TrueGS300

I think this is a no brainer, but I noticed while checking things over and the car running up in the air on a lift that the dump tube off of the waste-gate is puffing as if the spring or diaphragm is weak and unable to seal. A waste-gate should be sealed until spring pressure is overcome yes? Just wondering if some bypass and puffing out is normal or if I need to replace the darn thing. I am having several minor fine tuning processes to go through after my rebuild and all the changes. Fuel pressure being one of them. But the car doesn't really want to go into boost. Since I found this, I'm thinking this is probably why and not so much my fuel pressure setting even though minor changes are making a huge difference in the A/F ratio under acceleration. Waste-gate failure somehow.. even though the thing worked fine before the rebuild and just sat there about 6 months.

TrueGS300

Also, if I need to replace the waste-gate, any suggestions on a brand? I'd need a 44mm v-band style. Pretty normal one. Just a good value one, not a cheapo, not most expensive either, just good reputation.

firelizard

iTrader: (1)

Your wastegate is opening at idle? Or under load? It's perfectly possible that your wastegate spring is just too light if it's opening too early.

I don't think I've heard a bad word about Tial wastegates.

TrueGS300

I do have my eyes on a Tial most likely, but they are around $500 . And I mean my current one is open at idle. I can put my hand over the dump tube and feel it and hear it puffing out. And the car barely goes into boost at all while trying to test drive. So I'm pretty sure it's failed. It's just the cheapo CXRacing one that came with the kit. So I'm thinking I need to upgrade the wastegate and BOV before I go in for tuning.

TrueGS300

SummitRacing only sells decent stuff.. Never heard of this brand, but the price is right. https://www.summitracing.com/parts/vsg-vsr44wg wonder if it's any good. One of the reviews says you can replace parts with Tial internals if ever needed.

TrueGS300

I don't want to chance anything anymore. My build has gotten too expensive. So I ordered a Tial MVR 44mm. I want to go to a stiffer spring anyway, and this one is water cooled. Pretty good unit. MAPerformance coming through with best price.

KyleH

iTrader: (1)

My research into wastegates was super cheap or super expensive. Not really anything in between. So I had to go super expensive because I don't want to waste an engine on a faulty wastegate. I think you made the right choice. My only recommendation is to make sure you snug the airports that you aren't using well with the supplied hardware. I was chasing my tail for a minute trying to figure out why I wasn't getting anymore than wastegate spring boost pressure. Overall pleased with my Tials tho.

TrueGS300

Good to hear positive experience, I think Tial is good stuff and I'll feel at ease running their WG. Definitely have a lot invested in my build now and the WG protects it. I'll be careful to snug all fittings good. Not totally sure yet, but I think I'm going to start with the 10lb spring this time and adjust up with an MBC when tuning time comes. I think the 8lb might be a little too weak for my plans now. But I also think a 12 or more might be a bit much while the car isn't tuned for it. I imagine there is only so high you can go for each spring rate and an MBC yes? Like an 8lb spring could probably only achieve say 16lbs max with the MBC maxed out. However I definitely plan to run well over that. Closer to 20's? So maybe I should start with the 12lb spring. Any thoughts on this?

TrueGS300

I guess that is something I should ask as a whole other thread. Because it involves the theory behind it all. But if someone has a good basic understanding of it, please chime in. What is the usual psi increase that can be expected from an MBC on a particular spring rate? That's something I have no experience with.

KyleH

iTrader: (1)

If I remember my research correctly, a rule of thumb is you can run about 2x wastegate spring pressure with a boost controller.

In my real world experience, I used 7lb springs. As I was initially on 440s I wanted to be cautious as I was shaking down all the new turbo parts. Fast forward a month or so and I have dropped in my 1000cc units and have run as high as 17.9 psi with my Haltech controlling boost with the same 7 lb springs. I'm probably getting close to needing to step up, but no problems so far.

TrueGS300

My tuner recommended putting the 10lb spring in. The ones that come with the TiAL's are in bar. So it will be 10.15 apparently. Plus or minus with their given margin. I'm sure it will be sufficient for what I'm planning. I decided to get AEM's electronic boost controller. So should work out well.