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Old 04-06-2009, 06:06 PM   #1
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Replace engine in Boxster? 2.5 to 2.7?

Hi there!

Im new here on this forum and I would like to have some advices when it comes to a possible engine swap. I bought a Boxster -99 with 107k miles on the engine. The previous owner hit something and the r/h fender and the radiator was damaged. He continued driving home and as an result of that, the engine over heated.

When I now start the engine it blows white smoke and knocks. I would probably need to replace the head cylinder and the head gasket but I might consider buying an replacement engine instead. I looked at some engines and I thought that I might as well buy a 2.7L which is a better engine.

Does anyone have any experience in this? And can I just swap the engine to a 2.7 without any trouble?

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Old 04-06-2009, 06:39 PM   #2
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Quick answer - no.

The 2.5 is a traditional pedal/cable driven throttle body - the 2.7 is egas - drive by wire - the gas pedal is a potentiometer and a motor in the throttle body opens and closes the TB. This which leads to another issue - the DME (computer).

The 2.5 uses Bosch Motronic ME 5.2.2 while the 2.7 uses Bosch Motronic ME 7.2 (which also interprets the gas pedal signals to the throttle body).

The 2.7 uses a different intake manifold and fuel recovery/recirc. system as well as a new exhaust system which is not a direct bolt-up to the earlier cars.

Different wiring harnesses, and on and on.

You cannot easily remove components from the 2.5 and swap them with the 2.7 either.

The easiest swap is for a non-egas 3.4 from the 996, still some mods to make the DME and exhaust work, but easier swap than the 2.7 egas.

Use the Search function... LOTS of available reading here.

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Last edited by Lil bastard; 04-06-2009 at 10:09 PM.
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Old 04-07-2009, 09:09 AM   #3
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I'm in the middle of the 3.4 swap right now search my posts. I have most of the swap documented. If you need help. I am out on long island.
996 3.4 engine with 2.7 986 5speed transmission
Ebay Headers, Fabspeed high flow cats, JIC Cross, IPD Plenum, H&R Coilovers, B&M Short Shifter, AEM Uego Gauge Type Analog, Apexi S-AFC Select, 987 air box, Litronics, 2000 Tails and side markers, painted center console, 18" 987 S-Wheels, GT3 Front bumper with splitter.
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Old 04-07-2009, 10:18 AM   #4
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Hope your purchase price accounted for the damage and engine issues!

Good luck with whatever direction you decide to go!!

Current Porsches: 2002 Boxster S (Speed yellow)
Past Porsches: 1972 914, 1987 944S, 1976 930, 1986 951, 1999 986, 1992 968, 2001 986 S, 2006 Cayman S, 1986 951 track car, 2001 986 S, 2005 Cayenne
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