did i take too much?

[swankmetal]

this is the second time i've done this and just wanted to bounce it off you folks. i read the porting thread after i did my manifold and therefore have to open this thing waaay up. it gets pretty thin by the bolt holes. been running the other one for a little while with no problems near those spots though. got this one for cheap and then found out the old one has seven visible cracks in the center vane around the fan. anyway, whadya think?

 

[Greenleaf]

The cracks ain't good.



You don't want to nor have to hog it out. This will reduce speed and could cause cracking in the thin areas. Simply cut it out enough to follow the imprint of the gasket line and gently blend it and smooth it in as far as you can. Same is true for the exhaust manifold inlet/outlet ports.



GL

 

[swankmetal]

i didn't go any bigger than the gasket, gl. if that's what you were meaning? but on the porting thread hdm48 said to leave about an 1/8" of material on the outside sides (on the manifold) so that you wouldn't have to take the exhaust housing out so far as to thin it out. i did a whole lot of sculpting of the manifold that i hope didn't slow the gas down. here's a couple looks.

 

[Greenleaf]

I have a question for the *turbo guys* out there.



I have four turbo exhaust housings used for R&D. Two of them are cracked! ? ! ? These two are still in stock form. What gives with the cracking? I ain't that talented to post a pick of a hair-line crack inside a housing. I don't even know the name of the area where the crack(s) are located.



Swank, perhaps we can both get some answeres on this one.



I'd like to know "why" and if I can still run a cracked housing?



Scott

 

[swankmetal]

i'll see if i can get some pics when i'm at the shop today.



my stock (18cm, 350,000+- miles) housing had a couple cracks around the fan when i took it off. and the 12 that i've been running with cracks (but not to my knowledge) came off of a TORCHED 97. by torched, i mean you could stick your finger through the sheet metal. anyway, hope to hear more about this.

 

[swankmetal]

these the cracks your talking about, gl?

 

[Greenleaf]

YES YES YES



Exactly the same thing. What do you think?



Swank old boy. Perhaps our turbos are related? I have a waste gated housing. How do I tell if it's a 12 or 14 cm2?????? It's from a factory stock 97 3500. It has part numbers all over it..... and the cracks

 

[swankmetal]

if it's from a stock turbo, i would think that it's 12. i don't think (but am not positive) that the 14 came on any of our trucks. the arrows would be where you would find the 12 "stamped" in. as far as the cause of cracking, i'm thinking that it's from very cold, very hot, very cold type of operation? that section is a fairly thin piece of metal that doesn't really have anywhere to shed heat to. and i know that in the metal industry, stress relieving is an hourS long process. any other thoughts? by the way, check for cracks around the wastegate port as well. i was changing housing yesterday and noticed cracks around that whole scene. i did enlarge the whole and put it through the center vane too, though.

 

[moparguy]

So, what are you guys seeing in the way of reduced egts with a drilled, ported housing vs non-ported 12 (stocker), and anyone able to compare a ported, wastegated 12 to a non ported, nonwastegated 16?



I've got my stock 12 on the workbench, just gotta buy a few porting tools and start working on it. I'm not displeased with the 16 nwg housing I'm currently running, just thinking I'd be better off with less boost as it's easy to hit mid to high 40s with the nonwaste gated 16.



Thanks, RJR

 

[swankmetal]

i'm no expert, but i think with the gears you've got the 12 doesn't work so well. gets to be a restriction at the top end, or something. i can't give to many details on egt reduction, because i did a lot of changes at the same time (along with the porting, i added more fuel). i know that when i got 'er all back together, i had a lot more power and the temps took longer to max out, but they are still not where i'd like them to be under full load.

 

[JLEONARD]

very cold, very hot, very cold type of operation

AKA thermal cycling.

And the cross section is very thin there... it doesn't surprise me that there are cracks. And don't forget, these turbos were likely designed with "normal" EGTs in mind... . There are a "few" of us guys that run EGTs into the stratosphere..... then back off so it cools down.

That's thermal cycling, probably past the intended design parameters.

Oh well, that's life.



I'll have to take a look at the housing I have that's a spare to see what those cracks would lead to or hurt if anything.

 

[moparguy]

Greenleaf, if it's from a stock 97 Dodge, it's a 12. No 14s came stock.



RJR

 

[Greenleaf]

That's what I have read. Thanks. I just don't see any casting marks like the 21 and 18 housing has. The waste gated housing does have a casting # of 12H6C on it and the #3533139.



I don't have any results yet. I'll be running with three or four different housing next year so will report back on my finding in October.



-S

 

[caleb c.]

I have a 12cm housing that I took off of my hx35. The housing divider was ported about a inch down from the mounting flange. But here's the weird part. If you look in the back side of the housing,(the opposite of where your exhaust hooks up)one of the outlets was welded all the way around. So,only one of the inlets coming from the manifold could pass exhaust through the housing. Anyone ever seen this?I'm guessing it was used on a ricer. I think you wuold have some crazy egt's if used on a cummins. I'm glad I swapped housings cause' I was about to try the 12 and I couldnt tell it was welded.