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Tue Nov 23, 2004 3:26 pm

1600dp 87 octane. No ping, no worries.

My granny used to pull up to the pump and say"give me the good gas!" because it cost more, so it must be better. Nice to hear the same logic lives on.

Wed Nov 24, 2004 10:05 am

Bruce wrote:
Its amazing how you can make yourself believe the opposite of what is really happening.
If you put higher octane fuel in than your engine requires, you will make LESS power. The reason is that high octane fuel releases less heat when burned compared to low octane. This is partly how it resists pinging.
If you think your engine runs cooler, it can only be due to the fact that you are making less hp.
However, when you put that low heat fuel into a high compression engine, the overall power produced is greater, due to the higher volumetric efficiency of a high compression engine.

Your right, it is amazing what the mind can do.

Maybe I worded my response incorrectly, isn't it true though that a higher octane gas can improve accelleration?

I "think" I am noticing a difference in the sound of my engine as well, is it REALLY in my mind??

Wed Nov 24, 2004 8:20 pm

FatboyOverthrow wrote: i run regular.
all higher octane really does is keep your engine from knocking, so if your engine doesn't knock when you use regular, there's no reason to use anything higher.

Once upon a time this topic came up here and as always simplistic answers and myths get bandied about, the young may take it as Gospel only to find out the hard way its only partially true or comes with other consequences... Without proper training into the theory cause and effect of internal combustion engines you cannot have a proper understanding about what takes place, generalities and old wives tales get people into real trouble.... ;-)

Put quite simply by the time audible pinging/ knocking is heard the damage has begun... There is such a thing as inaudible pinging and as the name implies you'll never know its happening, its a silent killer that does damage over a period of time but shortens engine life greatly.. So perhaps we should talk about preignition which leads to detonation/pinging the possible causes and what to do........

Jim-

Wed Nov 24, 2004 9:26 pm

my 1600 sp with kads runs on 87 but if i put 89 or 91 in. it will start up and idle a little quicker (kads with no choke) and shut off better when i use 89 rather then 87. i dont feel a difference from 89 to 91

Thu Nov 25, 2004 4:28 am

holmstedt wrote:
Your right, it is amazing what the mind can do.

Maybe I worded my response incorrectly, isn't it true though that a higher octane gas can improve accelleration?

I "think" I am noticing a difference in the sound of my engine as well, is it REALLY in my mind??

If you put high octane fuel in a low compression engine you will make less power. This is because hi octane fuel releases less heat than low octane.

Here's what led me to figure out what's happening.
Years ago a friend and I would always take our low compression street cars to the local drag strip in Vancouver. Our cars were very consistent. Once a year we'd also go down to Seattle and run at the track there. Both tracks are exactly the same distance, both level, and both at sea level. They are only separated by about 100 miles as the crow flies. Our cars were always a lot slower in Seattle than Vancouver. For 3 years we observed this. Then my friend saw an article in Hot Rod magazine dealing with fuel. In there they quoted the heat released during combustion of various octane levels of fuel. The higher the octane, the lower the amount of heat released. This seems impossible, right? The amount of heat released is only one factor in how an engine makes hp. A larger effect on hp output is the compression ratio. If you have high compression and high octane fuel, you will make more power than a low CR engine with low octane fuel.
The reason our cars always went slower in Seattle was that there was a gas station near the track that sold really high octane fuel at the pumps. I was using 100 octane and my friend was using 112 octane. Once we realized our mistake we stopped buying the high octane. The next time we ran at Seattle, our cars were both slightly faster than in Vancouver, rather than being a half second slower. Now when I run at the track on street night, I only use 87 octane.
The ETs at the track are purely objective, they don't lie. A seat-of-the-pants feel is so subjective.

Here's how you can prove it to yourself. Next time your car is near empty, ask your wife (?) to take it in and fill it. Tell her to randomly switch between low and high octane while you try to tell the difference.

Thu Nov 25, 2004 6:47 am

Bruce wrote: philip1 wrote: hi, you mite of gt a better answer if u sed wot engine you hav. vw heads wer designed to run on low grade fuel! FACT.

the unleaded head conversion is a big con, this is coming for vw in germany.

but i rub i thnk 91 in a 1600 dp
Hmmm, I thought they spoke English in Wales.......

me too. :?

Thu Nov 25, 2004 2:04 pm

I accidentally ran my engine on cleaner/diesel mix once. This was when I was test-running the engine (out of the car) after rebuilding it and I got the cans mixed up. Woops! But it ran fine, so I dont think the octane will totally kill your car if you use too low a grade. That's my idiot story for today.

Thu Nov 25, 2004 4:54 pm

after 26 years of driving 6 VW's for over 300,000 miles I only use 91 octane, which is the minium that the factory recommended in all VW's

Thu Nov 25, 2004 5:58 pm

According to Bartnick over at type2.com....

