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3.4L Swap Underway


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Steve

Not a new engine, has 20k on it, purchased off of a fellow on the Pelican Parts BB.

I will eventually do a write-up on the procedure when I am finished. I'm hoping it won't be any more involved than the 3.6 swaps I've don into earlier 911s or the 968 engine I put in a 944S.

The car is my daily driver and I can't afford to have it tied up for too long during the process.

Todd

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Steve

Not a new engine, has 20k on it, purchased off of a fellow on the Pelican Parts BB.

I will eventually do a write-up on the procedure when I am finished.  I'm hoping it won't be any more involved than the 3.6 swaps I've don into earlier 911s or the 968 engine I put in a 944S.

The car is my daily driver and I can't afford to have it tied up for too long during the process.

Todd

Where are you now with the installation of the new engine. I assume it is probably done and how is the car respoding to the new engine?

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A number of people have done this. If you have not, you should ask around for info. If memory serves me correctly:

1) you will have to fabricate engine mounts (the 996 motor is an inch taller (maybe shorter) and it must be dropped another inch to fit the boxster.

2) You have to change or flash the ecu

3) I am assuming you got a 3.4 motor. A 3.6 needs egas which your 99 does not have.

4) There are some issues routing either the fuel lines or the AC lines. Also I think one of these was not long enough and had to be changed.

5) There were some issues with the fuel rails and throttle body sizes. Details escape me.

6) You did not say what tranny you are using. If the original 5 speed you might want to put in a better clutch.

Good luck.

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A number of people have done this.  If you have not, you should ask around for info.  If memory serves me correctly:

1) you will have to fabricate engine mounts (the 996 motor is an inch taller (maybe shorter) and it must be dropped another inch to fit the boxster.

2) You have to change or flash the ecu

3) I am assuming you got a 3.4 motor.  A 3.6 needs egas which your 99 does not have.

4) There are some issues routing either the fuel lines or the AC lines.  Also I think one of these was not long enough and had to be changed.

5) There were some issues with the fuel rails and throttle body sizes. Details escape me.

6) You did not say what tranny you are using.  If the original 5 speed you might want to put in a better clutch.

Good luck.

1) you don't need to fabricate mounts, you use a combination of 964 C2 motor mounts at the rear and 3/4" spacers at the front.

2) as long as you don't have a '97 ECU it is easier to have the ECU reprogrammed, and not have to worry about the driveblock, you will utilize the Boxster DME harness as well not the one on the 996 engine.

3) as the subject title says it is a 3.4

5) I am getting around the issue of the fuel line connections being in the wrong location on the 996 fuel rails for the stock lines not by lengthening the stock lines but by swapping the 996 injectors onto the Boxster rails. This way you keep the stock lines and the parts are interchangeable, same FPR and all.

6) using the stock trans, it will hold up fine to the power with a new sachs performance clutch.

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2) as long as you don't have a '97 ECU it is easier to have the ECU reprogrammed, and not have to worry about the driveblock, you will utilize the Boxster DME harness as well not the one on the 996 engine.

When my 2.5 engine eventually explodes I will probably get this done, so:

1. What is the problem with the '97 ECU?

2. What is a driveblock?

Hope the project is going well.

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2) as long as you don't have a '97 ECU it is easier to have the ECU reprogrammed, and not have to worry about the driveblock, you will utilize the Boxster DME harness as well not the one on the 996 engine.

When my 2.5 engine eventually explodes I will probably get this done, so:

1. What is the problem with the '97 ECU?

2. What is a driveblock?

Hope the project is going well.

Based upon info on Trent Carter's site (before it disappeared), his '97 DME couldn't be reflashed, he had a DME ending in .02 that no one could reflash so he had to buy a later DME, which obviously increases costs. Not sure if this is still the case but something to look into if you have a '97 with this DME part number.

