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300Tdi VGT project


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It's a steady but slow project. I now have a manifold for my VG turbo, resplendent in cartoon red:

21072008856s.jpg

21072008859s.jpg

and since I'm curious, I took the end off it to see how it all works. They've added mechanical cleverness here:

21072008861s.jpg

Question is, how to control the vanes (and thus the boost)? The diaphragm on the unit needs vacuum to operate it. I could use the servo vacuum but I'd have to bleed this branch to generate a flow so I can modulate it, and I'm not keen to throw away my hard-worked vacuum when it's also working the brakes. The engineer in me would like to convert it to boost-sensing, so that the turbo always tries to achieve eg 1bar of boost. Any ideas (other than megasquirting the whole car, thank you FridgeFreezer)?

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Thanks Si - have you got any pictures of your setup? I'm going to have a play with it on the workbench at the weekend and see if I can make the rod move through the full travel with 1bar. My concern is that my chosen boost will need lots of 'trial and error' calibration to get the rod length correct, or else it'll be at full / no boost all the time.

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My turbo is off a 2003 Mitsubishi L200 Warrior, which is anywhere between a 110bhp 2.5 and a 170bhp 2.8 depending on which website I choose to misunderstand today. I've got no idea of part numbers etc, it was acquired for me and seemed suitable on paper.

I'd thought about drilling the vacuum diaphragm but since I can produce some movement by sucking it with my mouth(!) I expect it'll work at a lower pressure than the 1bar boost or greater that I want to run, limiting my available power. The answer there would be to bleed some of the boosted air out before the diaphragm so it sees a proportion of the manifold pressure, but I don't know if I'd damage the unit by drilling into it. I guess the answer here is to try it, since it's scrap to me if it won't do what I want. Thinking aloud, I do need to make sure that it works the right way round for my application, eg more boost is a signal to produce less boost and not vice versa, or else it could just run away with itself. I'll have to pipe it up and see if it works...

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Watching with interest..................

Just a small note on your manifold design, since you have omitted the expansion joint on the regular manifold i suggest you keep the flange holes at the head pretty wide as it will expand and contract considerably, if you make them tight there is a tendency for the studs to get sheered off or maybe developing a leak.

In the past i had seen a tdi with fitted turbo on a mag, i belive it was some sort of french landy with a huge turbo, it had the most amazing exhaust manifold made, it looked like rams horns making a neat 4 into 1. Wish i could find a pic!

Regarding the actuator, you can get aftermarket ones with different spring rates according to the boost required, but you will need to fit the whole thing, funny it works by vacuum

Keep it up........

Grem

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"since you have omitted the expansion joint on the regular manifold i suggest you keep the flange holes at the head pretty wide as it will expand and contract considerably, if you make them tight there is a tendency for the studs to get sheered off or maybe developing a leak."

Just like a TD5 ......

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The actuator will either push or pull to open the wastegate therefore controlling the boost pressure and putting an aftermarket capsule is easy as its only a simple rod connecting it to the wastegate so you could get a threaded sleeve made and then you have adjustable preload on the boost capsule this is better set as light as possible then the wastsegate will flutter when opening rather than a sudden dump of pressure which can cause the turbo to lose momentum , you could have an adjustable valve to bleed off the boost reaching the capsule so you can adjust the boost from in cab.

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Tonight my attention turned to boost control, and the plan is much as suggested above. I've found that the OEM diaphragm is sprung such that the vanes are naturally 'open', ie equivalent to a 'large' turbo (or 'wastegate open'). While nobody worries about wastegates sticking 'closed', it's nice to know it'll fail safe.

I've drilled and tapped the other side of the diaphragm to turn it into a pressure-activated unit. I've learned a couple of things from this process:

1) The tapping drill for M10 fine is 8mm, not 9mm (and now I need chemical metal).

2) However careful you are, drilling towards a rubber diaphragm means you'll put a hole in it (and now I need some more silicone sealant)

However, I now have this:

24072008872s.jpg

and I've sealed the small tear in the rubber moderately well with silicone - we'll see how long that lasts. With the compressor turned down to 1 bar, it travels around 11mm which is around the total throw of the vane lever, so we'll see how that goes. Don't know about preloads and adjustment yet, but since this is what I've already got it's worth a go. There is an adjusting sleeve with opposite threads (and the LH thread is on the turbo end so it'll be easier to make up my own rod later if I need to).

