CC Build: Porsche 996 to LS1 Conversion

[budget76]

at least you know the exhaust hardware aren't all sorts of rusted together yet! that's the worst part of any northeast exhaust jobs

 

[gtxracer2]

Small update....put another 200 miles on the car around town for short trips. Clutch seems like it's breaking in still and I need to pull the pan to reseal it. Other than that and a small battlery cable issue, it's been fun to drive with no real issues. I want to swap the 165 t-stat for the 185 again now that the front radiator fans have been replaced.

New shift knob from Manuel, it's a really nice piece. I cut down the factory shift boot to fit and filed down the shift blade to fit. Feels much better and I really love the look. I installed the Gbox 2nd gear detent which took about 3 hours and had to get crafty with a magnet. No more 2nd gear pop out now. New headlight switch installed but still no low beams. Must be something else. I'll check fuses and relays again. Horn works now, just needed the relay swapped out. I also ordered a Radium Engineering catch can and think I have a place for it in the engine bay near the water pump. The screws for the bumper showed up finally as well as the last trim piece for the HVAC controls. A quick sticky tape phone mount to the left side of the dash helped stash my phone for driving. I mounted the Holley Terminator X 4.5" screen on the GT3 console delete to make it easier to track my oil pressure, CTS, MAT, and other data. I have a new Porsche oil pressure sensor and cowl piece on the way too. The interior has really come together and it only needs a few minor things to be really complete and ready for some miles. New seats, new steering wheel, and finish the subwoofer box is all that really remains. I'll refresh the HIDs that are on my garage shelf with a 3M headlight restoring kit. I also need to install the H&R lowering kit and new struts sometime soon. The sunny days are dwindling here and I'll probably wrap up the difficult work later this winter. My Jeep is also coming back to the house soon and it needs some prep work before KOH.

Interior is on point now, leg room, cup holders, and good tunes

 

[popscotty]

It looks like you're well on the road, but I've completed an LS3 swap into a 996 race car. If there are weird nagging things, maybe I can help. Mine was built for autocross rather than a daily

 

[subybaja]

It looks like you're well on the road, but I've completed an LS3 swap into a 996 race car. If there are weird nagging things, maybe I can help. Mine was built for autocross rather than a daily

What's your camera broke? Start a thread!

 

[gtxracer2]

It looks like you're well on the road, but I've completed an LS3 swap into a 996 race car. If there are weird nagging things, maybe I can help. Mine was built for autocross rather than a daily

Sorry I just saw this! I'll keep this in mind. Did you wire the front fans to kick on with the LS computer or did you retain the Porsche DME control of the fans? Even with brand new fans and resistors, my fans are not kicking on. I am thinking of just wiring the LS trigger wires to the relays with spade connectors at this point or splicing into the wiring behind the seats. If you have info on this before I deep dive into the OEM wiring diagrams, please let me know!

Update on the 996 - I've driven it here and there since the sun has been out lately. It needs seats pretty badly and a Helmholtz resonator. I designed 3 different resonator configuartions and just need to find time to pull the car into the shop and make them. I also want to splice in a pair of tiny resonators to reduce the exhaust noise a bit. Hopefully I'll get the car into the shop by March and start working on a few more little items like AC before the summer cruising months begin.

 

[gtxracer2]

I've put another 500 miles on the car and I really like the way it drives and behaves now. Shifting is actually quite good now after adjusting the linkage and putting in the new knob. The interior has started coming together and I really like the GT3 console delete. It cleans up the center area and allows more leg room which makes cruising much more comfortable.

The Continental stereo is nice but clunky. I bought it from Bergvill F/X and would not recommend anyone buy their Continental stereo from Tore. He demands the customer ship back the deck on your own dime even though this deck is clearly having issues. The bluetooth skips all the time and will stop working at times. I have to hit play on my phone to start the music again about 2-3 min after inital start. Tore's prices are also significantly more than domestic suppliers. I paid about $65 more than I would if I had bought the deck through a US supplier. I wanted to support a Rennlist vendor but it definitely bit me in the long run. Shipping back to Norway is around $70. Not worth it, I'd rather just buy another deck and return this one directly to Continental. Lesson learned, stay domestic for complicated items.

