Octane On Fuel

**explorer** · 11-30-2003, 03:39 PM

Fellows I know this is not a detailing question but I am a little confused about Gasoline Octane.

What is the difference between all the different Octane levels?

Does one make the car run better than the other?

Can I use the higher Octane even if the car manufacturer says to use the lower Octane fuel?

Can you help me with these questions

**Dinzdale40** · 11-30-2003, 04:02 PM

Octane is simply the burn rate of the fuel.

One octane level isn`t any "better" than the other, the only reason to run high octane gas is if you have high compression ratios.(this includes turbos, superchargers, nitrous, along with changing cylinders or heads- anything that can be done to either get more air and fuel into a given area, or to get air and fuel into a smaller area)

**Quickstrike** · 11-30-2003, 05:56 PM

Depends on the car, most German cars recommend a 91 octane, while others are actually optimized to run at a lower octance. I believe the new mazda 6`s actually run better on 88 octane, or you will see no difference at all with a higher octane because it was "optimized" to run better on lower octane.. The best thing to do is look in your drivers manual and see what they recommend.

Some people with exotic cars find even the "premium" gas in their community is not enough to take full advantage of the cars capabilities.. for this people often use octane boosters..

You can read more about home-brewed octane boosters on this site: http://patriot.net/~jonroq/Tech/octane2.html here they use toluene.

**imported_BretFraz** · 11-30-2003, 06:33 PM

A higher octane fuel burns cooler. The reason some automakers recommend or require a certain octane fuel is due to the combustion chamber temps in their engines. Higher c.c. temps need a fuel that burns cooler, otherwise preignition (pinging) occurs.

If you are not sure what octane to use, start with the mfr recommended octane and use it for a couple of tankfuls. Stick with the same brand and try to buy at the same gas station to maintain test consistency. Pay close attention to fuel mileage as well as overall performance. If you hear excessive pinging from your engine, try the next highest octane and repeat the test.

If your engine still pings on the highest octane available, your engine has other problems that gasoline will not solve. Discover what the problems are and solve them instead of trying to cover them up.

Here`s an example of how using the wrong octane fuel can cause problems:

I have a new GMC Sierra with the 5.3L V8. My previous car, a Saab 9-5 with a turbo V6 engine, required the use of premium fuel. So I figured I`d use premium in the truck as well to avoid any problems. After an oil analysis I discussed my fuel usage with a lubrication expert and he told me *not* to use premium fuel in my engine. He said deposits can form on top of the lightweight pistons in GM`s modular engines by using premium fuel. The combustion chamber temps need to be high enough to prevent deposits. So using premium fuel in my truck would not only cost me more $$ but it would create engine problems for me down the road.

In short, use the octane recommended by the automaker. If you are having engine problems, fix them instead of covering them up by using more expensive fuel.

I hope this helps. Good luck.

**explorer** · 11-30-2003, 06:56 PM

You guys are the most

this is what I call a fountain for information:xyxthumbs

There is nothing wrong with my cars, but I was wondering if by using a higher Octane fuel they would run better ,or if it was better for the engine. :xyxthumbs Ford told my wife to keep using the lower Octane since it is what the Manufacturer recomended, wich we will do

I`ll also tell my father-in-law to go back to what his Manufacturer recomends:xyxthumbs he has been using the higher Octane because someone told him that the engine lasts longer running on high Octane:nixweiss

Once again thanks:wavey :wavey

**MBZ 500E** · 12-02-2003, 12:09 AM

Here`s a great website which describes benefits of Octane on the right type of vehicle. It also goes into detail about "Rocket Fuel", better known as Toluene as an octane booster. http://www.gnttype.org/techarea/misc...explained.html

A friend of mine with a (500E) dynoed on a DynoJet with 91 Octane and 94 Octane, the powerband was not only smoother with 94 Octane but it actually increased by 8Hp! These runs were back to back. This is on a 10:1 compression, a turbo or supercharged engine should typically benefit even more.

But not all engines like Octane. I remember reading a magazine article showing a test done on the Honda 4 Cylinder engine and the higher Octane actually reduced the Hp of the engine. Best suggestion is to use whatever the manual suggests and stick with it.:xyxthumbs

**AD Qi** · 12-02-2003, 08:21 AM

I have a stock 2001 BMW Z3 2.5 L engine. I have noticed better performance and milage from one tank of gas to another. I purchase at different stations. Sine my car is stock and no mods, will I benifit from adding Toluene to my tank? Also my tank is only 13 gallons max. How much Toluene should I add. I would love to get more out of this lil roadster.

**imported_garyo** · 12-02-2003, 09:35 AM

FredsZ3,

Your observation of different performance from different gas is very real. Not all gasoline is blended the same. Some are better than others. Find what works the best for your car and use it.

Your 2.5 NA Z3 was manufacture red with 91-93 octane gas in mind. Personally I would stick to this on a normal use basis. There are many thoughts on both sides of the fence with regard to octane boosters and their effectiveness. The arguments range from octane boosters being totally safe for your engine and effective to them being total snake oil. Most discussions don`t even take into consideration, that some engines are more restricted by the intake, exhaust and fuel management systems than by the octane of the gas burned.

Then there is a completely different discussion on effectiveness of the different octane boosters. Most have some downside that has to be weighed. The cost of over the counter octane boosters is quite high and their effectiveness is questionable. Many argue that once added to the gas they are unstable and their effectiveness dissipates with time.

