Heat on a 3.6 engine is similar to any other air cooled 911. It’s a matter of what exhaust manifolds and heat exchangers you use and how you get the air to and from them.
Heater Air Supply
There are two methods to force air to the heat exchangers above the sheetmetal:
- RS Duct -these were used on the lightweight RS 964 and 993.
- The Porsche factory tubes are made of ABS plastic, which is fortunate since the tube interferes with the driver’s side engine mount bracket on the chassis. This can be alleviated by the use of a heat gun or gentle application of a torch to create a dent to clear the bracket. The 993 version fits both 964 and 993 engines including Varioram and additional clearance on the back side was built in specifically for the varioram application. A 964 type shroud cap is required.
- Aftermarket carbon fiber units are also available. Be aware that these generally do not fit well for this application, and need to be modified by cutting a hole and re-sealing the area near the motor mount. These usually do not include the Varioram modification and clearance can be an issue.
- These are appropriate for defrosting the windscreen or occasional cool weather use but not if serious heat is needed.
- Factory heater blower
- These work well and put out plenty of heat. Wiring requires some expertise, bit on most cars 1974 on a blower was installed so relays and switches are in place. If not, additional wiring can be retrofitted triggered by a factory microswitch located on the heater controls.
- The factory blower WILL NOT CLEAR the driver’s decklid hinge. The Carrera2/4 and 993 hinges were moved outward about 30mm each to clear this and the stock air filter housing. we have developed jigs to modify the 911 hinge arm (C2/C4/993 will not work) without modifying the mounting points under the package shelf, decklid shocks or decklid.
- IG Decklid Hinge Modification We can modify yours on an exchange basis. We can do the same on the pasenger side for symmetry which also allows the use of the factory airboxes. They flow well with the addition of a K&N filter.
Below the sheetmetal the solution is dependent on your choice of exhaust. On all but the -73 style rear bumper, a 993 cast aluminum heater distribution tube can be used. This includes Happy Crab and our full exhausts. On early cars and backdates we make a special muffler setup with plumbing through the muffler bracket or a system that splits above the fan. On 964 engines we can offer solutions based on the individual combination of chassis, blower type and exhaust/heat exchanger. In all cases we will offer you a complete solution, not leave you hanging with a ‘figure it out yourself”. Heat exchangers are pointless if you can’t get make the air go through them!
Heat Exchanger to Flapper Valve
We make kits for every application of exhaust we support including the Happy Crab 993 exhaust in 911 and C2/C4.These come with solid euro clamps, adapters, etc, whatever is needed and are woven fiberglass and silicone/neoprene high temperature hose designed for this application.