Back to the 996 itself - I replaced the headlight switch and oil pressure sensor. I lubed the telescoping column after breaking loose the spring inside the mechanism as it was a little stuck. These are both normal 996 issues that come up and easy to fix. The oil pressure is always stuck at 5 even with the engine off - how do I troubleshoot this? I used a BNIB OEM replacement sender.

I also replaced the oil pan gasket as it had a small leak. All good now, no issues. I adjusted the throttle pedal inputs in the Holley software and it really changed the driveability of the car at low speeds. Much easier to control the throttle. The more I drive the car, the more I enjoy the exhaust note and the way it accelerates. It really does sound like a Porsche and not a V8.

I plan to keep plugging along at the little stuff. The driver's side power window is slower than the passenger, I want to replace that soon. I have a H&R 2" drop kit with new struts to install too. I think it's time to install the AC compressor and have lines made for summer cruising. I'll also be removing the 2000s era window tint for updated tint. Once all these little mechanical things are done, I'll look at getting the car prepped and painted in original color of rain forest metallic green and refurbishing or replacing the twist wheels. As for the interior, the last things on the list to update are seats and steering wheel. I think I want just a very nice leather or alcantera 3 spoke steering wheel and Recaro or Sparco seats. All in time. Hoping this car is "done" within a year of today and fully finished outlaw 996.

Here's some random pics of the car from the last two months that I shamefully never posted. New oil pressure sensor, 2nd gear detent fix, subwoofer box belted in place (for now), whiskey and catch cans, and catch can details (petcock runs through a hole in the body and down below to drain easily). The bracket for the catch can is 304 stainless, hand made one night because I felt like doing it old school versus my plasma CNC. Enjoy.

 

[gtxracer2]

One more thing...this '99 C2 has the right look I'm going for. Simple and clean. I think it needs to be dropped 1-2" but overall it's the style and look I want. $45k....for a 996 C2! Prices really have gotten crazy lately.

1999 3/98 build. Glacier / Black. No excuse car. Excellent condition, original paint - Rennlist - Porsche Discussion Forums

The Rennlist Marketplace - 1999 3/98 build. Glacier / Black. No excuse car. Excellent condition, original paint - What I consider a VERY RARE opportunity to own one of the best early cars you can find. I'm going to regret this one. 3/98 build. Original paint. Original interior. California dry...

rennlist.com

 

[Kyle]

I finally found who I think made the 8 into 1 exhaust. A guy named Trevin Baker

 

[gtxracer2]

I finally found who I think made the 8 into 1 exhaust. A guy named Trevin Baker

Sounds familiar :D

 

[Kyle]

Sounds familiar :D

Oh be him you I guess? Haha.

At some point I replied to someone on here about the 8-1 headers on a 996 and never found the person. And never really cared enough to post on the FB group but that post was so all over and it seemed like all of the header people were in it so well why not 😂😂😂

Edit yeah I replied to you in this thread. Who knows I saw a video and it was insane. Sounded like a formula car. Never found out who did it but it made me want to find a turbo or c4s and LS swap it.

 

[gtxracer2]

Oh be him you I guess? Haha.

At some point I replied to someone on here about the 8-1 headers on a 996 and never found the person. And never really cared enough to post on the FB group but that post was so all over and it seemed like all of the header people were in it so well why not 😂😂😂

Edit yeah I replied to you in this thread. Who knows I saw a video and it was insane. Sounded like a formula car. Never found out who did it but it made me want to find a turbo or c4s and LS swap it.

I never designed 8-1s for the 996, that was for my Jeep. They exit over the top of the intake. There is not enough space, at all, to run a collector over the LS intake in a 996. It's amazing to me how many people don't understand the technical challenges with creating an exhaust like this. I'm not saying you, just others that comment on it matter-of-factly like they have an idea of how to go about it when in reality it's much more challenging that it appears and that's why it isn't done regularly or by just anyone. People act like it's so easy to make one small change and they critique the design as if they could even get close to what I accomplished. It's hilarious and dumbfounding at the same time watching people without talent or experience criticize those with it. The internet has been amazing to share ideas and creativity but the amount of stupidity that bleeds over the good is overwhelming and washing out the high quality content. Sorry for the rant but it's awful to see people without talent or skills ripping apart those with it, or at least try to do it, just for the sake of feeling superior for a few seconds. :(

I haven't seen 8-1s on a 911 yet. I saw a set on a Cayman but have yet to hear a sound clip. I'm sure it sounds like the other 8-1s.