"There seems to be much confusion in the VW world about which octane gasoline should be used with air-cooled Volkswagen engines. Many people say 91 octane. Those people are technically right, as long as they are not in the US.

Volkswagen recommended 91 RON octane gasoline for use with their air-cooled engines. However, here is where the confusion sets in: The RON method of octane measurement is not used in the United States. In the US, a different method entirely is used, called the CLC method. The number that results from this method is the average of the RON octane number and the MON octane number, so (RON + MON)/2 = CLC octane number. This is the number that you will find printed on a yellow label on gas pumps in the United States.

91 RON octane is equivalent to 87 CLC octane. My source for this claim is the Volkswagen owner's manual for both the 1978 Bus, the 1974 Karmann Ghia, and the 1981 Vanagon.

Therefore, if you are buying premium gasoline in the US because you think you need it, you are mistaken and are wasting a lot of money. A stock VW engine with stock ignition timing, etc., will run without problems on regular 87 CLC octane gasoline in the US.

Octane has to do with the resistance of a fuel to preignition, that is, detonating in the combustion chamber before the spark plug fires. This event is destructive to cylinder heads and the VW air-cooled engines are especially vulnerable to damage caused by this "pinging." If you are experiencing pinging with a stock engine, there is most likely something wrong with your timing setings. Use your timing light to check your ignition timing persuant to my article on ignition timing. A fuel with a high octane number is more resistant to preignition than a fuel with a lower octane number. The only reason you would NEED high-octane fuel would be if you had a high-compression engine, which you don't if you have a stock VW air-cooled engine.

Some people like to use high-octane fuel because they feel it gives them better gas mileage or perhaps cooler engine temperatures. If you like to use high-octane gasoline, go ahead. It won't hurt anything except your wallet. However, this article is just so that you will not buy high-octane gasoline under the mistaken impression that it is necessary because VW recommended it. That's just not true. "

Sean Bartnik

Sat Dec 27, 2014 5:58 pm

This would also apply to a 1999 mexican beetle with a 1600i or fuel injected?
I got today 23 mpg doing between 75 to 80 mph with a roof bike rack and 2 bikes and about 500 pounds worth of humans and gear.

I was using 93 just because I wanted to try but I would definitely want to be able to use 87 if possible.

I just installed a head cylinder temp gauge and the temp was about 250 while driving at 75mph, but it went up a bit more while driving at 80mph. I have the cylinder head temp sensor in cylinder #3.

Sat Dec 27, 2014 7:15 pm

RON...research octane number is a worldwide octane number...not used in USA or Canada.

MON...motor octane rating...is 8 to 12 less than RON.

AKI...anti knock index is used in the USA. Regular, 86 or 87 octane is perfect.

Google RON to learn more.

Sat Dec 27, 2014 10:08 pm

My 65 bug doesn't care, it can run on rat piss!

Sat Dec 27, 2014 10:18 pm

Been using 91 just fine but now I have to experiment...

Sun Dec 28, 2014 1:47 am

How much ethanol is in your lower octane fuels? In Oz it's a lot higher percentage, the ethanol will gum up the carby and eventually stuff the older diaphragms and fuel lines. With lower performance four cylinders I've had anything to do with they run cleaner and better on premium. They also get better fuel consumption with premium, I have recorded fuel use over various trips and usually get about 15% better mileage with premium which more than makes up the cost.

Sun Dec 28, 2014 5:45 am

TimGud wrote: I run 87 octane.

Same here.

Sun Dec 28, 2014 5:47 am

Sorry for the double post.

Sun Dec 28, 2014 6:26 am

This needs a wiki, I think.

If you are comparing similar blends of gas/ethanol, you won't get better mileage on higher octane fuels in a stock ACVW. Claims to the contrary inevitably fail under controlled testing.

87 octane in the US is fine for the air cooled cars.

I run under spec gas in SWMBOs BMW as she has a 8 minute commute in local traffic and has a grandma foot. I worry that the second half of the throttle body has never been used sometimes. She had 240k on the original clutch on the last car we sold.

Sun Dec 28, 2014 4:24 pm

Regular is all you need. Anything else is a waste of money.It's in the owners manual.

Sun Dec 28, 2014 4:34 pm

wellcraft wrote: This would also apply to a 1999 mexican beetle with a 1600i or fuel injected?
When you open the gas filler door, there's a label that says to use "Magna Sin". In Mexico, this is what they call unleaded. And up until about 2000 or 2001, the only unleaded gas available everywhere in Mexico was 87 octane, measured on the same scale as the rest of North America.
IOW, your engine was designed to use 87 octane.

Mon Dec 29, 2014 3:00 am

Do you have any ethanol in 87 in the States?