Sigma Turbo `sternal gate issues?

[mistashitty]

Hey,

I`v had a turbo sigma coupe for a few years now, but I have never been too interested in it.

I got hold of a `81 base spec 2.6 (one owner, new 5speed, new head) and fitted a high flowed sigma turbo kit I got off ebay. Turns out the turbo was stuffed so I re-built it with undersize bearings and new carbon seal, and new water cooled core.

I fitted it all up with a straight through mandrel 3 inch system dumped at the diff.

The car runs great (although a little loud inside) but it has no boost control.
After bench testing the wasgate and repairing a worn diaphram I found that it still was leaking boost signal, After stripping the wastegate further I found that the valve "guide" was very worn ( you can see daylight through it with the valve in place).

I`m pretty sure this is where my boost control problem is (boost signal is lost into the exhaust system).

Without proper boost control I put in the too hard basket and left it for 12 months or so.

I was thinking of selling ms piggy but after reconnecting the battery and firing her up (3 sec. on starter) and taking it for a spin I`m thinking I might give it a bit more attention.

I`v got a few options when it comes to fixing the boost problem.

The first option: is find a NOS (new old stock) wastegate or good second hand unit (As I dont think Garrett have made one of these items in 20 years or so), or

The second option : Is to fit an aftermarket wastegate and modify it to suit the sigma (V-band converter and new wastegate pipe), or

Third option : Rebuild existing wastegate using off the shelf valve guide and machining it to suit.


I decided to go for the third option, The first option Just seems a little far fetched and any decent second hand unit would be almost worth its weight in gold. The second option (although being able to fit a modern, larger unit) would just be too much fart arsing about making flanges and extending the dividing plate, and it would probably not fit under the manifold.

I took the guts of the wastegate to the local machine shop (in Hobart the only shop that ryhmes with oranges) and they seem to think they can press the old "guide" out and fit an off the shelf exhaust "guide" to suit. I think this option to be the best as I don`t think it will cost a lot, and it should all go back in with little fuss.

I`m intending to fit a much weaker spring (3psi or so) so I can bring the boost up with a controler and keep the tune in check.


Is valve guide wear a common problem with these wastegates, and if so how do you get around it?

I`m looking forward to seeing how ms piggy will perform she seems to have very long legs (100kph @2000 in top).



Have to see if we can`t organise some sort of some sort of cruise in Tassie, Down the channel for some "hooning" and a BBQ maybe?


Take it easy,

[Paddles]

ur back online. brett and i tried to organise a cruise in hobart but only me nad him turned up. it would be good to meet up. i got a couple of turbo set up s in action. oranges should be able to help but as for ur diaphram, how did u got about repairing it>>

[karl_2ltgc]

Just buy a aftermarket wastegate an make it fit... best way to fit the problem. Original garret wastegates are quite ordinary compared to any descent brand one available now, just dont go for some cheap shit chinese made thing.