I'll have an update for the LS1 996 soon. I've been working on the AC system, new headlights, and some other updates.

 

[Gregj50!!!!!]

I'll have an update for the LS1 996 soon. I've been working on the AC system, new headlights, and some other updates.

Getting it ready for summer…..



Keep me posted…. I need to see this thing!!!!

 

[crispins]

love this build, please keep the updates going.

I want nothing more than a well done LS Porsche

My favorite car I ever had was a 996 Turbo, it was just awesome in every way, I real driver's car.

 

[gtxracer2]

Getting it ready for summer…..



Keep me posted…. I need to see this thing!!!!

Come on up sometime Greg, I'm in Kirkland now. Same number, shoot me a text sometime.

love this build, please keep the updates going.

I want nothing more than a well done LS Porsche

My favorite car I ever had was a 996 Turbo, it was just awesome in every way, I real driver's car.

That's a nice 996TT! I wouldn't mind a turbo car, but the GT cars rev high and that's my jam. Still can't deny the wider hips of the turbo cars are hawt!

New headlights for the trashy LS1 996, much better Litronic headlights. New installed, old on the right. I'll be replacing the small triangular trim piece. Don't mind the paint flake and other trashy parts of the 996, it's beautiful on the inside....of the engine bay!

The doggo approves

If anyone here has a 996 and wants to DIY their own Litronic upgrade, I have this kit from 996 Retrofits. It was $600 new, I'd ask for less than half that as I don't need them anymore. These are the same lights as the newer 992 style, just need to be retrofitted into the 996/986 style housings. The adapter plate is there and all you need to do is detach the lens from the headlights and mount the plate. I lost interest and found these OEM Litronics. It's an entire kit for two (2) headlights if anyone is interested.

Also found a Rennlist forum member making these sweet 17mm ball style phone mounts that take the place of the factory 996 hazard button bezel. Much better!

 

[Scooter]

Love it. Keep it up.

 

[gtxracer2]

Forgot to post these pics. I took the wife sightseeing aka a random drive in the 996 during a warm day in winter. I can say with full confidence that driving a 500hp 2wd 911 on backroads during the cold and wet season builds character.

 

[gtxracer2]

I finally got the LS1 996 on the road again. It’s been torn down for a few weeks. I decided to replace the leaky coolant expansion tank but I went with a 996.2 model for around $200 shipped versus the direct replacement 996.1 tank at ~$700ish for a quality part. It’s a bigger tank and has better fill marking lines IMO.

I also wired up the high and low speed radiator fans to the Terminator X ECU. Now they work well!! I drove the car today in 90 degree weather and stop and go traffic, car never got above 205. I’ll call that a win!

The issue I did have is the engine bay is extremely hot. The MAT sensor said the engine bay is 204 degrees!! I have some serious heat soak issues. I’ll be ceramic coating the exhaust soon and adding a huge engine oil cooler. I bought a MX-245 from Improved Racing along with a thermostat and insulation for the lines. I plan to put the oil cooler in the passengers side OEM muffler location since it’s available. There’s some decent air flow through this area according to a few fellow LS swapped 996 friends.

I also got the tach working perfectly. No more looking down to the digital display! The last gauge to get working correctly is the oil pressure. I think I have the connection backwards at the sending unit. I’ll fix that when I install the cooler.

While I install the oil cooler this winter, I’ll install the AC compressor and lines, finally. If I can sort out these last few issues, the car will be ready for daily driver duty and track time.

Couple pics of the tank install-

 

[Bebop]

The issue I did have is the engine bay is extremely hot. The MAT sensor said the engine bay is 204 degrees!! I have some serious heat soak issues.

You need an airbox. Cone filter is killing you.

That's non IC boosted levels of temps here !

 

[gtxracer2]

You need an airbox. Cone filter is killing you.

