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Making a tube header for the turbo side

I don't hate the idea of a 10.5 FF, but converting one to 6 lug is a bit pricy. Wouldn't you know that Yukon gears have dropped in price since I did gears last summer....:mad:
 
n8in8or said:
I don't hate the idea of a 10.5 FF, but converting one to 6 lug is a bit pricy. Wouldn't you know that Yukon gears have dropped in price since I did gears last summer....:mad:
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It would be a lot easier/cheaper to convert the front to 8-lug, just swap out complete steering knuckles, since you're at a parts yard anyway. Disconnect the ABS plug, unbolt the brake hose, pop the upper and lower ball joints, tie rod end and Voila! You now have a set of complete 3500 spindles, backing plate, rotor, caliper brackets and calipers in 8 lug bolt pattern to match your new 10.5" FF 8 lug rear!
 
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If you go that far, go all out, & pull the parts from a GMT800 6.0 gasser truck. You get the modern 2 piston disc brakes/bigger rotors (gotta ream knuckles to fit GMT400 balljoints & a different outer tierod end). You can weld, so welding in new spring perches & overload bumpers at the narrower GTM400 width isn't super difficult.

You'll end up doing gears in rear diff as most all the 6.0 trucks that got the AAM 10.5/14 bolt have 4.10's. I went with AAM gears to get the 3.73 ratio I wanted - the OEM's choose gears that are quiet. Newer rear has a wider track width (~2.5-3") that better matches the 9.25 IFS front track width.
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Huh, when I looked into this last year it sounded impossible to go 8 lug in the front. I even looked at Pirate4x4 because they do all kinds of crazy stuff over there. I would love to have 8 lug front and rear, not only for added strength, but it would just plain look tough! :cool: I may have to look into this further. Thanks for the info.
 
2WD, right? The easy and cheap way is just pull the complete knuckles off of a 2500 diesel or 3500 gasser/diesel and swap them. Of course, I would install new ball joints and tie rod ends while I had it apart, new calipers, hardware and pads, but that's just me. Everything bolts in easy-peasey, no reaming, welding, etc.
 
Husker6.5 said:
2WD, right? The easy and cheap way is just pull the complete knuckles off of a 2500 diesel or 3500 gasser/diesel and swap them. Of course, I would install new ball joints and tie rod ends while I had it apart, new calipers, hardware and pads, but that's just me. Everything bolts in easy-peasey, no reaming, welding, etc.
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Oh, there's the complication, nope my Tahoe is 4WD. I still have a hard time believing it's not doable, but without a roadmap I'm not super passionate about taking the time to try to figure it out.....at least not right now.
 
Header update: So far everything seems to be fine. I can smell the paint curing, so that's a good thing. I feel like I have more boost at a lower throttle position when driving around town, but I don't have any concrete evidence to support that.

This weekend I will retorque the bolts and then I can start doing some validation testing with videos.
 
n8in8or said:
Oh, there's the complication, nope my Tahoe is 4WD. I still have a hard time believing it's not doable, but without a roadmap I'm not super passionate about taking the time to try to figure it out.....at least not right now.
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Which front differential is in your Tahoe? If it's the 9.5", it's still just a complete knuckle swap. If it is the 8.25", let me do a bit of research and get back to you, it is doable, just a question of what needs to be swapped out to do it. GM wasn't stupid, rolling down the assembly line everything was bolt on/in as the vehicle went by. It may be nothing more than a knuckle and CV shaft swap, but I have a feeling it may mean swapping the differential, too. In which case it would mean making sure the front driveshaft front U-joint yoke matches the differential's, ie: a shaft shop cutting off and welding on a new one. Still, pretty much a salvage yard wrenching project.
 
Last week before starting the Moose conversion I did get a chance to make a couple videos to show how it's running after the header installation. I haven't really had a chance to do much before and after comparison, but one thing I did seem to notice was on the 1-2 shift there was about 1 pound LESS of boost than there was before the header. I think this shows that there is less restriction in the system as a whole if you think of the boost as pressure build up due to a restriction to flow. It was 56*F when I did these videos.

0-60 IAT

0-60 Boost & EGT

0-60 Speedometer

Highway Cruise 70 then 80

One thing I will say about the header - by the numbers it didn't seem to make a difference in acceleration with this particular combination. Now if the boost was turned up from here would it? Not sure. I do feel like it makes the system more efficient as a whole and will be a good addition for the Moose with the increased fuel and air flowing through the engine.

As a side note, with the installation of the wastegate controller I did let it run at a higher boost for a few days. Getting on the highway it could get up to 24psi and it felt like it was pulling just as hard from 80-100 as it was from 60-80. Unfortunately I didn't get a chance to do any documentation before going to the Moose so I lost the chance to document that part of the experiment.
 
UPDATE: a few weeks ago my brother was messing around with me on the highway do I laid into....I was concentrating on my surroundings so much that I neglected to look at my gauges. I don't know what the other gauges were doing, but my tach was sitting at 3700 in 4th gear so I backed out of it. When I got off the highway I noticed a tick.....oh great. After a little more driving I determined it was an exhaust leak so that made me feel better. Well over the past couple weeks it's gotten worse. I crawled under the truck and saw soot on the header so I knew I had a crack. Side note: that's a nice thing about having the header painted silver and not black - you can see leaks. I pulled it off today and sure enough it was cracked where I had welded one of the crossover tubes to #8. I guess with extreme heat #8 is moving around a lot more than the crossover and they didn't want to move together. At first I just tried patching #8 but to do it right I had to dissect further than that.
(Excuse the mess on the workbench, I've been doing some remodeling in the barn and not keeping it tidy).

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I made a patch from .120 wall tubing so it would be really robust. I got that in place, welded the crossover tube back in place and then tied them together again. Then I realized I'd probably just have the same problem again but the leak would be in the crossover next time. So I cut them apart and made a new support rod off the flange and tied into a tube weld where the material would be thicker. So now it's all wrapped and painted again and ready to be reinstalled tomorrow. I figured I'd have some trial and error with this design, but it was still a bit disappointing - I wasn't excited about having to remove it just a few months and few thousand miles later. Not a huge deal though I suppose. I did figure out one way to reduce removal and install time: I pulled the turbo and header out as a unit so I don't have to fight with the turbo flange bolts!! Big time saver for sure.

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n8in8or said:
I guess with extreme heat #8 is moving around a lot more than the crossover and they didn't want to move together.
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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.
 
schiker said:
Tubes coming from drivers side would also cool faster than number 8 tube I think.
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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????
 
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