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3.4L to 3.8L Swap Opinion

Brian Oaks
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Brian Oaks Member

Brian Oaks

Posted
Posted

Hi all,

 

I have a 1999 6sp manual Carrera 2, that has a 2007 3.8L S engine swap in it (I wasn't part of the swap).  The engine starts, idles, and runs "fine", but there is a very obvious lack of power.  If you're driving leisurely it's not real noticeable, but once you step on the accelerator at all, it bogs down and has just a slow gradual acceleration even under WOT.  I got a look at the DME and it's still the original 996, so my best guess is that the differences in variocam vs. variocam plus (and the inability of the old DME to process the info) is whats holding it back.  Feel free to disagree, as this is NOT my forte, and I'd love to learn more.

 

If it is the DME/Variocam issue, I'd like to ask opinions on what you would do:

1. Get a 1999 3.4L engine, swap it back in and sell the 3.8L engine to recoup cost.

2. Get an updated 997 wiring harness and DME, and try to get the 3.8L running correctly.

3. I've read a couple posts that suggest you can run an RPM switch to the variocam plus wiring to activate/deactivate it at the proper RPM's, which might allow the 3.8L to run correctly with the 996 DME.  Do you think that's actually a possibility?  And if so, do you have any guesses on what tuning the old DME might cost with such a switch in place?

 

Sorry in advance if any of this sounds dumb because I don't really know that much about these systems.  Thanks for any input you can provide!

 

Porsche pic.PNG

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