That's non IC boosted levels of temps here !

Yup I think so. I have a few ideas and even a concept for a shaker style scoop back there. I’m tempted to yank the deck lid and run without it for a bit. The factory setup has a puller fan to help move air out of the engine bay. I might have to setup one of those too.

 

[Kyle]

I never designed 8-1s for the 996, that was for my Jeep. They exit over the top of the intake. There is not enough space, at all, to run a collector over the LS intake in a 996. It's amazing to me how many people don't understand the technical challenges with creating an exhaust like this. I'm not saying you, just others that comment on it matter-of-factly like they have an idea of how to go about it when in reality it's much more challenging that it appears and that's why it isn't done regularly or by just anyone. People act like it's so easy to make one small change and they critique the design as if they could even get close to what I accomplished. It's hilarious and dumbfounding at the same time watching people without talent or experience criticize those with it. The internet has been amazing to share ideas and creativity but the amount of stupidity that bleeds over the good is overwhelming and washing out the high quality content. Sorry for the rant but it's awful to see people without talent or skills ripping apart those with it, or at least try to do it, just for the sake of feeling superior for a few seconds. :(

I haven't seen 8-1s on a 911 yet. I saw a set on a Cayman but have yet to hear a sound clip. I'm sure it sounds like the other 8-1s.

I'll have an update for the LS1 996 soon. I've been working on the AC system, new headlights, and some other updates.

Nice. Oh yeah I know what you mean.

I don’t know who did and it was a work of art to get it to all fit. It was sort of like the 180* ones but it was all 8 into one out the back. It sounded ridiculous in the video. Like a formula car. Like the caymans that have it too. I think it was on FB but might not have been in the ls swap group though. I hate that groups disappear in the night and there is no record.

 

[XtremeJ]

You need an airbox. Cone filter is killing you.

That's non IC boosted levels of temps here !

agreed, easiest way to gain HP on Porsche's that have a ton of bolt on's is usually to return to the OEM airbox. I would guess that a cone filter shows more ultimate HP on a dyno, but the airbox delivers more HP on the track, as everything gets heat soaked. If they are good enough for the Cup cars, good enough for me.

The gold foil (and other heat products) from DEI definitely helps with controlling heat

 

[XtremeJ]

I know you have an LS, duh. I like the layout of your cooling system plus the new upgrades. The 996 and 997's seemed to be a bitch to get the cooling systems bled. Best practice was always using a vacuum system, but even if that went well, there always seemed to be a few bubbles hiding somewhere. So I always would get the motor warm enough to open any thermostat, and then run the rev's at 3-4K for about 5 minute to get rid of the last stubborn bubbles, then put the cap on. And was usually worse if the OEM heater core was still in play.

Was always fun when we had a short turn around between sessions, and the drivers smashed up the front coolers requiring a full bleed.

Love getting the updates, nice ride man

 

[Roc Doc]

I finally got the LS1 996 on the road again. It’s been torn down for a few weeks. I decided to replace the leaky coolant expansion tank but I went with a 996.2 model for around $200 shipped versus the direct replacement 996.1 tank at ~$700ish for a quality part. It’s a bigger tank and has better fill marking lines IMO.

I also wired up the high and low speed radiator fans to the Terminator X ECU. Now they work well!! I drove the car today in 90 degree weather and stop and go traffic, car never got above 205. I’ll call that a win!

The issue I did have is the engine bay is extremely hot. The MAT sensor said the engine bay is 204 degrees!! I have some serious heat soak issues. I’ll be ceramic coating the exhaust soon and adding a huge engine oil cooler. I bought a MX-245 from Improved Racing along with a thermostat and insulation for the lines. I plan to put the oil cooler in the passengers side OEM muffler location since it’s available. There’s some decent air flow through this area according to a few fellow LS swapped 996 friends.

I also got the tach working perfectly. No more looking down to the digital display! The last gauge to get working correctly is the oil pressure. I think I have the connection backwards at the sending unit. I’ll fix that when I install the cooler.

While I install the oil cooler this winter, I’ll install the AC compressor and lines, finally. If I can sort out these last few issues, the car will be ready for daily driver duty and track time.

