Just wondering what you guys use as I'm putting my tank back in and it says 91, but how important is that?

as low as you can go without ping.
I ran 87 in my car 7.8:1 compression Ran better than when I used 89. was an absolute dog on 91.

the sticker in the tank is 91 Ron(Germain Standard I think) and when it's converted to Octane, how we measure our fuel in the US, it equals 87 Octane.
Joe's right, lowest Octane the car won't ping with, everything more leaves carbon behind when it doesn't completely burn.

I'm not sure but I think it converts to 89, not 87. Teeners ran on regular, "89 octane leaded gas" back then which is equivelant to mid/plus/89 today. I could be wrong on this since I've done no math but it makes the most sense to me.

Sense or not. I used what worked for me.
my new motor will be a whole new learning experience with octane.
10.4:1 compression

the sticker says 91 - so I use 91

btw - our gas stations offer 91, 95, 98 and some of them even 100 ...

Gustl

That's because the RON (research octane number) is higher than the R + N / 2 that the US uses
I think it translates to low grade fuel
Run as low as you can without pinging

I've been running 110 leaded the past year, and my car gas more snap than ever. When the engine was apart it looked very clean as well.

Where may I ask, can you get 110 leaded? Must be $15.00/gal!

Wiki

A few stations here carry it. YOu have to bring cans to put it in as they cannot pump into your car. I have 5 five gallon cans I fill up when I need. It is 6.25 a gallon. The 100 unleaded is 12.00 a gallon.

Joe's right on. We had a petroleum tech do a presentation at the Mid West Renegade Festival back in '96 and he said the same as Joe.
People started calling high octane "high test", which makes you think it's better right? Maybe for an old 327 Chevy with 12/1 compression.

The higher the octane the slower the burn. The higher octane, the more additives the fuel has in it, which ends up on the top of your piston and on you cylinder head. The more carbon build up you get means it raises the compression and you get carbon hot spots on the piston or cylinder head which results in pre-ignition, so you run higher octane fuel and the endless cycle continues.

Say it ain't so, Joe! My new car is "poppy" with my foot off the accelerator while in gear and maybe it would run better on LOWER octane?? This I gotta try! Thanks,

Paul

Cheapest shit I can find!

Hmm... Wonder if it's as harsh as the Utah shit that Gumby likes so much!

biz

We put 92 octane in ours. Previous owner said he put 87 octane in it once and it knocked real bad, so we just put premium in it.

Zach

Check out my previous post on this:

http://www.914world.com/bbs2/index.php?sho...mp;#entry805978

Porsche recomends ROZ91 whcih translates to 87 here in the US. No need for anything more than that unless your running something modified.

BTW: I always hear I have a fast 914 and am asked what mods have been done. I use 87 here in the US and think a properly maintianed engine and decent driving skills are way better than paying for the higher grade fuel unnecessarily. Save your money and put it into other areas of the car.

110 leaded race gas

[[/quote]

Say it ain't so, Joe! My new car is "poppy" with my foot off the accelerator while in gear and maybe it would run better on LOWER octane?? This I gotta try! Thanks,

Paul
[/quote]


I would say that doesn't have anything to do with the fuel. Sounds like an exhaust leak to me.

My '76 2.0L with FI runs just fine on 85 octane, which is regular at our altitude. It is also what my independent Porsche shop recommended.

98 RON all the time, but it will run fine on 96. The 98 costs about US$1.20 per litre.

Same here... anything more is just a waste of cash.

Air cooled engine + hot climate. Premium for me.
Mark D.

Hmm, I've always ran premium, which is 93 octane here on the east-coast.
Question now is how do you get all the carbon/additive buildup out of the engine? Should I use some kind of upper engine cleaner or BG44K?

Anyone have any suggestions?

I'll fill up with 87 next time I need gas, see if it pings (BTW my car is a carb'd 2.0 with mild mods).

I've always run 93 or higher. I don't have any carbon bldging up in my motor.

I run 87 octane. No problems - it IS a VW motor after all. When I was in the Army (decades ago) I used to swipe the 5 gallon reserve cans of 65 octane MOGAS from my Jeep & put it in my 65 Beetle. Ran great & free.

Yeah, I know it was "not quite right", but the bastards yanked me out of college! All because I had a 0.8 accum. See "Animal House". I got over it.

89 seemed to work, and I think was recommended by the mechanic as well. However I do agree it's all a waste of cash which could be used on sooooo many cool parts.

We have some gas stations in California that offer 100 Octane at about $5.50 USD a gallon.

Tracks sell several grades up to 110.

I occasionally buy 5 gallon cans of 110 leaded race gas at a local speed shop for about $9.00 USD a gallon.

Wow, trick racing 110 up here is only 6.25 a gallon. At the track there is Sonoco and others you can buy, but they sell trick near my house.

