1976 Porsche 912 build with 993 motor swap by freedomperiod

6 minute(s) of a 253 minute read

my answer to what ought to go under the bonnet:

..as you can tell from the SX4 thread, I'm going through an Orange phase right now

(my version of) Signal Orange!

It's the last and best of the air-cooled engines. The 993 series. The pinnacle of Porsche's air-cooled technology. With a simple ECU reflash and a nice exhaust, this lump will make a solid 300 peak hp at the crank on regular gas, and more bottom end torque than a 3.8 (because Vario Ram manifold)! Dead-solid reliable. Almost bulletproof! 

Now at this point, you might be thinking G50 gearbox. 

Remember, we're on a diet.

The old 915 gearbox is 50 lbs lighter. 

Sure, the G50 is better, stronger, etc, but I've mentioned in other threads that I've personally seen turbocharged 911's making upwards of 350-400 hp use the old 915 gearbox. Guys who go to the track love mating the 915 to newer, more powerful cars and they run with no issue whatsoever. 

There's no doubt the 915 can handle the power of a NA 993 motor, but mating it up with a clutch and flywheel requires some skill. ProtoSport is fantastic with custom fab. They're my go to guys for Porsche, and their workmanship is outstanding. They're part of the company Protomotive, who's claim to fame is their ability to get their aftermarket TT sytems to work with the factory Bosche Motronic system. They were one of the first.. if not THE first. They've been in the game for a long time and build some mean-ass twin turbo Porsches. They are by far, the fastest Porsches I have ever been in or driven. 

http://www.protosportinc.com/services.htm

http://www.protomotive.com/home.html

Now enter the "real" tranny of the thread:

This is no ordinary 915 gearbox. These are harder to come by over here in the states. This is a Euro-spec 915 gearbox. What makes it different? The LSD! 

915 gearboxes over here did not come equipped with limited slip diff, as far as I know.

Additionally, the gearing is a little different, with 5th being an extra tall gear compared to gears 1-4.

If there are any P-car trans experts, please shed some light on this for me. Thanks.

Here's a vid of the LSD in action... sort of :

So it all adds up, you see!?? ...or rather subtracts down ... 

...the weight. 50 lbs here with the trans, 80+ lbs there with the absense of a sunroof, lots of composite body parts, etc...

You might be wondering then, what's holding me back?

These:

Porsche Boxster brakes (front). Plenty of stopping power for what this car will weigh.

Much, much, much, much, much lighter than what was on there, and immensely more powerful.

So, how light is light??? 

The diet.. it's working.

Are you updating the trans at all for the extra torque or just hoping for the best?

Hoping for the best. It ought to be totally fine. 915's can handle way more than 300 hp reliably. The Euro-spec one is even tougher I think, but not 100 % sure.

This sounds lame, but these threads (Diablo, SX4, 912/911) are inspiring. They make me want to achieve some kind of success so I can have such fun. Until that happens, I am happy to read about your automotive endeavors.

It probably sounds lame because I'm guessing you haven't ever experienced a very lightweight car. You see, I used to be from the church of horsepower. Then I got my ass beat a bunch of times at the track by a lighter car. While I pulled away from lighter Porsches in my 600 hp twin turbo, the very same lightweights would shoot past me when I would brake hard before turns.

You can dive into turns, and brake much, much later than other cars. Also, there's a certain feeling you get from a lightweight 911, that no other car can deliver. It's part of the reason that even though the new Nissan GTR can outperform a GT3 RS in most departments, real driviers often prefer the GT3RS to the Nissan GTR.

Let me put this in perspective for you... This car will weigh an estimated 2000 lbs and make 300 hp (and believe me, that's a conservative #, because the engine reflash and exhaust could give this car up to 320 hp). That gives it a power to weight ratio of 6.7

A dodge Viper SRT10 with 510 hp has the same ratio. A 2011 Corvette Z06 has a p/w ratio of 6.4, If my car would have 320 hp (which is quite easy to do), it would have a better p/w ratio than the vette.

It's not anymore lame than these cars: