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Thread: Sams TFSI turbo conversion (maybe!?)

  1. #21
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    Great project and development work Sam.
    Track Car: 06 Polo GTI Red Devil mkII
    Daily: 2010 VW Jetta Highline
    Gone but not forgotten: 08 Polo GTI
    ** All information I provide is probably incorrect until validated by someone else **

  2. #22
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    Thanks fellas

  3. #23
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    Ok its looking like I'll have a stock wastegate actuator on hand soon which means i'll be able to thow in something that'll keep the car running around while I remove the Turbosmart actuator that's in the car now and mod it for use on the Golf Mk6 turbo. So this is my wastegate actuator spring question:

    It looks like Golf Mk6 Gti Stg 1 and 2 tunes run up to 18-20psi. Another member on here has sent me a log of a more conservative Stg 2 tune where even its 15-16psi peak held till about 4750rpm but then trailed off to 12psi at redline. That's on 2litres. While those numbers seem pretty high for such a small turbo relative to 2 litres, I'm thinking that with only 1781cc to play with, that I'll probably have to do the same. Stock Golf 6 Gti's run about 9psi peak boost standard on what I can tell are 5psi actuator springs. For my Turbosmart IWG-75 actuator I have 5psi, 7psi and 10psi springs, meaning that I can feasibly run gate pressures of 7, 10, 12, 15 and 17psi. My
    wastegate flapper's port will stay stock diameter although it will have its entry smoothed to flow a little better, so nothing dramatic happening there.
    So what gate pressure should I run? I'm thinking 10 or 12psi.

    caveat: I am on stock rods with this motor with 300hp/300 lb ft touted as the max they'll handle. Sounds very high to me given that its less likely to burst into wheelspin than most cars since it has an LSD and runs R specs when on the track.

  4. #24
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    Some tips from my experience with stock bottom ends (not VW's). Avoid lots of boost at low rpm as it places the same combustion pressure loads on the pistons, rods and big end bearings but it lasts longer than the same boost at higher rpm. Hence more time to bend the rods, "push" through the oil film etc. It also often requires retarding the ignition to avoid detonation, which isn't good for a stock bottom end.

    My rule of thump, don't get carried away with boost under 3,000 rpm. Plus I generally run lower boost in 1st and 2nd in a FWD car, it just results in wheelspin that is very difficult to control even with an LSD. I "tune" the engine on the dyno, but I tune the "car" on the track. Often what looks OK on the rollers doesn't work so well when the racing rubber hits the road.


    Cheers
    Gary
    Golf Mk7.5 R, Volvo S60 Polestar, Skyline R32GTST

  5. #25
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    Yep that was what we are most likely to do. We have the capability to do boost by gear. I haven't got that in place with the existing tune but yeah I reckon it'll be needed when the new turbo goes in.

    I think I've settled on the 10psi actuator spring. The 7psi Turbosmart spring would be a small 2psi upgrade over the stock IHI one, but we are going to be doubling the boost, so base based on that order of magnitude I think 10psi will be a good start.

  6. #26
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    I have most success (with controlling boost) when I use a wastegate spring that is not too much less than the minimum boost (in the usable rpm range). That way the boost controller doesn't have to work as hard. For example I'm running a 1 bar spring for a minimum of 1.3 bar of boost on the Skyline, on the Evo we ran a 1.25 bar spring for a minimum of 1.5 bar of boost. But they are built engines with turbos that don't really provide a lot of boost under 2,500 rpm. In your case 10 psi might be OK for up to the 3,000 rpm if that's your target.

    Cheers
    Gary
    Golf Mk7.5 R, Volvo S60 Polestar, Skyline R32GTST

  7. #27
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    I had a good look at the wastegate port last night. There is a 1mm wide ridge around the entire inside circumference of the port. It looks like the cutting bit that went into the port didn't go all the way in and left a lip that you could nearly cut your finger on. With that taken out the port will flow a lot better than it first looked so hopefully yeah 10 psi will be the go.
    Thanks for that Borg Warner pdf you sent me Gary. That was a good read. It was an eye opener to see them say that at full throttle you can have 40% of gases flowing through the wastegate - I hadn't imagined it'd be that much so I'm keen to do a bit of work in that area.
    I'll forward that to my mate who's planning the engine side of his 2J build now. He's agonising over whether an internally gated efr is the way to go with 550 whp or if he should start from scratch with an external gate so that'll be helpful. thx

  8. #28
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    You really don’t see many people going through all the fab work to fit non standard turbos anymore.

    I enjoyed the read. Plenty of great information here. I’m planning on doing a K04 conversion in my Mk6 GTI, and rather than just buying a kit, I’m planning on doing some machine work on the compressor housing to fit the DV and to remove the outlet muffler.

    Rather than go off topic here in your thread, I’ll send you a PM Sam.

  9. #29
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    Alright the project has begun.

    Sams TFSI turbo conversion (maybe!?)-img_3197-jpglots of fasteners needed and their lengths checked. Decided to run with studs on the bottom wedge plates rather than bolts. That bit me in the arse later on during fitment, but once its in its undoubtedly a better setup.
    Sams TFSI turbo conversion (maybe!?)-img_3195-jpgModified the turbosmart wastegate with a custom stainless rod onto a rose joint end fitting that bolts solid to the flapper lever. Three turns of preload on the 10psi spring and tested with a bike pump to check that it wasnt binding or snaring on any part of the exhaust housing at full extension. Earlier on I'd mentioned that there was a machining lip in the wastegate port behind the flapper. I removed that with files and file finished de-dagged the port to get it at its best flowing-ness.
    Sams TFSI turbo conversion (maybe!?)-img_3210-jpgSams TFSI turbo conversion (maybe!?)-img_3214-jpgAh the picture shows the appropriate amount of clearancing of the firewalls bubble that surrounds the steering column uni joint. Looks like I just knew how much was needed and sorted that. In reality that was about 3 hours of bench pressing a turbo, skinning knuckles while pulling it in and out about 6 times before I could get it situated with a pinky's clearance between the comp cover and the sheet metal. And then, I realised I'd gone too far in a couple of spots and the uni joint was touching the sheet metal so I had to hit it back out from the inside until I had a safe amount of clearance for the joint. With the firewall insulation back in place you can see the depression required. The FSI Borg Warner K03 off the Golf Mk5 Gti would have to be much the same. Apparently K040-064's off Mk6 R's fit too. Oh and in the second you can see a little stud on the left chassis rail. I removed that thinking it'd be right where the comp exit pipe would sit but it ended up being a non issue. I took the opportunity to remove the aircon pipes. They'd lost their gas a long time ago. You don't have to remove the AC. There's room for the turbo to be in there with them in place but I didnt want it any way because .......future race car. So I'm about 5 kgs lighter now.
    Sams TFSI turbo conversion (maybe!?)-img_3215-jpgSams TFSI turbo conversion (maybe!?)-img_3216-jpgDespite the firewall clearnacing being needed, there is actually way better room once its in there compared to the original frame turbo setup. From underneath you can easily access every manifold nut and from the top its an easy reach too. The wastegate is totally accessible and removable too in case I need to change the preload. The DV cover is fully accessible. What you cannot get to is coolant banjo on the back of the turbo. If that banjo had leaked it would have been a turbo out job. It has to be fitted and its orientation sorted before the turbo is fit up. I'd sooner drill a hole in the firewall to access it from the cabin than remove the turbo to add a bit more tightness to that if I;d needed too. I was very lucky that my clocking of the exhaust housing, CHRA and comp housing were all correct. I'd had the benefit of verifying all that on the my spare engine on a stand but it was still an unknown how it would clear the firewall, master cylinder, brake lines etc but luckily so far so good.
    Sams TFSI turbo conversion (maybe!?)-img_3225-jpgSams TFSI turbo conversion (maybe!?)-img_3226-jpgSams TFSI turbo conversion (maybe!?)-img_3227-jpg
    The other thing that I thought might be a major problem was clearance for the compressor exit to clear the chassis rail. Previously you may have seen that I lopped off the compressor exit silencer and welded on a short stub. To this I recycled the hose that comes off the standard K03s turbo. It fit the turbo perfectly and also the 2/1/4inch pipe I decided to go with. Even on the stock car, the stainless cross pipe in the engine bay is 2/1/4in, its just that it necks down later on at the awful rubber hose click joints to less than 2in in places. My custom pipe underneath was an easy run and links up to another pipe I had on hand, so now I have a full end to end 2/1/4inch boosted pipework setup on my car.
    Sams TFSI turbo conversion (maybe!?)-img_3233-jpgSams TFSI turbo conversion (maybe!?)-img_3228-jpgSams TFSI turbo conversion (maybe!?)-img_3229-jpgSams TFSI turbo conversion (maybe!?)-img_3183-jpg
    The factory passat oil line despite being a mongrel of a thing to fit (getting it through the nest of wires and coolant pipes on the side of the head gave me another bought of swearing fits) but once in it all lined up. The brace I made fit ok. Its too small where it only picks up on a single 8mm casting hole on the block but will have to do for now. I then had to lock wire in place the beginnings of the dump pipe and then drive the loudest Polo I've ever been in the 2 kays down to my mates workshop for the dump to get finished off. I can confirm that you cant run a normal radius 90 degree 3 inch bend straight off the turbo and down through the exhaust tunnel. It not only hits the gear change cables but fouls the firewall. As seen in the grainy pic above you'll need another 90 that;ll get cut into 2 x 45 degrees so you can dog leg it.
    It gets welded tomorrow. After that I'll get it back home, remove the 2.5inch MAF and old tune and work out a TIP for the 2.75inch Audi S3 MAF, wire/plumb up the N75 and DV and PCV and then put in one of Dave's base tunes and begin some tuning fun!
    Last edited by sambb; 06-06-2022 at 10:30 PM.

  10. #30
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    There's a few left overs that will be for sale
    - K03, K03s,K04-001 dump pipe. 3 inch. Just the first section straight off the turbo down to about the subframe. Only needs a 45 degree on the bottom of it to line up with the under body part of an exhaust. Its the part that was removed to make way for the new TFSI turbo dump.
    - 1.8t 20V ported exhaust manifold
    - A/C compressor
    - my K03s boosted pipe work from turbo to front mount entry. Includes black ceramic coated OE stainless top pipe, 2 inch aluminium under crank pulley pipe plus 2 inch aluminium pipe from that to around the front of the radiator assembly.
    - whiteline front anti roll bar 22mm
    Last edited by sambb; 07-06-2022 at 08:01 PM.

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