Does running an open wastegate cause more boost spikes?

i was under the impression that my wg spring was at 10 psi but i saw today that it was holding over 10psi.. i even saw it touch 15 psi on the gauge for about 2.5 seconds... i was stunned so i let off the gas cuz i got kinda worried.. i dont plan on leaving the wastegate open for much longer. just been tryin to get a better piping setup installed first, then my dump tube will get made.

 

bumpity bump bump

 

It's an External Wastegate, right? Any controller on it? You have it open 24/7, I assume - so it isn't technically operable?

 

i just dont have a dump tube on it. i dont think its always open, unless not having a dump tube causes that.

my boost controller isnt installed yet. ill be doing it in a week or so.

 

Okay, duh. Now I see what you are saying. For some reason that didn't click. I wasn't exactly sure what you meant at first for some reason.

And I have no idea if that effects it. I wouldn't think so... but I dunno for sure. What brand WG is it?

 

Sounds like wastegate is failing to open fully fast enough or is straight to small for turbo. I would go with a 40mm.

 

What he said... that's why I am curious as to what brand it is.

big turbo/low boost = bigger wastegate
big turbo/high boost = smaller wastegate
small turbo/high boost = smaller wastegate
small turbo/low boost = bigger wastegate

 

I don't really agree with that list.

 

You don't have to. The essentials are there. To run a 60 trim on 10psi, you're gonna have to dump more than a 60 trim on 20psi.

Its just more of a guideline, than the bible. I have had a few friends run into problems like the above because they are trying to run a BIG turbo on a small amount of boost, and a 38mm WG just won't cut it.

 

did it creep to 15 or did it spike to 15, they are different, if it creeped, than its the wasdtegate not dumping enough of the exhaust to slow the turbine down, if it spiked, than its prob lag in the wastegate from it not opening fast enough, or it not venting enough exhaust when it first opens, does it hold 15psi? or does it hit 15 than go down to 10?

 

i have a tial 38 mm.. and a t3 t4 50 trim garrett.


basically whats happening is when it hits full boost im at 10 psi and then the needle bounces between 10 and 15 till i hit the top of the gear.. but it never goes past 15 or holds. i was testing it tonight to figure it out.. unfortunately something popped lol.. idk wtf is up but im takin it in tomorrow anyway so ill see wuts up.

 

Running an open dump does not negatively effect the ability of a wastegate to regulate boost. In fact an open dump acts like running a larger exhaust and can help your wastegate if it was restricted.

Most 38MM are direct bolt on replacements for each other. I would try to get another and swap it out and see if the problem continues.

 

lol discovered the problem more install fail basically. my wastegate wasn't even installed.. installed the sucker and no more issues..

basically i was running unlimited boost. i ran it last night and it went up to 17 psi wtf.... i let off immediately. though

 

Lol!!

 

let me rephrase that. my wastegate was installed on the turbo mani. just wasnt connected to any lines.

 

well open wastegate will control boost better. Less restriction of flow. But that same waste gate I ran a garrett gt35r and never had problems. Alot of it boils down to how well your manifold is designed to dump the excess exhaust gasses. That wastegate should start opening before 10 psi. You can put a vacuum pressure sensor on the top and monitor wastegate opening if you really wanted to. Thats what alot of turbo race cars do.

 

I have a tial 38mm with my t3/t4 50 trim, the gate is recirculated back into my exhaust and my boost holds EXACTLY where my spring pressure is, i ran a 7lb spring for a while, now i'm running a 9lb and it's dead on...

Vacuum line on it should help, lol...

 

mine's gonna have a seperate dump but i think its a 9lb spring as well... it seems to be doing fine now.