Driveblock is part of the anti-theft system on the car. I believe it functions by the driveblock and DME are a matched set, if one doesn't recognize the other the car will not run. On 993's this function could be removed when the DME was reflashed, not sure if it can be done on the Boxster/996. Also on the 993 the euro cars didn't have the driveblock issue so you could run a 993 engine in a swapped car with a euro DME and DME harness. I think the driveblock is worldwide on the 996/986 series of cars but I am not sure.

The swap hit the first snag when removing the 996 headers. Even with the heating of the bolts with a torch, 7 of the 12 exhaust manifold bolts broke, so now I will have to weld nuts onto the protruding studs and try and remove the remains of the bolts. Hopefully I won't have to resort to drilling too many of them out. I don't know what Porsche was thinking with steel bolts, threaded into aluminum heads, high heat and no anti-seize and obviously these have never been out since the engine was put together.

Todd

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  • 2 weeks later...
Picked up the motor at the shipping depot yesterday, so my swap is now officially underway.  If anyone is looking for a good 2.5L or TPC supercharger let me know.

post-4060-1113578495_thumb.jpgpost-4060-1113578541_thumb.jpg

Todd

Todd, what was your experience with the TPC supercharger? I have been considering this "upgrade". Is it reliable? The 3.4L can't be that much of a boost versus the supercharger so what is driving your change?

Hats off to you for doing this yourself!

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The supercharger has worked perfect. No driveability issues or problems at all. The installation has approx 40k on it so it has been quite reliable. The supercharger is a small low boost setup and I find it seems to run out of breath at the top end or maybe it just has so much down low that you don't get the typical push when the car comes on cam at high rpm. Nice torque down low but just not enough HP and torque for my tastes. If I drive it after being in my '80 911 with a modified 3.6L 993 engine, it is quite tame. So I am looking for more of the same performance that I have in the 911 in the Boxster. I am hoping the 996 engine swap will give me that. I believe the supercharger is supposed to be 210 hp 210 ftlbs at the wheels vx ~142 and 132 for the stock car (based on the TPC site (I have the actual dyno runs of my car somewhere as well)) I think the 996 engine should be somewhere around 300-320 hp at the crank with a good exhaust and DME remap so hopefully I won't be disappointed.

My supercharger setup will be for sale after the swap, so if you are considering it you could pick up the setup for about 50% of what TPC will charge you for a new setup.

Todd

Edited by tholyoak
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  • 3 weeks later...

Jeff,

Unfortunately the demands on my time have not allowed for me to stick the engine in. I am also waiting on 2 gaskets I need that are on back order from Germany. They were supposed to be here today, if that is the case it will go in this weekend and I will have an update for you on Tuesday.

Todd

Are you done with the swap yet?

Jeff

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Please don't forget the pics of the S/C setup before you rip it out.

Thanks,

CW

What pics of the supercharger setup do you want to see? I took several pics of the wiring and installation that will be provided to the buyer of the setup.

post-4060-1117555110_thumb.jpg

Here is a pic of the 3.4L in its new home

post-4060-1117555160_thumb.jpg

The DME is being reprogrammed today so hopefully it will be running soon.

Todd

Edited by tholyoak
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One of the interesting things I found during the swap had to deal with the motor mount and oil pump.

As shown here the Boxster mount bolts to the block and these bolts function also to secure the oil pump to the block (along with some other bolts)

post-4060-1117642335_thumb.jpg

Now if we look at the bolt indicated by the arrow above, and then at the black circle in the pic below, this boss was not present on the 3.4L engine oil pump.

post-4060-1117642427_thumb.jpg

So instead of just swapping the cap and water outlet from the 2.5L oil pump housing (shown in the last picture (arrows), I had to remove the 2.5L oil pump and swap it onto the 3.4L block and then install the motor mount.

This turned out to be the only thing I encountered that I didn't expect. I have seen other 3.4L engines and the oil pumps seem to have the same boss that was on the 2.5L engine, so maybe I just got 'lucky'

post-4060-1117642595_thumb.jpg

Edited by tholyoak
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