924Board.org

[Squeaky]

Obviously it's not going to be as simple as say, a Chevy 350, but how complicated are these engines and turbos?

[Khal]

OK, I'm far from what could be called a competent mechanic but after many years of owning a 924 Turbo, many years of being friends with, talking to and helping people who are what could be called competent mechanics and, of course, many years of reading this 'board, I feel qualified to at least add relevant comment (gurus, please feel free to correct me if I mislead);

In my humble opinion, there are two sides to the engine of a 924 Turbo. The block and head, and all their internals, are, to the best of my knowledge, a pretty standard single overhead cam, eight-valve, four-cylinder-type arrangement. I would hazzard a guess that these basic components are no more or less complicated or difficult to understand/work on than any other similar type of engine... but:
The fuel system especially and, to a lesser extent, the turbo system are physically complicated and compact, by nature of their age/level of technology and their being crammed into the front end of a very low and very small car.
The fuel system is called Bosch K-Jetronic, commonly referred to as C.I.S. or (C)ontinuous (I)njection (S)ystem. There is reams of good info about this system on this site and out in the world (i.e. books you can buy) so I won't bother launching into a detailed description right now. Suffice to say the fuel system is surprisingly bulletproof when it's running correctly but it can be difficult to diagnose when it's not, due to its complexity. I reckon you need genuine experience, not just book learnin', to diagnose this system effectively. Just as a side note, I know for a fact this system is used in some BMW's and have been told that it's also used in some Audi's, Mercedes', Volvo's and perhaps other cars of similar vintage.
The turbo system doesn't seem too complicated, as far as turbo systems go, even to a relatively inexpert person such as myself (or maybe it's because I'm inexpert? ). It's no 997-type, twin turbo, computer controlled, variable vane, intercooled, etc, etc, sytem. But it's physically difficult to work on because it's seriously tightly packed in there.
There are two types of ignition systems depending on age/Series of the car. There's a 'standard' (as far as I'm aware) mechanical-type ignition system on the earlier models ('79 and '80?) and an electronic/computer-controlled ignition system on the later models ('81 and '82?), this latter called D.I.T.C., which, if memory serves me, stands for (D)igital (I)gnition and (T)iming (C)ontrol. As I understand it, the 'standard' mechanical ignition system is, like the block, head and their internals, no more or less complicated or difficult to understand/work on than any other mechanical-type ignition system. The D.I.T.C. is perhaps simpler in some respects, being somewhat a 'sealed' system. But like the fuel system, it can be difficult to diagnose when it's not running correctly.

I think that covers the basics. And I'm sure other, more expert members among us will add their comments. On the whole, it's not rocket science. It's just an engine. But it can be daunting for a complete noob and can be very expensive, both in time and good ol' cash money, to get it running right and keep it running right. I cannot, in good conscience, recommend one as a first car for a kid that needs a daily driver to school/work.
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'80 924 Turbo

[ideola]

Good summary Khal, accurate on pretty much everything. I agree regarding the student's daily driver comment. A couple more things to add:

All of my 931s are Series I / Series II hybrids, meaning that I have the series II throttle body charge tube and exhaust manifold, but I have the simpler series I ignition and turbo. IMO, this is the best combination of simplicity, power, and upgradability. If the DITC flywheel sensor goes in your SII 931, good luck finding a replacement.

On the other hand, the downside of the SI is the "snailshell" gearbox. They have weak synchros and dogteeth, and I have yet to drive on that doesn't need repairing. The problem is, the required replacement parts are pretty much unobtanium (unless you get lucky and happen to find a NOS stash somewhere). Fortunately, you can upgrade to the later style Audi box, but that's not a trivial project, considering you need to change the torsion carrier.
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erstwhile owner of just about every 924 variant ever made

[924RACR]

Very complex. Very bad to learn on. Price of failure (to do things properly, as the engineers intended) is quite high, and it's easy to fail without substantial prior German car experience. You cannot treat this engine like an SBC, you will end up selling a pile of parts to someone else.

They also require, as touched on previously, an extensive library of metric tools. One socket set ain't gonna cut it. I have, more or less, 3 different sets of metric wrenches of different types, for example. I think I have enough now. Lots of allen wrenches and bits, lots of extensions etc., triple square bits, etc etc.

Not a good place to start, as much as I love 'em.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Rasta Monsta]

[ideola]

Rasta, I will definitely take you up on that offer!!! Actually, I have two rebuilt snail shells, one for the UWB project (with LSD!!!) and one for the 941, but both are awaiting installation. I hope to have the gearbox swapped out on the 941 within the next month, so I'm looking forward to driving it without crunchy 2nd gear
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erstwhile owner of just about every 924 variant ever made

[Rasta Monsta]

I say take it as a challenge, and succeed, Squeaky. I'm a big clumsy dumbass, and the Shagster turned out pretty good so far!
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[Cedric]

I wouldn´t say that it is that complex and nor is it that hard to work on. Except for the turbo parts wich need tiny hands and heaps of patience
On the other hand, i have never touched a v8 so i dont know how easy that is. But i do know whats its like to have to learn everything you do from scratch. It isnt that expensive either, compared to the 924 most of 931 specific things are twice the price but compared to other performance cars it isnt bad at all, people on this board tend to not understand that this is a car, all cars cost money, regardless of bonnetbadge, i will never understand why people want to buy second hand brake drums. Please explain it to me



I would never change my g31 box to an audi one, g31 is far cooler. Learn heel toe when going to 2nd and it will work like a dream
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1980 924 Turbo
www.instagram.com/garagecedric/

[Khal]

Most of this information has previously been posted, in considerable detail. You should really learn to search before starting a new thread for every thought you have.

It's not that we mind answering questions, I just wanted to point out that nearly all the info you have asked for is already available and would probably only take a few moments to search it out...
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'80 924 Turbo

[J1NX3D]

lol Khal, your cut and paste skills are supreme!
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'86 944

[Squeaky]

[Stampedetrail]

So, just for review:
No 924 Turbo, no 924S, no 944, no 968 until you finish your 924 N/A project. They are out there, go get 'em.
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1977.5 924 "Martini" head / New Old Stock rebuild
1985.5 944 Why? Because I can.

[macBdog]

My answer to the question: Yes 924 turbos are hard to work on.
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1979 931 with a 350 chev
1973 911E with EFI

[-nick]

I'll second that. Not a good first car for anyone. Not just due to wrenching on it; it isn't an easy driver. The first time you give it a bit too much gas from a stop and the boost rolls on mid-corner - you need to know how to react. 924na is a good first car. 931 is not. You'll be a much better driver if you learn how to drive a slow car fast (not referring to street driving).
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[emoore924]

931's aren't hard to work on. You just pay your mechanic a lot of money and ATAFMO, things get fixed.