Engine Swap/Conversions FAQ Options

[lapuwali]

What conversions have been done?

In many ways, the 914 has traditionally been a hot rodder's car. The chassis is far more capable than any of the engines the factory provided, and for many years, the cars have been inexpensive used. This has lead to a wild array of engine combinations, spawning an entire cottage industry in creating 914 "hybrids".

The most commonly done are Six conversions (911 engine) and Chevy V8s, though Subaru fours are gaining fast in popularity. The Mazda rotary, Chevy V6, Buick V6, and Nissan V6 have also been done more than a few times. The Porsche 928 V8 has been done at least twice, but is very difficult and requires a huge effort to make work. The earliest known swap was a Wankel rotary, which was presented as a gift to Felix Wankel himself.

914club member neo914-6 maintains a list of all known engine conversions.

What about other Porsche engines?

The 944 engine has been mentioned, but it's not known if anyone has managed to make it work. This engine is very long, and won't fit without heavy modifications to the firewall.

Will I kill the transaxle?

The 914 transaxle has been known to hold together up to around 200ft/lbs of torque. It's basically torque that kills transaxles, not so much horsepower. Certainly, the factory themselves used the 901 (the 911 gearbox the 914 gearbox is based on) on race engines up over 200hp. There are also billet intermediate plates (which hold the major bearings) that help a bit more. Both the 915 and the 930 Porsche transaxles have been adapted to the 914 to handle more power. Both are fairly expensive to buy and convert. WEVO makes a shift linkage conversion for the 915 for a very high price. Cable shifters have been fabricated for both. The four-speed 930 seems to be able to handle even a pretty hot V8 without blowing up.

Are there any suppliers of kits and parts?

Yes. Kennedy Engineered Products (aka KEP) provide adapter plates to bolt a wide variety of engines to the 914 transaxle. They also supply flywheels and clutches. They can be found here.

Renegade Hybrids specializes in conversions for several Porsche models. They provide a drop-in radiator kit for any water-cooled engine swap into a 914 that's generally regarded as the best available. They also provide complete kits for Chevy V8 and Subaru installations into a 914.

[lapuwali]

Subaru conversion

(NOTE: many thanks to Evan Thompson [mongrel-gs] for providing this section).

The Subaru 4 cylinder conversion is popular because of the price, power, and parts availability. A radiator is required for this conversion, but it may be successfully placed in the engine bay or front trunk. There is a kit available for this conversion from Renegade Hybrids, or the cost may be kept down by doing some home fabrication. There will be some cutting of the car involved... if the radiator in put in the front trunk, a venting system will need to be worked out. If the radiator is to be put in the engine bay, removing the front engine shelf is recommended (although many going this route remove all the engine shelf metal, anyway). As far as weight, the 4 cylinder n/a Subaru conversion should weigh the same or maybe even a bit less than the stock type IV engine. Turbo Subaru engines obviously require more plumbing work, and getting everything to fit without cutting the rear trunk floor is very challenging.

Which engine do I want to use?

From the NASIOC forum

EJ18: Found in Imprezas from 1993-1997. Rated at 110hp and 120 ft-lbs
EJ22 Phase I: Found in Legacies from 1990-1998 and Imprezas from 1995-1998. Comes rated at 130hp and 137 ft-lbs, 135hp and 140 ft-lbs, or 137hp and 145 ft-lbs.
EJ22 Phase II: Found in Legacies in 1999 and Imprezas from 1999-2001. Rated at 142hp and 149 ft-lbs.
EJ22-T Phase I: Found in Sport Sedan and Touring Wagons (Legacies) from 1990-1994. Turbocharged and non-intercooled. Rated at 160hp and 181 ft-lbs. Closed deck, cast pistons, forged rods, oil squirters: turbo motor. Poor flowing heads.
EJ25 DOHC Phase I: Found in Legacies from 1996-1999, Imprezas in 1998, and Foresters in 1998. Rated at either 155hp and 140 ft-lbs in 1996 or 165hp and 162 ft-lbs in 1997-1999.
EJ25 SOHC Phase II: Found in Legacies from 2000+, Imprezas from 1999+, and Foresters from 1999+. Rated at 165hp and 166 ft-lbs. There was a slight compression ratio change from 1999-2000 where it went from 9.7:1 to 10.0:1.
USDM EJ20: US Domestic Market WRX. Found in 2002+ WRXs. Rated at 227hp and 217 ft-lbs. Turbocharged, intercooled, open deck, and decent heads.
EJ25T DOHC: Available in 2004 in the Forester XT. Rated at 210hp and 235 ft-lbs. Turbocharged, intercooled, VVTi (Variable Valve Timing), and drive by wire.
EJ25T-STi DOHC: Available in 2004 in the WRX STi. Rated at 300hp and 300 ft-lbs. Turbocharged, intercooled, AVCS (Active Valve Control System), drive by wire, intercooler sprayer, and semi-closed design.
EG33 and EZ30- The six cylinder boxers... it may be possible to fit them in, but the radiator will most likely end up in the front trunk.

