clayne

2150$.. forget that!

dgeesaman... Do you know if the cracks are actually contributing to any loss of performance? Because in this case - what you don't know is for the better...

ruos

iTrader: (1)

Funny you say that, because Pettit employed that same treatment to their turbos.
I bought a brand new set, and had them do the hybrid hiflow treatment on them a while back.

F0RSAKEN

I think Swain Tech's Ceramic coating would help alot in keeping the turbo manifolds from cracking. Most recent European Car mag had a small section on their take on the coating, and their test of its durability. They took 2 Wiesco forged pistons and some thrmo-couples and tested to see what temp/how long exposed it would take for the pistons to experience thermal breakdown.

The non-coated piston went like 6 minutes under 2050 degree flame before it started to break down. The coated piston, after 6 minutes only had some slight discoloration. It took a full 20 minutes of 4k degree flame before it broke down.

But I guess the turbo manifolds are a slighly different case, what with thermal expansion being the culprit. No matter what you coat it with, it still gets hot, and cools down.

poss

iTrader: (5)

I have read on here as well as other sources that the low nickel content in the stock manifold makes it more prone to cracking. Not really a fix for that unless Mazda( or hitachi) decides to change their manufacturing process.
As Jimlab eluded to, a radius on the sharp edges makes sense.

salamander

Do the '99 spec turbos have the same problems?

SomeGuy_sg

Mm....thermal FEA analysis ? If you don't mind , whats that about ?

bajaman

Wow! After seeing rynberg's manifold at 85K I am downright GIDDY with how mine look after 93K! (see my "looky at the broken pieces" thread)

bajaman

I am assuming he means Failure Effect Analysis (?) We do Failure Mode Effect Analysis on some of our processes at the place I work at....similar thing. You basically say, "What is the worst that can happen, and what do we do to prevent that FROM happening?"

rynberg

Gee, thanks!

Geez, there's more than one meaning for FEA -- it also stands for finite element analysis.

dgeesaman

iTrader: (7)

Yes, thermal finite element analysis. This answer might be more than you care for, but here's the scoop for the techheads:

Engineers have equations to calculate stress, heat conduction, fluid flow, deflection (bending), etc using really basic shapes. Shapes like rectangles, round bars, etc. If you want to apply these equations to complicated shapes like a manifold, the results are really crude. So somebody with a computer figured out how to take fancy shapes and model them as a huge mesh of simply-shaped elements (like pyramids, boxes, triangles, or rectangles) that fit tightly together and, as a group of elements all tied together, do a very good job of behaving like the actual complex structure. The smaller and more numerous your elements are, the more closely it will approximate reality.

So if you see for example a computer illustration of a car part that is all faceted and multicolored, you're probably looking at a finite element analysis result. The colors are set up just like radar: red is usually the highest stress, and blue is zero. Or in the case of a thermal analysis, temperature.

There are some examples in this Ansys brochure:
http://www.ansys.com/assets/brochure...ilities-90.pdf

In this case, I will attempt to first model the shape accurately, then maybe do an analysis where the housing is kept at say, 250F near the water and oil passages, and subjected to exhaust gas temperatures at the center of the housing. Because metal expands when it's heated, a part that has varying temperatures will have some stress built up in the areas in between the cold and hot spot. So an analysis should show that stress is high in the areas where the manifold commonly cracks. I'll post the results when (if) I get done with them - I'm not enough of an expert in the subject to guarantee it will be accurate or useful.

Dave