I am currently running a Tial 44 mm wastegate with a 13 psi spring with the boost controlled with a Greddy Profec B to 16 psi. Lately I have been on a mission to clean up my engine bay and keep everything as simple as possible. I also don’t like how my boost response seems to ramp up very fast to 13 psi then it’s noticeably slower up to 16 psi and even then it fluctuates (boost gauge ‘flutters’).

Since I only run at 16psi right now, I was thinking of just running off the wastegate spring. Did some research and if I combine a “big red” and a “small green” spring I would have a total of 15.95 psi spring pressure.

Would this set-up be safe and provide consistent boost with no other boost control?

Thanks,
Matt

 

You can run just spring but usually you will have to play with it a bit to get desired boost pressure. Putting a 15lb spring wont always net 15lbs. Also you may find it a bit lazier on just spring as well as lower boost levels.

 

the pressure source for the wastegate would also affect boost response. Correct me if I'm wrong, but if you used a manifold pressure source to the side port on the wastegate (as opposed to from the compressor outlet), it would crack open later and probably be more responsive--but you'd increase the risk of overboost.

 

if you run a wastegate spring with a "ball/spring" style manual boost controller (hidden away nicely) it will help with spool a bit.

I ran one on my Skyline and noticed that I hit full boost faster and with less pressure drop when using the ball/spring controller.

Think of it this way... when you run just a spring, say 15PSI the gate dosen't just open at 15psi. It starts creeping air out as you get closer to 15psi. The ball/spring controller helps combat this.

 

Quote:

Originally Posted by Zero R

Also you may find it a bit lazier on just spring as well as lower boost levels.

Sean, can you elaborate on this a bit? Do you mean that if you run only a 15 psi spring, you usually reach less that 15 psi as well as have lower boost response?

Quote:

Originally Posted by arghx

the pressure source for the wastegate would also affect boost response. Correct me if I'm wrong, but if you used a manifold pressure source to the side port on the wastegate (as opposed to from the compressor outlet), it would crack open later and probably be more responsive--but you'd increase the risk of overboost.

I don’t know if it will make too much of a difference, but I will be using the manifold for the pressure source.

Quote:

Originally Posted by aaron_bc

Think of it this way... when you run just a spring, say 15PSI the gate dosen't just open at 15psi. It starts creeping air out as you get closer to 15psi. The ball/spring controller helps combat this.

Interesting; I would have thought the opposite. That the wastegate wouldn’t start to open until 15 psi, and there would be a risk of over boost while the spring compresses to match the manifold pressure.

 

if you run an open, unrecirculated wastegate, you will know EXACTLY when it is opening. And without a boost controller it can be 3-4 psi less than the rated spring pressure. That's how it was on my HKS standard wastegate: 10psi spring, it would crack around 6 or so.

 

If you want 15psi and have the appropriate spring for it your wastegate will be FULLY open at 15psi but will start to open at 10~12psi. Because of this the turbo will act a little "lazy" taking a little longer to climb the last few psi. You will have snappier turbo response with some kind of boost controller in line, because they will keep the wastegate totally closed for as long as possible and then snap it wide open (in theory). Depending on the turbo and driving style it may not be a big deal.

I run spring only, I cannot complain about response. Under 4000rpm im sure there would be noticeable benifit, but up higher in the rev's it snaps to full boost nearly instantly. Where your source your pressure line from shouldnt effect boost response at all, but MAY change the overall boost. Manifold air is cooler and denser and *potentially* lower PSI than air sourced directly off the turbo. Ive always run my wastegate from a boost source off the turbo, it works well so I dont mess with it. So I cant really comment on real differences between the two.

 

also need to worry about boost creep. 15lb spring might hit 17lb and fall off to 15lb. use a controller.

 

I don't agree. If spring pressure is 10psi and crack pressure is 6psi, a pressure source from the compressor outlet will reach 6psi before a pressure source on the manifold. How noticeable of a difference there will be depends.

I vote for an in-line home depot or Hallman manual boost controller. clamp stainless AN hose (or install fittings) for enhanced reliability.

 

How consistent is your boost now when you turn the controller off? Do this and you should see how your car reacts to a 13psi rated spring, actual boost vs rated spring pressure. 16 is pretty close so the effect will be similar.

As others have said you can run a manual controller to get faster spoolup if the wg produces laggy boost response.

 

I run a HKS 50mm with spring only (HKS log manifold and 62-1)

had the original spring at 11psi and was perfect everytime.

Bought an ebay 1bar spring and it's been perfect- I mean perfect (14.5-14.9) everytime (1-2 yrs now).

They will open up earlier. I can hear mine open up as little as 5psi (very slightly though - they are progressive).

I personally perfer the spring over a boost controller.

Takes more work to change boost lvls but worth it imo.

 

I used to run spring only which was around 11 psi on my setup, so yes it can be done.

I now have a profec B II. Boost response is faster with a boost controller because you can keep the wastegate closed longer. Without a boost controller the spring will start compressing and crack open several psi before the actual target boost is reached. This bleeds off the gasses early and turbo spool suffers. Some people prefer this because the power doesn't come on as peaky and abruptly.

If your profec B is not building boost fast enough for you, then turn the start boost (set gain) up until it starts spiking then back it down some. usually about 3 psi before your target boost is good. You will not be able to get it any faster at this point, and removing the boost controller will just slow the response down for the rest of your boost curve (0-13 in your case will be slower).

If the boost is surging (you said the gauge flutters) then you need to back the gain off until it stops. Changing the source for the boost controller and wastegate can help with boost issues too. As far as the gauge fluttering you need to determine if its just the gauge doing it, or if the turbo is actually surging. (you should be able to feel it)

These settings I mentioned are for the spec II. I imagine the profec B and profec B Simple have similar features but IDK. Either way, adding springs is not going to help your problem until you're running boost levels over double the spring pressure.

The only other thing that could help is running a larger wastegate or dual gates, then the gate can be held closed longer and still have enough time to bleed off the boost.

 

Thanks for the replies. Glad a few of you are running (or have run) on spring only...

I ended up just using a Hallman MBC – still having some trouble though. I switched to a 10 lb spring with the Hallman and it worked ok for a week, boosting to 16 psi but with fluttering on the boost gauge at 16 psi (which had me nervous). Today, for no apparent reason, the wastegate isn’t opening at all at all – I didn’t hear it crack at all with no MBC in the loop on a 10 lb spring.

I’m starting to think that my boost control troubles were from a bad diaphragm in the wastegate. When I changed the spring, it looked fine from inspection, but there may have been a small tear in it that I didn’t notice and may have now ripped beyond repair. I’ll pull it tomorrow and see…

Has anybody ever have a Tial WG go bad on them before?

 

Nevermind.. just found the problem. 2 inch tear in my 3 week old vacuum hose (hose techniques). Pressure tested the WG and it works fine.

 

[QUOTE=arghx;9147738]I don't agree. If spring pressure is 10psi and crack pressure is 6psi, a pressure source from the compressor outlet will reach 6psi before a pressure source on the manifold. How noticeable of a difference there will be depends.
[QUOTE]

Thats exactly what i said... the RESPONSE should be identical IE how fast the turbo ramps up but it my only ramp to 12psi instead of 14psi

 

Vacuum hose doesn't hold up to the heat at the wastegate. Better to use braided steel or what i used is copper line. It works really well. I have 3" silicone vacuum hose to connect at the uim nipple.

 

the anarchy of language my friend, the anarchy of language. I see where you're coming from now.