Motor Trend Posted this article about what type of gas should we fill in our car. they mentioned about Supercharged car has to fill premium Gas and here is the reason why!


"Today's engines use highly evolved versions of a device called a knock sensor to adjust settings automatically for low-octane gas. And more engine control computers have adequate memory to allow separate sets of instructions for various octanes. The engine control computers keep pushing to maximize performance on whatever grade of fuel is used.

Extreme pressure inside the cylinders causes knock, which is the sound of the pistons literally rattling inside the cylinders. Too much too long can damage the engine. A little now and then won't.

The only modern engines that should really need premium are those with superchargers, which force-feed fuel into the cylinders. "You're driving along and just tramp the gas and the knock sensor cannot sense the knock fast enough in some cases," because the supercharger boosts pressure so fast, says Bob Furey, chemist and fuels specialist at General Motors."
To view the whole article:
Motor Trend

 

The only whaaa? Where? Huh?

You'd think someone who writes for Motor Trend would be at least vaguely familiar with automobiles, all of which require premium fuel. Well, with the exception of a few American cars and the odd base-model Accord. Of course, the stupid jerk is probably so smitten with his 86 octane guzzling Escalade that he's not even aware that cars are even an option in the US.

 

"You'd think someone who writes for Motor Trend would be at least vaguely familiar with automobiles, all of which require premium fuel. Well, with the exception of a few American cars and the odd base-model Accord."

vespa, explain yourself! You seem to me saying that premium fuel is required for such fine machines as the Kia Sephia and Hyundai Excel.

 

Oh, had to play the Korean card, did you?

But seriously, the majority of Japanese, German, British and Italian *cars* do require premium fuel. Forced induction or not (and I'll even give him the benefit of the doubt on his omission of turbocharged engines)

 

Any engine with external (turbo/supercharger) or internal (high compression ratio) means of increasing volumetric efficiency can benefit or even require premium fuel.

An engine equipped with a knock sensor can be made to respond very quickly to a knock event whether or not is has forced induction. This is mostly a case of ECU sophistication and programming.

A case can actually be made for a non-boosted high compression engine needing a faster knock retard system than one that is turbocharged, because while a turbo setup needs some time to make boost (and this happens gradually in the grand scheme of things) a high-compression engine has it's knock producing potential available at the first crack of the throttle.

 

Vespa - this has been discussed here at length before. I believe MOST cars are made to run on 87 or so and therefore will not with regular unleaded gas. And adding higher octane probably won't increase performance. Unfortunately, I can't explain in detail why...I'll let someone else who knows the technical stuff explain.

 

quote from the article: "Automakers say they don't test premium engines on regular to check the difference, but some auto engineers estimate that power declines roughly 5%."
5% of 163 is about 8 HP.
I've seen people spend more on performance parts that give 8 or 9 HP, than what they'd spend on the difference between regular and premium gas for 2 or 3 years.

 

premium is good for a MINI S, MINI is not necessary to be premium gas. this is my point. it you are MODS fan you should use premium anyway. who race with 86 and 87 must be dum. hahahaaa

I can smell burn in this topic. calm down everybody, it just a article. not all people buy cars to push to limit, not all cars necessary to use higher grade gas. this is the point of the article means to me.

 

My general feeling is that high compression engines, especially super/turbo-charged ones, need the added octane to prevent detonation (knocking). When running on premium your MINI's engine will be most powerful and efficient. The buck or 2 you save when filling up doesn't really add up to savings as the decreased mpg will make up for the perceived savings.

For those of you interested in race gas but have no local outlet, it is possible to add octane to your tank. Xylene and Toluene, both readily availble from paint/hardware stores and can be mixed to create blends of whatever octane you would like.

When I was a research chemist, we had about 10 gallons of expired xylene and toluene to dispose of. I disposed of it by blending it with premium gas to create my own higher octane. Those "Octane Booster" bottles you see in the stores are nothing but blends of xylene and toluene. The only problem is that you need to get about 10-15% toluene/xylene into the gas and it would take one heck of a lot of bottles to do this.

I would add a single gallon of my xylene/toluene mixture to a nearly empty tank in my VW GTI 1.8turbo and was very please with the results when I filled the rest with pump gas. Too bad I don't have a source for free pharmaceutical grade solvents anymore! :???:

Anyway, here is an explanation I found that is pretty good, despite the website it comes from! I'll take no responsibility for anyone doing something as crazy as trying to make your own race gas, but I will pass on this helpful info to those interested.

Octane Explained Here

 

And if you take that MCS to 7,000 above sea level (where I live) you don't need the premium because there's not enough oxygen to use it efficiently ... or that's what the stealer told me!

 

>>My general feeling is that high compression engines, especially super/turbo-charged ones, need the added octane to prevent detonation (knocking).

