924 Turbo - what to look out for

[Belgian951]

I may be in the market for a 924 Turbo, but the price will have to be right. This means: cheap. And with cheap cars come not so cheap repairs. So I'm wondering what to look out for. What are the problem spots? How can I verify good working order of the main systems?

As you know I already own a 944 Turbo so hoping some of the knowledge is interchangeable.

[zooklm1]

From what I remember reading in the past, the nominal power for the 924 turbo was the same as that in the 87/88 924s. Because the turbo was not water cooled, it had a tendency to cook the residual oil in the turbo if shut off hot. The engine was a modification of the Audi engine that Porsche agreed to use as part of their agreement when they bought back the 924 design/right to produce.

[zooklm1]

One other thing, have you tried researching/ looking at 924 Org Board? Not sure how active it is now but I went there a good bit when I had an 1988 924S about 20 years ago.

[Belgian951]

Thanks! I'll check out that board, hadn't heard of it.
The 931 is interesting, but I believe it will be harder to find parts for it. Lots of stuff is NLA apparently. I may have to focus on my 951 first hehe. Still, it's nice to hunt for a new car!

[Bbean]

What do you mean by “cheap”? These are fun cars but there’s nothing cheap with any Porsche. Some parts are NLA so check it over carefully. My sister has an 81 with 26,000 miles, garage kept and has had a lot of things replaced. Not as much power as our 951 track car, but it is peppy and fun to drive and see where they went from the 924 to the 944.

[j1nx3d]

I had a 1980 924 Turbo for a few years and loved it. It was a 170 hp 'Series 1' 932 (RHD 924 Turbo) , ex-UK, with a 924 Carrera GT bodykit. With every panel fibreglass except for the shell it was a very rapid car and quicker than my '86 944 when it was still a 2.5 L 8v.

The 1981< 'Series 2' 924 Turbo's were 177 hp which was from a few small changes. The 924S 1986-87 were detuned 944 engines somewhere around 150 hp except for the 924S Le Mans version which was 163 hp like the 944, then the 1988 versions of the 924S and 944 switched to the same 160 hp engine.

It's been some time but the some common issues for them were:

* Oil cooling. They could get very hot. Mine had an oil cooler and a turbo timer. Ideola's Garage (Dan) who was an innovative enthusiast/vendor around until the early/mid-2010's did some neat stuff with this 931 like a hybrid turbo using the watercooled housing and plumbing from a 944 Turbo.

* Intercooling - The 924 Turbo never got one. The 924CGT got a top-mount, the CGTS and CGTR got front mounts. You can fit a 951 i/c but it's tight. Another issue with front intercooling is the plumbing. It can be done and has been done for some power improvement but it's a lot of work. Ideolas Garage developed a water to air i/c but I don't think very many of them were produced.

* OEM upgrade parts. Don't expect to find any parts from top tier 924 CGT, CGTS, CGTR models and if you do they will be incompatible or $$$$$$$$$. There's a few people trying to do true replicas of these machines and I don't envy what they are up against.

* They still used mechanical fuel injection (MFI) which is fine as long as it's left alone and not interfered with. If it has issues it can be hard to find someone willing to look at it. A few people on 924board have gone EFI (usually megasquirt).

* The getrag/porsche G31 snailshell transaxle. These share design and parts with the 911's 901 gearbox but have unique 924 Turbo parts. They are a dogleg 5 speed and are very strong but they had synchromesh problems. They changed the transaxle in later 924 Turbo to the audi style ones like the 924 and 944 but they still used variants of the G31 in the 924 Carrera GT, GTS and GTR- which is a testament to their strength. Parts are hard to come by with the occasional group buy to get some made.

* NLA parts. There is a lot of parts no longer available. That's where Ideola's Garage and other enthusiasts at 924board really came through for bespoke OEM+ solutions. I needed a new head for mine, I blew the head gasket and it was too soft and porous to rebuild. I eventually found a good used one, but that was back in 2008. I heard that the DITC box (an electronic magic box thingy for the ignition) on the series 2 931 has been NLA for a long time and that thing is essential for these 40 yr old cars.

That's all I can remember off the top of my head but you will find a ton of information on 924board.

[Belgian951]

What do you mean by “cheap”? These are fun cars but there’s nothing cheap with any Porsche. Some parts are NLA so check it over carefully. My sister has an 81 with 26,000 miles, garage kept and has had a lot of things replaced. Not as much power as our 951 track car, but it is peppy and fun to drive and see where they went from the 924 to the 944.

Yeah, I know. There's a 931 for sale for +- 9000 EUR. But I haven't looked at it yet, but it'll be a mess like they all are in that price range. It would be fun to have one, but with all the NLA parts, the 951 I already am working on, and the need to rent another garage, it's probably a fool's errand for now.

@j1nx3d , thanks for the exquisite overview of potential issues!