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Old 12-18-2017, 09:38 AM   #5
78F350
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Join Date: Jul 2014
Location: Oklahoma
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Garage
Quote:
Originally Posted by Erlinrys View Post
I'd appreciate as much feedback from experts in the process and the steps required...
I'm far from an expert, so I can't offer much help, but your post made me curious. Why are you doing this particular swap?
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The shop will begin the engine swap process Tuesday.
I'm sorry... did you say Tuesday? as in this week, tomorrow? ..and you are asking these sorts of basic questions now? ...I mean, "NOW?"
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I can drop in the 2.7 motor into the 98 Boxster and to utilize the 2.7 motor mount(s).
Yes, physically they fit and mount the same.
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Wiring Harness (Can I utilize my 2.5 engine harness in the 2.7 motor?)
Here's another issue for you to consider: The Tiptronic transmission harness is bundled into the engine harness. If you don't use the 2.5's harness, you will need to tear it apart and rebuild it or find a 2.7L Tiptronic harness.
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Throttle Body Intake Manifold (swap the 2.5 to 2.7 engine? ... just as simple as running a 12v wire and another wire to Pin 59 into DME ... and smooth operating Boxster, I can probably consider it.
Know what you are going to do before the shop tries to put the replacement engine in. (Are they experienced and do they have any suggestions about these issues?)
Throttle body: 1998 is actuated by a cable and gives position (load demand) info to the DME.
With the 2001, the gas pedal has a position sensor that gives load demand to the DME, which activates a servo on the throttle body, then a position sensor on the throttle sends feedback to the DME.
My guess is that the 5.2.2 DME will only work with the cable throttle and the 7.2 DME will only work with the eGas throttle. Programming and wiring will not fix that.
Either DME and throttle set-up will need custom programming to function well.
The 12v wire and DME pin 59 is specifically for controlling the flapper valve on the 2.7 intake's second cross-tube with the 5.2.2 DME. I don't think that pin 59 on your 1998 986 DME is going to be active without reprogramming. The engine will run without the flapper. It will have trouble meeting the correct fuel/air mix and have some flat spots in the power curve.
Unless you are ready to pay en experienced, skilled pro to get it all configured, swapping various parts will just be a poor compromise and give less performance than a proper 2.5L engine.
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Transmission (Shall my Automatic tranny bolt into the 2.7)
Yes. TC and tranny bolt up, no issues.
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... Alternator (for Automatic), Starter, Engine Air/Oil Separator, Water Coolant, thermostat, Air Filter, Engine Oil Filter, Fuel Filter, Spark Plugs, Crank Seals, Oil Cooler O Ring Gaskets, Lower Upper and Idler Pulleys, Serpentine Belt, Three Gallons of Porsche Antifreeze.
That's good planning. Other thoughts: IMS bearing and seal. Cam tensioner/adjuster pads.

My related experience is swapping a 2.7L manual engine into a 2.7L Tip and owning a 2000 S that had a 2.5L (1997) swapped into it before I bought it.

My advice.... Read Woody's (itsnotanova) post about a dozen more times and let it sink in. Don't take any action until after the holidays.
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Last edited by 78F350; 12-18-2017 at 09:43 AM.
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