CC Build: Porsche 996 to LS1 Conversion

[gtxracer2]

Dyno tune this Friday. Hoping for over 400hp but would be happy with just better driveability and increased mpg. Gas is $5.50/gal here.

Progress on the subwoofer box. I sanded this with a belt sander on the faces and then broke the edges gently. Then I took sheets of sandpaper and hand sanded the edges to give the rounded smooth look. I painted this with Savannah Beige spray paint and it came out very well but I should've used a sealer on the MDF. My wife came out and informed me of my mistake after I had already painted it.

I'll be designing the hold-down brackets soon to attach to the single bolt that is also the rear set backstop. I think this will be enough holding force, they're quite large (12mm I believe) and should stop the box from flying forward in an accident or hard braking.

I've been playing with heat shields and different intake setups to lower IATs. I'll post that update as soon as I find a configuration I like.

Enjoying the beat up seats with my lil monster this summer has been a treat. I'm not sure I'll rush into replacement seats as I really liked having her in the car on the way to the dog park!

The looks of the 996 body style have grown on me. With the right wheels and tires this car will look really good I think.

 

[ProjectTwin]

Poly prime. Paint.

Or…

Roll with oil-based primer and a foam roller. Let dry. Light sand. (Maroon pad) Another coat. Light sand. Repeat until happy with texture. Paint

 

[stjames151]

Sorry if I'm re-hashing old shit, but what are you doing for an intercooler?

 

[Roc Doc]

Sorry if I'm re-hashing old shit, but what are you doing for an intercooler?

It's not turbo'd.

 

[gtxracer2]

Dyno day! I wasn't very happy with the outcome of the dyno day with Turbo Technologies in Tacoma. Although Matt at TT came highly recommended at the time, I wasn't allowed to watch him tune the car and he was very cold and dismissive towards questions. I figured this was due to covid precautions but I could've stood back 20 feet and listened to the car while he worked. The car also behaved somewhat oddly still, surging sometimes, stalling, and fuel consumption was less than others in LS swapped 911s had shared.

Troy at Carburetor Connection in Kirkland, however, was amazing. He was very friendly and eager to work on my car. He has tuned a few of these LS swapped 911s, including a few interwebz friends I have locally. A couple notes from the day:

• The car now idles better and does not die coming off hard throttle
• Overall rpm band is smoother and delivers power steadily
• Leaner fuel trims, where they should be
• Better behavior at cruising speeds, no surging
• More power can be pulled out of the car with a cold air intake and heat management
• All LS1s smoke! I have the LS6 pcv, the catch can, proper routing and it still SMOKES at WOT!

The car made 385 rwhp this time and around 370 ft-lbs! This is slightly less than the 393 I had in the original dyno, probably due to the change in weather (it was 70+ deg F this time) and the software pulls timing with high MAF (150 deg F this time). Overall I'm very happy with the results. I'm working on uploading the videos, I need to sort through them and edit. But for now, here's a teaser!

 

[Lilyota]

Maybe Matt is a little Leary with all the BS with the EPA that's been going on.

 

[gtxracer2]

Maybe Matt is a little Leary with all the BS with the EPA that's been going on.

Maybe, I’ve never heard of small tuning shops caring about EPA regulations in WA. I could understand if so, but that wasn’t expressed to me and I think a welcoming atmosphere can be established no matter the situation, especially if I’m paying for a tune.

 

[gtxracer2]

I've been avoiding replacing the cowl plastic piece even though I ordered it months ago. It actually only took about 30 minutes to swap out. I really like that Porsche has tons of places to find replacement parts. I replaced the cowl and seal this time and I'm looking to order and replace the roof rack mounts and tabs next.

