Over the many years since these cars were new, quite a few of them have had their engines replaced by previous owners, usually to provide more performance. When new, these cars came with what was essentially a 2.0 liter 911T engine which at that time was the least powerful engine available in the 911 range. In the early 70s, the 911 engine grew in displacement from 2.0 liters to 2.2 then 2.4 then 2.7 and eventually to the 3.0 liter version found in the 911SC. Any of these engines and the later 3.2 and 3.4 liter engines will fit in a 914 and pretty much bolt right in with the appropriate changes to the engine mount, intake and exhaust systems and wiring harness.
The original 914/6 (911T) engine was rated at somewhere between 110 HP to 130 HP depending on who you talked to or what magazine you read and how the measurement was made. In 2.0 liter form this engine could be rebuilt with S pistons, cams and valves and taken up to about 190 HP. Larger displacement engines could produce 300 HP or more. Hummm... 300+ HP in a 2000 pound mid-engined car. No wonder 914/6s won the PCA Parade Autocross FTD for so many decades.
Now that these cars are getting collectible, it is generally more desirabe for a car to have its original engine and there are 2 considerations here. One is a car being advertised for sale with its original engine and having an engine number provided. How do you know that this engine is the correct one for the chassis? The other case is where an engine was swapped out at some point by a previous owner and the current owner is searching for its original engine. How do you know what engine was originally in which chassis?
The best starting point to verify an engine serial number would be the Porsche supplied Certificate of Authenticity (COA). It has been shown in various Internet forums that this is a good place to start but the engine number supplied by Porsche on the COA does not always match up with the engine number in any particular chassis when the engine is known to be original to that car. Frequently they do match but it is a bit of a crap shoot with the COA.
The following Engine Number vs Chassis Number scatter chart was put together by 914World member Dug. The chart shows the coorelation between engine numbers and chassis numbers. The first chart is only for North American 901/38 engines. The second chart is for European cars originally fitted with 901/36 engines. The Euro chassis VINs are in sequence with the US chassis numbers, but the Euro engines have their own range, so as batches of euro destination cars came off the line, the USA engine serials would stop incrementing. This chart includes kardex or COA documented VINs but that doesn't mean that these are 100% accurate.
Following is a Link to a discussion of engine numbers on 914World. A different version of these charts is shown on page 5 of this discussion. This also lists 914/6 engines that have been found out of cars around the world. If you are looking for the original engine for your car this is the place to start looking.http://www.914world.com/bbs2/index.php?showtopic=111670
Last Update Oct 2016