I managed to buy this boat engine and instal into my 1987 S4, but before I got it I did as much research I could online and even reaching out to Porsche directly and all they had was a brochure of basic specs. Nothing informative. Does anyone out there know more? Anyone else have one or had on boats or cars? What do the serial numbers on block mean?

Let me know thanks.

Ricco

 

Marine 928 engine.

 

Did I get the 6th engine made based on the number stamped on block?

 

Engine M28/23 does not exist on the 928gt website, so maybe yes....

So, you bought it?

 

K would be a 1989 year motor, so 2R heads and the longer head bolts at the corners.

Out of interest - did you take the oil pan off? Was there anything unusual in the sump? Asking as there was a mystery crank oil scraper which turned up years ago on ebay (there's a thread somewhere here about it), and suspicion is it was a marine part.

 

Let me get home and respond and post more pics! This thing was new when I took apart! NEW!!!

 

I'm thinking you have a piece of history there!

https://www.stuttcars.com/wizeman-wp...e-engine-1986/

 

Her











e are some pics of the polished new allow parts. So puuuurdy.

 

So to answer the question, yes I did buy it. I did install into my car. At first it didn’t run well and that’s because the firing order on boat engine was 1-2-7 and so on, and the cars rubbing sequence was 1-7-2. Put old camshafts and car hauls ***! New engine in my 1987! Solid performer.

 

Here’s a few more pics.

 

Not so much anymore.

 

 

Very interesting engine, thanks for posting and all of the pictures.

I would be interested in hearing more about this.

 

It might be a sister to this one in the Porsche museum in Stuttgart?

 

Wow, so very new. The cam chain tensioner guides are completely un-run white plastic, and the intake costing is both immaculate and still silver.

Congratulations - very well bought and used!

Looks like the boat motors had both a different type (M28.23) and a different numbering series.

Factory bulletin 8902 (1/20/1989) specifically says
"For 928 S4 cars, a new cylinder head
PN 928 104 014 03 is installed from
Engine No.: 81 K 00121 Manual Transmission, 81 K05240 Automatic Transmission"

So it seems likely your motor is the 6th boat motor of 1989, likely including any factory-used / test engines, given the engine number series is different than the cars.