I've been driving the car when I can and it's much smoother than before. It's easier to drive and has better power. When I give it full throttle in 2nd gear, the rear end breaks loose and I get a nice little wiggle

 

[gtxracer2]

I'm shifting my attention back to the subwoofer box this week. I'm working through it slowly as I'm trying to implement some new tools and technology into this mini project. I have an iPhone 12 Pro which has LiDar cameras and PolyCAM will allow me to 3D scan sections of the car. The issue I find is the data processing and export of the raw STL files is somewhat lumpy and cumbersome. I'm still working through it but it's coming along. There's a lot of post-scan processing to do and I'm hoping to find better software to process the data after the scan.

Importing to Solidworks has been fine but the STL import never matches the raw STL data when viewing in a standalone viewer. I'll have more to report later this week as I design the subwoofer box mounts and eventually get to the air box and/or heat shield I'm going to fabricate.

Picture of the rear seat area:

STL Import:

PolyCAM raw data (viewer):

 

[gtxracer2]

Been busy tinkering on the LS 996 and am now burnt out. I will post some updates below. Car is softly for sale, looking to part ways with my projects and focus on some other areas in life at the moment.

Asking $30k OBO for the car as-is. I’ve sunk at least 30k into it in the last few years. It’s fast as hell but I’d like to get back into regular surfing, mountain biking, and some other sports. I’m also shifting back into off-roading with Raptor which lost its engine a week ago. So I need make some adjustments and this 996 project needs to go.

I pulled the exhaust and ceramic coated the headers. I also added smaller resonator style bullet mufflers after the existing mufflers. It’s quieter now and a lot less heat in the engine bay.

I also added a LN Engineering water to oil cooler with a stainless mount behind the rear bumper and tire. It tucks neatly into the area where the OEM mufflers used to live. I used all AN fittings and lines again and it’s a super clean install. I’m very pleased with the outcome!

I designed new offset washers for the subwoofer box mount and has them 3D printed. They came out perfect! The mounts themselves were a couple degrees off, so those are being recut right now. This will close out the subwoofer box mount.

While the exhaust was out I tidied up quite a few areas. I replaced the 20AN line on the passengers side with a longer hose so the line is tucked away now, leaving more room for the air filter. I drilled holes for the air filter to pull fresh air out the deck lid. I mounted the MAT sensor in the air filter base for a nice clean install. I also found some tiny hood latch buttons from Quik Latch and installed those. Now the deck lid is flush with the tail lights and rear quarters, it came out very clean.

I replaced the cheap Canton dipstick with a new freshly black anodized Lokar dipstick and it’s muuuuuch cleaner. While I was in there I also installed two Spal puller fans to push fresh air through the bottom of the engine bay. I need to finish wiring these. I install a new coolant level sensor and cleaned up a few of the hose clamps with Gates heat shrink style clamps for a cleaner look. All in all it’s very clean looking now!

AC hoses have been custom made by Cold Hose in Florida. They were easy to work with and welded a fitting and crimped hoses to my existing Porsche lines. I also bought a low mile C5 Corvette bracket, pulley, and tensioner since mine was crusty. Those early C5 parts are spendy! AC should be able to be installed and working in the coming weeks.

I have a T96 steering wheel on order that was supposed to be here weeks ago. Still hoping it arrives this month. Hah!

Car just needs seats, wheels/tires, and paint and body work. Everything else is basically done or only needs minor tweaking. I’ve taken this car a long way and wish I had the motivation to finish it out properly but I’ve moved on. Someone take it off my hands!

 

[Grendel]

Let's talk.

 

[Gregj50!!!!!]

Nice work!!!!

Surf???? You must have moved again?????

Sorry to hear your burnt on this… but if selling makes life better, so be it!!!!
GLWS!!!!

 

[Thatg9659]

I lose 20 min every time I see exhaust like that. Mesmerizing Usually Sounds awesome too.

 

[gtxracer2]

Nice work!!!!

Surf???? You must have moved again?????

Sorry to hear your burnt on this… but if selling makes life better, so be it!!!!
GLWS!!!!

Still up north Greg! WA has some decent surf spots actually. The water is still cold in August, unlike SoCal, but it’s one of my favorite sports. We take a few long weekends a year just to hit the waves for ~6 hours a day. It’s getting harder and harder to pull me out of the water so I figure it’s time for my own board and a better adventure vehicle. The Raptor gets 13mpg on a good day.

