Build: '99 Porsche C2 996 LS1 Swap
10-23-2019, 05:54 PM
#1
Build: '99 Porsche C2 996 LS1 Swap I figured it's time to finally start by build thread! I recently purchased a 1999 Porsche 996 C2 with the M96 and Tiptronic combo. Unfortunately, the engine has a rod knock and needs to be rebuilt or replaced. I looked at a few options and made up my mind that this deserves a LS1/G96 swap. I drove across the state in the dead of winter last year to grab this car after it had been sitting a while. It's in rough shape in a few areas and has some beauty scars for sure. It definitely has been in an unreported accident as the front bumper is chipping and has yellow paint underneath and there's a couple small dents underneath the doors. Minor stuff, nothing too crazy. The interior needs a bit of help too, the carbon fiber Tip steering wheel is cracked and the seats have seen much better days. I would never really want an automatic sports car, so that's why I'm swapping to the 6MT at the same time.
I've LS swapped my Wrangler after extensively modifying it with coilovers, custom built 1 ton axles, custom front frame, and a 5.3L/4L80e/Stak Dana 300 combo pushing around 380-400 hp at the crank. I run a 3000 stall converter through this with quite a few coolers and love it. I miss my BMW 135i, so therefore the barely running 996 came home with me.
Here's a pic of the Jeep for reference. I built everything you see on it over the last 10 years:
Onto the Porsche build!
Dragging the 996 home for it's new life:
It was in rough shape after the blizzard coming home
Cleaned up, it's not so bad. Definitely a 10 foot car instead of a 1 foot car though...
I started searching and found a few things I needed to get started. I did TONS of research before deciding to go with the Porsche G96 6 speed manual with a limited slip. I also knew I wanted an aluminum block variant of the LS and found a disassembled LS1 waiting for pickup at a great price. I brought that home and cleaned it up. It's in fantastic shape! I sold the LS1 intake and 853 heads in favor of a Fast 90 intake and drive by cable throttle body as well as a set of 243 heads. I am reusing the hot cam that came with the LS1 for now.
I used new gaskets, seals, and ARP head bolts. It's 100% freshened up and ready to go! If anyone wants more details on the LS1 build sheet, just ask!
Finally, I was able to stash away the Jeep and pull in the German to the American garage for a teardown:
More to come!
I've LS swapped my Wrangler after extensively modifying it with coilovers, custom built 1 ton axles, custom front frame, and a 5.3L/4L80e/Stak Dana 300 combo pushing around 380-400 hp at the crank. I run a 3000 stall converter through this with quite a few coolers and love it. I miss my BMW 135i, so therefore the barely running 996 came home with me.
Here's a pic of the Jeep for reference. I built everything you see on it over the last 10 years:
Onto the Porsche build!
Dragging the 996 home for it's new life:
It was in rough shape after the blizzard coming home
Cleaned up, it's not so bad. Definitely a 10 foot car instead of a 1 foot car though...
I started searching and found a few things I needed to get started. I did TONS of research before deciding to go with the Porsche G96 6 speed manual with a limited slip. I also knew I wanted an aluminum block variant of the LS and found a disassembled LS1 waiting for pickup at a great price. I brought that home and cleaned it up. It's in fantastic shape! I sold the LS1 intake and 853 heads in favor of a Fast 90 intake and drive by cable throttle body as well as a set of 243 heads. I am reusing the hot cam that came with the LS1 for now.
I used new gaskets, seals, and ARP head bolts. It's 100% freshened up and ready to go! If anyone wants more details on the LS1 build sheet, just ask!
Finally, I was able to stash away the Jeep and pull in the German to the American garage for a teardown:
More to come!
