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Title: N75 leaking during pressure test Post by: KasperH on August 17, 2017, 09:41:33 AM I noticed something strange while pressure testing.
N75 was leaking into the TIP. But only if I exceeded 1 bar, everything below that, and it can hold pressure all day. But when I exceed 1 bar it would begin to leak, and leak all the way down until the system was empty. Tried with 3 different N75 valves and all exert the same "failure" :-\ I think it is bleeding more air than the duty cycle is telling me? And would cause unpredictable boost control. Is this a feature of the valve or am I just unlucky and have 3 faulty valves that failed the exact same way? Title: Re: N75 leaking during pressure test Post by: KasperH on August 20, 2017, 05:14:53 AM Can't really find anything useful on this problem.
All I found was some technical documentation from pierburg. Title: Re: N75 leaking during pressure test Post by: nyet on August 20, 2017, 11:12:20 AM N75 should be able to hold just fine. You sure you have it oriented right?
Title: Re: N75 leaking during pressure test Post by: KasperH on August 20, 2017, 12:29:02 PM Yes.
Long leg->TIP Bottom leg->charge pipe Short leg on side->wastegate The N75 operates fine. But maybe this is just a thing it does when static? (As in "spring pressure" in N75 is 1 bar) as it would begin venting when request is higher than spring pressure and/or during spool up. The wastegate would actually never see 1 bar, because it would be vented in the N75. Title: Re: N75 leaking during pressure test Post by: nyet on August 20, 2017, 12:33:05 PM yea. wgs don't need 1 bar to crack. As long as the n75 is holding enough pressure to open the WG when needed it shouldn't matter. Under boost the N75 should be dumping pressure away from the WG anyway.
Title: Re: N75 leaking during pressure test Post by: KasperH on August 20, 2017, 12:54:04 PM So this is just me chasing a solution to a problem I created myself(that really isn't a problem)
Apparently :D Edit: but I can see this could be a potential problem if someone is using a wastegate with 1 bar spring pressure or greater. That could result In some interesting overboost, or boost control issues? Title: Re: N75 leaking during pressure test Post by: nyet on August 20, 2017, 01:09:19 PM So this is just me chasing a solution to a problem I created myself(that really isn't a problem) Apparently :D Edit: but I can see this could be a potential problem if someone is using a wastegate with 1 bar spring pressure or greater. That could result In some interesting overboost, or boost control issues? IMO any waste gate system that needs 1 bar over ambient to crack the wgs is probably going to be uncontrollable. Dual port wgs are generally used if you need a very strong wastegate holding pressure Title: Re: N75 leaking during pressure test Post by: KasperH on August 20, 2017, 01:19:10 PM IMO any waste gate system that needs 1 bar over ambient to crack the wgs is probably going to be uncontrollable. Dual port wgs are generally used if you need a very strong wastegate spring. True, but I have seen people mention running 1 bar springs a couple of times. Maybe they just run it straight to pressure and delete the N75 completely? Title: Re: N75 leaking during pressure test Post by: nyet on August 20, 2017, 01:28:04 PM True, but I have seen people mention running 1 bar springs a couple of times. Maybe they just run it straight to pressure and delete the N75 completely? Dunno. No experience in the matter. [edit]: BTW I corrected an earlier post: dual port wastegates if you need more holding pressure *without* using a stronger spring. Title: Re: N75 leaking during pressure test Post by: nyet on August 20, 2017, 01:32:27 PM BTW did you try pressurizing an n75 all by itself? I would not surprise me if it couldn't hold more than 1bar
Title: Re: N75 leaking during pressure test Post by: KasperH on August 20, 2017, 02:52:43 PM BTW did you try pressurizing an n75 all by itself? I would not surprise me if it couldn't hold more than 1bar Nope, just turned the red silicone hose up and plugged in the pressure tester(PVC pipe end with tire valve) |