fatty wrote:If it were me, I'd just leave it how it is. I really doubt there will be much difference. But then, I am a bit lazy on things like that.
Nah. I'm pretty-much anal about the little details. 10 little .1 things adds up to, . . . well, . . . one.
I purposefully didn't go with the likes of the fine Steed-Speed unit as I figure our mess doesn't wind-up enough to warrant the larger runners. In fact, with our lower revving VE fueled mess, with more normal driving, I'd lose some thermal efficiency in that there'd be unnecessary expansion of the exhaust gases in the manifold that could be better utilized in the turbo(s). Keep the heat in the gases.
matthewh wrote:Oh, look at all that puuuurty stainless tubing. Awesome find on the doughnuts, never seen something like that before, usually just deal with 180* bends.
What's your reasoning for wanting 14ga tubing versus standard 16ga stainless exhaust tube? What's your plans for welding it all together?
And an fyi, I still have access to the laser table and brake press here at work, so if you end up needing some one off plate or something made up you can't find lemme know and ill see what I can come up with
My thinking with the SS hot stuff is the fact that SS conducts approximately half that of mild steel. Keep the heat in the gases.
The donuts are to accomplish the sharp turn coming out of the secondary and the WYE feeding the primaries. The typical mandrel-bent tubing sports a larger bend radius than I'd like to use. There's apparently an industry standard that identifies the tube size / bend center-line radius. And I can't remember any of it at the moment (see note below). Any-hoo, the typical mandrel-bent tubing get really thin on the long-side, with really tight bends. The donuts are two plates, stamped, cut out, welded together affairs with uniform wall thickness. They should be handy for a number of off-the-wall angle turns.
(These are NOT the stupid expensive articles readily found on the interwebs).
On that note, it appears most ALL those donuts readily found on the interwebs are from the same maker and they sport 14 gauge construction. Digging much further on the interwebs finds at least one reference to some 16 gauge units available over in Europe. The ones I got are MUCH less expensive compared to that most seen. I got'em off Ebay. I figure, they're either the 16 gauge European units, or blemished units from the expensive fellas. I drilled a small hole in one of them to try and see the size. Ehh. I'll have to measure it when I cut them.
I prefer the heavier 14 gauge for the better long-term strength though the primaries will be independently supported. I'll have a four inch long, 3" SS sleeved/bellow type expansion-joint next to a 3" V-band clamp in the hot-pipe. This should accommodate most longitudinal and torsional loading due to thermal cycling.
It's ironic that the 304SS is subject to intergalactic metallurgical fkcu-ups beginning in the temperature range our EGTs commonly operate in. This same issue is seen in the outermost section of the typical heat-affected-zone of welds in 304SS. It seems the chromium tends to precipitate out and convert into an other element and galactic ionization ensues (see note below). High temperature annealing in a controled environment fixes it.
Shit.
I've got a Miller inverter type TIG welder (and yes, I'll be purging).
I appreciate the offer of shop/machine time. I'll keep it in mind.
I get pleasure in hand-crafting stuff.
NOTES:
1- I'm at the beach.
2- My reference/engineering books are at home (though I do have a copy of Mark's Handbook next to the throne here at the beach. Seriously).
3- Been "Drank'in" a bit.