10-23-2019, 05:59 PM
#2
The LS1 build up:
This was as of a few months ago. I am now looking into a dry sump setup since so many LS owners have oiling issues. Some say an accumulator such as an Accusump and good pan baffling and trap doors will do the trick. Unfortunately, that just isn't the case if you seriously track the car. As of now, I am looking at a 2 or 3 stage dry sump pump from Nutter Racing in Vancouver, WA. I'd also have a mechanical tensioner with a Gilmer toothed belt pulley on the front of the 6 rip serpentine pulley. Some like to run the Gilmer drive off the crank but I am not looking to do that. My alternator will run off the opposite side of the water pump, low near the oil pan. The AC compressor is hopefully to be a factory F body type mounted in the factory position below the water pump outputs. I may have to do some custom plate work for mounting the AC tensioner. I'll definitely have to make a mount for the dry sump pump mount.
I've been mocking up all of this in Solidworks CAD software and also designing a very early prototype of a 180 degree exhaust system to maintain a more high pitched and exotic sound to the car.
As for the LS1 to Porsche G96 adapter, I bought it from Eric at Kit Car Chassis with a stage 2 Spec clutch. He was nice to work with but it took about 6 weeks for the adapter and one of the bolts does not line up with the transaxle mount. I'd probably go with the Stuttgart Muscle adapter if I were to do it again but Eric does include a starter which is a plus.
Back of the LS1:
Adapter kit
Adapter installed with 4L60e dished flex plate used for starter engagement
SPEC Clutch which is a M96 996 variant, not a custom clutch
Note that the flywheel is 2 piece. First piece bolts the small adapter and flexplate to the crank (shown previously). Then the larger flywheel is bolted to that piece and the clutch afterward.
Assembled and ready to go LS1 to G96 transaxle
- 243 heads, dual springs, hardened pushrods
- Tick Performanece SNS Stage 2 cam
- Melling high flow oil pump
- All new gaskets, seals, etc
- ARP cam bolts, ARP head studs, ARP crank bolt
- Fast 92mm Intake
- PTM 92mm throttle body
- 42lb LS3 injectors
- Holley fuel rail
- Holley Terminator X engine management system
This was as of a few months ago. I am now looking into a dry sump setup since so many LS owners have oiling issues. Some say an accumulator such as an Accusump and good pan baffling and trap doors will do the trick. Unfortunately, that just isn't the case if you seriously track the car. As of now, I am looking at a 2 or 3 stage dry sump pump from Nutter Racing in Vancouver, WA. I'd also have a mechanical tensioner with a Gilmer toothed belt pulley on the front of the 6 rip serpentine pulley. Some like to run the Gilmer drive off the crank but I am not looking to do that. My alternator will run off the opposite side of the water pump, low near the oil pan. The AC compressor is hopefully to be a factory F body type mounted in the factory position below the water pump outputs. I may have to do some custom plate work for mounting the AC tensioner. I'll definitely have to make a mount for the dry sump pump mount.
I've been mocking up all of this in Solidworks CAD software and also designing a very early prototype of a 180 degree exhaust system to maintain a more high pitched and exotic sound to the car.
As for the LS1 to Porsche G96 adapter, I bought it from Eric at Kit Car Chassis with a stage 2 Spec clutch. He was nice to work with but it took about 6 weeks for the adapter and one of the bolts does not line up with the transaxle mount. I'd probably go with the Stuttgart Muscle adapter if I were to do it again but Eric does include a starter which is a plus.
Back of the LS1:
Adapter kit
Adapter installed with 4L60e dished flex plate used for starter engagement
SPEC Clutch which is a M96 996 variant, not a custom clutch
Note that the flywheel is 2 piece. First piece bolts the small adapter and flexplate to the crank (shown previously). Then the larger flywheel is bolted to that piece and the clutch afterward.
Assembled and ready to go LS1 to G96 transaxle
Last edited by gtxracer; 10-23-2019 at 06:16 PM.
10-23-2019, 06:01 PM
#3
Since I knew I'd need to do something for hydraulic lines, I researched the factory P car lines and finally figured out the entire interior has to be removed for the clutch lines to be installed AND they're very expensive and hard to source. No thanks. I'll be using braided stainless 3AN lines with these custom adapters I designed and had machined. Pretty slick, they have the same flare and geometry as the P car lines for 996/997 and insert into the Master Cylinder.
