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The Great (and stupid) DIY 3" Exhaust Tread

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Old Oct 2, 2020 | 11:50 AM
  #21  
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Originally Posted by x_25
You're gonna have to cut the shelf with that.
Yep...It's been trimmed already, and the area underneath has been "massaged" with a 5-lb sledge. I'm gonna do a test-fit tomorrow to see if more clearance is needed.
Old Oct 3, 2020 | 08:00 PM
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Did a quick visual check of the adapter/DP combo (holding it against the Churbo outlet upside down just to see where it landed). It looks like this adapter is about 1/4" shorter than the 2.5" adapter that's on the car now, and the DP is shallower than what's already there. All told, I'm pretty confident that this will clear the shelf with room to spare.

Crappy picture follows;
Old Oct 7, 2020 | 07:58 AM
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Quick update - I've been sidelined for a few days with a leaking oil fitting on the turbo. The Churbo fitting came with a weird thread pitch (7/16 x 24 - straight), so I'm tapping it out to a more "normal" 1/4-NPT and using a 1/4-NPT to -4 fitting. My challenge has been getting a tap that'll go deep enough into the "blind" hole so that the taper is wide enough at the top to engage enough threads on the new fitting.

Ah, the joys of wonky parts on Chinese turbos! One day, when I grow up, I'll get a 6758 and all my troubles will be gone.
Old Oct 17, 2020 | 07:25 PM
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Are you keeping tabs on expenses? Curious to see what it totals out to...
Old Oct 18, 2020 | 08:38 PM
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This is going to be on hold for a while. I spun a rod bearing this past Thursday, so I'm doing a rebuild right now. I just got down to the crank today and the #1 rod bearing was toast.

Strangely, everything else looks fine. There were big pieces of bearing material on the pump screen, but the oil didn't look silvery at all. I'm getting the block and head hot tanked and I'm on the lookout for a used crankshaft.
Old Nov 5, 2020 | 06:46 AM
  #26  
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For anyone interested...

The block is clean, there are minor scuffs on the #1 wall, but those pass the "fingernail test" so they'll get honed out. The only bearings that were damaged were the rod bearings on #1 & #4 . The cap end on #1 was completely gone and the cap end on #4 was beat into foil. The #1 piston is toast, when the bearing "left the building" there was enough inertial slop for it to lightly kiss the squish area on the head (there are witness marks on the crown of the piston to show the contact). I was considering "refurbishing" it, but I decided to be cautious and order a new one (should be here tomorrow). The only other thing that I'm considering is to swap out the head for one that's been collecting dust in my garage. I might just do that - again, for safety's sake - and do some experimenting on the old head; radical porting, new guides, larger valves, etc...

One other adjustment that I'm making during this rebuild is to use King bearings instead of ACL's. Twice now I've had to rebuild because of a spun bearing and both times I've used ACL Race Bearings. The first time I blamed the failure on poor assembly technique - I didn't check the bearing clearance then. The second time (now) I think it was because I had low oil supply and roasted the bearings. I can't guarantee either cause, but I can say with certainty that I used ACL bearings both times. Maybe it's "Bad Ju-Ju", but I'm changing to King bearings just in case.

Anyway, tonight is "Valve Lapping Night" on the new head and tomorrow is "Piston Balancing Night"!! Re-assembly begins on Saturday.
Old Nov 5, 2020 | 08:30 AM
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FWIW I made an 3" exhaust w/ cutout with my buddy with nothing but amazon pre bent piping and a shitcago welder from HF. Fitment is meh and welds are meh but its totally sealed and works for how cheap it really ended up being. I already had the welder for a couple years to use for random odds and ends just like this. It's definitely hot garbage but it will make metal stick together.

The worst part about a cheap welder is the duty cycle, i could only get maybe halfway around one decent weld(2 minutes?) before it would start to get super choppy.

Old Nov 5, 2020 | 09:17 AM
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What kings did you use, race or street? All race bearings are more tolerant to poor tunes, but less tolerant to. Imperfect bearing surfaces. I haven’t had a set of race bearings survive on a crank that wasn’t ground for .25 over sized bearings. AKA You can almost never slap them on a used surface.
Old Nov 5, 2020 | 12:21 PM
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Originally Posted by curly
What kings did you use, race or street? All race bearings are more tolerant to poor tunes, but less tolerant to. Imperfect bearing surfaces. I haven’t had a set of race bearings survive on a crank that wasn’t ground for .25 over sized bearings. AKA You can almost never slap them on a used surface.
I've been on the same crankshaft since 2003 with std size ACL bearings. I did a rebuild 3 years ago and the bearings looked perfect. New bearings went on and I've got 15k hard miles on it now and it's perfect. The crank is literally the same one I've been using since 2003 when I blew up a b6 motor and went BP. ACL bearings are very very good.
Old Nov 5, 2020 | 01:55 PM
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Originally Posted by irollgen4s
FWIW I made an 3" exhaust w/ cutout with my buddy with nothing but amazon pre bent piping and a shitcago welder from HF. Fitment is meh and welds are meh but its totally sealed and works for how cheap it really ended up being. I already had the welder for a couple years to use for random odds and ends just like this. It's definitely hot garbage but it will make metal stick together.

