which spring rate for 35mm tial??

[quickersol]

which spring rate should i use? does it even make a difference? the shop i'm ordering it from said it wouldn't make a difference and to just go with the smallest spring (5psi). mods are a t3/t4, 50 trim stage 3 .63ar housing, 750cc injectors, aem ems, etc. i would estimate running anywhere from 22-28 psi with this setup. thanks in advance for any help!!!

 

[quickersol]

^

 

[DSMJim]

basically yeah, just get whatever spring you want. Just make sure the spring is smaller than the minimum boost you want to run. If you get a 10psi spring you won't be able to run 5psi if you want to.

On DSM's its not really an issue because even stock we run pretty high boost already so don't worry about it. Just order whatever. You will likely run 15psi for daily driving and 22-28 with race gas or racing or whatever (something like that) and will always be higher than 5psi regardless so it doesn't really matter.

 

[mclaren55]

Doesn't really matter. I run a 1 bar spring in my 40mm.

Jim - I did that thing you asked me to do for you. You should apply.

 

[larryd]

I disagree that it doesnt matter what spring you choose. On my car I have the o2 dump tube which opens up as soon as the wastegate allows it to. When I had the 0.5 bar (7lbs) spring in the wastegate my dumptube would open up at 7lbs of boost and be like that all the way to whatever boost I was running which was 15-20 at the time which is quite loud and also keep the turbo from spooling as fast as it can due to exhaust pressure.

Someone can correct me if Im wrong on that..

 

[candela]

Regardless of spring pressure... your wastegate should open at your specific setting. It may start to open a bit and get a little louder but as for being fully open how would you have been getting more than .5 bar??

 

[larryd]

all I can tell you is the wastegate would open up at 7lbs and the exhaust would dump through the o2 housing but the car would still build up to 20lbs of boost if thats what I had the boost controller set to. When I put in a heavier spring (1.1 bar) the car is building boost faster since the wastegate doesnt open to 17lbs.

 

[DSMJim]

Internal wastegates work differently than an external wastegate.

Internal gates open earlier and bleed off pressure before your maximum boost and eventually are fully open by the time you hit full boost. This is how they work and why they are bad in high boost situations with nitrous etc... Internal gates all around are OK, just not great.

An external gate on the other hand stays closed until the very second of full boost (or close to) where it opens up enough to bleed off exhaust to keep you at that full boost. This is why external gates are said to help you spool quicker and reach full boost sooner (which is true in the cases we have tested ourselves).

Larry that is why you saw the exhaust leaking sooner because as you stated you saw it comming from your O2 dump which means you were using an internal gate. If you had a Tial external gate it would stay closed until the very point of maximum boost. For atmospheric dumpin an external is nice because your car only gets loud as soon as your at full boost so if you hit the gas a bit and don't hit full boost you will never hear the dump until your right on it.

 

[larryd]

actually no, i have a Tial 40mm external gate mounted onto my victory performance o2 dump tube.

 

[SJC]

So if I'm understanding this correctly, getting a higher psi spring will cause you to lose some flexability (can't put boost below the spring rate you choose) but make your internal wastegate act more like an external (hold more boost until closer to target boost levels)?

Please correct me if this is wrong...almost everything I know about turbos I've learned in the last week from this forum...

SJC

 

[BoostinDSM]

My good ol deltagate opens before I reach full boost. You can hear it slowly open at around where the spring pressure is, then just gets louder until full boost.

 

[DSMJim]

OK, hmm. thats odd Larry whatever your setup is doing is contrary to every external gate I have ever seen. Obviously I'm not doubting you it's just that I have never really had anybody with that external say that before. Does it just open slightly before full boost? or like an internal gate which at 50% boost an internal gate is almost 50% open? (well not really but close enough..)

Your saying that you can hear your dump come on when your not even close to full boost? That is odd. What boost controller are you using, that also can have an effect as to when it opens. It will be different if your using a bleeder style manual vs. an electronic etc etc...

We have used 40mm tial lots of times and they pretty well stay closed until the point of full boost with a Profec-B or EVC4, but even with those boost controllers an internal gate opens sooner.

 

[larryd]

yea im not sure why it was doing that either. I was using my Greddy Profec B at the time. Now I have a Hallman MBC and the 1.1 bar spring.

 

[TSi92]

I have a 1 bar spring on my HKS. you don't need stiff springs unless you're planning to run high boost (20+ psi).

 

[Violater101]

Perhaps I missed this somewhere in the thread, but if your going to a 35mm WG, then you already somewhat cutting down your ability to control low stable boost to begin with ..hence get a larger WG ie 40mm. You also have to take into consideration what type of boost control your going to use. If you use a profec b, you probably want to go with a bigger spring rate since you can only typically run double the boost of the spring. I would just go with a 1 bar spring, but i'm not sure how stable 14.7lbs of boost will your turbo. From what you said, you want to run around 22lbs anyways on a consistant basis, so that should be fine.