Engine number question 74 911S targa
 

I read some of the older posts on decoding engine numbers and wanted to inquire about help with a 74 911s targa.

Engine number *6144599
VIN #911 4 10 2692

The deck lid says 911S but I checked the engine number in bruce's re-build book for 1974 and it was a little vague. Said also seen with 30/32 intake exhaust ports. I am assuming there was just one version of the 1st generation 2.7 CIS motors installed in impact bumper cars, rated at 150 HP with 32/33 ports. Was it not until 1975, that porsche had a base 911 2.7 and a S engine versions for the USA? Base rated HP at 150 and S rated at 165, most likely due to the larger 35/35 ports.
This car does have a 11 blade fan and has the 74 exhaust with out the head build up issue that occurred in 75 with the addition of more emissions regulations. Was it not until the mid year when the 5 blade fans were used?

Any information you may be able to provide would be great.

Thank you

My '74 911S targa has it's numbers matching engine and 11 blade fan, as well as heat exchangers.

VIN#: 9114310811 (911 - 1974 - 911S 2.7 CIS - Targa - 0811)
Engine #s: *6342564* (911/93)

I think Wayne's engine building book has port size numbers.

Yes Wayne's book has the port sizes there seems to be two possible sizes, I was looking for more info in regard to the engine number and differences between the base 74 911 and the S. what my engine numbers HP rating is.

from what i can see
 

Porsche 911 Fahrzeugidentifikation
and waynes engine book.
614 = 911 engine type 911/92 valves 46/40, ports 32/32, hp =150
634 = 911S + us Carrera engine type 911/93 valves 46/40, ports 35/35, hp = 175

Thanks 47 Silver, looks like a possible re-badge. Do you what other changes the motors had to generate 25 HP beside the valve ports?? Seems like a lot with out other changes Cams ect. Has anyone discovered that a engine number may not match the heads on a original motor, un altered? Guess Im grabing at straws when the VIN all say 911. Did they offer a S car with a lower HP motor in 74?

Interesting.... I, too have a 74 911S Targa. The engine has been rebuilt in the past and appears to be a stock 2.7 with heat exchangers and 11 bladed fan. I referenced the above link to decode the engine number but it is completely different from any of the listed numbers, all of which begin with a 6. My engine serial number is: 3281427. Does anyone know what this means? Is this a replacement case perhaps?

There' something fishier there...

the VIN 911 410 xxxx is for a 911 coupe, not targa...

numbers
 

328 looks like a 1968 case

IMO, this could be a major issue for the OP. It's one thing to rebadge a normal 911 into an S, but changing a coupe into a targa or changing VINs, is another issue entirely and much more serious.

maybe a typo?
 

might be a typo and perhaps someone made a targa from a coupe, after all it is in hawaii, so may have wanted a targa.

Dammit...you are correct sir! I didn't think to look back that far. The motor was rebuilt by Ottos in Venice at some point so I wonder if they did an exchange or if the original case was toast...

Anyone care to share how Porsche bumped the 25hp between the base 2.7 and the S engine. I know about the bigger port heads but what were the other improvements. Cams? Pistons?

Higher compression pistons.

Re: Anyone care to share how Porsche bumped the 25hp between the base 2.7 and the S engine. I know about the bigger port heads but what were the other improvements. Cams? Pistons?

Aloha JED, Yap .5 in. more compression [S was 8.5cr.]and cams with a little more valve duration and lift.