dcrasta

Throw in a bottle of octane booster. Its about 4 bucks and treats 20 gallons. I daily drive my car and during the week I run 87 + Octane booster, and when I go to 93 on the weekends its a totally different car.

davek9

Thanks Jim, I keep forgetting that the early ones were just a bit over 200 hp and not 300 hp like the later 16v euro's.

FLYVMO

Barry,

As RPM's increase, the engine is less "sensitive" to timing (within reason) and/or lower knock rated fuel grades. Most likely you are experiencing some knock/pinging during low RPM/high load conditions, as you mentioned below 2,000 RPM because of the lower octane rating fuel. Once at higher RPM's the timing cycle is so short that it does not have "time" to knock. Of course within reason...way too much timing or extremely poor fuel would be detrimental at any RPM.

I can bet that if you run a higher grade (and good quality) fuel, and run a few bottles of Techron in the car you will no longer have any hesitation issues at low RPM's. Providing of course that the engine is set for the correct timing and is in good working condition. You may not have to go all the way to 91-93 octane but might get away with 89 octane if it is a good quality.

I think if you look at a 32-valve engine, running a low octane rating, let's say 87, will register a lot more knock events at low RPM/high load conditions. The difference is that 1987-up cars can automatically retard the timing for these knock events. All 928's from 1977 to 1986 has NO way of retarding the timing or even sensing that knocking is occurring. So my point is why risk thousands of dollars in engine repairs because you want to save $180 dollars per year?

When I tuned my 1986.5 with the TEC3r system, I could see the difference in knock events from one gas station to the next. So not only does different gasolines have different properties and knock points, but some contain more ethanol than others.

Just my thoughts

Cheers!
Carl

finally!

Octane boosters = waste of $$$$$$$$$ They do nada.

WallyP

Some comments (mostly repeats, but it makes me feel better to say them).

1) The USA and Canada show (R+M)/2 on the pumps. Our 87 is 89R-91R in the rest of the world. There are no real "low octane" fuels commonly sold here any more.
2) Higher octane fuel is not better fuel, it is slower burning, more detonation-resistant fuel. If your engine does not detonate on 87, it will NOT run better or make more power on higher octane fuel.
3) Fuel quality levels do vary, but there is only a very loose relationship with octane rating and quality. Better fuel usually has a better additive package (detergents, dispersants, etc.).
4) The 16-valve USA car specs say to use 87 (R+M)/2. Porsche should know what they need. RoW (Euro) cars are different.
5) There are NO effective commercially-available "octane boosters". They are a scam. If you read what they say, they promise to boost octane by ten points. They do. That means that they boost 87 all the way to 88. A "point" is 0.1 octane number.

Barry Chan

well went out and got myself a bottle of that octane booster and drove for an hour, guess what...hestitation is gone, smooth idle is back. i appreciate all the response, althought there are mixed result from different people but all i know from this is 87 octane doesn't work for me(i buy gas from the same station-Esso) and the booster works for me, til the next fill up - back to 91 octane!
Thanks again
Barry

finally!

Agree except only in part to number 2, For a car which is DESIGNED or TUNED for higher octane it WILL run better and with MORE power on higher octane. Just clarifying especially since doubtful any human can themselves "sense" or "feel" detonation".

finally!

If you really want to boost the octane, try putting some of tolulene (sp?) in the tank, about 15-25% of the volume to gas. Can get it at Sherwin Williams. Used to do this in my 1990 Nissan 30ZX Twin Turbo, change the ECU setting to higher octane mode and wow! Tolulene is one of the ingredients which gas companies use to increase octane.

James Bailey

To avoid the placebo effect have someone else put high and low test into your early 928 so YOU do not know what is being burned when. The same as blind tasting wine so you can not see how "good " the wine is supposed to be as this GREATLY changes the perception. And as Wally points out so well the commercial octane boosters do almost NOTHING. But it is hard to fight so many years of advertising........

Strosek Ultra

Over here in Scandinavia the gas i rated as 95 octane (regular) or 98 octane (premium). I have never heard of anyone having a knock or pinging problem. BTW my wifes old Volvo 740 is now seeing 420.000 miles and the engine has never been apart. The oil consumption is low. It is serviced on a regular basis. This is swedish quality. Now Volvo is owned by the Chinese!!!!!

Ake

Bill Ball

I've run 87 in my 89 since I've owned it; that is, when it did not have a supercharger. When it did, I ran 91. Anyway, it does not knock and anybody that has ridden with me knows I am not gentle on the throttle. Sharktuner monitoring has not shown any knocking on 87. Now that the supercharger is gone, I'm back to 87. Unless you have knocking, there's no reason to use higher octane.

Ethre

I can verify that - this is from the owners manual for my 82.

Strosek Ultra

You guys over there in the new world must be the happy ones. Over here the price of gas is around $ 8.80 a gallon. In Norway even higher and they have their own oil wells! That is why I spend more time in the garage working on the cars than being out driving. However we have the E85 which is very knock resistant. The price is lower about $ 6.00 a gallon. The fuel consumption is up by one third. Will convert two of our 928 for E85. Expect to be able to run CR 12:1 with long duration cams and E85. The third car having four Dellorto DRLA 48 carbs will not be converted, it is more difficult with the carbs. Have a BMW six that has been on E85 for six or seven years. So far no problems at all except I had to install a new fuel pump a couple of years ago. I don´t think that was E85 related.

Ake

Strosek Ultra

You guys over there in the new world must be the happy ones. Over here the price of gas is around $ 8.80 a gallon. In Norway even higher and they have their own oil wells! That is why I spend more time in the garage working on the cars than being out driving. However we have the E85 which is very knock resistant. The price is lower about $ 6.00 a gallon. The fuel consumption is up by one third. Will convert two of our 928 for E85. Expect to be able to run CR 12:1 with long duration cams and E85. The third car having four Dellorto DRLA 48 carbs will not be converted, it is more difficult with the carbs. Have a BMW six that has been on E85 for six or seven years. So far no problems at all except I had to install a new fuel pump a couple of years ago. I don´t think that was E85 related.

Ake

Barry Chan

is there a problem the Chinese actually own something???????