Turbo Downpipe Options?

[par]

Looking for any advice & guidance on options regarding the turbo downpipe. The reason I am asking is I noticed the exhaust front pipe was cracked so removed it along with the cast iron section from the turbo:-



Original plan was just to get it welded up or replaced with standard but decided to do some checking on here for other options. I read most of the 20 pages on the Piper thread and probably ended up more confused than before. I like the idea of replacing all that cast iron but it seems a few people have experienced overboost after fitting the Piper downpipe which may or may not be attributable to the downpipe as there are other factors in the mix.

For the record my set up at the moment is a 91 SE (so no cat), Paul Matty stainless exhaust (2.5 I think), standard ECU, standard wastegate but going to get it ported now as I have easy access to remove it. A PCE has also been mentioned as an option.

My biggest concern around the Piper downpipe route is the possibility of inducing overboost, I have only experienced it once and that was enough. I have picked up comments on here from a few members saying they have suffered from overboost after fitting however it has usually been done at the same time as other changes. It is difficult to quantify if there are many satisfied owners who have fitted and had no issues - it is a bit like reading TripAdviser and only hearing about the bad experiences. A PCE has also been suggested as an improvement.

Options as far as I can see are:-
1 - Standard
2 - Piper downpipe
3 - Piper PCE
4 - Something else??

Thanks in advance of any replies.

[Simon_P]

Hi Par,

You don't say what you are trying to achieve.

If it is just a repair, then repair it.
Or if you seek more power, or just don't like the cast iron bits...

Over boost / creep is caused by the turbo producing too much pressure due to the free flowing exhaust, and not being able to get rid of it because the waste gate is too small.

So I think your question is, does porting the waste gate cure this when a different (xyz scenario) is fitted?

I can't answer that as I have 2 cats to restrict the flow so don't have a problem. I do have a Piper system, which I am very satisfied with.

Make sure you know which bits are available before you start, and be aware that some of the nuts are designed not to undo.

[par]

Hi Simon,

Good point about what I wish to achieve.

This part wasnt on my radar to do at all during this phase of rebuilding however discovering the fracture means I have to do something. Original thoughts were just to weld it up but now that it has been removed along with the cast section and having such good access at the moment I started thinking what else should I do or is available to either improve/future proof - typical project creep! Porting the wastgate seems a no-brainer but the Piper downpipe seems like it may be an expensive way of potentially introducing issues.

Just canvassing for opinions and options as I would hate to finish the rebuild and replace the clamshell, bumper & bonnet and a few months down the line think - why did I not do such & such at the time.

[Enright]

Porting the wastegate while the casting is off is indeed a no-brainer.
Once done you shouldn't have any problems with whatever you decide to fit - the problem is the restriction that you're about to remove (by doing the porting).
The cast part may be ugly, heavy, and a massive heat-sink, but it does it's job fairly well. The only problems I can think of related to it are snapped heatshield fasteners, and the very occasional problem where the honeycomb moves out of alignment and plugs the exhaust - not an issue with SE's anyway.
As for the downpipe, I have a good used one you can make me an offer on, if you want to do away with that tired-looking thing!