After a mechanical over-rev of my 2.7L engine bent most of the valves, I was faced with having to either rebuild the engine, or upgrade to a later unit. After weighing the cost and benefits of various options, everything from rebuilding my 2.7 to installing a turbocharged engine, I decided to go with a 3.6L 964 engine. I use the car for daily transportation, as well as frequent autcrossing and occasional track use, and I decided the 964 engine would give me good power and economy without the excessive maintenance problems of turbocharged engines, and wasn't tremendously more expensive than a 3.2L Carrera engine.

I found a rebuilt engine, complete with harness and brain in fairly short order. I bought a ready-made kit for the conversion from Instant-G (www.instant-g.com), and the stage was set for the conversion. The Instant-G kit handled the details of the wiring harness, sheet metal, fuel system, oil lines, throttle cable, flywheel and instructions. The implementor has to resolve the exhaust system solution. I chose to go with a stainless-steel B&B exhaust, as they make a muffler to fit the 911 body and uses their stainless steel 964 headers, and still provides heat. There are other minor upgrades one can undertake at the same time, such as changing the "engine console" to the version without the A/C bracket; removing the power steering pump bracket and replace it with a specially made block-off; eliminating the dual-pulley on the 3.6L fan with a special fan pulley which locks the two shafts togethter and provides a single pulley, along with a matching single-belt lower pulley. The 915 transmission can handle the power of the 3.6L with a good safety margin, although one should upgrade the clutch. I upgraded my clutch to a Sachs Power Kit, which includes high clamping force aluminum pressure place and composite segmented disk

The actual conversion is very straightforward, and the kit vendor provides excellent instructions and tech support. The 964 bolts right onto the 915 transmission, although a notch for the DME sensor must be cut out first, and one must use a special flywheel to match the 915 clutch to the 964 engine. The CIS-era fuel pump is sufficient for the 964 engine (earlier cars need to upgrade the fuel pump), and the lines to adapt the CIS fuel lines to the 964 fuel rails are provided. A hole must be cut in the body behind the rear seat to route the harness for the DME, which itself is mounted under the driver's seat. Additional wires are provided to re-wire the tach and fuel pump relays for the 964 engine. It's commonly thought that the 964 heater blower and stock airbox won't fit in an earlier 911's engine compartment, but some people have made it work. I chose not to use either, instead forgoing the heater blower entirely, and using an aftermarket cone filter in place of the factory airbox. If you don't use the factory airbox, you need to remove the vacuum canister from the airbox and and install it somewhere in the engine compartment, and run a vaccum line to in order store the vaccum needed to operate the resonance flap. I also had to modify my accelerator pedal by cutting off the 1.25" 'stop' on the back, in order to obtain complete wide open throttle.

All told, it's anywhere from 10 to 20 hours of work, depending on the experience of the mechanic.

The result is a very strong, but very drivable car, combining the excellent torque of the 3.6L with the lighter 911 chassis. My 1977 targa with spare and tools weighs and 1/2 tank of gas weighs in at 2680lbs. The car dynoed at 208HP at the rear wheels, although changes to the engine which are currently underway should increase that figure. As it is, the additional weight (approx 100lbs) of the 3.6L engine, coupled with the large amounts of torque, have the effect of overpowering the stock rear torsion bar to the point that the car squats tremendously on take-off, so much that it would hit the rollers on the dyno during testing. To combat this, I'm installing 28mm torsion bars in the rear with 22mm bars in the front, and 22mm sway bars. I've also upgraded to 930 brakes, although for street use, the stock brakes are more than adequate, even for autocrossing, as long as they are in good condition.

The engine is the most critical aspect of this conversion, and it's also the biggest wildcard. If at all possible, get some sort of pre-purchase inspection on the engine you wish to buy. Instant-G offers ready-to-go engines to complement their conversion kits.


Found in: Porsche   Other pix from Thom
My new engine My new engine
Thom
http://www.vintagebus.com/3.6
Here's my zero-mile 3.6L engine for the 911 (hey, if Everett can have type 4 pix on his site, I can have 911 engine pix on mine!
 2001-08-11 (123.95k)
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My new engine My new engine
Thom
http://www.vintagebus.com/3.6
Here's my zero-mile 3.6L engine for the 911 (hey, if Everett can have type 4 pix on his site, I can have 911 engine pix on mine!
 2001-08-11 (87.93k)
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My new engine My new engine
Thom
http://www.vintagebus.com/3.6
Here's my zero-mile 3.6L engine for the 911 (hey, if Everett can have type 4 pix on his site, I can have 911 engine pix on mine!
 2001-08-11 (112.81k)
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Parts for 3.6L Conversion Parts for 3.6L Conversion
Thom

 2001-08-23 (111.59k)
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Parts for 3.6L Conversion Parts for 3.6L Conversion
Thom