The worst part about a cheap welder is the duty cycle, i could only get maybe halfway around one decent weld(2 minutes?) before it would start to get super choppy.
When I get to that point, I fear mine will be similar...
Old Nov 5, 2020 | 01:59 PM
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Originally Posted by curly
What kings did you use, race or street? All race bearings are more tolerant to poor tunes, but less tolerant to. Imperfect bearing surfaces. I haven’t had a set of race bearings survive on a crank that wasn’t ground for .25 over sized bearings. AKA You can almost never slap them on a used surface.
The ACL's that I used in the past were "Race". The Kings are "Standard" and the journals mic out within tolerance and are / seem to be "round". I was going to mirror-polish them, but didn't know if that would inhibit the ability to retain an adequate oil boundary layer - I'm open to advice there.
Old Nov 5, 2020 | 02:00 PM
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Originally Posted by andyfloyd
I've been on the same crankshaft since 2003 with std size ACL bearings. I did a rebuild 3 years ago and the bearings looked perfect. New bearings went on and I've got 15k hard miles on it now and it's perfect. The crank is literally the same one I've been using since 2003 when I blew up a b6 motor and went BP. ACL bearings are very very good.
I'm not saying that ACL's are "bad", just that I've had bad luck with ACL Race bearings. Change is good, right?
Old Nov 5, 2020 | 02:02 PM
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Originally Posted by rwyatt365
I'm not saying that ACL's are "bad", just that I've had bad luck with ACL Race bearings. Change is good, right?
No for sure. I was just sharing my experience. By all means King is a quality bearing as well
Old Nov 5, 2020 | 02:19 PM
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While I've got a little bit of attention and totally unrelated to what's been said before...does anyone use a steel gasket between the exhaust manifold and their turbo. And if so, from where? I have a Kraken manifold and a churbo from EMUSA. Initially, I used the el cheapo steel gasket that came with the turbo - predictably, it was junk and soon failed. I did a tiny bit of research and came to the general conclusion that using a gasket was a waste of time, so I've been running without one for about a year. I know that the sealing surface on the turbo is not 100% so I'm planning on having it "machined" (i.e. flat, level steel plate, progressively finer sandpaper on the flange until I achieve reasonable "flatness").

If I do that, will that be good enough without a gasket?
Old Nov 5, 2020 | 02:41 PM
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Originally Posted by rwyatt365
While I've got a little bit of attention and totally unrelated to what's been said before...does anyone use a steel gasket between the exhaust manifold and their turbo. And if so, from where? I have a Kraken manifold and a churbo from EMUSA. Initially, I used the el cheapo steel gasket that came with the turbo - predictably, it was junk and soon failed. I did a tiny bit of research and came to the general conclusion that using a gasket was a waste of time, so I've been running without one for about a year. I know that the sealing surface on the turbo is not 100% so I'm planning on having it "machined" (i.e. flat, level steel plate, progressively finer sandpaper on the flange until I achieve reasonable "flatness").

If I do that, will that be good enough without a gasket?
I run a gasket from ATP turbo and its been good for a long long time, but back in the day I ran no gasket there and was also fine. If you make it flat, once the car heats up the metals expand and there is no leak there. So yea youll be just fine.
Old Nov 5, 2020 | 10:42 PM
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I also used the cheap one that came with the turbo and had it decay away. After that I lapped the mating surfaces flat with wet/dry paper and used Permatex copper spray gasket; it seems to have held up very well.
Old Nov 6, 2020 | 01:50 AM
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Similarly had a cheap one fail. Huge pain... Haven't seen any reports or personally had issues from mating the surfaces so that's the route I'd go to cut down failure points
Old Nov 6, 2020 | 01:55 AM
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I used churbo gasket on taco manifold and had the same problems. So I took it out and coated both flanges in some axle grease and never had an issue.

On my current setup I set it down bare and left it that way, no gasket. It's been fine so far. I don't want more unnecessary **** in that joint causing potential slop than I absolutely have to have.
Old Nov 6, 2020 | 06:29 AM
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I have never used a gasket between manifold and turbo with a dozen different manifold and turbo combinations.
Old Nov 19, 2020 | 02:21 PM
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Engine is mostly back together again - hope to have it in the chassis this weekend. In celebration (and in line with the original intent of this thread) I've ordered some bends from Columbia River. When they get here, I'll pick up where I left off.




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