Then the 180 degree headers have gone through changes here and there. I think I finally decided on a front exit, toward the balancer. The early versions exited toward the transaxle.
More to come tomorrow!
Then the 180 degree headers have gone through changes here and there. I think I finally decided on a front exit, toward the balancer. The early versions exited toward the transaxle.
More to come tomorrow!
Last edited by gtxracer; 10-23-2019 at 06:21 PM.
10-23-2019, 06:02 PM
#4
After finding a low profile motorcycle lift jack at Harbor Freight, I dropped the old M96 and Tiptronic out of the 996 donor. These engines are massive. I was expecting it after hearing the stories but this is a BIG setup. I can see how the LS1 would be lighter now that all of this is out.
Fresh slate, ready for the initial LS1 mockup:
Referencing this picture again:
I reversed the direction of the collectors to exit towards the rear of the car (balancer side). I've been doing a ton of research on 180 degree headers in a LS application. Most people do not like the sound with a crossover, which is shown below. I am leaning against it. Most of the best sounding 180 degree header designs are shorter with small or no mufflers. Take a look at the GT40 headers and you'll see what I mean. I also thought about using a muffler that has a dual in and dual out with an internal crossover but I doubt I'd like that after hearing the reviews on them.
It will be a bit of a mix and match experimentation for the mufflers and final output after the collectors. I don't want it to be irritating or loud. I'll have V band clamps after the collectors to make swapping easy. I may have to make a temporary exhaust while I experiment with placement of the AC, alternator, and hopefully a dry sump setup.
Shown above is all the components I've been managing and test fitting. A mechanical manually set tensioner with a Gilmer drive gear on the same pulley as the 6 rip serpentine belt, a 3 stage Aviaid dry sump pump, factory AC compressor, and factory alternator. I am likely going with a Nutter dry sump pump after talking with AC, the man that runs that small company out of Vancouver, WA. I will run 3 pickups out of a shallow pan but will likely design the headers to allow other pans as some fellow 911 LS swap guys have requested them. I will likely mount the dry sump pump on the same side as the water pump outputs and have it mounted high, off the cylinder head on that side. The motor mounts are directly bolted to the heads so I will have to manage that as well. I will also likely use a dedicated oil cooler with remote filter and a 3-5 gallon dry sump reservoir with a separate vent/catch can. Coleman Racing has a neat dry sump reservoir with built in cooler, filter, and oil level sight tube that I might try. The dry sump setup is a recent change so I'll have to tear down the LS1 for the new pan. I am still planning to use the Melling internal oil pump for pressure. This entire dry sump setup will cost less than half of most entry level kits.
Fresh slate, ready for the initial LS1 mockup:
Referencing this picture again:
I reversed the direction of the collectors to exit towards the rear of the car (balancer side). I've been doing a ton of research on 180 degree headers in a LS application. Most people do not like the sound with a crossover, which is shown below. I am leaning against it. Most of the best sounding 180 degree header designs are shorter with small or no mufflers. Take a look at the GT40 headers and you'll see what I mean. I also thought about using a muffler that has a dual in and dual out with an internal crossover but I doubt I'd like that after hearing the reviews on them.
It will be a bit of a mix and match experimentation for the mufflers and final output after the collectors. I don't want it to be irritating or loud. I'll have V band clamps after the collectors to make swapping easy. I may have to make a temporary exhaust while I experiment with placement of the AC, alternator, and hopefully a dry sump setup.
Shown above is all the components I've been managing and test fitting. A mechanical manually set tensioner with a Gilmer drive gear on the same pulley as the 6 rip serpentine belt, a 3 stage Aviaid dry sump pump, factory AC compressor, and factory alternator. I am likely going with a Nutter dry sump pump after talking with AC, the man that runs that small company out of Vancouver, WA. I will run 3 pickups out of a shallow pan but will likely design the headers to allow other pans as some fellow 911 LS swap guys have requested them. I will likely mount the dry sump pump on the same side as the water pump outputs and have it mounted high, off the cylinder head on that side. The motor mounts are directly bolted to the heads so I will have to manage that as well. I will also likely use a dedicated oil cooler with remote filter and a 3-5 gallon dry sump reservoir with a separate vent/catch can. Coleman Racing has a neat dry sump reservoir with built in cooler, filter, and oil level sight tube that I might try. The dry sump setup is a recent change so I'll have to tear down the LS1 for the new pan. I am still planning to use the Melling internal oil pump for pressure. This entire dry sump setup will cost less than half of most entry level kits.