My credentials are not that of a chemist or scientist, but with a career in the retail automobile business it became my understanding that you should burn the lowest octane gasoline that the motor can operate on without pinging (pre-detonation). It is also my understanding from lessons learned the hard way that a normally aspirated gasoline engine that is fitted with a turbo or supercharger without the benefit of lowered compression will not enjoy longevity of operation.

 

Yucca,

Very good post ! I did read the whole article, and found it very informative. Based on the formula, AND a MINI Cooper S' tank size, AND figuring the use of 93 octane pump gas, what / or how much Toulene should be added ???

Further, how much do you feel it is safe or good to add on a more moddified car that has more HP and boost ?? Ex ; pulley, intake, throttle body, header, exhaust etc... etc ......

 

One further point. With higher percentages of Toulene in the mix, is there any more of deposit left in the combustion system becaus of it.

As higher octane fuels are perhaps slower / or slightly more difficult to ignite, I could start to see the benefit of a stronger spark signal as found with some aftermarket ignition add on's such as MSD Ignitions OR Ignition Systems / M7's Plasma Booster for the MINI Coopers. Would you agree with this ?

 

Do NOT blend your own racing gas unless you can afford to replace/rebuild your engine. And avgas (aviation gas), while high octane, is not suited to the demands of high performance cars... the additive package in avgas is designed for low RPM engines operating at very high altitudes.

There is a very detailed thread on race gas recently on this site:
Search for "Cam 2" or "Cam2".

The two biggest producers of 100 octane nolead are 76 and Sunoco. Both are distributed nationally. Sun can give you their closest dealer by dialing 800-RACE-GAS.

If you're in New England or the northeast, and have tech questions, call us.
My company distributes both brands. New England Racing Fuel 860-673-9555

 

Valid point 200mph, but was just asking questions for some others out there. Further, here is a link for Sunoco's Race Gas Race Gas

 

Jigster, I would start with about 1/2 gallon of toluene/xylene in a full MINI tank. This is about a 5% of the total volume of the tank. You could go as far as a gallon of Toluene/Xylene if you wish, but best to start slow and see how it feels.

I would not put more than 15% total volume of toluene/xylene in the tank. Of course, buying race gas is easier, but experimentation at home is a lot of fun if you are careful and have some knowledge of how to handle volatile chemicals safely.

Just for fun, I will go out and buy a gallon of Toluene or Xylene and see what I find out by the seat of my pants in my stock MCS. With computer programming to compensate for the added octane, the differences would be more significant.

As 200mph reminded us, doing such things on your own has its own potential hazards and you are at your own risk doing such things.

Definitely do NOT use Aviation gas.

 

And here is the link for 76's web sight which also has a state by state locator on it , the same as Sunoco does ! 76 Race Gas

 

Yucca, with the toulene / xylene mix, are you saying to go with a 50 / 50 mix of each, starting with a 1/2 gallon total to start ? To my knowledge, they are sold seperately, correct ?

 

Here is a handy chart breaking it down further, based on 76 100 octane, mixed with 92 octane premium, just as an example of course ............

76 RACING GAS --UNLEADED
100 OCTANE
GALLONS
1 2 3 4 5 6 7 8 9 10 11

76 1 96.O 97.3 98.0 98.4 98.7 98.9 99.0 99.1 99.2 99.3 99.3
s
u 2 94.7 96.0 96.8 97.3 97.7 98.0 98.2 98.4 98.5 98.7 98.8
p
e 3 94.0 95.2 96.0 96.6 97.0 97.3 97.6 97.8 98.0 98.2 98.3
r
G 4 93.6 94.7 95.4 96.0 96.4 96.8 97.1 97.3 97.5 97.7 97.9
u A
n L 5 93.3 94.3 95.0 95.6 96.0 96.4 96.7 96.9 97.1 97.3 97.5
l L
e O 6 93.1 94.0 94.7 95.2 95.6 96.0 96.3 96.6 96.8 97.0 97.2
a N
d S 7 93.0 93.8 94.4 94.9 95.3 95.7 96.0 96.3 96.5 96.7 96.9
e
d 8 92.9 93.6 94.2 94.7 95.1 95.4 95.7 96.0 96.2 96.4 96.6

92 9 92.8 93.5 94.0 94.5 94.9 95.2 95.5 95.8 96.0 96.2 96.4

10 92.7 93.3 93.8 94.3 94.7 95.0 95.3 95.6 95.8 96.0 96.2

11 92.7 93.2 93.7 94.1 94.5 94.8 95.1 95.4 95.6 95.8 96.0

I also submit the disclaimer that I do not know if this table has been calculated correctly, OR take any responsibility for it's use ! I found it on the web !!

 

OK,OK, here is a much better chart to look at ...............

 

Racing gas. Xylene/Toluene. This is getting pretty weird. Use premium or don't. Just motor.

BTW, don't use av gas. Its leaded and we pilots needd what little there is left.

miniwanna