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944 Turbo S Engine Rebuild Thread

Done loads of little bits, sorted all the vacuum lines for the new engine, fitted a new aircon compressor, replaced the alternator, power steering pump and all the other ancillaries and belts, tensioners, etc.

Waiting on some new Comex fans to replace the ancient boat anchors and a couple of oil lines left to make up. Waiting on my inlet manifold to come back so I can button all the relevant bits up once and for all.

Replaced some manky braided nitrile hose for the fuel feed with cotton braided PTFE hose and ordered the relevant bits to do the return line too. Left enough length on it to loop both hoses around the back of the head rather than running them over the exhaust manifolds. Using a creeper under the car was a godsend, my daughter asked if I’d been working down a mine when I came back in though!

What's happened to the pictures David? I was going to post asking about the feed and return hoses in the fuel bay. Doesn't seem to be anyone in the UK making aftermarket hoses. The originals are still available from Porsche but looking at around £500 for both! With the only aftermarket options being the usual shops in the U.S. (Lindsey Racing, 944 store, 944 online, paragon, Lart). But with import duty and VAT probably looking at over £200. Do you have a list of parts you'd be willing to share that were used to make these? Also did you make a replacement for the jumper hose between the rail and damper? (y)
Given that the forum does not automatically update after we spoke on the phone then this is the website I find is the best reference material for redoing the fuel lines:

I used PTFE/Teflon AN6 Hose throughout.
Given that the forum does not automatically update after we spoke on the phone then this is the website I find is the best reference material for redoing the fuel lines:

I used PTFE/Teflon AN6 Hose throughout.

Thanks David - yes bookmarked that one, also found some useful guides on youtube for assembling the connectors.
Had a slightly too interesting day yesterday - the type where you leave the house at 06:45 to go to the Dyno and arrive home 11 hours later in an Uber from the train station . . . .

Got to the Dyno no problem, car seemed to be using more fuel than usual and was misfiring at 4krpm but had bags of power and torque below that so it was a joy to drive down. Got it loaded on the dyno and strapped down:


A few runs up through the gears and a fuel cut issue at 2400rpm was resolved followed by the 4k misfire being fixed - the extra fuelling needed with the cam timing sorted meant it was running crazy rich under full boost hence the misfire, pulling the cells back had it revving out sweetly. Autotune hadn‘t helped as they were too far out of spec for it to bring them back in line - I could have resolved it myself by tweaking the map from the logs but as I was heading down to see Dan I figured it would be easier for him to do it.

Dan commented how great the car was to drive even on the dyno and it was reaching cells we hadn’t populated before due to how much earlier it was spooling up. Knowing that this was the boring bit going through all the rev and load cells I left him to it and went for a walk to Tesco’s for mini muffins and biscuits for mid-morning coffee break. I was nearly back when I got a phone call. There was a problem. It was a significant one. We’d had a fire but it was all under control and no apparent damage. 🔥🧯👩‍🚒

When I got back they were unstrapping it from the dyno and opening up the doors (for those that haven’t been in a dyno cell its pretty much a sealed box with huge industrial fans), so when a powder fire extinguisher goes off the fans turn the thing into a cheesy nightclub with too many smoke machines! This was what greeted me:


A cursory check over showed that the clutch reservoir to master cylinder hose had split, dumping all the Dot 4 fluid onto a very (very) hot exhaust manifold. The teflon fuel lines run over the master cylinder and although the nylon braiding was singed they were fine. Dan had reported that the clutch went to the floor, he looked down to flick it up with his foot and when he looked back up - 🔥. Luckily for me he’s very quick on his feet!

10 Minutes later and a member of staff was blowing it all off with an air line outside, no time for a belt or pulling his trousers up:


And then while they mopped up and cleaned the dyno cell, I got the hose out and rinsed all the last vestiges of powder off the car before going round with the airline to get it back to how it should be so we could inspect it properly:


Within an hour of being extinguished we utilised the pump-prime feature of the DME to pressurise the fuel system and check for any leaks or issues - luckily it’s just very superficial cosmetic damage to the hoses but I’ll replace them of course. Everything seemed fine so we started it back up and let it run up to temp/pressure and all is well . . . . Apart from the lack of clutch obviously.

New master cylinder arrived there today, being fitted tomorrow, and I’m back on the 06:40 train on Tuesday to finish the dyno tuning and drive it home. On the one hand it’s terrible bad luck but on the other I’m so fortunate it happened when and where it did - Dan’s quick actions saved a lot of trouble.

So there you go - pretty much the only original part of the engine bay has borked and now been replaced, if I didn’t have bad luck I’d have no luck at all sometimes!

Of course the answers to the two . . . . erm . . . . “burning” questions are:

1) Yes I have told him to add the cost of a fire extinguisher refill onto my bill


2) The mini muffins were delicious
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That was the best place for your car to combust, I think you have been very fortunate!

Have you ordered my fuel lines yet?? I think that has now become a priority................:rolleyes:
That was the best place for your car to combust, I think you have been very fortunate!

