Jump to content

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

3.4L to 3.8L Swap Opinion

Recommended Posts

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

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.