Porsche is still softly for sale. I’ve had 2 people express interest. I’m tempted to keep it for the summer, so if someone really wants it, I’d get it now before I change my mind.

I took temporary ownership of a e92 M3 this past weekend. It has a brand new S65 engine with the rod bearings replaced. Revs to 8250 rpm and has ITBs on the 4.0L V8 This thing is fun and comfy. It’s a little more comfy than my 996, but the 996 is definitely faster and has better cornering but not by a huge margin. I can see why the e9x platform has such a huge following. This car has straight pipes but it’s still tolerable most of the time. I’ll be doing some minor rejuvenation on this car in the coming months as I drive it occasionally.

Back to the 996…I ordered a T96 steering wheel back in December and it finally showed up. I wanted a slightly smaller wheel with thicker grips and an understated look to replace the cracked carbon fiber Tip wheel that was cutting up my hands. I think this nailed it.

I’m dialing back upgrades to the 996 after this, so you may not see a lot of updates to this thread besides driving it. The alternator needs to be swapped under warranty and that’s about it. I think the car may have had high crankcase pressure, I’m still verifying this. The dipstick used to pop out after high rpm pulls, even with the LS6 PCV conversion and the Radium catch can. I think valve cover breathers might be necessary but I’d like another valve in-line as not to have open air to the crankcase. Most likely the cam and intake plus headers are asking too much of the OEM LS6 PCV system. More on this later.

If anyone has experience with LS PCV systems, please speak up!

Old wheel

New T96

 

[gtxracer2]

Pics of the e92 I’m babysitting for the next 1-3 years. It needs some love. The front carbon fiber hood and bumper need attention, along with the CF roof. We’ll see what I can salvage.

 

[gtxracer2]

Small update - been driving the car a bit and it's still a blast when it wants to run right. lol. I have a scheduled visit with the tuner to fix that and take a look at the crankcase pressure. We think the car just needs to breathe and this is true for most LS engines with a cam swap.

I also have ALL the parts for the AC install now and I'm itching to get it in. Since it's 75+ here now, it's kind of a necessity now.

Subs are mounted, came out great. I need to post the pics and a few other odds and ends I've been working on.

I've had 4 people come to our house to buy something from FB marketplace recently....all 4 stop and look at the Porsche, ask to take a pic, then gawk at it for a few mins :D Every time I take it to a local spot, someone sees the LS intake sticking out the back and starts asking questions. If I give the throttle a tap before I park, heads turn, people start crowding, and asking what it is. Love that about this car!

Lastly....I got tired of trying to get my scanner on my iPhone to give me good enough results to design and bought an Einstar from Shining 3D to start scanning the deck lid and intake area. I'll be designing a cold air intake ram scoop for the back, as low profile as I can get it, and figuring out how to vent the engine bay still. I have some ideas. Stay tuned!

 

[Grendel]

I am still interested, but we never talked it would be fun to boot around in this for the summer, while I drop an LT5 and associated torque tube with transaxle into this:

 

[gtxracer2]

AC has been installed! The compressor went in easily, and clears just barely, as designed.

I bought a new compressor mount and I’m glad I did. The original mount that came with the LS1 has seen better days and didn’t have a good tensioner and idler. This new one was spendy but it has low miles and matches my low mileage LS1.

I had the hoses made by Cold Hose and bought their crimp kit with barbed union. I also bought the specialty crimp pliers, which were not cheap, and ultimately didn’t use them. The crimp rings slid onto the new #10 hose but barely slid onto the Porsche existing hose and I couldn’t get them over the hose once the union was in place. I messed with it for too long, realized it wasn’t ever going to work, and decided to use two of the Gates PowerGrip clamps. Since this is the low pressure side, I think this will be fine and I’ll keep an eye on it.

