Current View of the Engine Bay!

A Few More Glamour Shots:

This 1980 Porsche 924 Turbo S was given to me by a fellow enthusiast who wanted to see it brought back to its former glory. At times it’s been hard for me to determine if this was a blessing or a curse! These pages give a log of my restoration and enhancement of the car as well as lots of esoteric 924 Turbo tidbits along the way. Enjoy!

I’ll give a quick synopsis on this first page, then dive into more detail in the following pages. To start off, here are a couple before and after shots:

When I received the car it was in what I would describe as "staying together out of sheer stubborness". As I dismantled the car I found all sorts of broken and worn pieces. Anything that was questionable was replaced.

I completed the restoration after 14 months and turned it into a very sweetly running and looking machine. About 6 months later, the JE forged pistons had all but melted down and it was time for the engine to come apart again. Here I am, three years after acquiring it, going through, hopefully, the last round of engine rebuilding and enhancement.

I began stripping the car down when I received it in March 2003. Here I am in November 2006, getting ready to assemble yet another engine.

Engine troubles:

Engine #1

The original engine. I opened this engine up for a complete rebuild as soon as I got the car. It was caked in oil and needed to come out anyway for the repaint. When I opened it up I found the top compression rings all broken - not an atypical sight on these old 931's. The pistons ended up being out of round, and the cylinders weren't in much better shape. It amazes me that it ran at all. I actually took it out on a test drive like this before getting the car. After the test drive I had it towed to my home/garage and didn't attempt to start the engine again!

Engine #2

The first engine build used the stock CIS injection and forged JE pistons. When I opened this engine up after about 10k miles, I found one piston with the crown and compression ring completely missing, and another piston with a 1/2" chunk missing from the crown. I've seen two other engines that have failed in an identical way using JE pistons. I bought JE because of their outstanding reputation, but they truly screwed the pooch in their 931 piston design. The stock cast pistons hold up much better.

Engine #3

I decided to use 87mm flat-top VW pistons in the new build along with the MS EFI + EDIS conversion. This likely would have worked just fine if it hadn't been for the fact that I bought new standard size rod bearings on a crank that was turned 0.010" under on the rods... Lots of detonation-sounding noises and a quickly blown headgasket. I also saw cranking compression numbers as high as 176psi. Some of that could have been due to the extra ten thou that the pistons now had in travel. More of it could have been due to the fact that the block seems to have been decked by a significant amount by my old machine shop. Probably a good 0.020" or more.

Engine #4

Voila! Up popped a completely rebuilt 931 engine on ebay. The seller was a shop owner who told me that new standard size factory Porsche pistons were bought and used, the crank journals were turned 0.010" under, the clutch was new, the turbo was rebuilt, the head was rebuilt, the bores were checked with a boroscope, etc., etc. Turned out, this engine had been sitting for over a year and at some point was flooded with water. The cylinders were rusty and pitted, the top compression rings were all in pieces, there was some surface rust on the crank journals (which turned out to be standard), and the inside of the block was covered in surface rust. This engine burned oil from startup and had enough crankcase blow-by to cover the entire engine bay in nice clean oil. I replaced the rings (after finding them all broken) and ran a ball-hone on the cylinders. Put it back together and still smoke. I'm working with my credit card company on a chargeback on this swindler.

PS- Don't buy anything from Gary Wilkins owner of Preferred Imports in Deland, FL, ebay handle: piparts !!!

Engine #5

Getting tired of pulling the engine. I bought 88mm flat-top VW pistons with coated skirts for this build. The block was decked and bored to the pistons. The crank in the junk engine turned out to be ok, just in need of a polish. Through lots of number crunching, I decided to carve about 2cc out of the head to lower the compression ratio down to a calculated 8.2-8.3:1. The balance work alone came in at almost $400! This engine is perfect. We'll see how it runs...

And this engine has decided to burn lots and lots of oil... argh!

Engine #6

Enough is enough. The car is now in the very capable hands of Marc @ German Performance, Inc.. I have no idea why I didn't find this fellow sooner, he's right around the corner and great to work with!

An initial leak-down test was showing up to 18% blow-by, so the rings weren't doing their job.

After tearing into the engine Marc found that the rings that I gapped generously at 0.027" had turned into 0.040"+ which is enormous for the bore size. The rings that come with these Chinese-made VW pistons just don't seem up to the task. So we've employed Total Seal to make a replacement set of rings using a nitride top ring to hold up better under the turbocharged environment.

The car will go straight to the dyno after the rebuild, so I should have some good baselines to go from!

The following pages give more info on this on-going saga...

Page 1: Intro
Page 2: Engine internals
Page 3: Fuel and Ignition
Page 4: Turbo and Wastegate
Page 5: Clutch and Transaxle
Page 6: Suspension and Braking
Page 7: Interior work
Page 8: Bodywork

Post Script

Many people have questioned what the "S" designation is all about. Well, here's what I know- there was only one year (1980) for the 924 Turbo S. The S option included 4-wheel disc brakes (same as the 944 introduced in 1983), 23mm front & 14mm swaybars, Koni adjustable sport shocks, 16x6" alloy wheels with 205/55/16 tires, and a slightly higher ratio steering rack to make turning the wider tires easier. Some cars came with a large "S" decal on the hood, some not. I found this pic to the right on an ebay auction- it readily shows the larger alloy wheels.

There were several other "S" models in the 924 line. The 1979 924 S included much of the same as the 1980 Turbo S with the exception of the '79 using 15" wheels and the steering ratio didn't change. Lastly, there was the '87-'88 924S, which was really just a 944 with 924 fenders.