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flat6pilot 08-25-2015 10:08 PM

Another 911sc Turbo Conversion
I have a 1980 SC that has the Euro motor with 8.6:1 compression.

I've had this car for about 8 years now. So far it's run flawlessly. It came with all the usual recommended updates for this year 911. I didn't know it at the time, but it had been in a wreck earlier in its life. The previous owner must have know but didn't reveal that bit of info. Of course I wasn't the most experience of Porsche buyers at the time and it wasn't obvious. I found out after adding the IROC FG bumpers and noticed I couldn't get them to line up perfectly. (Reasonably perfect that is.) My suspicions were confirmed after a corner balance.

I eventually got over it and decided it wasn't all that bad having a "flawed" car. That meant I wouldn't get caught up in doing a q-tip restoration anytime soon and just enjoyed the car for what it was.

Over the past eight years I've added headers and a performance exhaust, 930 Fuchs, removed the CIS in exchange for a Megasquirt programmable EFI, Carrera intake manifolds, re-did the interior with light weight felt (and removed a LOT of weight) added some better seats and even a roll bar.

I put it on the dyno a few years after the upgrades and I scored 190whp. Not too bad for what changes I made. She only weighs about 2350lbs. I did a few minor changes to the suspension like stiffer TB's and new shocks. I even replaced the bushings with Elephant Racing polybronze.

I did autocross for a bit and started doing DE's about 4 or 5 years ago. That's been fun.

She currently has 180,000 miles on it. I know what you might be thinking: Adding a turbo? Are you crazy!? Well, I look at it this way: I'm 45. I'm not getting any younger and the way the car is going it'll probably last another 10 years. I know I won't tear into a perfectly good motor if there's nothing wrong with it. It doesn't smoke or burn any (much?) oil. So what if I add a turbo and have a little fun? If I blow it up... there's my excuse to rebuild. If it lasts another 10,000 or 20,000 miles, so be it. (I'd be happy with 10,000 turbo miles.)

So that brings me to now.

I'll go ahead and document my build and you guys can watch in eager anticipation. What will a low boost (.5 bar) turbo do to a motor with 180,000 miles on it?

The car currently has:
Megasquirt II EFI
Carrera Intake

Let's find out....

My current parts list as of today's post:

The first part of the project will begin with fitting a small intercooler. I have a ducktail and wouldn't mind keeping it. So I'll have to squeeze this thing in there.

I'm still working on the mounts in back but it shouldn't be too hard to do.

Next up will be mounting and connecting the MSD Boost Retard box.


kenikh 08-25-2015 10:45 PM

Looking good. Two concerns:

The IC looks like capacity might be an issue.
OBX headers have a bad rep. Would hate to see that TK turbo grenaded by FOD from shoddy welds.

Great project. Keep the pics coming.

Tippy 08-26-2015 04:40 AM

Whoa! Love it. I too agree, the IC may be choking up top. Needs more core width, or change direction of airflow. Second, that one would probably not be up to the task of a large track with extended time in boost. Heat would accumulate I'd imagine.

Measuring PSI/bar after turbo outlet/before intercooler would tell you if it is too restrictive. It may not, but from quick glance catches attention.

Love these conversions! :cool:

OldSpool87 08-26-2015 05:11 AM

Duck tailed turbos are very cool (my opinion). As mentioned above the IC fitment is the trick. It's been done before by forum members and there are very reputable vendors on the board who can assist. The 1/2 bar boost may not require as much IC volume. I don't have the technical wherewithal to offer advice but hope the project keeps moving forward. Looks great!

gumba 08-26-2015 06:53 AM

If you need a different i/c I suggest you contact Bell Intercoolers. I sent them my engine specs and max i/c dimensions for my project. I had a drawing by their tech guy by the end of the same day. The i/c was ready to ship 3 days after I placed the order. The cost was $600 + shipping. By far, the easiest and smoothest transaction I've had throughout my project, (no affiliation).

Tippy 08-26-2015 08:03 AM


Originally Posted by gumba (Post 8768023)
If you need a different i/c I suggest you contact Bell Intercoolers. I sent them my engine specs and max i/c dimensions for my project. I had a drawing by their tech guy by the end of the same day. The i/c was ready to ship 3 days after I placed the order. The cost was $600 + shipping. By far, the easiest and smoothest transaction I've had throughout my project, (no affiliation).

Wow! That's a great price! I thought they were easily double that?

The parts prices alone add up to about that. I guess they factor that in to the fabrication? Good to know.

gumba 08-26-2015 08:50 AM

Mine was very simple, approximately 8" x 17" x 4.5" deep w/3" inlet/outlet. I welded the mounting tabs on.

