Conversions & Swaps LSX Engines in Non-LSX Vehicles
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2002 Porsche C4S (996) LS3 525HP

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Old 12-11-2016, 02:41 PM
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Default 2002 Porsche C4S (996) LS3 525HP

I've been intending to start a build thread on this for several months...just got the engine started last week, here's a quick recap of my progres. Huge thanks to all of the other build threads, I've probably read all of them at least twice!

Bought a 2002 Porsche 4S (All wheel drive wide body...similar to the Twin Turbo model, but with a regular carrera S motor).
Miles: ~150K
Mods: mostly stock...but with a TPS turbo kit
condition: engine starts, but that's it...huge cloud of smoke, and coolant in the oil.
Cost: $12.5K

Engine: LS376/525 crate motor w/ electronics
Kit: Renegade Hybrids kids w/ manual water pump
*after selling the motor and turbo kit, I'll likely be just over $20K total invested.



TPS Turbo kit: fits nicely in the rear passenger fender area. It was super rusted...overall the car has had a rough life:


Draining the oil. I had hoped it was an AOS issue...so I drained the oil, and went to fill up the cooling system w/ water; that's when I heard fluid filling the exhaust. the water had a direct path into the exhaust...


Pulled the engine...easier than I had thought, many thanks to all the forums and DIY threads!:



My last car build was a Lotus 7 replica kit by MNR. 1.8L Turbo Miata drivetrain ~220 HP and 1,400lbs. there was a lot more to do, but in many ways it was simple b/c there wasn't much of an interior and the motor and ECU were pulled from the donor car, so less integration issues compared to this new LS3/996 project.
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Old 12-11-2016, 02:51 PM
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Question: How are others connecting their L3 switch ignition signal?

background: I used the existing power wire from the driver's side O2 sensor from the Porsche, as these get power once the ignition is ON, and they don't loose power while starting.
1) I confirmed that when the ignition is in the ON position, the LS3 fuse panel and ECU get power (you can hear the ECU and various sensors making noise)
2) When I turn the ignition off, I also confirmed the LS3 ECU is off
3) When I started the engine, it fired right up...I only intended to let it run for a few seconds as I just wanted to ensure I had things connected properly; but when I went to shut it off, the engine kept running, even with the key pulled out. I had the fuel pump relay jumpered, so I pulled that and within a few seconds the engine died.

I'm wondering if the Porsche O2 sensors get power for XX seconds after the engine is off...or do I have some other issue?

Thanks!!
Old 12-11-2016, 03:51 PM
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I used the stock Porsche wiring. I also installed all the Porsche and GM engine sensors with stock wiring so the Porsche ECM will run the dash. I still get the Porsche ck eng light, I just covered it internally.
Old 12-11-2016, 04:09 PM
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Great to see you started a build thread, cant wait for more !

Last edited by Outlaw 911; 12-11-2016 at 04:38 PM.
Old 12-14-2016, 01:00 PM
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Good to see one more swap A+.
Old 12-14-2016, 05:05 PM
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should be able to make some good money on that turbo kit!
Old 12-17-2016, 12:14 AM
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I'm on my last few items of my TODO list before I go for a short drive around the neighborhood...but my clutch line is giving my fits; when I removed the stock engine, the clutch line got caught and bent badly...so I replaced it, but the small union retaining clip was old and won't hold pressure (it looks like a small wire cage).

Anyone know what the part number is or were I could get one quickly?


Here it is installed...it's the last segment before the clutch slave cylinder. I made all the connection, bleed the line, and when I stepped on the clutch pedal I heard a small pop and the pedal went to the floor.



Here's the pieces taken apart. I need the small wire cage looking piece...it's what slips inside the union and retains the male connector.



Here's what it looks like when it's put together...that retaining clip (wire cage) is in the middle.
Old 12-17-2016, 12:45 AM
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So close, yet so far...
Can you get a brass ferrule / olive at an AN fitting shop that will fit? Or even a brass plumbing ferrule in a compression fitting?
Old 12-17-2016, 05:25 AM
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Just a quick search ,Looks like you can only buy the whole fitting.

http://www.porscheatlantaperimeterpa...roduct=3866953

If you can figure out if they are the same as the ps fitting i have a couple of those.
Old 12-17-2016, 05:56 AM
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this might sound stupid but - are you sure it was leaking ? The 996 clutch is really difficult to bleed .I would bet the cage is fine and you have a lot of air in the system .Based on my experience it takes a power bleeder and a big bottle of fluid .At least 30 seconds of open bleeding and maybe several shots
Old 12-17-2016, 08:35 AM
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Stuff like this are why i didnt remove my fittings, i just unbolted the whole slave from the trans and tied it up.
Old 12-17-2016, 10:05 PM
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Thanks for the help guys...luckily I have an old freind who's a Porsche mechanic; he had a spare one in his tool box!

dcd215 - yep, 100% it was leaking...fluid all over the floor; the retainer failed and the whole joint came apart

Outlaw911 - Agreed...I've spent nearly as much time fixing OEM issues on this car as I have doing the Swap. but I knew it needed more than just a new motor...so it was somewhat expected.


FYI - finishing up the cooling system tonight and Monday...then hopefully going for my first drive Wed or Thurs!!
Old 12-18-2016, 04:30 PM
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Subbed and want to see more pictures or it didn't happen... I hear ya on the OEM issues and fixes, if your car had 150k miles then there is a lot to deal with.
Old 12-18-2016, 10:50 PM
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Q: How did you wire the Porsche Coolant Temp Sensor? When I sold my engine, I forgot to cut the electrical connector off, so all I have is the sensor. I've called countless places, but short of buying a whole engine wire harness from eBay, I can't get this connector.

My temporary plan is to use a makeshift connector...while that's good enough for an initial drive, I want something close to OEM.



Old 12-19-2016, 10:04 AM
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I kept the whole engine harness, as a temp fix your idea will be ok.
Old 12-19-2016, 11:10 AM
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My car had no engine, so i bought a whole engine harness off Epay. I think it cost $50 or so, but I was able to build a Porsche only sensor harness, from it.
Old 12-19-2016, 11:45 AM
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You can buy small female terminals and build your own connection or simply solder wires directly to the sensor terminals and then seal the connector port with silicone or black RTV.
Old 12-19-2016, 08:49 PM
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I talked to Porsche and they said they should be able to order just the electrical connector and wires directly from Porsche, but they need a picture of the car-side electrical connector. Can someone take this picture and send it to me? I searched for ~30 minutes and haven't found a pic online...

Thanks!

shanghai_todd - that's what I did...it's curing in the garage as I type. Thanks for the idea of the RTV, I like that it adds strength. should be good for the next month as I do test drives.


Originally Posted by First350



Old 12-19-2016, 10:10 PM
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Ask on 6speed, I wouldn't be surprised if someone had one laying around. 6speed and Rennlist are the goto Porsche boards.

Edit: another good one is Pelican parts, discount seller of Porsche parts with a decent forum for help finding stuff and tech

http://forums.pelicanparts.com/porsc...997-991-forum/
Old 12-20-2016, 12:41 PM
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Mine is still out , i will get a pic of it today and post it.


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