unleaded fuel-what years?

[rfuerst911sc]

Hello I am a 911 owner thinking of adding a 914 to the stable so my knowledge of 914's is minimal. My question is do all years of 914 run on unleaded fuel? If not what years do? Thanks

[teenerted1]

yes
and if you dont change the compression you can run regular unleaded if you like too.

[rfuerst911sc]

Thanks................I probably only have 1,000 more questions to go!

[lapuwali]

Actually, early 1.7s ('70-'72) need premium (91 octane, at least). They have higher compression than the '73 1.7, and MUCH higher compression than the 1.8s.

In general, any engine with aluminum heads (which probably includes all road-going Porsches) will work with unleaded gas. Many older iron-headed engines had their valve seats cut straight into the head, and the soft-ish iron needed the lead to keep the seats intact. Aluminum is so soft it would die very quickly without hardened valve seat inserts, so all such engines have the inserts, and thus work with unleaded gas.

[nine_one_4]

Here's the information from the Haynes manual. IIRC, 91 RON corresponds to 87 AKI that you find on gas pumps in North America.

From Wikipedia:

The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel through a specific test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane.

There is another type of octane rating, called Motor Octane Number (MON) or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON.

In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-95 (regular) in Europe.