Have you ordered my fuel lines yet?? I think that has now become a priority................:rolleyes:
Fuel lines? I really should replace the 33 year old fuel lines on my car :unsure:.
Sorry to hear of the temp setback David...keep the faith..I'm sure you'll sort it soon.

Ordered the bits I need to replace the engine bay fuel lines as the feed is a continuous run from just after the filter to the rail so I’ll stick an AN joiner in the wheelwel. Ordered enough fire sleeve from Torques to cover all the engine bay fuel lines too. It doesn’t look great (especially with their logo plastered all over it) but I’ll do my best to make it blend in and I’m a firm believer in “Build Back Better”.

Sorry to hear of the temp setback David...keep the faith..I'm sure you'll sort it soon.


“High Temp” Setback 😇
Sorry about this mishap, but I enjoy hearing that even the tuner said the car felt better now that the cam timing is correct.

The slave cylinder on mine has been slightly leaking for a while, I think I will replace it before attempting to drive to Scotland and through Newcastle next summer - I don't want to have the excuse of a failed clutch if you leave me for dead on a straight 😜
Jeez, as soon as you mentioned the 'F' word I feared the worst. Thank goodness it happened then and Dan was so quick on his feet. Did you buy him a new set of underpants? :cool:
Had another fun day at the Dyno the other week - spent ages chasing an over boost issue, now matter what we did the turbo was spooling up with zero control (26psi by 3k rpm anyone?). After trying everything else, Dan managed to lift a floor panel in the dyno cell and get under the car (very tight squeeze) to find that the banjo on the side of the wastegate was loose - quick nip up with a spanner and all was well in the world again . . . for now.

Left the car at wastegate spring pressure (12psi) and finally got on with some mapping - it was making a solid 300ft lbs and 300bhp with the fuelling dialled in and that was even before we got to sorting the ignition advance. We were getting 10 psi boost by 3370rpm and 12psi boost by 3440rpm with it taking 0.235 seconds to go from one to the other - just as reference and a reminder that a decent electronic boost controller that can quickly build and more importantly, maintain, required boost is very important - the MAC solenoid valve that VEMS controls can cut 100% duty cycle to 20% in 5/100ths of a second.

We were just about getting started to make progress when the plastic nipple on the new master cylinder melted again and another (thankfully CO2 this time) extinguisher was used as a precaution.

So the day ended up with the flatbed of shame home:

So I got to work replacing the fuel lines with new ones and fire sleeving them, replacing the clutch reservoir, hose and nipple, along with fire sleeving and heat protecting those too, building some kind of master cylinder heat shield and reducing the cam advance to control EGTs.

First step though was 4 hours neutralising and scrubbing all the ABC fire extinguisher powder out of every nook and cranny on the car and then a liberal (nearly a whole can) dousing of ACF-50 too.


Then it was time for some CAD (cardboard aided design) work:


Then used that as a template to make one out of aluminium heatshield material (make sure you fold your edges or they’re quite sharp :rolleyes: as I found out):


Installed that along with the new lines I’d made:



And finally . . . . . FIXED THE ABS!!!!!!

The short story involves a broken ground strap, a blown (but hidden fuse) and finally a dirty/loose connection on the driver’s side +ve jump post in the scuttle. Also, reset the physical cam advance to “normal” rather than “maximum attack”.
The end of last week rolled around, the weather was nice so time to see what’s what.

Left it idling on the drive for 15-20 mins to burn off all the clutch fluid from the exhaust - acrid plumes of white smoke, not fun! Then set the boost to 16psi and went for a spin to do some logging and a bit of live tuning.

So, this was the first time that I got to drive the car with the correct cam timing AND some of the engine mapping done (not higher boost and not higher revs) and OMG - transformed. Everything I’d hoped the car would be and more.

Smooth and easy to drive off boost, progressive and early to build it and then an absolute weapon once you did. 30mph in 4th, put your foot down and off you go, although my testicles weren‘t large enough to do anything over 4k rpm in 4th as high revs in 3rd puts you in “lose your licence even on the motorway“ territory (I’m lead to believe anyway 😇).

45 mins later and the only missing fluids from the car were V-Power, no lights on the dashboard for once either:


So tucked the car up in the freshly painted garage (I didn’t waste that time the car was stuck down at DanST):


All ready for the first big PCGB club run of the year yesterday with 30-40 cars, about 3 hours driving on some fabulous Northumberland and Scottish roads with no holding back and no issues at all. Even with the boost turned right down and the ignition advance not mapped yet it was certainly more than sufficient (the 930 driver following asked me to slow down as he couldn’t keep up and didn’t know the route - oops). Also, when coming in hot over a humpback bridge to find a sharp corner just afterwards, I can confirm that the ABS works perfectly and those big stoppers do the job admirably as well!


The sun even made a reappearance to give me time for a quick bubble bath too - all fluid levels present and correct apart from the fuel gauge that was only dreading half of what it did that morning for some strange reason 😎

Voltage on the dash is still reading low - VEMS shows over 12v with the engine off and over 14v with it running so I know It’s not an alternator/charging fault. But if that’s the only issue then I can live with that for the time being. Now to get back to the Dyno . . . AGAIN!


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