Couple pics of the tank install-

Once you get the AC system in and the interior done the way you want, it will be time to corner balance the car. I had to do mine when I took the 2.7 out and put the 3.2 in. Moved the battery to the smugglers box, then back to the factory location as it needed the extra weight over the front wheels. The added weight of the oil cooler and fan in the passenger side fender wasn't enough to offset the additional weight of the 3.2.

I used the sending units for oil temp and oil pressure for a 2.7, they screwed right into the 3.2 and were the correct impedance for the 1976 VDO gauges.

 

[Roc Doc]

agreed, easiest way to gain HP on Porsche's that have a ton of bolt on's is usually to return to the OEM airbox. I would guess that a cone filter shows more ultimate HP on a dyno, but the airbox delivers more HP on the track, as everything gets heat soaked. If they are good enough for the Cup cars, good enough for me.

The gold foil (and other heat products) from DEI definitely helps with controlling heat

On the old air-cooled cars it was commonly held that the engine fan moved enough air in the engine compartment that an air box wasn't really necessary for getting cold air. I cut the face out of mine, just to get more intake noise, didn't seem to make a HP difference one way or the other.

 

[Bebop]

On the old air-cooled cars it was commonly held that the engine fan moved enough air in the engine compartment that an air box wasn't really necessary for getting cold air. I cut the face out of mine, just to get more intake noise, didn't seem to make a HP difference one way or the other.

Hot air kills your timing advance. It's generally a percentage of the total output.
On an old aircooled VW that was making 70hp, I doubt you'd have felt 10% of power loss.

Once you get the AC system in and the interior done the way you want, it will be time to corner balance the car. I had to do mine when I took the 2.7 out and put the 3.2 in. Moved the battery to the smugglers box, then back to the factory location as it needed the extra weight over the front wheels. The added weight of the oil cooler and fan in the passenger side fender wasn't enough to offset the additional weight of the 3.2.

I used the sending units for oil temp and oil pressure for a 2.7, they screwed right into the 3.2 and were the correct impedance for the 1976 VDO gauges.

Did you do that with you in the car ?
I'm curious as I'm trying to do something similar with my buggy.

 

[Roc Doc]

Hot air kills your timing advance. It's generally a percentage of the total output.
On an old aircooled VW that was making 70hp, I doubt you'd have felt 10% of power loss.



Did you do that with you in the car ?
I'm curious as I'm trying to do something similar with my buggy.

Yes. Me in drivers seat 1/2 tank of fuel.

 

[XtremeJ]

Yes. Me in drivers seat 1/2 tank of fuel.

cool, but totally irrelevant fact. Land Rovers used to have handed springs, one side a slightly stiffer rate than the other - just so the vehicle would ride level with a driver.

The airbox stuff I was talking about was definitely post air cooled era. I have worked on some older cup cars from the pre996/997 era, but more just for fun. I do have a buddy with a very early 912 that now has double the original horsepower. So like about 110hp -

 

[gtxracer2]

I’ve been driving the car to work and to the gym every day, no major issues. I had to tighten the clamp on the new expansion tank. The system seems to be bled and I have had no overheating issues at all. I know the fans are working as I can hear them engage with the key forward engine off after a drive. My only complaint so far is the car will stall sometimes, I think a tuning issue, and the sub box will fly forward if I slam on the brakes. Hah!

I think I’ve averaged 10 mpg this last two weeks so I’ll be making an appointment with the dyno soon. I think I have an idea on how to fix the high IATs with a square air filter and a custom box in the place of the OEM spoiler. I’ll need to cut away the rest of the sheet metal and plastic surrounding the spoiler and vents. I also might need to install a puller fan next to the air filter to vent the engine bay. More on this design later as I get time to 3D scan the rear of the car and export it to Solidworks.

For now, this is my mod to keep the IATs lower. It’s worked well so far.

 

[WaterH]

I think I’ve averaged 10 mpg this last two weeks so I’ll be making an appointment with the dyno soon.

If your serious, I think you have a fuel leak.

 

[gtxracer2]

If your serious, I think you have a fuel leak.

It's coming out the exhaust, so yes, it's a leak