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Porsche 993tt M64/60 Engine Rebuild and power upgrade

Porsche 993tt M64/60 Engine Rebuild and power upgrade

Mahle 3.8 liter kit with Tial Alpha 28 Turbos, GT2 Web Cams

It’s been far too long since our last post. We’ve moved a good amount of our updates to our Facebook page, which in turn has left our site content looking a bit dated.

Finally, after the summer rush we’ve had a chance to sit down and offer our site-followers some more details on projects we conducted over the winter and summer.  This particular post will review our first Porsche rebuild, a 993tt M64/60 motor.  In stock form this engine produces about 400hp at the crank. We know from past dyno runs, and from running other cars on the dyno that while this is a big number only about 70% of that power makes it to the ground (in this case about 310whp to all four wheels) In the late 1990s that was something to still brag about. Now, not so much so it was time to upgrade.

The Porsche M64/60 motor. The last iteration of the Air cooled generation

The Porsche project started with the intention of freshening the motor and increasing displacement from 3.6 to 3.8 liters via new cylinder “jugs” which are essentially the cylinders for those not familiar with air-cooled Porsche motors. The engine had some upgrades already; a pair of Tial GT28 Alpha turbos but that was it.

Mahle 3.8 liter jugs with the Protomotive Twin Plug, big valve heads in the back

Much like a Harley or air other cooled motorcycle the cylinders un-bolt from the engine case. With these new cylinders came new pistons to match the larger bore. We used Mahle Motorsport pistons.  Much like the M3 that Bill was simultaneously working on, the project grew in scope and we were soon receiving boxes from famed 993 tuner Protomotive with high quality head studs, Web GT2″ Evo” cams and even custom machined twin plug cylinder heads. We also installed new forged connecting rods while the engine was open.  With the bottom end and heads done we did some work on ancillary parts to support and promote the power increase, Protomotive Intercooler,Tial Alpha 28 turbos, Aquamist HFS-3 methanol injection and a Bosch “044″ pump in place of the standard pump.

To hold the power we replaced the viscous coupling unit for the center differential with a fresh one and rebuilt the rear differential with plates from Guard Transmission. We also installed a Sachs Motorsport single-disk clutch before putting the engine and transaxle back into the car.

The transaxle with the rear differential removed.

The project took  a long time; about 4 months. Part of the reason it took so long, aside from it being our first time, was the twin-plug conversion which used a newer distributor (two of them connected internally with a belt) which occupied valuable engine bay space. We were trying hard to maintain OBDII compatibility and HVAC which made the project difficult as well. Ideally we would have used a Motec or similar ECU but that wouldn’t have passed emissions. Todd from Protomotive was instrumental in helping us tune the car once the motor was built as he holds proprietary software and years of experience to do so.  Thanks Todd! With Matt and Todd working together for over 15 dyno sessions (about 250 pulls!)  the car made over 600whp and is one of the most powerful 993 in the ’states.

To see a photo gallery of the build process click HERE

Stay tuned as there might be some Alpha 30 turbos in the near future.

Posted in Alex, Updates.


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