Super Fuels

[ACE Motorsport]

Many of the large petrol companies have launched 'super fuels' - petrols and diesels that have a higher research octane level. These fuels are said to increase power in many vehicles, deliver less pollution than regular fuels and help to maintain a cleaner engine. Tesco will soon be selling Super Unleaded 99 Octane petrol, supplied by Greenergy, the highest octane level petrol available in the UK.

Using Super Fuels
One of our users commented that using higher octane fuel than your engine requires actually gives no benefit and may be a waste of money. This is because virtually NO engines require 98 RON over 95, and the market for 'super' fuels seems to be based on people's misunderstanding of octane ratings and the placebo effect of filling up with 'more powerful' fuel - making motorists think their engine is running better in some way.
What do the fuel companies say then, to justify the "increased power" claims for the super grade fuels? Some companies say that while all fuels contain cleaning additives, 'super' fuels contain more or better detergents to keep the injectors cleaner than standard fuel. Others say the fuel is a few percent denser which gives slightly more power per litre. These benefits may be marginal though in comparison to the extra cost involved so it is worth ensuring that your engine will actually benefit before filling up.
Some engines actually do need higher octane fuel, such as race engines with very high compression and some supercharged engines, such as the import version of the Nissan Skyline. Also, a few vehicles, such as the new BMW K1200R motorbike, can sense knock and adjust their engine tuning to take advantage of higher grade fuels.

[Notso Swift]

100% Agree - It is fair to say that if you do nothing to your car the effects will be marginal

To get any benefit you will need to tune it with the new fuel in mind.

However, this is not necessarily the case with a dedicated racing fuel which may be the same RON/MON, however it could have a greater active ingredient (IE Oxygen) which has been added to maximise the regulations it has been designed for. These fuels will give a bigger bang, creating more power, all by themselves.

[graham bahr]

Originally Posted by ACE Motorsport

[

Some engines actually do need higher octane fuel, such as race engines with very high compression and some supercharged engines, such as the import version of the Nissan Skyline. Also, a few vehicles, such as the new BMW K1200R motorbike, can sense knock and adjust their engine tuning to take advantage of higher grade fuels.

nearly all modern vehicles can sense knock and react in such a way, i suspect if you tested a lot of almost new high compression engines quite a few wouldn't have any performance difference, but if you tested the same engines when they had higher milage and the combustion chambers are getting a bit coked up and a little oil is finding its way into the chamber than i bet you would find a difference.

not forgetting that quite a few engines on our UK roads are intended to be run on european 99 octance so the knock sensors are running them slighly retarded here in the uk

[Al Weyman]

I use the 99 stuff, if for no more than a bit of insurance as I detonated and destroyed one of my engines on a dyno once when the engineer swung the dizzy too much advanced, in seconds it melted a piston crown.

[greenamex2]

I have a BMW K1200S (basically the same as the K1200R) and the engine runs better on higher grade fuel. It also does better fuel mileage, partially offsetting the cost.

OK so the running COULD be perceived rather than actual but the better mileage has been checked running an identical journey over one hundred times.

[graham bahr]

Originally Posted by Al Weyman

I use the 99 stuff, if for no more than a bit of insurance as I detonated and destroyed one of my engines on a dyno once when the engineer swung the dizzy too much advanced, in seconds it melted a piston crown.

thats why i love the engine management so much, no dizzy swinging, using the keyboard you dial in 1 or 2 degrees and do a power run, adding advance in such small steps means you never endanger the motor with way too much advance, and theres non of this holding it under full load while you try to do it stuff

[Chucky]

Is that really how you tune?!?!

Not that many have knock control and even fewer have knock control that it is clever enough to have a beneficial effect. Typically, the sensor is ususally fooled by a similar noise and the car just drives around with 3-6 degress less timing than it should. Most OE tunes are so conservative that they never even get close to MBT to start with.

[graham bahr]

Originally Posted by Chucky

Is that really how you tune?!?!

.

its the best way when your mapping the big throttle high rpm load sites, the rest you can do under a steady load,

[graham bahr]

Originally Posted by Chucky

Not that many have knock control and even fewer have knock control that it is clever enough to have a beneficial effect. Typically, the sensor is ususally fooled by a similar noise and the car just drives around with 3-6 degress less timing than it should. Most OE tunes are so conservative that they never even get close to MBT to start with.

err just about every new car made now does have decent knock control,

in any case on modern production cars 3 degrees retard doesn't make a huge difference, a couple of degrees only get significant with very high c/rs, mega revs, turbos and alike

[greenamex2]

Originally Posted by graham bahr

err just about every new car made now does have decent knock control,

in any case on modern production cars 3 degrees retard doesn't make a huge difference, a couple of degrees only get significant with very high c/rs, mega revs, turbos and alike

I know for a fact (can't say how, might get some people in real trouble) the modern cars from at least one manufacturer are setup and tested on 'non standard' fuel so I would have to say that many of todays cars will take some advantage from the 'super fuels'.

However, as Graham said, production engines tend to be very tolerant of timing and fuel mixture so the gains are going to be small.

[Notso Swift]

Originally Posted by graham bahr

err just about every new car made now does have decent knock control,

in any case on modern production cars 3 degrees retard doesn't make a huge difference, a couple of degrees only get significant with very high c/rs, mega revs, turbos and alike

Err.. sorry Chucky, have to agree with Graham, even our Aussie Dinosaurs from about ’96- on have knock control, I will agree it is not very smart in the way it operates, but it is effective.
My wife has a Golf 2.0FSI, and I reckon it almost lives on the knock sensor when you run 95 Octane, but it does have an 11.5:1 CR. Some times it gets fooled though, and you can hear/feel a slight knock, but that is generally a good system.
Another fine invention from the people of SAAB before GM destroyed thier soul.

[Tim Falce]

So what about us mere mortals who have engines with things called carburettors and distributors, oh I have just gone into the 20th century so have an electronic ignition module but no knock sensors (what's one of them anyway)
how does superdupa unleaded or 99ron affect these engines and do I need it, I have my doubts. 4.2 jag engine with 9:1 compression if I am optimistic.

[Notso Swift]

.2 jag engine with 9:1 compression if I am optimistic.

If you can get more advance, you will get a better output, but, is it worth chasing a minimal amount of extra ommph? You need to answer that yourself. Race/Road,?Availability and cost are all factors You may get 3% better MPG, but it Costs 10% more...

[Tim Falce]

Originally Posted by Notso Swift

Race/Road,?Availability and cost are all factors You may get 3% better MPG, but it Costs 10% more...

It's readily available, is only 4% dearer and at 4mpg on track I don't worry about fuel comsumption too much.
My main concerns are will my engine run cooler and last any longer with 99ron petrol, I doubt I would notice any power benifit.

[graham bahr]

falcemob maybe but only if your engine is running on the absolute limit of detonation or pinking on your current fuel and ignition settings.

although in this case the higher octane rating is cheap insurance just incase something else is slightly out

[Tim Falce]

Graham, I have been using Tesco 99 since it first came on the scene last year or the year before and Optimax before that (although I never noticed any difference between Opti and regular). Just want to be sure I am not wasting my money although the extra £1 on a tank full hardly makes much difference.

[graham bahr]

with a 9.1 compression i wouldn't of expected your engine to be too fussy either way, my old 2002 engine wasn't bothered whether you feed it 97 or 98 octane despite 11.75:1 c/r although it has to be born in mind it was on full engine managment.

i've only ever feed the turbo optimax and dont plan on doing any different as that is what it was mapped on.

in all probability you are wasting your money on the full strength 99 stuff, but then the amount we burn and at only a £1 a tank difference you might as well put it in anyway and collect the clubcard points

[Al Weyman]

I had an interesting chat with a guy the otherday about my car after being a bit disappointed with the performance at Brands. He got me to fill in a form on his site about the car and engine and reconed with my Mallory points ignition and with the very very stout cam I am using I was running way way to far retarded although I actually have it set at 8 degrees BTDC. He reconned the engine can stand far more advance because of the killer cam and is not getting that degree of advance form the Mallory dizzy. He has offered to do me a custom curve along with an electronic ignition and MSD, but God knows what this will come to, probably too much.

So tell me Graham what about this computer stuff, is there an aftermarket system that will work on my car that you can recommend.

[graham bahr]

Originally Posted by Al Weyman

So tell me Graham what about this computer stuff, is there an aftermarket system that will work on my car that you can recommend.

until people make the switch to managemnt they cannot comprehend how much better engines are in every sense on it, depending on how restrictive your carb is, peak power may or may not go up but a guarentee you you will get more power throughout the rev range, better smoother running, economy, ok i know we are not in the economy game but no need to burn more fuel than we have to. engine management usually has the effect of making cammy engines far less cammy.

i've sited this many times but when my old 2002 was on a race cam with dizzy and carbs (correctly set up) it have a usable power band of 5000-6500 1 rpm below 5000 you didn't even dare think about opening the throttle or it would just sulk and go nowhere, same engine on management would pull full throttle from 2000rpm and the power held on to 7300

personally i would only recomend emerald as i've know dave walker for quite a while now, they are in business because they want to be rather than to make a mint and dave's totally down to earth no bull attitude

generally they supply ecus etc for DIY fittment but will fit them but be warned they are busy.

