it was also a good few years ago.


The conclusions were clear to them at the time, that once driven under hard boost and suitable ignition advance, the inferior fuels were simply knocking the motors to bits through detonation.


How much of it could be down to their tune and set up? We'll never know i guess, but it did clearly show the inconsistencies in the supermarket fuels for sure.


Incidentally, a friend of mine involved slightly in that research, was capable of building a 640bhp impreza for a gentleman who wanted the wildest subaru in malta, which meant it had to run on nothing more than pump 95!

[Veesix75]

I didn't know tesco did a 99 Ron.

On a serious note shrew, I do remember the supermarket fuels getting bad press a number of years ago, I think for sulphur content ? It accelerated the demise of multiple bmw engines with the nikosyl treated rings/blocks.

It's partly the reason I added octane boost, which might have made no difference I really don't know, but it made me feel better about using the fuel in the first place.

The tests you quote are conclusive enough on that front.

You've spurred me on on two fronts

1. I'm going look for the closest shell station
2. I'm going to do a bit of googling on this topic.

[PETROLHEAD]

Both wise decisions i would say, personally, but the key one would be number 1 for me.

Incidentally, a knock sensor / converted counter is quite an available thing nowadays to add to pretty much any engine, and is probably the best source of a definitive answer regarding suitability of both fuel and ignition set up on a live data basis,

Im not sure the local saino's would like us all dipping tanks in white coats and armed with pipettes and chemistry set!

[Veesix75]

Dont forget your goggles - I personally prefer those huge ones that strap over the back of your head, a bit like a snorkel mask (but without the snorkel).

Initial googling has pointed to the additives being pumped in at the refinery - so while the base fuel is the same (as I said, just a few refineries), apparenlty the branded additives are pumped in at the same time as the base fuel. Therefore the Sainsbury's tanker gets the same base fuel as the Shell tanker, but the Shell tanker also gets the 'Shell' specific additive pumped in (as do the Esso Tankers, Tesco Tankers, Jet Tankers, BP Tankers - all lined up at the same refinery)

Briefly read something about the additive in Tesco 99 and 'calorific values' but I havent done chemistry since O level (and that was mostly setting things on fire - magnesium was the best for that) so it bypassed me I'm afraid in terms of what it meant.

Read some pretty terrible things about Morrison's fuel tho ........

[PETROLHEAD]

i think they all have their moments Tim!

[rsfruitbat]

Food for thought there gents.

On a slightly different note Ii tow the rally car with a 159, 1.9 diesel. A few weeks ago I thought I would try shell nitro diesel as pump prices are are cheap at the mo.
I am now on my second tank, getting on for 900miles done and I cant tell any difference. No more mpg, doesnt feel any quicker etc.

Should it be an instant improvement or does it take a few tanks to condition the system?


rsruitbat

[Veesix75]

Ahhh....that question about seeing a benefit straight away or not, another debate in its own right! does the ECU learn it etc etc........

I'm going to try the same in my 535d - I get a consistent 36mpg from it average, if i take a steadier 70mph run up the A1 from my house to Leeds and back for work (100 miles round trip) it will just tip 40mpg - now before anyone thinks thats rubbish for a diesel, it is the older twin turbo with 270 hosses, not the later stop/start engine. The average of 36mpg includes plenty of tyre ripping acceleration (I cant help it - its just so quick )

I'm racing at Oulton Park Gold Cup next Sunday, so the Sprint is getting a couple of jerry cans of Shell Nitro - thats where I think I will see a difference?

I've just had the pleasure of driving an old M3 (3.2cc, 340bhp) and it was filled with the BP best stuff and it did an incredible 38mpg on a lazy 80 mile trip across A and B roads, plus a bit of motorway. I didnt expect that but cant say if the fuel helped or not.

[PETROLHEAD]

Blimey. I'm also amazed, in fact astonished at an m3 doing 38mpg!

I've always been led to believe that the manufacturers insist that the benefits of their fuel comes from extended and contant use, but then they would wouldn't they.

If it was a clear and notable octane difference, i would expect modern ecu's and sensors to pick it up immediately, and so at the very least i would expect the car to feel better straight away.

This is an easy one to fall into a placebo trap i suspect.


As for mpg, I'm skeptical here too im afraid, given that youve just invested 80 quid and got less for your money than you normally would i suspect that whilst experimenting with the soundness of your choice, its human nature to drive even more carefully than normal.

