Well, I just purchased the car recently from a friend who owned it for a year. Car ran great was very fun to drive. Car is a Jspec TII swapped into an 85 gsl-se.

Link to pictures when I bought it
https://www.rx7club.com/1st-generation-specific-1979-1985-18/my-85-gsl-se-tii-swap-957421/

Over this summer it started to get louder and smelt really bad so I figured I had an exhaust leak. I started to track down the leak at the turbo and found that the housing to the turbine was tapped for a short runner to the external WG. The crack is at the junction of the turbine and the runner. turbo is a hybrid s4 with an tial WG

You can see the crack near the weld[URL=http://imageshack.us/photo/my-images/42/img1180ph.jpg/]
close up of the crack


full system
[URL=http://imageshack.us/photo/my-images/815/img1183ac.jpg/]

This setup seems a little "thrown together" looking at the welds and how it was done. Im not sure why the previous owner decided to tap into the actual housing instead of welding on a flange somewhere. The setup worked great and originally dynod around 350whp, i had it detuned to 299whp and meth injection added for reliability at the track.

dyno plot from the tune and meth
[URL=http://imageshack.us/photo/my-images/827/img1199g.jpg/]

Im not too upset, but it sucks that the car is down. Im currently researching a new S5 hybrid setup that will get a stage 2 BNR treatment. I intend to dump the external WG. Thats the plan as of now.

 

any configuration that involves welding aluminized piping to 25 year old cast iron probably isn't going to last.

 

^this, its hard to weld cast iron, and one that has been heated and cooled god knows how many times and its embedded with soot and carbon will never weld correctly, the only way to fix that and do it properly is recast it.

 

yeah, i knew this wasnt the a good idea, im just surprised that the guy who originally built it used that short cut. the car had a ton of money dumped into it, he must have run out of cash.

now my debate is to go bnr stage 2 S5 turbo or upgrade to something like a T04. decisions, decisions.

 

You would think that welding carbonized cast iron and mild steel ,flex couplings on the downpipe and wastegate tube would have been high on the priority list,even running out of cash.

 

Interesting that the crack developed on the steel side, rather than the weld cracking away from the cast iron...

 

^Yea i think a flex pipe would have prevented this. I would run open dump and have it rewelded if your tight on cash.

 

I am flirting with this idea as a bandaid fix so the car can run for the rest of the season, but Im pretty set on upgrading. From everything ive read, this is not the way to go. how loud is an open dump? any boost creep issues?

 

bump for any help.

whom should i talk to? im in Ohio.

How would I go about this with keeping an S4 or S5 turbo? Im pretty sure I want to swap on a new hotside and get some kind of custom exhaust work done.

Can an external wastgate be used with an s4/s5 turbo and manifold? or would I have to get a custom manifold built?

Where could I get a new hotside?

 

If your setup wasn't creeping before, it won't creep with an open dump. With the open dump, there is zero backpressure impeding the flow of wastegate gasses.

I would consider fixing the weld, and putting a flex coupler on the wastegate pipe for better reliability. You already have a nice setup that is getting you solid performance numbers reliably (except this crack).

Or you can go open dump. In that case, I'd patch the existing downpipe instead of replacing it.

Or you could return to an internal wastegate. You would need a turbo that has an intact internal wastegate, which means buying one from rx7club or ebay, and then having it modded by BNR or similar since the stock hotside will need work to support your boost level. Then there is a chance you will have boost creep after all this.

You can either max out the stock turbo setup (like you have), or you go full aftermarket manifold with an aftermarket T3 or T4 frame turbo, new exhaust work, and new intake work.

In conclusion, I'd choose to fix the current setup. If you have reservations about the current setup and some money, then upgrade to a full aftermarket manifold and turbo.

 

That setup looks very efficient, and Ideal for the hybrid turbo.

Bring it to a Very qualified welder, have them grind it down , and reweld another thicker piece of piping.

 

thanks, for the advice!

I think i want to leave this setup alone. it worked well and was very fun to drive. I really think anything more and it would need a more capable chassis.

Ill have to find someone in my area (cleveland) who can tackle this.

does anyone know where i can find hotsides? in case this one isnt salvagable.

 

Im in Elyria, 15ish min from cleveland. Can do or get you anything you want done.

 

I recieved the turbo today.Wow, talk about gggghheettoo. I think the the holse that are drilled for the external wastegate is smaller than the factory internally gated hole. Getting new Exhaust housing and putting the wastegate on the manifold like it should be. There should be no flex pipe in this system. The issue is a mis-aligned wastegate. you have to bolt everything "sorta" together all at once. You can tell in the picture, if you bolted the DP down how much stress it would put on the wastegate setup. The "weak link" with all the tension on it was the pipe welded to the manifold. The reason it was weak link A. It was a hobjob weld job B. someone grinded the weld down and the area was paper thin.