3.8 engine going into my Boxster S
 

I am planning to begin work this week on an swap, putting a 2002 Carrera 3.8L (orig 3.6L) motor into my 2000 Boxster S. This motor has been rebuilt at 100k due to scored sleeves using the LN 3.6->3.8 JE piston kit, and has the LN IMS upgrade. I believe the conrods and all chains and guides have also been replaced. The motor saw about 5k of action in the Carrera, and it is very very very strong feeling, on par with a 997 by butt dyno measurement, it really puts you back into the seat and makes 2nd gear feel like 1st.

I know that the electronics will also need to be swapped, and I have access to the entire car to steal parts. I already have a very healthy rebuilt transmission, new clutch and flywheel, rear wheel bearings and half-shafts. I will be using Topspeed headers, test pipes, and OEM 986S muffler (to keep it ~somewhat~ quiet and avoid resonance).

I plan to remove the Carrera parts first, then begin swapping one part at a time, trying to get a running car as soon as possible into the process so I can spot any issues before it's all together. IE, do the motor, DME, immobilizer first, then see if it runs before doing secondary stuff like HVAC, ABS, exhaust


Parts I know that I'm going to swap into the Box:

engine, including intake and 74mm throttle body, MAF

7.8 DME

Immobilizer

Key transponder "pill"

CANBUS HVAC brain

ABS 5.7 Brain w/ TC

Gauge cluster

OBC 4th lever

wheel speed sensors (for 4-channel ABS)

fuel pump with return input

engine wiring harness

Things that I'll to fab up, or otherwise obtain (* means optional, although I ought to do it):

some way to extend the camshaft position sensor and VarioCam II wires to the back side of the motor

CANBUS wires to HVAC, ABS unit (think I can just use off-the shelf twisted pair cable and some shielding)

fuel line with return

either some spacers to lower front engine mount for clearance OR 987 engine lid so I can retain 996 intake with both resonance flappers

*rebuilt fuel injectors

*new ignition coils

*987 airbox and filter

*silicone coupling for MAF to airbox

*Porsche or Quaife LSD to install into my rebuilt 6 speed Boxster trans

*997 shifter

*DME tuning and flash to take advantage of headers, cat deletes, remove SAI CEL

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Please please please give any tips and advice, as I've never done this before. I am going to try to avoid breaking anything, but realize that's inevitable... Anyone in the NY area is welcome to come by and lend a hand too; I'll buy you beer and let you take a spin when it's done!

I will be posting pics and build progress as I go, and am hoping to finish the job in 2-3 weeks of a couple hours a day. Looking for a 986 that will hang in the corners with 987 S (after a little more suspension work) and accelerate on par with a 997 C2 for about $20k all in. Too bad I can't do much about the crappy worn out 986 interior....

That sounds like it will be a rocket, as far as interior if you're putting that much in why not some sport buckets, there are some nice aftermarket units that don't cost what the factory units do. New clutch or not as long as it's apart make sure you don't need a stronger clutch for that kind of extra power, good luck.

i think you have your fuel systems reversed; your car has a return system; the engine going in does not. Also, the top speed headers, regardless of primary/secondary pipe diameters, will be to small; the outlets on the 986 heads are smaller than on the 3.6/3.8 engines so the flanges on the headers will have openings that are too small. perhaps you can machine them bigger, but my understanding is that most folks go with aftermarket 987/cayman exhaust on these conversions.

you'll also want an aftermarket airbox (the 986 air box will be too restrictive and would have to have the maf housing sawn-off); folks are using modified cayman/987 air boxes or you can also look at a bmc unit (CDA or DAI); the k&n universal unit is too small at 70mm.

if you have money to burn perhaps look at the ipd/softronic plenums that can take an 85mm gt3 throttle body.

from what i understand, the aftermarket flashes won't let you delete your sai without a cel; you need a row base flash for that. i.e., get a row base flash, then push a tuned flash onto that.

Sounds quite ambitious...hope it goes well.:cheers:

The whole thing sounds like a great experience; fun and equally frustrating. Wish you the best with it and keep us posted along the way please, with pictures :p

Looking forward to watching this come to fruition. It will inspire my swap!

Update: this is still happening -- the owner of the lift I use had some problems with his DD mitsubishi so I haven't been able to get started yet.... still planning to get to it soon though.

Do you have any update on your progress with this?

Best of luck! Wish I could lend a hand!