Quote:
Originally Posted by Ranatsu
But what about all of the header designs on subaru's without flex joints, they always crack at the flanges.. Borla, gt spec, perrin, all of them seem to do it. The only exhaust manifolds I have not seen crack, are the ones with the flex joints.
Its honestly the only reason I never switched from the factory manifolds on my STi.
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That is due to extremely exhaust gas temperatures on forced induction engines and the fact that many of those companies do not run thick wall pipe (Sched 10/Sched 40) on their designs iirc. Perrin uses 16ga .065 wall tubing. Our header on this car is the same 16ga, but the difference thermally between an N/A header and a turbo header means less impact from coefficient of thermal expansion of the T304 stainless.
Our header for the STi is Sched 10, no flexes and hasn't had an issue. Sched 10 is .109 wall. Not light, but insanely strong:
[IMG][/IMG]
[ame="http://www.youtube.com/watch?v=ZjzZzORfvPU"]Suby STi EL Manifold Collector Fun - YouTube[/ame]
Hanzo, if you heard the back story as to why we call ourselves Nameless you might have some further appreciation of our company. We call ourselves Nameless Performance for two reasons: One, we heavily involve our customers in our development process and didn't feel right putting our own names on our company when we have multiple engineers, designers, manufacturing experts and enthusiasts as customers who heavily influence the direction we take our product line. Two, it's a sardonic tongue in cheek jab at the flood of emerging market 'no-name' products the flood the market. We're the exact opposite of that. And over one thousand exhaust customers in the last year have taken us seriously and been extremely pleased with the results. We have an excellent reputation in the Subaru community. Feel free to search details of our company over on NASIOC for a full history of our growth as a company.
arghx7, I like how you think. Optional is the best way to go. Configurability is our middle name. I'm going to keep our software under our hat unfortunately, but it's a readily available header design software. It does NOT take into account cam phasing and variable cam timing, but it does take into account typical 4 valve per cylinder scavenging based on a lot of data we pump into it that we discussed earlier. Also as discussed earlier, changing a few of these variables like camshaft duration still puts us in a round up or round down to the two tubing diameters we are using on these test units, so it's not terribly critical in the overall scheme of things - also, that is why we are testing multiple designs on the dyno. The software is going to get us on the green but the dyno will let us putt to the cup, so to speak.
Tainen, we were hoping to have time to test fit the GroupN STi motor mounts on your car but I don't think that is going to happen this time around. As for the impact on the header, that's not the real issue in needing flex couplings, the concern is rather, that the thermal expansion of the tubing will result in each side fighting one another (expansion and contraction) and impact the welds. One note, we do have slotted holes on these flanges to prevent any stress from impacting the studs. I've certainly seen that on turbo manifolds with non stepped or non slotted hole designs.
We will be thermally monitoring surface temperatures of the header on the dyno for a number of reasons (heat shield requirements as well as calculating actual thermal expansion distances/stresses).
J