Whatever the choice, get as much included with the engine as possible. Longblock, intake, alternator, engine wiring harness, front bulkhead wiring harness, ecu, main and fuel relay, exhaust, engine mount blocks, O2 sensors and harness. Depending on the model, you may need the intake tube and MAF, ignitor on firewall, air pressure sensor. Additional OBD-I and OBD-II codes may be avoided by using all the EVAP solonoids at the gas tank, a sensor simulator from Small Car Performance, or by strategic use of resistors. In the later models(at least the EJ25 SOHC) there is a difference in the manual and automatic transmission engines. Either will work, just make sure you get parts matching the same year, model, and transmission.

What parts do I need?

Besides the engine, you'll need the following:

An ECU- The stock Subaru ecu will work, and will require no dyno tuning time. Additionally, it is possible to make the engine OBD-II compliant, meaning troubleshooting ease with a code scanner. It is also possible to use a Megasquirt system as a controller, and possibly some other commercial systems such as SDS. If you use the stock ecu, it is critical that you match the year, model, transmission, and if possible the vin. Note that most of the later engines have no distributor, nor any provision for one, so converting to carbs and a distributor is not really an option.

An engine mount - Can be purchased in the kit from Renegade Hybrids or fabricated.

A flywheel/adapterplate - Can be purchased in the kit from Renegade Hybrids, or separately from Kennedy Engineered Products to mate the engine to the 901 transmission.

A radiator and mount- A front trunk mounted kit can be purchased in the kit from Renegade Hybrids, or a engine bay mounting frame and ducting can be fabricated for use with a stock Subaru radiator, or an aftermarket radiator such as Koyo.

A air filter- A simple K&N universal filter or the 914 round filter assembly can be adapted.

A oil pan- Although the stock pan can be used, there will be very little ground clearance. The pan can be cut down. Shortened pans are available from many suppliers such as Kennedy, Small Car, Outback Motors, and may be included in the Renegade kit.

A shift linkage- The sideshift shift linkage may need to be cut and rotated 90 degrees, depending on the mount and exhaust designs.

An exhaust system- Can be fabricated by modifying the stock system. Stub pipes are available from Outback Motors.

Assorted bits/pieces/notes/links
Alternator- The top of the alternator bracket shout be cut off and the alternator rotated 180 degrees. A tensioner may be fabricated, or a club member may be producing a very nice bracket system.

Intake manifold- In most cases is rotated 180 degrees to face the front of the engine bay. Stock manifold gaskets can still be used. This provides more rear trunk clearance. Some engines will require this modification, others will not.

Gauges- A water temp and oil pressure gauge are recommended. The oil pressure light sender on the engine can be used for the oil light in the dash.

Tachometer- Early (silver button) 914 tachometers will not register the stock Subaru ecu tach output signal. They can be modified to work with the addition of one resistor (search the forum). Later 914 tachometers should work fine. The basic 5" Autometer tach(~$100) will fit in place of the original tach and register correctly.

Heat- Now that there is some hot water available, any hot rod heater core can be used. These can be found for $100-200, and may be located in/around the engine bay with ductwork routing to the stock hot air ports, or in the front trunk, which may provide more heat. Renegade also sells a heater that replaces the fresh air blower for ~$400.

Renegade Hybrids- http://www.renegadehybrids.com - complete conversion kit, assorted conversion parts
Kennedy Engineering- http://www.kennedyeng.com - adapter plate and flywheel
Small Car Performance- http://www.smallcar.com - assorted conversion parts
Outback Motors- http://www.outbackmotors.com - assorted conversion parts, stub pipes, performance
Cobb Tuning- http://www.cobbtuning.com - performance parts, tuning, high performance heads, etc

How much does this cost?

(NOTE: prices age quickly, so view this as a rough guide)

If bought as a package, the original engine and extra bits can be had for under $2K. JDM (Japanese Domestic Market) longblocks can be found on ebay much cheaper, but less complete. Longblocks from salvage yards can be found for between $500-1000. Expect to pay much more for the Sti engine, and beware the possibility that it may have been run hard with little maintainence. It can generally be assumed that these are interference engines, so a timing belt replacement would be wise if the mileage on the engine is > 60,000 miles ($125 in parts), and seals on a stored engine will tend to leak on startup.

Exhaust stubs are ~$250, the remainder of the system can vary greatly.

The Renegade Hybrid kit is $2,000, with an additional $1,000 for the front trunk radiator kit.

A stock radiator should cost around $125.

The Kennedy flywheel and adapter plate is ~$500.

A shortened oil pan will run $250-300.

It is possible to complete a conversion with home fabrication and some good finds for under $2,500. Renegade quotes a complete conversion cost as $7200, without the engine. However, that price does include bits for a turbo setup, heater, carrera suspension, etc. Their basic n/a kit and radiator intallation would come in at $3,000, plus a good deal on an engine and other bits would probably put the price in the $4,000-5,000 range.