If you really want higher octane gas then seek a local gas station that sells it. Depending on your location there may be some stations that sell "race" gas which can sometimes have octane ratings of 100 or better. You can mix this gas with your regular premium gas to achieve your desired octane rating.

**MBZ 500E** · 12-02-2003, 11:03 AM

FredsZ3,

To stay on topic we should start another thread discussing the types of Octane Boosters.

93 Octane available at most stations on the East Coast should be more than sufficient for the Z3. If you want to try higher octane the safest bet as Brian suggested is to find Unleaded Racing Fuel and blend it with your 93 Octane. Sunoco sells 5 Gallon Containers of 104 Octane Race Fuel, you`ll need to research and make the correct calculations to determine final octane after it`s added to your 93 Octane Gas. Search online for the Sunoco distributors in your area.

**imported_Faceman** · 12-13-2003, 05:30 PM

Hi,

When I was in the USA a couple of months me and my Dad were moaning about how much cheaper your fuel is that here in the UK. you guys were paying about $1.70 a gallon - we are paying about $7-ish a gallon.

But then we noticed - and please don`t take this the wrong way, as it`s meant in a good-natuered manner - how crap your fuel is! very cheap, yes, but still crap!If memory serves me right, we were filling up with something like 83ron or 85ron. No wonder you get such sh1tty mileage from your 4.6 v8`s

In the UK the lowest ron we can buy for even the most bog-standard car is 95ron. We then step upto 97ron as the premium fuel. Personally, my car`s recommended fuel is 98ron, which only one chain carries in the UK, but I have several gas stations with it in the local area.

In fact we were talking with a cab driver one night, and he had a 4.? litre car. He put his foot down in a bid to impress us and to paraphrase "that`s the 4.? engine giving me 220-ish horsepower. Ain`t that impressive". I have a 2.0 straight-4, unmodified engine, giving out about 180-ish bhp, so no, I didn`t think it was all that impressive.

BUT SAYING THAT - i bet you Race Octane fuel is still half the price of our 95ron fuel. Ho Hum.

Horses for courses, i guess.

Cheers,

face

**Spilchy** · 12-13-2003, 05:48 PM

I have been using Shell Premium (93 Octane I believe) gas in my wimpy 96 Honda Civic DX for ages now.

My car is a cream puff receiving regular servicing and driven like a little old lady around town. I just had the 30K major tuneup and had the fuel system and engine flushed and cleaned.

You mean to tell me that I am causing engine problems?!

:scared

I`m only paying like an extra dollar or two per fill-up and only need to fill the tank twice a month so the extra expense is meaningless for me.

I am shocked to hear that I could be causing more harm then good!

Should I use the middle grade fuel? My Honda has never had regular. Please explain to me!!

**imported_Faceman** · 12-13-2003, 05:51 PM

Your shell premium is 93ron... Shell is where I have to get my 98ron... Wow.

On the clio site that i visit, I`m led to believe that an engine will only take advantage of a higher ron fuel if it has an advancing ecu that can adapt itself to various types of fuel. I`m no mechanic, so this may well be BS.

Face

**butchdave** · 12-13-2003, 05:52 PM

Originally posted by Faceman

Hi,

When I was in the USA a couple of months me and my Dad were moaning about how much cheaper your fuel is that here in the UK. you guys were paying about $1.70 a gallon - we are paying about $7-ish a gallon.

But then we noticed - and please don`t take this the wrong way, as it`s meant in a good-natuered manner - how crap your fuel is! very cheap, yes, but still crap!If memory serves me right, we were filling up with something like 83ron or 85ron. No wonder you get such sh1tty mileage from your 4.6 v8`s

In the UK the lowest ron we can buy for even the most bog-standard car is 95ron. We then step upto 97ron as the premium fuel. Personally, my car`s recommended fuel is 98ron, which only one chain carries in the UK, but I have several gas stations with it in the local area.

In fact we were talking with a cab driver one night, and he had a 4.? litre car. He put his foot down in a bid to impress us and to paraphrase "that`s the 4.? engine giving me 220-ish horsepower. Ain`t that impressive". I have a 2.0 straight-4, unmodified engine, giving out about 180-ish bhp, so no, I didn`t think it was all that impressive.

I`ve been waiting for someone to fall for this one! US and UK fuel is in fact quite similar in terms of octane level - but the measurement system is slightly different.

4l vs 2l - well it depends on the state of tune. A tuned 1300 mini will provide the power of a 1.9l. If you have a 4l engine, you can afford for it to produce low power but on the other hand it typically produces a lot of torque

**imported_Faceman** · 12-13-2003, 05:56 PM

Well, I`m glad it was me who fell for it! You`re right about the measurement system being slightly different - 3 times the price is different

I do have a lot of torque (from about 3000rpm to about 7500rpm). Not keen on the french but you have to love their hot hatches. Most people are surprised when a clio races past them at any speed!

cheers

Face

**imported_Faceman** · 12-13-2003, 05:58 PM

PS are you saying that if i had my engine tuned/modified I cound get even more power out of it? It`s the renaultsport engine.

if you have some links or stuff, i would love to know... MORE POWER. there`s some M3`s around here i`d like to scare

Face