Am I wasting my money?

I have a euro 1984 911 3.2 with the non cat 231 hp engine. I always add a lead replacement product called "Castrol Systemreiniger TBE Benzinzusatz" when I fill up the fuel tank.

By coincidence this morning when looking for something else in the book "Porsche 911 - Forever Young" by Tobias Aichele I see the following:

Modelljahr 1984 (E-Programm)

"....- Die Saugmotoren sind auf die neuen Abgasvorschriften abgestimmt, zwar gibt es in vielen europäischen Ländern noch keinen unverbleiten Kraftstoff, (now comes the important stuff) DIE MOTOREN SIND JEDOCH SCHON DARAUF VORBEREITET!!!

In short it says: The euro non cat 3.2 engine is already prepared for unleaded fuel in 1984.

So have I been wasting my money on this lead replacement? Can I run the car on unleaded without a lead replacement product, or does the lead replacement still improve the protection against wear on the top ends in spite of the engine being prepared for unleaded fuel? I always thought that only US spec 911s were prepared for unleaded (different pistons, lower compression etc.)

There was a very informative feature in the British "911 & Porsche World " magazine in December 1998 on the matter. According to the feature the only threat from the absence of lead is valve seat recession if the metals used are not hard enough. Porsches especially of the era of your car have very hard valve seats which do not need the protection that lead provides. Compression ratio has to do with the octane rating of fuel whether leaded or unleaded. So if you use unleaded you might need to use super unleaded, otherwise your horsepower might suffer but not your engine because the electronic engine management on your car would retard ignition so as not to suffer from pinking or knocking.

Hi Mikkel,

All cars starting from the 2.7 CIS can be run with unleaded fuel.
Reason is, that the engines (heads, valves, cylinders) are the same for European, US, and ROW models, and they started to fit Catalytic converters with some 2.7 models.
As catalytic converters are demanding unleaded fuel, you can run every engine from 2.7 upwards with unleaded.

BEWARE: this statement is only valid for non-tuned, non-modified engines with standard CIS! E.g., a 2.7 RS, a modified 2.4, or an engine with modified valve train might be different!

The only advice I have is to regularly check the valve clearance.

Jens
'76 CIS with '73 body conversion
running unleaded fuel for 4 years now.

I can't believe after all these years there is still hype out there about leaded fuel. ANY car can run unleaded fuel. Lead is an additive used in the dark ages to enhance the octane rating of the crap the oil companies called gasoline. Many other additives were added on top of the lead to offset its bad qualities - namely buildup on the valve seats and in the combustion chamber. You all know the reason it is not used today is because it kills catalytic converters. The absence of lead does no harm, no motor "needs" lead. What they need is high octane, so be sure you give it to them or de-tune your motor so it won't ping. The falicy about unleaded harming valves is pure crap. Poor fuel blends (read oxygenated) and improper octane levels are what is doing the damage. I ran a motor from the "leaded" era for 15 years on unleaded fuel. When I tore it down it was worn out, but absolutely nothing unusal found. So - fill 'er up with high tech and hit the highway!

Maybe I'm overprotective. Anyway the octane thing is no problem. I've always used 98 octane, as the owner's manual says I have to.

Thanks for your info guys.

Uh, here in Calif we've been running unleaded in ALL cars since 1975...and there are a LOT of old cars still humming along just fine here.

Be careful what sort of valve guidance/seats you have. Its also depending on the style of driving.
I have seen 2 engines with stuck/broken/burned valves after switching to unleaded fuel (1VW, 1 Opel(GM))
These were high compression engines with non-hardened valve seats-no Porsche.

Jens


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I just happen to stumble on a German Porsche site, http://www.mittelmotor.de/deutsch/startdeutsch.htm where they advised for all engine until '84 to use 1 tank of leaded fuel on every 4 tanks of fuel! Check out the site it's quite nice

I'm not sure about lead being something of the dark ages, I am under the impression that valves, valve guides, camshafts etc. do benefit from the extra "lubrication" of lead.

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Joris
75 911S
http://members.xoom.com/joogie/Joogie.htm

[This message has been edited by jorisg (edited 11-08-2000).]

Lead does not lubricate. I'm not sure where that myth originated. Think about it - the temperature in the cumbustion chamber is extremely high. How is anything in the fuel going to lubricate moving parts? Bromine additives in leaded gasoline were put there to keep the lead from depositing on the surfaces. It is possible that these additives helped the valves out by keeping them clean of other impurities as well. Harder valves may be needed because modern fuels contain "detergent" additives (read solvents) that burn hotter or have less octane than their leaded counterparts. Seriously, the only issue with fuel is the octane rating for YOUR application. I have tuned all of my vehicles to run on 89 octane, this saves money and removes the hassle of finding stations with premium fuel. Low octane tuning does not have to hurt performance. Keeping the engine cooler than stock goes a long way tward fighting pre-detonation.

Bruce Anderson once printed the Rockwell hardness ratings of the various porsche valve/valve seats for cars over the years. Below a certain Rockwell hardness level, he says you probably should use leaded gas.

All Porsches built after the 356 have valves and seats plenty hard enough to use unleaded gas, according to Anderson, this includes very early 911s and 914s. The later cars, like SCs and Carreras, are all fine on unleaded, in his opinion.

This was published in, among other places, Excellence in the last couple of years.

Hello Mikkel!

In the first year of the produktion of the 3,2, the 930/20 engine has got different valve-seats from the 930/21 cat-engine. This I´ve been told directly from the factory (its has been a matter of money). You can regognize those modells from the chassis-number. It should be beginning WPOZZZ91ZES... The E is the code for the modell-year ´84. With the F-Programm ´85 the problem vanished. Porsche says: If You are using unleaded gas, You shoud change the intervall for controlling the valves from 20 000 to 10 000km.

Regards

Tobias

Don't lose any sleep. My first job was pumping gas (there is no self-serve in Oregon) and I still stop in to see the station owner when I am in town. He told me back in 1987 (?) that there was no difference between the leaded gas and the unleaded. The delivery truck would fill his "leaded" tank if he was running low and the next guy's "unleaded" tank from the same truck. They just sold two kinds because, 1)People thought they needed it for their old cars (the Ford & Chevy owners would have been right) and 2) "removing the lead" justified the higher price.

Bruce Anderson actually recommends against using leaded gas as he says it actually shortens the life of motor do to the deposits left behind. It was a cheap shortcut instead of using octane.

Bobby