and came across this;

https://www.rx7club.com/attachment.p...1&d=1298066563

Apparently the wastegate decided to port itself. It did a terrible job.

Obviously this won't fly, and explains my minor boosting problems...

The other side of the housing didn't fare to well either...

https://www.rx7club.com/attachment.p...1&d=1298066563

The gaskets seem okay, but I'll be replacing them anyway...


https://www.rx7club.com/attachment.p...1&d=1298066563


Obviously I need to do something about this. I figured that if the turbos were in this rough of shape, the exhaust manifold must be destroyed.

 

Nope. I was wrong. As far as I can tell, it seems fine. If anyone out there sees any imperfections or has any other opinions, please share them. I'm way in over my head here...

The weird part is, the gaskets look to be in MUCH better shape than the other ones. Almost new. Is this normal?


Also, keep in mind, this car has only 50K miles on it...

 

The cracking is common.
especially on the side that bolts to the manifold, on yours its not to bad at all.
the wastegate Im not sure about though, i actually have mine pulled apart doing the same thing, and there isn't any signs of cracking on the wastegate side.

 

What kind of minor boosting problems did you have? I have seen a few sets of FD twins with cracks in the wastegate area like yours, and after porting, still worked fine. Obviously you don`t want large cracks leaking air around the wastegate hole but yours doesn`t really seem too bad. Most times, the surface that seals with the wastegate flap isn`t very flat after a lot of miles and doesn`t seal very well anyhow. This leads to airleaks but doesn`t do much to hinder rising boost levels.

 

The cracking is acutally a bit worse than it looks in the pictures. The upper one by the flapper is wide enough to see light through, and continues past the flapper and curves to the edge of the housing. The crack is also offset so that one side is about 1/16 of an inch higher than the other. I might be able to grind it down and widen it out enough, but I don't think that will be a very long-term solution.

I'm in the very tough position of deciding whether to try and fix these, replace them with some used ones, go to a single, or jump on the BNR group buy.

I just bought an HKS dp and M2 intake that would be useless with a single, and I plan on aiming for 400ish whp in the next couple of years, so I'm leaning towards taking the plunge with the BNRs.... It's still going to cost me $2200ish for the turbos, gaskets, studs, etc. to get this back in, but I can't really find a single turbo set-up that I'd be happy with for under 3 grand.

 

If you want a reliable 400, the stock twins won't get you there. You know what my vote is

Btw, the manifold to block gaskets tend to stand up to the years pretty well. Good news b/c they list for over $100 *each*

 

Haha. I'm really leaning towards the BNRs. I was planning on going single in the next 2 years, but this might be a better route for a track DD.

A couple of questions for you though...

1) Would these turbos still be good for a core? Besides those cracks, everything else is great and they ran fine.

2) What kind of power can I reasonably expect with the BNRs (sequential) on a stock motor with Power FC, CC3, open exhaust and an M2 intake on 94 octane?

-Devan

 

A suggestion. You might try looking around to see if you can locate a good turbine housing. They are out there after folks have replaced their turbos because the CHRA assemblies started leaking oil & began to smoke. However, if you are thinking of making 400 HP in the future, Goodfella is right on his advice. The stock twins aren`t the way to go.

 

That's definitely another good option. I'll have to look into that. I will be looking for more power, it's just a matter of when...

My plan this year was an intake, IC, exhaust and port the wastegate. I figure if I'm planning on doing the BNRs, I might as well do them now while everything's already ripped apart. I'm not a huge fan of the idea of doing this again...

 

Here's some pics of what I can see from the exhaust port. Should there be that much carbon build-up?

Apex seals look good. granted, I have no idea what I'm talking about...

 

Ideally? no.

 

They're not the ideal core, but they'd work ok. I'd need more pictures of any other cracking that's on the turbine inlets.

I'd think you can get to the upper 300s with that setup. You'd need a ported motor to make more peak power and possibly crack 400 IMO. Keep in mind you can run at that level all the time and reliably.

Btw, that amount of carbon isn't a great sign..... let me guess, the engine has a fair amount of mileage and was owned by a conservative driver at some point in the past?

 

50K miles. I imported it from Japan. It was registered and week-end driven until the day I bought it. It had an Apexi intake, cat-back and Power FC.

That's what worries me. There's no reason for that much carbon.

I'll be installing water injection along with the turbos. Hopefully that will help clean out the carbon and keep it fresh. I really don't like the idea of having all that carbon build-up blasted through my shiny new turbos though...