Last edited by gtxracer; 10-24-2019 at 01:36 PM.
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dcd215 (10-24-2019)
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10-25-2019, 09:25 PM
#10
TECH Addict
So I've worked on a lot of track cars with dry sumps, mostly sprints and Midgets,,
these are sort of the memory dump of stuff I've run into.
Your dry sump pump should be No higher than the bottom of the block.
You want the scavenging hoses as short as possible. Despite its size it can
be hard to prime if it has to lift too high.. And since it has to outrun the supply side
but with suction and that's much harder the plumbing is pretty critical.
No suction hose should ever go up and down, from start to finish up from pan to pump,
if the line goes downhill/uphill/downhill you will get air bubbles in the lines.
Same with the tank to pump line.. No "bumps smooth down from tank to pump is best.
And you want the pump at least lower than the midpoint of the tank or more..
Not sure why your keeping the internal pump.. The dry sump pump moves so much more oil and
it can supply oil at volume.. You can eliminate several week points in the LS oiling system by getting rid of that
old dinosaur..
You'll plumb it all with -10 / -12 Lines..
Use screens on all your scavenger pickups, and the return to tank line needs a Oberg or steel mesh style filter.
I'd recommend at least a 3-scavenge, 1 supply stage pump.
Dirt track sources are way cheaper for Dry sump parts than other types of stores..
these are sort of the memory dump of stuff I've run into.
Your dry sump pump should be No higher than the bottom of the block.
You want the scavenging hoses as short as possible. Despite its size it can
be hard to prime if it has to lift too high.. And since it has to outrun the supply side
but with suction and that's much harder the plumbing is pretty critical.
No suction hose should ever go up and down, from start to finish up from pan to pump,
if the line goes downhill/uphill/downhill you will get air bubbles in the lines.
Same with the tank to pump line.. No "bumps smooth down from tank to pump is best.
And you want the pump at least lower than the midpoint of the tank or more..
Not sure why your keeping the internal pump.. The dry sump pump moves so much more oil and
it can supply oil at volume.. You can eliminate several week points in the LS oiling system by getting rid of that
old dinosaur..
You'll plumb it all with -10 / -12 Lines.. Use screens on all your scavenger pickups, and the return to tank line needs a Oberg or steel mesh style filter.
I'd recommend at least a 3-scavenge, 1 supply stage pump.
Dirt track sources are way cheaper for Dry sump parts than other types of stores..
11-12-2019, 01:02 PM
#11
As of right now I'm going with a Canton front sump pan and GM pickup. I'll likely add an Accusump and a dedicated oil pressure idiot light and gauge to the dash before any track events. This Canton pan has trap doors and baffles which make it the ideal wet sump setup for our LS engines of this application IMO. In a reversed rear engine configuration, this becomes a rear sump. It also has a very shallow portion ahead of the sump that will allow plenty of space for my exhaust tubes to route underneath the pan but not hang below the sump. Win-win. It could also be converted to a dry sump setup later if needed. Not sure which oil filter block I'll be using. I do plan to have a remote filter and oil cooler.
Pan-
https://www.cantonracingproducts.com...drift-pan.html
LS oil pan stud kit-
https://www.cantonracingproducts.com...unting-gm-ls1/
As for power steering, I have been figuring out the power steering lines and fittings situation. I'd like to use a Mini Cooper electric pump and remove reservoir. Hopefully I'll find space to mount it in the engine compartment compared to the frunk. We'll see. I designed a couple of adapters for the fittings to reuse the P car line fittings and make it a bolt on adapter to 6AN and 8AN for simplicity.