Umm, doesn't this belong in the "tell us your sins" thread?

Paul

I run 93 since this is the high grade fuel here. I will go down as the engine can handle it. If you can put lead aditives in your fuel do it; specially on new engines. Use the grade that dosen't make your engine ping when all is tunes up. A little Marvelous Mystery Oil dosen't hurt either in your fuel to get rid of carbon deposits.

I run 93 in my modified 2.7L/6

Seems to me that guys with stock teeners run the regular more and guys with built engines (ie higher compression) run premium. Does that sound like a reasonable statement?

Yes you are correct brother except for me. I run premium to mix with all the oil it burns

Actually it is due to compresion ratio. When one gets to or passed 9:1, higher octanes are needed to keep air/fuel mixture from combusting ahead of timing as in pinging or preigniting.

Dan,
you can get away with less octane at altitude. (and on cool days)
brant

Having only ever owned modern cars before I bought my teener last year, I've been feeding it premium. The car seems to run great, but apparently I've been suffering from a common minconception, that premium fuel is better/cleaner/whatever than regular. Maybe it'll run even better on regular! I love this site, I'm always learning stuff.

That said, I want to try out some 87. A lot of people have said something along the lines of "as low as you can go w/o engine knock". So what exactly to I listen/feel for? Engine knock is not something I've ever experienced, at least not as far as I know.

Because I understand it's a consideration, I'm driving a stock '74 2.0 @ 3500 feet.

And please, be gentle...like I said, I'm learning.

Thanks

You should be fine running reg. Just make sure you are not going to stations that have chitty gas. I swear by Chevron, but shell and 76 are good. I have had to drain a few customers cars who said they only fill up at Safeway and other club stations. The detugents are what is really not good for these old cars. That is why I run 110 leaded in my six. So, go to Chevron and fill with reg and see how it goes. If it knocks it will sound like a pinging noise. It shouldn't though.

I used mid grade until I realized that mine ran as well on regular Chevron as anything else. I've got a 4 cyl 2.3.
BTW: Porsche recommends the Techron as a FI injector cleaner.

87 in the DD's, 91 Shell in everything else (including ATV, lawn tractor, weed eater, etc) because it has no methanol in it up here.

For the past 13 years I use premium . Never had a problem whit my car .

I run 91 octane with a little Marvel in tank. The premium gas is to avoid any possibility of pinging and the Marvel is to keep the valves clean. I have heard that the premium fuel does not contain any methonal in it and some lower grades do. I am not an expert with this, but that is what I have seen labeled on the pumps. With old fuel systems I think methonal in any amount is taboo. Just my opinion.

93 nothing less for the turbo teener

Back in 2007 when this thread last came up I was running 91. Now I'm still running 91.

I've read that newer computer-controlled FI engine management systems may take up to three tanks of fuel to fully adjust to optimum settings, not sure about early 70's technology?

I use to run 87 in both of our [stock] 914s, but run mid-grade in the recently built 2056 (9:1 CR).

I agree, you can run a low grade but avoid pre-detonation, and watch your temperature readings. If you change the grade of fuel, be prepared to readjust your timing (and jetting if running carbs) to account for the difference.

I don't want to use the ethanol enhanced fuel so I use high test which is around 91 octane where I live, the regular 87 octane does have the ethanol and I really want to stay away from that stuff. The extra few cents per litre is worth it to me, just for piece of mind, I want to go for a trouble free drive, not worry about what's in the tank. I find a lot of the older mechanics all use 91 octane, they feel it is the better way to go, sometimes experience is a good indicator even though they may not have graphs and computer printouts to back up what they are saying.

Ian Stott
Moncton
Canada

I believe with current US emissions (especially california)
all grades of gas should now have ethanol

if I am wrong then good for you
but I know in Colorado this is true and all grades of gasoline have ethanol.

I thought this was the federal standard in the currently required, subsidized, energy and fuel plan that Mr. Bush left for us when he signed it into law in 2007.

So the question really is about what grade of fuel your motor and octane require
I don't believe there is any way to avoid the ethanol (not methanol as one poster mentions)

You have to search to find it but if you are lucky you can still get ethanol free gas.

I run 92 Sunoco (etahanol free) when i feel like driving to the other side of the valley to get it. If I don't (or cant) get all the way over there to get it ill run 87,88 or 89 depending on what the station has.

and I would guess that one station that you use for ethanol free, probably has a label right on that pump that states it is not legal for highway use.
I think they are selling it as an "offroad use" fuel

if I could get it, I would do the same.
maybe with the draught someone in washington will realize they need to repeal this law. Although I doubt the corn growers would feel that way.

I am running 91 in my 2056, I also use mystery oil in every other fillup.

Runs like a champ