T77911S 08-26-2015 09:23 AM

you need to seal up the area around the IC. the fan is what pulls air in across the IC. like it is the air just bypasses the IC.

you can get the tial WG much cheaper from HEMNI-RACING. i want to say around $2-300

porsche 930twin 08-26-2015 03:22 PM

http://img7657Hey Gumba what engine are you running in your do you get cooling to your intercooler... what transmission are you running.. I have a 1977 VW twin cab ute running a 3.2 with standard 4 speed but want to swap transmission

gumba 08-26-2015 04:44 PM

Porsche930twin, the engine write up is here: VW Type 2 Bus: 930 3.3 Turbo Engine Swap. You can email me with any questions.

flat6pilot 08-27-2015 09:59 AM

OBX Headers Showed up.
I received the OBX headers sooner than I expected. Only 2 days. (I was expecting a week)

The package they came in was impressive as they did a great job of using "form foam" to squeeze everything in the box.

I'll post a few pics of the welds. I have a camera snake that I sent down to see if there was any obvious slag showing, and didn't find any. I'll still run a chain down everything and shake stuff up just in case.

This looked like the worst of the welding skill. Although I'm not a welder myself and really know nothing about good and bad... this looks a bit sloppy to me.... Otherwise, the welds looked ok for the price of the headers. The difference between $500 and $2500 headers. You get what you pay for....

The only thing I'm concerned about is the trueness of the flanges. I ran a straightedge (ok, it was my metal ruler at my desk) and one of the flanges seems about 1mm or 2mm off. Maybe a gasket width or so difference. Otherwise, the headers look ok. I don't expect them to last forever. I just want to get the project up and running within a decent budget and I'll upgrade in the future as I go along. Besides, I'm not even sure how long the fun will last by adding boost to a 180,000 mile motor.

Tippy 08-27-2015 11:49 AM

I wouldn't sweat the small stuff with the headers. I've never seen a crowd that gets so worked up over non-perfectly fitting parts. Aftermarket, you're going to run into this occasionally. I'd just use a belt sander on the flange until you are happy with the trueness. I know a super well respected Porsche mechanic trained at the factory who does this. It's not totally shadetree. ;)

Second, I rather have 100% penetration in a weld, than a cosmetically perfect weld. From what I can see in the photos, you got your 100% penetration.

I'd run them and enjoy. :)

klefroid 08-27-2015 12:46 PM

I had the OBX before... did not fit so good at the turbo and had to weld it after 2 or 300 miles because the header was under stress...
Other then that, the power over the stock was pretty good!
If I'll go for such an expensive turbo then I would not go with the OBX ... 1 failure and you loose $2000 :(

gavinc69 08-27-2015 01:42 PM

Ive got OBX headers on my SC turbo conversion, fitted great and had no issues at all so far after about 3000 miles.

klefroid 08-28-2015 08:07 PM

I guess you need to be lucky :)

gavinc69 08-30-2015 05:25 AM

Someone also did a duck tail turbo install and used a 944 turbo intercooler!

flat6pilot 09-27-2015 11:26 PM

1st Start
Quick update: 1st start-up happened today. I let it run at idle for a bit to check for oil leaks or anything else that might look or sound bad.

The only exciting thing that happened was smoke began pouring out from somewhere. At first I feared: Oh no, I just burned the turbo up due to oil starvation! Did I hook everything up right?? Shutdown engine...

After I shut the motor down and inspected, I could see smoke coming from the turbo exhaust. Could it be burning off new machining oil? (It's a new Garrett 30R). I fired it back up and within 30 seconds the smoke stopped and all seemed well. The turbine wheel still spun freely afterwards so it looks I didn't sieze anything!

I'll be back to rewind and post a better update with better pics plus video links.

The only thing left is all the boost/vacuum hose connections, purchase a zork tube and install O2 sensor and wait for the turbo mount and wastegate dump pipe to show up.

...And of course tuning the Megasquirt system for a boost set-up.

quattrorunner 09-28-2015 07:36 AM


Tippy 09-28-2015 09:32 AM

Prolly oil contamination all over the headers burning off. I've always been amazed how much smoke comes from just a light coating of oil.

gavinc69 09-28-2015 10:58 AM

I had a bit of smoke and burning smell on my first startup.
Think its normal, just surface oils etc plus new gaskets and any lube like copper lube used on studs/bolts all burning off or heating up for the first time.

Looking forward to the results and how it goes with tuning as I'm doing that with mine now.

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