Obtained a LS3 Corvette water pump and tensioner. 996 water temp sensor will be threaded into the LS3 extra port, M16x1.5. I'll need a male M16x1.5 to female M14x1.5 but it threads right in place. No need to tap the cylinder head on the LS1. The oil pressure sensor is the same deal, same threads, same adapter needed. I used the ICT Corvette low alternator mount with truck alternator and obtained an early Corvette AC pump instead of swapping clutch parts. That should complete the accessories. I'll be buttoning up the last of it and should be able to cut the body for clearance and slap the LS1 in place soon. I just need to plan out the 996 oil level and temp sensor. Coolant system will have custom 20AN adapters made for the 996 hard lines. I didn't want to cut the factory hard lines but I might have to, unfortunately. All lines will be AN type for simplicity, reliability, and ease of maintenance.
Tight fit, LS1 oil pressure sensor with P car sensor that will replace it. Not sure if I'll have enough space once the adapter comes in.
F body AC Compressor (only the clutch is different for Corvette) and the Corvette bracket that bolted right up the LS1. This is the smallest OEM LS AC package I could find.
Belt routed, just awaiting final bolt-together of the AC compressor, tidy up the injector mounts, and then we're ready to cut the 996 body to mount the LS1 and start plumbing.
Pan-
https://www.cantonracingproducts.com...drift-pan.html
LS oil pan stud kit-
https://www.cantonracingproducts.com...unting-gm-ls1/
As for power steering, I have been figuring out the power steering lines and fittings situation. I'd like to use a Mini Cooper electric pump and remove reservoir. Hopefully I'll find space to mount it in the engine compartment compared to the frunk. We'll see. I designed a couple of adapters for the fittings to reuse the P car line fittings and make it a bolt on adapter to 6AN and 8AN for simplicity.
Obtained a LS3 Corvette water pump and tensioner. 996 water temp sensor will be threaded into the LS3 extra port, M16x1.5. I'll need a male M16x1.5 to female M14x1.5 but it threads right in place. No need to tap the cylinder head on the LS1. The oil pressure sensor is the same deal, same threads, same adapter needed. I used the ICT Corvette low alternator mount with truck alternator and obtained an early Corvette AC pump instead of swapping clutch parts. That should complete the accessories. I'll be buttoning up the last of it and should be able to cut the body for clearance and slap the LS1 in place soon. I just need to plan out the 996 oil level and temp sensor. Coolant system will have custom 20AN adapters made for the 996 hard lines. I didn't want to cut the factory hard lines but I might have to, unfortunately. All lines will be AN type for simplicity, reliability, and ease of maintenance.
Tight fit, LS1 oil pressure sensor with P car sensor that will replace it. Not sure if I'll have enough space once the adapter comes in.
F body AC Compressor (only the clutch is different for Corvette) and the Corvette bracket that bolted right up the LS1. This is the smallest OEM LS AC package I could find.
Belt routed, just awaiting final bolt-together of the AC compressor, tidy up the injector mounts, and then we're ready to cut the 996 body to mount the LS1 and start plumbing.
11-12-2019, 05:00 PM
#13
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Looks good!!
How hard is it to change from the auto triptronic to the manual 6 speed porsche trans?
Ive been looking for 996 car to ls swap but always come across the 911 auto cars for good deals compared to the manual cars.
How hard is it to change from the auto triptronic to the manual 6 speed porsche trans?
Ive been looking for 996 car to ls swap but always come across the 911 auto cars for good deals compared to the manual cars.
11-13-2019, 12:08 PM
#14
Thank you! As far as I can tell and the research I've done, it will bolt in place. I have to route the shift cables and mount the shifter still, so I'm hoping that's not too bad. I am planning to remove the AT shifter this week so I can tell you more soon. As for the hydraulic lines, I am going to run separate clutch lines, braided 3AN stuff instead of finding OEM lines ($$$). I also designed and had made a few fittings to convert the clutch cylinders. The last thing involved is removing the AT pedal assembly and installing the MT 3 pedal assembly.
