Consider this a public service announcement:
1. I learned the hard way that long iron pipe headers screwed into a flathead can tear out the block's threads. All the rattling.
2. I've experimented with aluminum fittings at the block port to reduce this damage. Followed it with steel flex pipe to keep weight down, too.
3. Posted about it, too. I was going with my gut and figured they'd at least share the same expansion rate. Welp, see the attached chart on why cast iron is #2 only to titanium in terms of stability and I had wrongly considered the different metal expansion rates to be a co-culprit.
4. When I recently treated my stainless steel flex exhaust to a fiberglass wrap, I also came across some advice -- that you shouldn't wrap the first few inches of a header -- to let some heat dissipate because the wrap won't allow for it further along the pipe.
5. My aluminum stubs had been working great on my minis, to date. Always came a little loose, but never came out (like the iron pipe did that one day ...). I even wrapped the aluminum stub with some copper foil I had, not expecting a problem.
6. Took my newly wrapped header out for a ride today and the aluminum fitting had finally seen enough. I believe the design eventually channeled too much heat through that little stub. I felt some stinging on my leg from the slag and looked down to see it just starting to melt and spit molten aluminum from 2 different spots (and likely would have soon melted through had I not shut it down).
Phew. Don't use aluminum.
I'm not in the market for a titanium header just yet, but yeah I'm probably going back to good ol' black pipe here.
And see attached for references.
1. I learned the hard way that long iron pipe headers screwed into a flathead can tear out the block's threads. All the rattling.
2. I've experimented with aluminum fittings at the block port to reduce this damage. Followed it with steel flex pipe to keep weight down, too.
3. Posted about it, too. I was going with my gut and figured they'd at least share the same expansion rate. Welp, see the attached chart on why cast iron is #2 only to titanium in terms of stability and I had wrongly considered the different metal expansion rates to be a co-culprit.
4. When I recently treated my stainless steel flex exhaust to a fiberglass wrap, I also came across some advice -- that you shouldn't wrap the first few inches of a header -- to let some heat dissipate because the wrap won't allow for it further along the pipe.
5. My aluminum stubs had been working great on my minis, to date. Always came a little loose, but never came out (like the iron pipe did that one day ...). I even wrapped the aluminum stub with some copper foil I had, not expecting a problem.
6. Took my newly wrapped header out for a ride today and the aluminum fitting had finally seen enough. I believe the design eventually channeled too much heat through that little stub. I felt some stinging on my leg from the slag and looked down to see it just starting to melt and spit molten aluminum from 2 different spots (and likely would have soon melted through had I not shut it down).
Phew. Don't use aluminum.
I'm not in the market for a titanium header just yet, but yeah I'm probably going back to good ol' black pipe here.
And see attached for references.
Attachments
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