Making a tube header for the turbo side

[ak diesel driver]

Might put one of those braided flex pipes on in the crossover

 

[Will L.]

#8 is always the classic hot spot anyways. Plus the whole bad cast issue in the 506 blocks where the #8 cylinder was goofed in casting. Where it really showed up was the centermounted turbos with the up pipe trapping extra heat to the head. Combined with the lesser flow from unbalanced water pumps- gm warrantied a ton in hummers and vans.

When your pushing the egts up there the extra 5% heat in the #8 could make the difference.

The patch should do it I think.

 

[n8in8or]

I don't know just typing first thoughts.

I agree the tubes are different temps. Might be the (2) crossover tubes coming from drivers side aren't exactly balanced and one gets a little more flow. Tubes coming from drivers side would also cool faster than number 8 tube I think.


If it happens again.....

Might consider beefing up the standoff and stabilizing the drivers side tubes to it instead of the tube from number 8 or maybe not so close to the cylinder. The way the crack developed in the face of the curve where the gas hits to turn sorta gives me pause to wonder it is seeing the extremist hot spot.

Maybe not. The gases in the drivers tube would have a delay of temp change heating up and be a bit cooler from distance but might delay cooling too. The face of the curve would also see the fastest cooling effect of cooler exhaust coming out of number 8 say on a compression braking event????

Interesting thought on the delay in heating and cooling from driver side to passenger side. The other thing I'm thinking too is that with the mass of weld right there from where I tied the tubes together, that would be a place where heat could collect and not disperse very readily. I bet that helped to fatigue the pipe right there.

I didn't explain it very well in my earlier post (I was rushing to get it all posted while I was grilling), but I did untie the tubes and now the crossover tubes are just supported by the stanchion. But yeah....they are still quite close and that is still going to be a hot spot.

Might put one of those braided flex pipes on in the crossover

Probably not a bad idea. Things are so tight though that I'm not sure how to fit that. I'll save that idea for the center mount someday!

#8 is always the classic hot spot anyways. Plus the whole bad cast issue in the 506 blocks where the #8 cylinder was goofed in casting. Where it really showed up was the centermounted turbos with the up pipe trapping extra heat to the head. Combined with the lesser flow from unbalanced water pumps- gm warrantied a ton in hummers and vans.

When your pushing the egts up there the extra 5% heat in the #8 could make the difference.

The patch should do it I think.

I'm a little concerned about the heavier gauge patch being a place for heat to propogate and do weird things to the rest of the tube, but time will tell. If it happens again I'll do a better job redesigning the problem rather than putting a bandaid on it.

I sure wish I had glanced at the pyro gauge when I was on the highway, that would have been a good number to note to prevent future header damage.

 

[n8in8or]

Well I just got it together and all is well so far. Man installing the turbo to the header on the work bench is sure a time saver!!! Plus I can be sure to get the bolts tight since I'm getting good leverage on them. Things are quieter than they've been for a while.....I wonder if I've had a crack for longer than I thought?

 

[Will L.]

A hairline crack willjust give a tick. And between the wrap and the natural sound of a 6.5, it would be impossible to hear.

Something that hits me now I should have said earlier. peen the welds, heating in an oven up to 450, hold for an hour. Lower to 350 for an hour, 250 an hour, then shut off and let cool in the oven. Really there is a ton of temperature levels and range of drop. The exact temps are better known by a real exhaust guy, but any heat tempering like that will help. So when the wifey starts wanting that new stove in the kitchen, rember you get the old one as another tool. Maybe a little ceramic coating here and there...

Best thing in the world if you get rich and famous is cryogenic treatment. That makes a massive differece in strenght, but if it is just concentrated heat related, that wont help much. It's more for vibration and overall strenght.

 

[n8in8or]

A hairline crack willjust give a tick. And between the wrap and the natural sound of a 6.5, it would be impossible to hear.

Something that hits me now I should have said earlier. peen the welds, heating in an oven up to 450, hold for an hour. Lower to 350 for an hour, 250 an hour, then shut off and let cool in the oven. Really there is a ton of temperature levels and range of drop. The exact temps are better known by a real exhaust guy, but any heat tempering like that will help. So when the wifey starts wanting that new stove in the kitchen, rember you get the old one as another tool. Maybe a little ceramic coating here and there...

