911 Engine Compatibility

[AS14]

I recently purchased a 1975 911s Targa. I am very new to cars and it is a total project but I am up for the challenge. I am currently looking for a new engine and was looking a 3.2 or 3.4.

My question is - what 911 engines would fit in a 1975 911? For example, can I install a 2013 911 3.4 in it?

The same goes for transmission. I know this might be against the grain but IF I wanted to, could I put a newer PDK transmission in it?


Hopefully this is not stupid question if so my apologies but your help is much appreciated.

Thank You

[darrin]

welcome to the forum -- since your targa was built/designed to use an air-cooled engine, it lacks the systems/plumbing necessary to run a water cooled engine. Porsche 911s were equipped with air-cooled engines through the 1998 model year -- any newer 911 engine would be water-cooled. While people have found ways to retrofit water cooled engines into their 911s, it requires a fair bit of work.

Transmissions -- since the PDK relies on a car's computer system to work, it would be very difficult to integrate into an air-cooled 911. In fact, even upgrading to the g-50 transmission used in 1987 and later 911s requires some significant surgery and the addition of a hydraulic clutch assembly.

[AS14]

Thanks Darrin! So just to confirm i want to stick to a 911 engine that is 1998 or earlier and then a transmission before 1987, right?

Anything that matches this criteria will work in the 1975 911, correct?

[darrin]

pretty much, though I'd go with "can be made to work in the 1975" vs "will work" - e.g. a 3.6l engine from a 1990-1998) lacks the internal oil cooler that were on engines through 1989, requiring some modification/thought to avoid overheating.

[HarryD]

While the engines will fit, the real issues include (others can chime in):

-Capacity of transmission to handle the additional power;
-Cooling. Anything with more than about 140 hp will most likely require an external cooler of some sort.
-Brakes. With more power comes the needs for more brake.
-Suspension. The suspension may need to be tweaked in some way.
-Emissions-Depending on where you live, there may be issues.

[dannobee]

If you go big on the engine, the original 915 transmission will not live long, regardless of what anyone else tells you. A few drag race starts and it'll break parts. They simply weren't made for the torque of a 3.6L. When I was working at the dealership I rebuilt a LOT of them. G50's were a godsend in our eyes.
You'll need an oil cooler if it's a 75. For the most part, the regular 911's didn't have a front mounted cooler nor the lines going to the front with the trombone cooler.
75 is the holy grail for hot rod cars in California. Since they're smog exempt, do what you want with the engine.
PDK in it is a non starter. Unless you have access to unobtainium parts or your own machine shop, they weren't offered with the air cooled engine's bolt pattern.

[AutoXer23]

Welcome to the forum !!

[fanaudical]

Welcome to the forum - there's lots of help here.

What exactly are you starting with for a '75 Targa? Complete car? Roller without a motor? Empty shell? Got pictures? That might help provide some ideas.

A '75 Targa is easy to mod, light, but not really a stiff chassis. (I have one.) My opinion - You can add more engine than the chassis can use...

[Sboxin]

IMHO of course - - you already have a 911S (already a "hot" engine)- just rebuild it and the trans and update the suspension bushings and enjoy the car . . . or take it to a really good Indie shop and have them check the drivetrain out and then enjoy the car . . . others have already answered the question of "what will fit" in your car . . .

As a reference - - we have had a 3.2L/915 1978 911 coupe race car for over ten years and upgraded to a 3.8L 1992 964 race built engine with race built 915 ( a whole lot of money ) . . . but in the beginning my son won races with the 3.2L stock engine and our friend with a 3.2L short stroke was just as fast (mostly because of the more experienced driver) - - - but, my point is you don't need to spend a lot of money to enjoy a nice Porsche 911 . . . me I drive a 2002 Boxster S that is very quick on the track and has all the road comforts this 70+ driver can enjoy driving a Porsche and listening to the Flat Six sound tract . . .

Enjoy and Regards,
Roy T

Originally Posted by AS14

I recently purchased a 1975 911s Targa. I am very new to cars and it is a total project but I am up for the challenge. I am currently looking for a new engine and was looking a 3.2 or 3.4.

My question is - what 911 engines would fit in a 1975 911? For example, can I install a 2013 911 3.4 in it?

The same goes for transmission. I know this might be against the grain but IF I wanted to, could I put a newer PDK transmission in it?


Hopefully this is not stupid question if so my apologies but your help is much appreciated.

Thank You