Al talk to dave walker at emerald, http://www.emeraldm3d.com/

at the moment they are converting a chevy lump in an ultima to injection, it was previously fitted with a carb and hot cam, and chucked so much unburnt fuel straight out the exhaust that you didn't dare light a fag within 300yards of it!

[graham bahr]

Originally Posted by Al Weyman

Mallory points ignition and with the very very stout cam I am using I was running way way to far retarded although I actually have it set at 8 degrees BTDC. He reconned the engine can stand far more advance because of the killer cam and is not getting that degree of advance form the Mallory dizzy. .

the trouble with very lumpy cams is that you do need lots of advance upto and after the point at which the cam really starts to work and you just cant achive that with a dizzy

if the leap to full engine management is too much it would still be well worth considering going on an ignition only management which can be done much cheaper, again talk to emerald

[Al Weyman]

Thanks for the advice Graham I will check it out, as you can see from 'the video' the car was chicking out a lot of unburnt fuel and I feel there is real scope for improvement because for a big V8 it has quite a narrow powerband and does not really get busy under 4000rpm.

[breezeblock]

i tried to get optimax for last weekends track day couldnt find a drop in scotland i have been told it was taken off the market because it screwed up too many subaru engines

[Notso Swift]

Can't agree with Graham enough on this - you will not believe the delivery and increase in torque and as a result power through the range. One of our members has just converted his car (with 1972 tech, a Holden Torana XU1 GTR) from triple Weber’s to a full Motec with TB. Now I know Motec is worlds best and is not cheap, but I use a $1000 computer of a similar spec to the Emerald unit (but an Aus produced unit) and I use to have an $4500 Motec and the difference is minimal for club racers.
Anyways
Extra power at the wheels was 2kW, so nothing, the dyno calibration would be out by more. At 5000 rpm he was up 18kW, at 6000 14 kW , a huge amount for a 3.3 Litre motor that was optimised over that last 10 years.

As far as the cost with TB's I am sure you can source something like these:

http://www.speed-technology.com/efi_throttle.html

which have the 4 injectors mounted close to the throttle plate. You even get to use the old manifold. That is the thing with Chev 350's - they aren’t called the worlds most popular motorsport engine for nothing! I am sure you could get something similar from E-bay in the US, plus a local ECU. ONLY get a local ECU, by the way, you will need support if it is your first time. And if you have a regular Dyno tuner, you are best to get something they are at least a bit familiar with, as you don't want to pay for their time learning. (I have stories!)
Only driving 4 injectors, and with reasonable revs (say 6500 = 13000 sparks/ min), (we have a few mega dollar Chev engined Holden’s running 8000 and putting out 620 hp or rotaries running 11,000, with twin plugs and wasted spark that is 22000 sparks/ min) means you can use a "cheaper" system because you do not need the fine resolution.
Where the premium systems really come into place is for turbo cars, but that is another story!

[graham bahr]

Originally Posted by breezeblock

i tried to get optimax for last weekends track day couldnt find a drop in scotland i have been told it was taken off the market because it screwed up too many subaru engines

curious, afterall its not exactly new on the market and why only scoobies,

it works just fine on my turbo race car, which gives 460bhp on pump optimax, without any additives or water injection, just a properly mapped ecu, which by the way also looks after the boost pressure

[Notso Swift]

Funny most I know steer away from Optimax in Aus, even though it is 98, like BP and Mobil, you seem to get a little more advance without a problem on BP/Mobil. Note that BP Mobil in Melbourne come from the same Terminal Station, but have different additive packs. Shell have recently (4 months) released a 100 which is an ethonol blend, which I will try next time my car needs to be dyno'ed. Problem is that it is very limited supply, literally 6 servo's in Melbourne, which is a city of 4 Million, and 8 in Sydney, which has 5 Million people (details are on the Shell website)


Re Subie problems
I think some of the street/cruise guys may work on the basis that if a little boost is good more must be better..
"...so that is what detonation sounds like, opps too late, must have been bad fuel, because 'SikDude' on the net runs 30 psi in his Hyundai and has no problems as he runs a 11.5 1/4 mile..."