LS swapping the Porsche Boxster/Cayman (photos)
The Porsche Boxster/Cayman platform has long been praised for its chassis balance and razor sharp handling, but has been overshadowed by Porsche's more powerful 911. That said, if your Boxster or Cayman has a failed intermediate shaft bearing and is in need of a new engine, an LS V8 swap is a most cost-effective solution for more power.
1. Not the Easiest Swap
Swapping an LS motor into the belly of a mid-engined Boxster or Cayman is not as easy as in many front-engined cars, but it fits and can be done. One of the few companies offering a LS conversion kit for the Boxster/Cayman is Renegade Hybrids, who are well known for their 911 V8 conversions. Their kit offers much of what you need to transplant an LS V8 into 986 & 987 cars, make no mistake, it is MAJOR surgery and not a direct bolt in. This will require fabrication skills to be done right, and modifications to the firewal which reduce the seat travel by a bit. However, all the gauges still work, the Porsche fuel pump and tank are compatible, and even the radiator can be reused. If you are shopping for a project car, it is best to start with the Boxster S or Cayman S.
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2. Engine and Transmission Cradles/Mounts
The most significant fabrication needed to install an LS engine into a Boxster/Cayman is cutting away a large portion of the factory firewall for clearance of the larger V8, and welding in a new cross bar behind the seats. Factory Porsche transmissions mounts do not align with the Renegade transmission brackets, so a set of aftermarket Porsche transmissions mounts such as Wevo mounts or custom fabricated ones are needed. Individuals who have completed the swap also indicate that Renegade supplies the engine cradle, but not the LS engine mounts to attach to the cradle (which are stock GM or aftermarket).
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3. Exhaust
When swapping an LS into a Boxster/Cayman, all of the stock exhaust can be tossed, because a custom system will have to be made. With the position of the engine in the Porsche's chassis, long tube headers interfere with the rear suspension, so either the stock exhaust manifolds or a set of block hugger headers need to be used. You will need O2 sensor bungs on whatever you use so the oxygen sensors can communicate with the ECU. As far as the exhaust routing, most choose to follow Porsche's original design and route it up and over the axles to allow for ground clearance.
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4. Water Pump and Cooling
Although an LS engine meshes with Porsche's cooling system, an electric water pump will be needed. There is little room for accessories between the front of the motor and the firewall. A compact electric water pump, such as from Stewart Performance, is able to be neatly tucked away in the tunnel to utilize the stock cooling hoses/hard lines. The stock dual-radiator setup has proven quite efficient and can easily cool cars making 400+ horsepower, but it's worthwhile to invest in a third radiator kit if plans include big power numbers.
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5. Transmission Setup
The stock Boxster and Cayman transmissions can withstand over 500 horsepower in stock form, as they (according to GBox) have the thickest gears of nearly any Porsche model. The Porsche gearboxes easily bolt up to the LS engine via a Renegade or Kennedy Engineering adapter plate, although an upgraded clutch is recommended. One thing not included in the Renegade swap kit is an LS starter, so plan on adding one of those to your parts list. The transmission does sit back 4" further than the stock setup, but the rear axles are still able to work within the limits of the CV joints.
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6. Power Steering Kit
As with the water pump, the stock LS power-steering pump will also interfere with the firewall, so Renegade has designed their kit with an electric power-steering pump in mind. The power-steering kit is an additional cost to the LS swap kit, but apparently its is simply a 2000-2005 Toyota MR2 electric power-steering pump that is completely self-contained. The pump simply needs a source of power, reservoir, and new hoses to restore power-steering functionality, however, some have ditched the power-steering entirely and left the Porsche without power-assisted steering, which provides great road feel and is still relatively easy to maneuver.
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7. Fuel System and Intake
The stock Porsche fuel pump setup is adequate for any stock LS engine, but a new fuel pressure regulator will be required for your particular engine setup. On the intake side, the manifold is rotated 180 degrees for clearance. There is just enough clearance for the throttle body, however, custom intake piping will need to be fabricated for the filter.
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8. Wiring
One of the unknowns about this swap kit is how to get the Porsche dash and electronics to talk with the LS's ECM. Renegade says it can be done, but doesn't give the details. Those who are willing to ditch the factory dash setup can instead opt for an Arcflash or similar digital dash setup that is plug-n-play with the LS 10-pin wiring connector. Otherwise, it is easy as you retain all of the LS sensors and the factory computer.
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For help keeping your LS powered car in fine tune, see the how to section of LS1Tech.com