The manifold was made by a friend at work to return a favour, and he refused to take any money for it. He jigged a spare 300Tdi manifold and made the new one to the same pattern so it should mount to the existing exhaust too. However, I'd told him there was 'loads of room' in the area away from the block, and it looks like he took me at my word.

24072008873s.jpg

(Standard 300Tdi on the left, my manifold on the right)

Wandering round the engine bay with the tape measure, the washer bottle has got to go and I may have to rearrange the inner wing a little. I'm concerned about the cantilevered weight but not enough to go back and ask him to start again. As a favour I'm touched that he put so much effort in, and more so that it uses the standard exhaust. If it fails I'll have to chop about what I've got and move the exhaust too, but meanwhile it seems ungrateful to ask him to start again. I'll have to suck it and see with expansion joints - I'm not wild about slotting the studs; to my mind if they're slack enough to allow any slip then there won't be enough tension to hold up that weight. Maybe I'll get it hot and then tighten them.

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Watching with interest..................

Just a small note on your manifold design, since you have omitted the expansion joint on the regular manifold i suggest you keep the flange holes at the head pretty wide as it will expand and contract considerably, if you make them tight there is a tendency for the studs to get sheered off or maybe developing a leak.

In the past i had seen a tdi with fitted turbo on a mag, i belive it was some sort of french landy with a huge turbo, it had the most amazing exhaust manifold made, it looked like rams horns making a neat 4 into 1. Wish i could find a pic!

Regarding the actuator, you can get aftermarket ones with different spring rates according to the boost required, but you will need to fit the whole thing, funny it works by vacuum

Keep it up........

Grem

i know which article your on about they tested it in a forest and it black smoked a little!!! :mellow: i'll go hunting later for it...
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  • 2 weeks later...

Update: I have time, spanners and me in the same place so:

Manifolds off:

060820081039s.jpg

The turbo is passing a little oil, and this could be a contributor (no blue smoke though):

060820081041.jpg

The cartoon red manifold fits after a little tweaking with a round file:

060820081046s.jpg

And the turbo isn't as comedically large as the mockup on the workshop floor suggested:

060820081049s.jpg

The washer bottle will have to move and when the turbo is offered up to the flange the heater interferes with the diaphragm which I so lovingly drilled through modified last week. I'm going to try using the standard 300Tdi diaphragm on a custom mount instead, and it'll probably give greater movement for the pressures involved.

For the spectators, this is a dull update because its just bolt-together stuff but this conversion has been in my mind since I chose a username, so this marks my move from vapour builder to real spanner swinging. Eat that, Will Warne :P

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This evening saw fettling and planning. No photos, no discernable progress, but I sank a few more hours into it, mostly playing with the diaphragm off the old turbo which I'll use to operate the VGTness. Now I've got a shopping list for thinwall pipe, silicone intercooler hoses, nuts'n'bolts and some hydraulic hoses for the oil lines. Unless anyone's got any bright ideas I'm going to have to promise my firstborn to Hyphose/Pirtek/similar.

Will - can't do dyno plots I'm afraid, the auto gets in the way of the power escaping to the wheels. Unusually for me I'll just have a host of qualitative comparisons and hopefully a big grin.

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Hyd hoses - IMHO they are overkill for oil lines. Take your old oil lines (to determine the block thread sizes) and the turbo (for the other connector sizes) into a hydraulic supplier and get some 45 / 90 degree (as appropriate) push-fit connectors and a foot or so of appropriate hyd hose for each line. Some decent jubilee clips will join the push fit connectors to the line.

I did the Pirtek thing and it was a pain - you'll never get the hoses exactly the right length and orientation.

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Will - can't do dyno plots I'm afraid, the auto gets in the way of the power escaping to the wheels. Unusually for me I'll just have a host of qualitative comparisons and hopefully a big grin.

Go to a shop with a modern rolling road, no problem with an auto box!

Mo,

Vapour is a game of bluff, Will has the best hand in the game for that :P;)

Lara.

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