Best thing in the world if you get rich and famous is cryogenic treatment. That makes a massive differece in strenght, but if it is just concentrated heat related, that wont help much. It's more for vibration and overall strenght.

That's true, it would have been more of a tick not a rumble. I guess my ears were just out of calibration.

Good thought on the tempering of the welds, I'll keep that in mind for the future. I've often thought how it would be nice to have an oven in the shop for stuff like that and also for powdercoating, prepping for paint, etc....it just seems like a lot of floor space for an occasional tool. Hmmmm, I wonder how hot you can get an Eazy Bake Oven????

 

[Twisted Steel Performance]

Not being mean here.. you will be chasing a crack every time you turn around, just in the nature of the material & way it was welded, kinda thin & miged, both are going against itself...

 

[schiker]

I didn't explain it very well in my earlier post (I was rushing to get it all posted while I was grilling), but I did untie the tubes and now the crossover tubes are just supported by the stanchion. But yeah....they are still quite close and that is still going to be a hot spot.

It looks like the tubes are welding together from underneath view. So if you separated the No. 8 tube from driver side tubes I think that might help. Being the only area that is not wrapped is also allowing faster cooling. I have seen a dulled air chisel or air file used to peen relieve some stress of through hardening heat treated piece of flat tool steel that bowed in heat treating. For peening would an air needler work on a weld?.

 

[n8in8or]

Not being mean here.. you will be chasing a crack every time you turn around, just in the nature of the material & way it was welded, kinda thin & miged, both are going against itself...

I'm not taking your post as mean, Chris. You may be right, I may be chasing cracks for a long time...and if so, there's only one way to find out - keep running it and addressing issues as they pop up. However if I do have issues I don't think it will be from the tube thickness or welding method. I have seen plenty of ptofessional headers that are put together with MIG and with thinner tubing. I used 16 gauge tubing which is thicker than most store-bought headers. The failure I had was a poor design choice by me: I'm sure no header manufacturer puts together headers and ties tubes together like I did.....and now I see why. Also this is the same material and welding method I used for my downpipe adapter over 2 years ago and I haven't had a single problem with that. That's a lot simpler piece though. If/when I have more issues I'll be sure to report back so we can all learn from my experience.

It looks like the tubes are welding together from underneath view. So if you separated the No. 8 tube from driver side tubes I think that might help. Being the only area that is not wrapped is also allowing faster cooling. I have seen a dulled air chisel or air file used to peen relieve some stress of through hardening heat treated piece of flat tool steel that bowed in heat treating. For peening would an air needler work on a weld?.

Yeah I bet that could work. I think sand blasting would work too? The only problem there is that I'd also be removing material thickness which wouldn't be helpful. I wonder too, how many heat cycles from just having the header installed it takes for the stresses in the system to normalize?

 

[Will L.]

That weld area is so small that using a neddle deslacer would work great for peeing it.

As for how many heat cycles to neutralize the stress and trying t bring the yield strenght in line with the modulus, it wont happen from the engine heat. The way that works is an even heat across the entire surface at the same teperature going through the same expansion/ contraction at he same time. Then going through the varied max temp ranges back to back under controlled cooling at levels to stabalize the molecules.

Thats why cryogenics works so well. Super freezing brings all the molecules to such slow movement that the free running ions will travel great distances through the material to even it all out as it disipates it's heat.

A friend of mine that works here a jpl le me come in and watch them do a titanium piece from 1800f all the way down to -325f and cycle it through lesser and lessr ranges. Iirc they did like 7 cycles. Took 2 days to complete. They let me weld some test coupons and do before and after load tests. I knew it worked, but after that now I KNOW it works. 5 times shear strength, over 4 times pull strength. Simply amazing. Any high dollar build I do in the future will get sent off to the chamber. Imo they should build a huge one for the submarine builders.

 

[FellowTraveler]

Here's a good read: http://www.burnsstainless.com/technology-turboheaders.aspx