Tomorrow I’ll get the system charged and put on the AC belt. I need to wire the compressor and deep dive into how to get the Porsche system to like the GM compressor. I’m a little concerned that the Porsche DME won’t trigger the compressor when I hit the snowflake button on the dash. I have the Porsche trigger wire identified in the engine bay, but I’ll be shocked if I just connect it to the GM trigger on the compressor and it works.

 

[Grendel]

You will want to crimp those hoses.

 

[Thatg9659]

When the ac is off, there is no low pressure side.

 

[Arps]

This thing is badass!

 

[WaterH]

When the ac is off, there is no low pressure side.

Yes, there is no high pressure side either, but the low side can see around 125 psi.

 

[gtxracer2]

Hmm…I don’t know how much pressure these gates clamps hold. If I still had my air compressor I’d hook it up to a test hose. I have extra clamps and a simple aluminum barb, I could try to make a test setup.

Alternative is to use hose clamps, I’ve seen this done already, or find bigger crimp rings that are slightly oversized.

 

[Grendel]

Hmm…I don’t know how much pressure these gates clamps hold. If I still had my air compressor I’d hook it up to a test hose. I have extra clamps and a simple aluminum barb, I could try to make a test setup.

Alternative is to use hose clamps, I’ve seen this done already, or find bigger crimp rings that are slightly oversized.

That's my concern too and why I stated you should take the line, write some witness marks on it and go have it clamped.

Or just have a new one made, modelled after it. It's like 55.00 to avoid a lot of frustration and loss of Freon.

 

[gtxracer2]

This is the line that’s connected to the hard lines on the chassis - unless I take it to a shop and have them crimp it right there, it’s going to be clamped.

I have some clamp rings on the way. We’ll see if they’re any better than the Gates powergrips. I’m still going to attempt to test the powergrip holding strength because I’m curious.

 

[Grendel]

This is the line that’s connected to the hard lines on the chassis - unless I take it to a shop and have them crimp it right there, it’s going to be clamped.

I have some clamp rings on the way. We’ll see if they’re any better than the Gates powergrips. I’m still going to attempt to test the powergrip holding strength because I’m curious.

Ah, sorry, I missed that part.

I'm interested to see if they hold.

 

[Norm]

This is the line that’s connected to the hard lines on the chassis - unless I take it to a shop and have them crimp it right there, it’s going to be clamped.

I have some clamp rings on the way. We’ll see if they’re any better than the Gates powergrips. I’m still going to attempt to test the powergrip holding strength because I’m curious.

When I did a sanden 709 conversion on my old vette, I found assorted crimp rings at harbor freight of all places. I learned ac hose and fittings are all not the same size between brands and they make thick and thin hose. After a couple of failures with the crimp style I went to clamp style and won the battle. Nice work anyway.

 

[gtxracer2]

AC system is filled and no leaks thus far.

The filling machine tests the system for leaks before filling. 95% is the minimum to fill and my car had….100%! Held to 93psi and all I need to do now is finish wiring and test the system itself with the compressor running. The AC belt was a very tight fit and squealed a little after installation, so I need to check the idler bearing and tensioner when I’m in there. Hopefully I’ll have some time Sunday or Monday to finish it and test.

Took my favorite person in the world to get a burger with the 911 and even she likes it now. I also found a stash of Fikse FM10s to build a set for my car…and I’m gonna throw the fattest tires I can find under it.

Stay tuned, more coming. If anyone knows who can supply Recaro Sportster CS seats with savannah beige covers to match my interior, let me know. I’ll settle for black, but prefer to keep the OEM color balance.

 

[Gregj50!!!!!]

Slight derail:
Ran up in this today just west of the narrows bridge….

You must have sold it????
Or… you’re a Dodge guy now????

 

[gtxracer2]

Slight derail:
Ran up in this today just west of the narrows bridge….

You must have sold it????
Or… you’re a Dodge guy now????

Good eye Greg!! I literally just sold it! Nice guy, he’s taking it up to Tahuya right now. Bittersweet, but it was time to move on. Porsche has a bigger budget now.