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as according to the genearl gas law, as temperature decreases so to does the volume of the gas (at a given pressure)

therefore, cooler the gas, the lower volume of air through the turbine. hence a less efficeint turbo!!!

Also a long piece of thin pipe like that would lose too much heat would it not and be very inefficient at spinning the turbo... Dont turbo's work off heat as much as gas flow?

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Is that turbo also mounted to the block? If not i doubt that pipe would hold it up for long... WARDAT's J-pipe setup goes down under the engine mount and bolts to the hreaded holes in the front of the block for support, its not particularly thick steel but its not going to break.

A T28 on a 1.5 litre engine should be spinning at idle.

I had a giant T04 on an FJ20 which had a huge turbine wheel and was bush bearing and it still span at idle.

If you have a think about it, there is still a noticable amount of gas passing out your exhaust even at idle and the shaft of your turbo is suppose to be free spinning. I'd say your T28 was stuffed.

Sundat.... U da man thanks 4 the link on J pipe!!!! Now must extract digit{s} and build it.. I was going in another direction but it was such a fabricated tangle it was driving me crazy. Must remember K.I.S.S-- KEEP IT SIMPLE STOOPID. LOL

Can the J pipe be made from regular exhaust tubing or does it have to be more robust? I have some 1 3/4 inch aluminized mandrel bends laying around that I'd like to put to use.

Did you search for a j-pipe picture? Here's a good thread with more info on making a j-pipe.
http://datsun1200.com/modules/newbb/v ... ic_id=10219&forum=1#34954

Can I see a pic of a J Pipe on an A series please???

You sure on that i had a t28 on a 1.5L et turbo that boosted to 19psi, 130fwkw, wasnt smokey and that too didnt spin over at idle, maybe its a bit to do with bush or roller bearings as well. Beware the 2nd hand turbos, i wont ever buy another unless ive seen it running fine. Bought way to many fukt ones of the net and importers, they can look fine, have minimal shaft play but still smokey because of the seals. The turbo on the 180b i had used to smoke a bit untill it warmed up then it was ok, still used to spit a bit of oil through the cooler. We cheated and put a tiny as restrictor in the line to stop it, cant be good though. My exa turbo used to smoke massivelly when the exhaust wasnt on from the dump pipe to exhaust, must have been the back pressure helping or something.