Sorry for party pooping. But the only real noticeable difference I've felt in fuels is a negative one.

Some fuels, and stations either sell crap fuel, or very little of it. There's a bp near me on the A1 which i have been wanting to snitch to customs and exise for years. Fill up there and your mpg suffers to the tune of about 15/20%!



Anyway, personal rant over. Im sure there are better fuels than others, diesels too although I'm struggling a little more with that one if im honest.


In your average road car. I doubt they are worth the extra cost. But im all ears if anyone can convince otherwise with some proper science stuff!

[KevJTD]

my own experienec of all the v power diesels etc (are they not called that now?) was that it made not a blind bit of difference to mpg/power/smoke out the pipe.
and i drove it accurately so that was tank to tank, same journeys, same usage.
done with several jtd's so not just taken the first car as gospel.

i do try and use the shell or esso type stations though rather than supermarket pumps but i've no evidence that they give less mpg's as i usually get the same 47.--mpg. usually within a few tenths per tankful difference, never more. certainly never seen anything like the +3mpg benefit that others claim.
i also never trust the fuel computer as it's easily fooled

[BS25]

For n/a race cars on pump based fuel, the higher octane just gives a little extra knock protection - for noticeable performance gains you have to go proper race fuel which is blended very carefully and has a higher oxygen content. For turbo's it's always been a little easier to measure measurable gains in power/torque with better fuel (even pump fuel). For us though, a higher octane is just a little extra added knock protection. The last time I looked, legal race fuel started at £5.50 a litre......

With regards to fuel economy (gasoline), all certification testing takes place on reference fuels depending on the market - different fuels for US, Brazil, China, Europe, etc. For Europe, E10 is becoming widespread on the mainland and will soon head over here (E5 is being phased out) - E10 has a greater ethanol content and is currently giving marginally better fuel economy - even on our Bentley's at work! The difference is approximately 5-10 g per km - on a vehicle that emits above 300 g/km. However, this is on a very defined drive cycle in a lab - not especially replicable on the road. Even slight variations in road driving will effect your fuel economy - on the rollers just selecting a gear 0.5 seconds after the prompt (and then accelerating harder to regain the trace line) can effect the fuel economy by 10-15g/km - so more than the newer E10 fuel!

So, more variables on the road than the 'possibly better magic fuel' will contribute to with regards to fuel economy. Any variations in 'throttle response/feel' are more likely to be down to the differences between 'ok' pump fuel and that from a bad batch - or, changing your shoes from wellies to race boots! All the Bentley engines make maximum power on 95 octane and feel no different on 98/99 - and thats a 4.0 V8 twin turbo with upto 580ps, a 6.0 W12 twin turbo with upto 642ps and the 6.75 v8 twin turbo with upto 537ps - but 1100 Nm of torque -

[PETROLHEAD]

So a branded fuel should keep us out of the "bad batch" scenario more reliably, and the gimick octanes are largely just that, except for the knock protection,

Is that about the sum of it Bryan?


Well im all for the knock protection. But its a shame we have to pay such a premium for what should be the norm in my opinion.

The motor industry is so affordably deceitful isnt it?

They have the funds to make claims that are virtually unprovable, or benefits that are largely unachievable, and simply pay the fines for it IF ever proven otherwise.


A bit like a Michael Jackson kindergarten chain!

[Veesix75]

Thanks Bryan, useful update.........although I have to contradict slightly on my own experiment conducted today.

I put some super unleaded in a motor that usually gets basic fuel, I got to the end of my journey quicker, and managed at least one extra stripe on the same consumption.....




Lawn looks great.

[PETROLHEAD]

maybe your timing was out initially!

has your briggs and stratton wandered out of tune!

[Veesix75]

It's a B+Q made in China cheapo special - I might put some Castrol R in just to enahce the experience......

[PETROLHEAD]

Saweeet!

[KevJTD]

been reading some old practical classics maagzines, well from 2011 anyway, and millers oils do a good few addtivies as you'd probably epxect.
now i usually don't do a bundle on these type of things but one seems worth a go for us classic drivers with regards to ethanol and the corrosive nature for our metal fuel tanks are brass parts of crbs' etc.
millers do have a great reputation so are probably worth trying.

you put one bottle in per 40litres of fuel which seems like it would soon add up but what would it cost to replace expensive tanks and carbs?

we'll soon be at the stage where we have no choice to use E10 or worse....

http://www.millersoils.co.uk/automotive ... itives.asp