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Some turbo questions


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Ok folks need your help and advice before embarking on things.

I have just bought a boost gauge 20psi and want to know the best place to put the t-piece, is it on the pipe between turbo and actuator or the turbo pipe at the ip?

The pipes from the turbo to the intercooler and from the intercooler to inlet manifold feel soft. The first section of 'flexi' pipe from the turbo to the metal intermediate pipe expands when the engine is revved is this normal?

Now, what i've described as the intermediate metal pipe between turbo and intercooler narrows and this seems it could be restrictive to airflow. Can any power or torque be gained by replacing this pipe with a less restrictive one?

Looking forward to your replies.

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What engine? Assuming a 300tdi....

I have a test gauge which I plumb in on a small T piece right at the turbo end where the little bit of flexi pipe goes on at the back of the turbo with a small spring clip and then goes into a plastic pipe to feed the boost pressure to the injector pump diaphragm. I suggest this would be the best place. though you could do it anywhere. I've seen it said somewhere that you are better off to move the wastegate pipe to feed from the inlet manifold to counteract the slight pressure loss in the intercooler, but I'm not sure it makes that much difference, probably easier to just wind the boost up a couple of psi :)

The first 90 deg pipe out of the turbo does delaminate inside but yes it is normally soft as are the others, and will expand slightly under pressure, but it shouldn't be too much, certainly less than 10% increase in diameter. There is (IMHO) a lot of guff talked about silicone hoses and how they don't expand like this, but if you think about the volume of expansion compared to the volume of air going into the engine it is absolutely nothing. The main benefit I can see with silicone hoses is that they don't delaminate, but as I've never suffered problems with the ordinary ones, that is what I've got.

Not sure about the restriction though it does seem like an odd design. Try it and let us know :)

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the metal pipe with the pressed side can be replaced bugger all difference is noted though IMHO

the boost gauge

there is (on a 300TDI) a bolt at the rear of the inlet plenum chamber

this can be removed drilled and tapped the boost gauge connected here

you'll need to restrict the pipe to the gauge though to stop the needle fluttering

I used a small g clamp used on fish tank air supplies

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im guessing its a 200Tdi as i reckonise the thought 'wtf does that get thin there?' i was going to try replacing this bit of pipe with something that didnt get thinner to see if it made a difference but never got round to doing that alone. i have now replaced it, but it was while plumbing in a larger intercooler so i couldnt say how much difference the pipe made if any.

my boost guage is t'd into the pipe between the turbo & actuator. the screw in plug out of the 200tdi manifold, its screwed in the side next to the rocker cover about halfway along & doesnt do anything. this plug is a standard BSP thread so im told. get a converter from a plumbing place & put the guage in there if you want manifold pressure.

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An update.

I have now fitted the boost gauge mounting it under the cigarette lighter and running the pipe through the grommet for the clutch cable in the bulkhead.

I have then run the pipe around the back of the engine to the pipe between turbo and actuator and t'd in there.

I'm very pleased with the result.

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