3.4 to 3.6 engine swap complexities

[spg356]

Greetings,

 

I have searched this subject and obviously much has been written about it, and I am trying to determine if this project is worthwhile. I inherited a 2001 996 C4 (actually was an asset of a repair shop I purchased last year) and it has a “story”. Blown 3.4 engine long gone, now a 3.6 bought from Parts Heaven is installed and running, but has similar symptoms I have read about related to VariCam and VariCam Plus issues. The project was put on hold when the old GM left the business (it was to be his driver), and the car was an asset of the business when I bought the shop from the owners.

 

From what I understand it is a big issue getting past the differences between VarioCam and VarioCam Plus. My guys fully believe they can get it to run as it should, but I want to see if it is worth it to me. Keep in mind that I am not a horsepower nut and going back to a 3.4 engine would be just fine with me.

 

So, in a nutshell, I will go forward with this project IF it can be done in a fairly straightforward manner. I don't mind sourcing the correct modules etc, but if I have to change out instrument clusters, do custom wiring, deal with fuel delivery stuff and more, then forget it. I don’t want my guys spending time on my car, I want them working on customer cars! I would then just sell the 3.6 and buy a complete 3.4 to get it going again.

 

I know that Todd Holyoak has done this before so I know it can be done, I just do not need a huge time consuming project when I would be fine with a 3.4l engine. 

 

Any guidance here is greatly appreciated.

[Dharn55]

PM me your email and I will give you a DropBox link with a bunch of info on the difference between the VarioCam and VarioCamPlus systems. Theu are quire different. In a nut shell the VarioCam system is a simple advance of the intake cam at a certain RPM and then releases the advance at a higher RPM, and vice versa. The amount of advance is fixed.

 

The VarioCamPlus system has a variable amount of advance and can change the lift of the intake valves. So the control system is entirely different. And the Engine Management System is entirely different between the two to control this, and the later system is CanBus. So it is very complex to install the later system in an earlier car and get it to function properly. Lots of horror stories from people who have tried this.

[cbr786]

hi I am reading this with great interest. I too have a 996 C2 2001 year sitting in my friends work shop which has undergone this conversion.

History is the car a 2001 996 C2 had blown engine the car had egas pedal and was a manual. The car had a 3.6 C4 manual engine transplanted into it. The car would not start initially then we copied the software from the donar cars ecu the 3.6 ecu soft ware was copied and placed onto the 3.4 DME. This was done but I feel maybe all the soft ware was not carried across because the 3.4 DME has less memory then the 3.6 DME.

 

the problem I am at is the car starts and drives fine up until it reaches 60 mph it seems really slow getting past the 60 mph speed and slowly makes progress to 70 mph. 

 

I do want to finish this project off and would like some input from any one who has some more knowledge on the topic. 

[Youri Ko]

Funny, I strated the same topic on Renlist. 

 

Question to cbr786 - why haven't you swapped the DME from 3.6? I'm following the Pelican's article logic on this, they say that 2001 Boxters are prewired for future CAN bus and can accept pretty much anything as long as you bring the 7.8DME with it, article says that only few wiring modifications are required to plug 7.8DME into 7.2 harness, but this is for 2001 Boxter. What's your take on this? How different are 01 boxter to 01 996 to follow the same logic?

 

Article is here :

 

http://www.pelicanparts.com/techarticles/Boxster_Tech/11-ENGINE-911_Engine_Swap/11-ENGINE-911_Engine_Swap.htm

Edited April 19, 2016 by Youri Ko

[cbr786]

sorry for taking so long to reply I have been away from PC. I did not swap out the DME because I had no key and alarm module from the other car only the ECU. I am going to swap out DME for a 3.6 with matching alarm module and key and see what goes from their. 

 

I did find out my mistakes of trying to swap soft ware maps I have been informed this cannot be done because the memory on a 3.6 DME has a bigger capacity then the 3.4 DME hence soft ware swap would not have worked 100% as not enough memory. 

 

I will read that article you sent a link to with great interest and see if I can figure out where I am going wrong.

[spg356]

To anyone who is following this topic:

 

It CAN be done and is not as nearly complex as you might think. After my initial post I received an email from another forum member. He informed me that he had done the swap successfully a couple of year ago and that while it was not bolt on/plug and play, it was by no means as difficult as the internet would have you believe. He was amazingly helpful during the process and the only reward he wanted was knowing that another 3.6 swap would be done. I am currently driving the car with no issues, it has terrific power & drivability and I could not be more happy with it.

 

There is one tiny trick he revealed that when you hear it, it makes all of the sense on the world and it solves the programming issues between modules, the key transducer and the immobilizer which in turn solves the problem between VarioCam & VarioCam+. We are going to post a write up on the swap procedures so that others can do it with the same success. What I liked best about the process was that there were no "workarounds", aftermarket pieces or hacks needed to make it work, it is all 996 and is very straightforward.  Please note: we are not doing this for any kind of reward or fee, we are just so pleased that it can be done that we will share it with the forum, and that should happen soon.

[Ahsai]

I'm curious to see what the solution is and thanks for the update and sharing of info!

[Hobbes]

Spg356 -

 

It was a great experience working with you on this conversion.  I was able to learn a little bit more about the process.  The 2001 C4 takes advantage of the CAN BUS network compared to the 2001 C2.  This also helped minimize rewiring/re-pinning of the cluster wiring.  As I continue to develop the DIY, I'll run it by you to make sure I capture the 3.6l work you did correctly.

[LGP951]

On 7/8/2016 at 12:42 PM, spg356 said:

To anyone who is following this topic:

 

 

 

 

It CAN be done and is not as nearly complex as you might think. After my initial post I received an email from another forum member. He informed me that he had done the swap successfully a couple of year ago and that while it was not bolt on/plug and play, it was by no means as difficult as the internet would have you believe. He was amazingly helpful during the process and the only reward he wanted was knowing that another 3.6 swap would be done. I am currently driving the car with no issues, it has terrific power & drivability and I could not be more happy with it.

 

 

 

 

 

There is one tiny trick he revealed that when you hear it, it makes all of the sense on the world and it solves the programming issues between modules, the key transducer and the immobilizer which in turn solves the problem between VarioCam & VarioCam+. We are going to post a write up on the swap procedures so that others can do it with the same success. What I liked best about the process was that there were no "workarounds", aftermarket pieces or hacks needed to make it work, it is all 996 and is very straightforward.  Please note: we are not doing this for any kind of reward or fee, we are just so pleased that it can be done that we will share it with the forum, and that should happen soon.

 

Spa356,

 

Is the DIY write up for the swap available?  I have been searching and just get bits and pieces of stuff that people have done but can't seem to find a complete write up.  

 

I have a 2000 996 C2 manual gearbox without an engine (spun #2 rod bearing).  Mechanic tore it down and found the crank was also damaged.  Didn't bother to put it back together so its all in pieces.   I just got a 3.6 from a 2003 996 with a triptronic gearbox.  Along with the 3.6 engine and transmission I got the DME but not the rest of the electronics and wiring.

 

When you get a chance can you post or PM me a link to the write up.  

 

Thanks in advance for your assistance.

 

If anyone else has any info on a complete write up please post or PM me.  Thanks.