944 Turbo S Engine Rebuild Thread
- Thread starter Eldavo
- Start date
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Car went to the fabricators for a week and while it was there we decided that rather than modify the existing 2.75” downpipe for the new turbo (as it’s a 3” V-band outlet), they would make me a new downpipe.
The turbo sits at a slightly different angle too so the crossover pipe needed a bit more work than just swapping the T3 flange onto it too. The downpipe is tight but is a true 3” ID with a V-band at either end and can (just) be removed with everything else bar the brake booster heatshield in situ too . . . not that I’m planning on going back in there again anytime soon!
The turbo sits at a slightly different angle too so the crossover pipe needed a bit more work than just swapping the T3 flange onto it too. The downpipe is tight but is a true 3” ID with a V-band at either end and can (just) be removed with everything else bar the brake booster heatshield in situ too . . . not that I’m planning on going back in there again anytime soon!
Got the rest of the engine put back together (and the strut brace bolt if you’re eagle eyed).
Turned the fuel pressure up to 4 bar and tweaked the VEMS req_fuel settings - for once the theoretical calculation was actually the correct practical application - usually it’s close but still needs a tweak.
Also fitted a remote pressure gauge to the inlet oil feed of the turbo and zip tied it to the wiper - I wanted to see what oil pressure was under WOT to ascertain whether I needed a restrictor plate in there or not (Holsets are happier with higher pressure than BB-cartridge Garrets and the like). Voltmeter also decided to sit at 10 for no reason - despite the voltage when running being 14.4v according to VEMS - there’s always something isn’t there?
Weather was reasonable yesterday so got it fired up and out for a spin with plenty of logging and VE fuel table autotuning on the move too.
Turned the fuel pressure up to 4 bar and tweaked the VEMS req_fuel settings - for once the theoretical calculation was actually the correct practical application - usually it’s close but still needs a tweak.
Also fitted a remote pressure gauge to the inlet oil feed of the turbo and zip tied it to the wiper - I wanted to see what oil pressure was under WOT to ascertain whether I needed a restrictor plate in there or not (Holsets are happier with higher pressure than BB-cartridge Garrets and the like). Voltmeter also decided to sit at 10 for no reason - despite the voltage when running being 14.4v according to VEMS - there’s always something isn’t there?
Weather was reasonable yesterday so got it fired up and out for a spin with plenty of logging and VE fuel table autotuning on the move too.
Car was very lumpy to drive and I could see that there was a lot of fuelling correction being done so did lots of transient load acceleration whilst keeping off boost and pulled over every 5-10 minutes to burn it to the ECU. After half an hour the fuel correction table went from the first picture to the second and the car drove really well.
Now time to add some boost! I’d turned this down to about 12psi and didn’t use more than gentle throttle but even so it was still a decent kick in the back and some decent speeds and overtakes were accomplished. This turbo is much more efficient with the bigger hot side and the duty cycle numbers I was getting from the log files to update the boost table were considerably lower than the old ones. Less duty cycle to hit the same boost at the same rpms means better spool up and better efficiency.
Only issue I really had was one of the block-offs I’d put on the crossover pipe (new turbo is oil cooled only) was leaking and it took a bit of detective work with a torch and a mirror on a stick to find it - just a jubilee clip that needed nipping up thankfully.
Just need to wait for another dry and warmish day (in November) to get some more boost and fuel logs from higher up the rev/pressure range and then I can take it to the dyno with most of the hard work done.
Now time to add some boost! I’d turned this down to about 12psi and didn’t use more than gentle throttle but even so it was still a decent kick in the back and some decent speeds and overtakes were accomplished. This turbo is much more efficient with the bigger hot side and the duty cycle numbers I was getting from the log files to update the boost table were considerably lower than the old ones. Less duty cycle to hit the same boost at the same rpms means better spool up and better efficiency.
Only issue I really had was one of the block-offs I’d put on the crossover pipe (new turbo is oil cooled only) was leaking and it took a bit of detective work with a torch and a mirror on a stick to find it - just a jubilee clip that needed nipping up thankfully.
Just need to wait for another dry and warmish day (in November) to get some more boost and fuel logs from higher up the rev/pressure range and then I can take it to the dyno with most of the hard work done.
blade7
Well-known member
Good job. Did you consider some exhaust wrap on the downpipe, to protect the AOS. Seen a few pics of that on big turbo/downpipes.Eldavo said:
Changing the subject, I have a big K&N cone filter 200mm long x 150mm dia wide. I was planning to cut off the headlamp bracket, and site it behind the headlamp. I'm guessing it will be too big to fit in the wheelarch?
blade7
Well-known member
Eldavo said:
Had a quick google, and the K&N I've got is a fair bit bigger. It will only fit behind the headlight if fitted vertically. Still it has the right size inlet, and because the box was a bit damaged it was cheap. I'll drill a few holes in the plate underneath where it's going, and hopefully it wont get covered in crap.
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