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3.4 in 1998 boxster 2.5

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Hello, I am in the process of upgrading from a tiptronic 1998 boxster 2.5l Motor to a 996 3.4L. My questions are:

1) Will the 986 tiptronic fit the 996 motors or do I need to modify flywheel, pressure plate or clutch so it will bolt to the 996 motors?

2) When bolting back hoses, pipes and other component to the motor, how do I figure out the number of torque pounds needed to bolt the bolts back "I don't want to break seals by over tightening the bolts"?

3) Do I need an early "1999-2001" 996 tiptronic instrument cluster + cluster cover and if I do, do I need to modify it?

4) After the upgrade should I worry about covering fuel lines or placing them in specific locations other than original in fear or fire hazard?





Ok so I finally got the time to do my upgrade. I started on Wednesday 9/12/07and got the engine running on 9/21/07 “yesterday”. The project was actually straightforward lol. It was almost like removing a boxster engine then re-installing it back. Here are issues I had to deal with:

1) I used the boxster fuel railing, and modified it to fit on the 996 engine “easy mod”

2) I had to figure out a way to lower the engine down. So

A)I used a caliper and figured ½ inch is the way to go.

B)The front of the engine was easy to drop “front Engine mount” went to hardware store got ½inch solid bar and drilled 2 holes in it to make my two adapters to lower engine mount. “ p.s at first I only lowered the front engine mounts by ½ inch which allowed the engine cover to go on, problem is engine wont start!!! The torque converter was touching the engine at an angle. Lesson learned: make sure you drop both front engine mount and rear transmission mounts D'oh! lol”

C)The back of the engine “transmission mount” was the tricky part. Some used C2 engine mounts to lower the car. I even thought of using solid aluminum C2 mounts “the sport kind, which will add more torque to the car, but also make it noisy lol” them C2 mounts cost over $200 each !! I found some used C2 mounts for $75 each on ebay.I figured out a new solution. I basically used a hand saw and cut ½” out of the mount holder, then put a ½ inch washer behind” from hardware store” and it did the trick . I know it sounds confusing, but I shall post pics later.

I bought a 996 cluster off of Ebay it was for an early 996. All the plugs in the back “3 plugs” matched my boxster plugs. It seems to work the same way as my boxster so far. I will update if there are any future problems. I got 3.2 headers off of ebay, and the fabspeed cat + exhaust for a 3.2 s boxster. I noticed the passenger side cat pipe was shorter than the driver side and it made the pipe leak some air. I used a sleeve to fix that and every thing seems dandy now. I like the sound of the fabspeed kit “not too loud”. I had a GHL exhaust for my 2.5 engine, the GHL was LOUD MANG!!!

I installed an Evo cold air intake and used silicon pipes “3 inch” to rout it. Also installed cross-drilled brake rotors and colored the brake caliper red. As of now I am using the boxster 2.5 ECU and it seems to be running fine. I know FVD has a sport ECU for 2.5 to 3.4 conversion at $1500 !!! if any one knows of a more Economical way could you guys let me know? Anyhow I am still not 100% done with the car, I have to finish the ECU upgrade, then my sound system. I shall give more updates later and post pics. Thanks to all the members in this site for the tips that helped me finish my project

Thanks again


Edited by goldnogard
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