11-14-2019, 03:12 PM
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Thanks! Glad to hear it! I am leaning towards the mini pump or a GT3 Cup pump.
Thank you! As far as I can tell and the research I've done, it will bolt in place. I have to route the shift cables and mount the shifter still, so I'm hoping that's not too bad. I am planning to remove the AT shifter this week so I can tell you more soon. As for the hydraulic lines, I am going to run separate clutch lines, braided 3AN stuff instead of finding OEM lines ($$$). I also designed and had made a few fittings to convert the clutch cylinders. The last thing involved is removing the AT pedal assembly and installing the MT 3 pedal assembly.
Thank you! As far as I can tell and the research I've done, it will bolt in place. I have to route the shift cables and mount the shifter still, so I'm hoping that's not too bad. I am planning to remove the AT shifter this week so I can tell you more soon. As for the hydraulic lines, I am going to run separate clutch lines, braided 3AN stuff instead of finding OEM lines ($$$). I also designed and had made a few fittings to convert the clutch cylinders. The last thing involved is removing the AT pedal assembly and installing the MT 3 pedal assembly.
11-18-2019, 04:40 PM
#18
Thank you!
You're welcome and thanks! I'll be able to make more adapters for sure. I am thinking of putting together a kit for the little stuff to make things easier.
It would but harder to package. 180 degree headers should sound badass.
It would but harder to package. 180 degree headers should sound badass.
11-18-2019, 04:56 PM
#19
New AC compressor is on and looks like it will work. Still need a belt and to verify tensioner and bracket is correct.
Found out my C2 is actually metallic GREEN not black. Someone painted it at one point to black and did a poor job on the paint work. I like the 2B4 paint code color so I may go with that in the end when I respray.
I removed the F Body Camaro LS1 oil pan and installed a Canton LS1 front sump road race pan with baffles and trap doors. I'll likely add an oil cooler when I start the remote filter plumbing. So far this pan is looking great and I think it will be perfect.
AC compressor and pan to show how it all fits together:
LS1 with motor mounts, nearly ready to go in. Waiting on some conversion pieces for the 20AN water pump fittings, metric fitting adapters, and a few other small pieces. Stuttgart Muscle motor mounts added as well. Super easy to install these mounts and the instructions were top notch.
Motor mount base plate, F for front with arrow
Rough body cut made. Two more small cuts and then some edge clean up and it will be ready for it's new heart
F Body Pan vs Canton front sump pan
Trap doors and baffling
Still left to figure out:
But the list is getting smaller!
Found out my C2 is actually metallic GREEN not black. Someone painted it at one point to black and did a poor job on the paint work. I like the 2B4 paint code color so I may go with that in the end when I respray.
I removed the F Body Camaro LS1 oil pan and installed a Canton LS1 front sump road race pan with baffles and trap doors. I'll likely add an oil cooler when I start the remote filter plumbing. So far this pan is looking great and I think it will be perfect.
AC compressor and pan to show how it all fits together:
LS1 with motor mounts, nearly ready to go in. Waiting on some conversion pieces for the 20AN water pump fittings, metric fitting adapters, and a few other small pieces. Stuttgart Muscle motor mounts added as well. Super easy to install these mounts and the instructions were top notch.
Motor mount base plate, F for front with arrow
Rough body cut made. Two more small cuts and then some edge clean up and it will be ready for it's new heart
F Body Pan vs Canton front sump pan
Trap doors and baffling
Still left to figure out:
- P car oil level/temp sensor
- Holley fuel injector rail mount plates are wrong
- AC belt and bracket/idler/tensioner
- Heater hose hookup plan
- Steering line caps (for now)
- P car O2 sensor hookups needed?
- Tachometer LS 24x to 58x pulse conversion
- Finalize 180 degree headers
- Convert pedals from AT to MT
- Mount clutch master cylinder and reservoir
- Plan and order clutch lines
- Find P car ignition on hot wire
- Find P car neutral safety switch and bypass or deactivate
- Lots more I haven't thought of
But the list is getting smaller!