 2001-08-23 (108.67k)
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Mechanical Overrun Mechanical Overrun
Thom
Here's the #6 piston; you can clearly see wherethe valve hit it and pit a nice little scratch in it.
 2001-08-23 (147.55k)
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Conversion Work has begun Conversion Work has begun
Thom
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Coil packs are mounted
 2001-08-28 (117.25k)
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Conversion Work has begun Conversion Work has begun
Thom
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Brain mounted
 2001-08-28 (122.46k)
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Conversion Work has begun Conversion Work has begun
Thom
http://www.vintagebus.com/3.6
I need to engineer a solution to connect this hole to the heater boxes
 2001-08-28 (117.99k)
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Conversion Work has begun Conversion Work has begun
Thom
http://www.vintagebus.com/3.6
Here you can see where the trans was notched to clear the DME sensor
 2001-08-28 (119.7k)
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Conversion Work has begun Conversion Work has begun
Thom
http://www.vintagebus.com/3.6
Nothing special, just another shot of the flywheel side of the engine...
 2001-08-28 (132.48k)
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Conversion Work has begun Conversion Work has begun
Thom
http://www.vintagebus.com/3.6
New fuel lines
 2001-08-28 (122.7k)
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Conversion Work has begun Conversion Work has begun
Thom
http://www.vintagebus.com/3.6
This the the A/C bracket that I'll remove if the replacement piece comes in today
 2001-08-28 (124.33k)
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More 3.6L pix More 3.6L pix
Thom
http://www.vintagebus.com/3.6
Here you can see the fabricated oil line which makes up the distance where the oil cooler lives on an earlier engine. The bluish-green thing is the power steering pump block off cover.
 2001-08-29 (111.74k)
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More 3.6L pix More 3.6L pix
Thom
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B&B Headers
 2001-08-29 (127.71k)
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More 3.6L pix More 3.6L pix
Thom
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Notch for the DME sensor
 2001-08-29 (134.79k)
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More 3.6L pix More 3.6L pix
Thom
http://www.vintagebus.com/3.6
"Motor Console" 964.115.011.02 which replaces the air conditioner compressor bracket
 2001-08-29 (71.07k)
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More 3.6L pix More 3.6L pix
Thom
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Here's a shot from the flywheel end, ready to hang the transmission. Notice the power steering pump blockoff
 2001-08-29 (123.4k)
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More 3.6L pix More 3.6L pix
Thom
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Hanging the transmission
 2001-08-29 (125.06k)
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More Progress More Progress
Thom
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Engine and trans all ready to go!
 2001-09-04 (118.37k)
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More Progress More Progress
Thom
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Cone filter support
 2001-09-04 (47.02k)
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More Progress More Progress
Thom
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That's a tight fit!
 2001-09-04 (41.47k)
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More Progress More Progress
Thom
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Rolling the engine and trans into position
 2001-09-04 (113.02k)
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More Progress More Progress
Thom
http://www.vintagebus.com/3.6
Going up... (actually 'down')
 2001-09-04 (114.49k)
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More Progress More Progress
Thom
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It's in!
 2001-09-04 (116.08k)
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More Progress More Progress
Thom
http://www.vintagebus.com/3.6
It's in!
 2001-09-04 (117.28k)
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More Progress More Progress
Thom
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It's in!
 2001-09-04 (129.35k)
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Almost, but not quite... Almost, but not quite...
Thom
Three issues remain: throttle cable, breather hose, and muffler. The muffler is the biggest one.
 2001-09-07 (121.87k)
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Almost, but not quite... Almost, but not quite...
Thom
Here's where Frank engineered a proper fuel line setup, without having to hack the original lines.
 2001-09-07 (110.09k)
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Almost, but not quite... Almost, but not quite...
Thom
Here's where the new fuel line comes in on the right side. I wish that connector faced the other way, so we could avoid that big loop!
 2001-09-07 (113.7k)
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Almost, but not quite... Almost, but not quite...
Thom
The original heater-connector tubes won't reach with the B&B headers
 2001-09-07 (114.23k)
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Almost, but not quite... Almost, but not quite...
Thom
What is this, and do I really need it?
 2001-09-07 (111.29k)
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Done (well, almost...) Done (well, almost...)
Thom
I picked up my 'new' car today - oh wow, this is a totally different beast! Here's a shot of the muffler from underneath - some engineering had to be done here.
 2001-09-10 (129.74k)
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Done (well, almost...) Done (well, almost...)
Thom
Here you can see where the muffler had to be modified to clear the engine hanger
 2001-09-10 (113.57k)
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Done (well, almost...) Done (well, almost...)
Thom
Frank admiring his handiwork...
 2001-09-10 (114.34k)
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B&W test B&W test
thom

 2001-12-06 (96.04k)
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RS Heater Bypass Tube