ra996tt

In the middle of doing this with help from Chris @ TurboKraft. Beware of the 964 heads which are ceramic lined and chunk off at high egt's and might destroy your build. Best solution is a set of 993 gt2 heads without this ceramic bs. Best of luck, let me know if you need any more info. Thanks.

psiegel

Driving my 93 964 C4 Turbo is very fun, it is very fast and serves as my year round DD. The spin up with a dual system will be quicker but my feeling is that the basic conversion needs will be similar. The following is what I did, well, what Todd Knighton and his team at Protomotive did and can act as a guideline of things that should be looked at to include for your turbo conversion. These conversions are not bolt-ons but are complete systems that need to be integrated throughout the entire car. You will need to make some designs decisions that will help you select the correct parts and engineering to achieve your desired end result, such as max horsepower vs. longevity, etc.
Good luck and have some fun:
Peter Siegel
1993 964 C4
Work by Protomotive (Todd Knighton)

Engine Rebuild @ 142,000 Miles and Prep for Turbo
Valve Job
Disassemble/Reassemble Case
Racing Valve Springs- 93034RSR
9MM Rod Bolt Kit -204-6005
Engine Case Studs - 99310117051
Install Diliver Head Stud - NTL31014
Piston Rings 100mm - 99310392551
Spark Plug Wire set twin plug - 108533607
Spark Plugs Bosch - Ik20
3.6 Chain ramps r/l - 3.6 Chain ramps
Timing Chain - 99310552900
Chain Tensioner left 1-3 - 96410507900
Chain Tensioner right 4-6 - 96410508000
Temp Sensor - 92860614300
Rod Bearing Set - 93010314715
Main Bearing Set - 93010190100
Intermed. Shaft Inner 90110113500
Intermed. Shaft Outer 91610113700
993 engine case gasket kit - 993100090300
964 Manifold Feet - 96411071101
Drive Belt Dist - 96460200000
964 Cruise Cable - 96411002502
Valve Guides
Oil Return Tubes - 90110735101

TURBO CONVERSION @ 142,000 Miles
Resurface Head
Resurface Pistons (to lower compression)
Turbo - Garrett TO4B 60-1 Ptrim
Tail Wastgate - 1 Bar Spring
993 Mass Air Flow -Part # 993 606123 01
C2/C4 Mass Flow Software
Divider Network
993 Air Box - 99311036704
993 Air Temp Sensor - Part # 993 606 113 00
Fuel Pump 993 GT2 Twin Turbo Part #- 0580254044
Fuel Injectors - 993 Twin Turbo
Duel Oil Cooler Installation - 96420722002
Oiler Cooler Fan Thermo switch Modification ( 11k in series, on too hot), (2.2K in parallel on too cold), ( 1.1k parallel low 195 hi 210)
Intercooler - Custom full size (see photo)
965 Turbo S Fixed Wing FVD 512965S- Cut Fab wing to fit

TRANSMITION @ 142,000 Miles
Clutch - All 996 GT2 Twin Turbo Components
GT 2 Pressure Plate - 883083726
Clutch Release Bearing Fork - 95011608606
TO Bearing Kit - 101518086
Clutch Release Bearing - 95011608008
Trans Gasket Set 964 C4 - 96430091100
964 C4 Rear Trans Mount OEM - 96437502301

CHIP VALUES
Some are as Follows:
Injector cranking value lowered from .55ms to (see Todd Knighton)
Cold Idling fuel values enriched on warm up
Cold idling rpm,s raised to (see Todd Knighton)
Idle ignition timing has been bumped a couple of degrees to help with the altitude
Idle cranking ignition values have been bumped up to 5 degrees to give a stronger fire

EXHAUST
Replaced Primary Muffler with Cup Pipe FVD 170111044

OTHER (non-Turbo stuff)

BRAKES @ 142,000 Miles
Install new front Calipers, rotors & Pads - All OEM
Install FVD Stainless Brake Lines B6435594
Install new Rear Rotors and Pads @ 144,000

SUSPENSION
21 mm rear sway-bar - 96433370107 + (2) 4774113130
FVD Front Strut Brace - 115500337
MO30 ROW Coils 96534353101505/96533353103504
Bilstein HD Shocks Front-VE3-5277-HO(L) / VE3-5278-H(R) & Rear B46-01547

ELECTRICAL
H-4 Conversion Kit with Oshram Silverstar
High / Low beam bridge 96461018302
Replaced Fog Lamps

MAINTENANCE SPECS
Air Filter- K&N RF-1003 (needs to be as large to provide proper air flow)
Oil Filter - Mahle OC-54
Oil Filter - Valvoline Vr1 Racing 20W - 50 (10 Quarts) / Now BradPen
Fuel Filter - MAHLE KL - 21
Fuel - 91 , preferred 93
Spark Plug - 12 OEM , Torque to 30lbs
Coil - 2 OEM
Spark Plug Wires - 12 OEM
Distributor Caps 2- OEM / Replaced distributor Belt
Distributor Rotor 2- OEM
Gear Oil - Valvoline 80W-90 gear oil 4 Quarts
Brake Fluid - Dot -4
Head - Torque to 30lbs

biggles

It's not a cheap proposition but it is doable and if you were interested, this would be a good start, although a 2-in 2-out muffler would make sense. You can run low boost, about 5-6 psi but most will still go for an intercooler, especially on the 3.6 unless you drop the engine compression. Most critical will be tuning and fueling. Good luck.
biggles.