Mustang and Ford Performance Forums banner
1 - 20 of 24 Posts

·
Moving on up...
Joined
·
4,776 Posts
Discussion Starter · #1 ·
Do WG springs affect boost controllers? I'm asking opinions from the turbo army because I want to see what you guys think. Conversation time:

Say you have a turbo car (single, twin, etc.) with an electronic BC. In said combination you have 10 psi wastegate springs installed. You have your BC set for 17 psi. You notice that once passed 10 psi, your boost whips right to 17 psi and holds steady. In the back of your mind you think, well that makes sense that they come on hard at 10 psi because that's when your wastegates are wanting to open and the BC keeps them shut and ramps up the turbos to your desired boost level. Now what if you changed your spring to say...3 psi springs. Would your turbo's spool faster with the lower springs because the BC can take charge of the spooling sooner? Simply stated, would the opening of the WG sooner allow the controller to spool the turbo faster?:dunno2:
 

·
Registered
Joined
·
6,795 Posts
I don't think your wastegate spring pressure would have too much to do with the spooling characteristics of the turbo(s). That would be a factor of the turbo(s) themselves. All the boost controller is doing is keeping the wastegate completely closed until the desired boost level is reached. So whether the spring is 3 or 10 pounds, reaching 17 pounds and how the boost responds on it's way there as set by the controller, wouldn't matter. When the gate is closed, it's closed.

The only way I could see the spring being a factor would be at a high boost level if the controller couldn't maintain the desired pressure. Then a stronger spring would be needed. If the spring is too light, and you try to run high boost, the gate may open slightly, and bleed pressure.
 

·
Registered
Joined
·
4,454 Posts
All the boost controller really does is fool the gate. Just like Tony said, it holds the gate closed until it reaches its desired level then opens it.

If you put a 3# spring in there and tried to make 20#s, it probably would be very difficult. Usually an electronic controller will go twice whatever the spring in the gate is.
 

·
Registered
Joined
·
261 Posts
my EBC will only do exactly what Juiced said, twice the spring rate. But my EBC also has some features that aid in spool time and how fast the wastegate opens.
 

·
Registered
Joined
·
6,795 Posts
I have 8 pound gate springs, and have run 28 pounds without issue. Eboost2 EBC.
 

·
Moving on up...
Joined
·
4,776 Posts
Discussion Starter · #6 ·
I have 8 pound gate springs, and have run 28 pounds without issue. Eboost2 EBC.
Do your turbo's seem to take off at 8 psi? In my mind, it shouldn't matter how low of a spring you have. If your BC is going to assist the spring stay closed with boost pressure on the top side...even a 3 pound spring should function fine to whatever psi. I keep thinking that the sooner your wastegate wants to open, the sooner your BC can take over and control the spool from there.
 

·
Registered
Joined
·
6,795 Posts
Do your turbo's seem to take off at 8 psi? In my mind, it shouldn't matter how low of a spring you have. If your BC is going to assist the spring stay closed with boost pressure on the top side...even a 3 pound spring should function fine to whatever psi. I keep thinking that the sooner your wastegate wants to open, the sooner your BC can take over and control the spool from there.
Their "take off" point is an RPM, not a boost level.

Somewhere between 3900-4200 RPM it is an on/off switch.
 

·
Moving on up...
Joined
·
4,776 Posts
Discussion Starter · #8 ·
That is a good point. Spool time is more a product of volume going through the hot side housing than the volume coming out of compressor side.

But with that being said, any BC that can adjust "ramp rate" or "gain" (the terms for how quickly/aggressively your turbo's spool to desired boost once spinning) should be able to control that gain once the wastegate spring wants to open. The reason I'm bringing this all up is because I noticed in my car, as well as one other turbo car, at the psi of my WG springs (my case 11.5 psi, theirs 9 psi) that's when the turbo's seem to "snap" to (again in my case) 18 psi. (in his case 15). It kind of seems like too strange of a coincidence that this is happening. I thought about it and it kind of makes sense that when the WG wants to open the BC over-rides it. So technically, if you put say a 3 pound spring in...shouldn't it snap to 18 psi from 3 psi instead of 11.5 because of the BC's "rate" or "gain" settings?
 

·
Registered
Joined
·
1,272 Posts
If you put a 3 lb spring in there regardless of the boost controller, the exhaust pressure alone will open the gate! Your turbos will work harder to achieve whatever boost level you have the controller set to. You should reach your set boost pressure faster with a heavier spring.
 

·
Moving on up...
Joined
·
4,776 Posts
Discussion Starter · #11 ·
It is an interesting idea, why don't you swap in the 3lbs spring and see what happens, let us know!!
Going to do it when I get back from the sandbox...(3.5 lb spring is the smallest they make)

If you put a 3 lb spring in there regardless of the boost controller, the exhaust pressure alone will open the gate! Your turbos will work harder to achieve whatever boost level you have the controller set to. You should reach your set boost pressure faster with a heavier spring.
A spring is augmented by boost pressure; so regardless if it a 2 lb or 20 lb spring if you're running a controller boost pressure will assist the spring open and close. I guess I don't quite follow your logic:dumb:, could you explain
 

·
Registered
Joined
·
4,454 Posts
You have to remember the boost controller is just tricking the gate as to what pressure it is seeing to achieve X amount of boost. With a 3# spring in there it will be harder for for the controller to accurately control boost w/o that spring opening. Running higher boost can be a problem if you are running a 3# spring. Twin57cobra is right, you would want a heavier spring in there to ensure that the gate is staying fully closed and not opening with exhaust pressure.
 

·
Registered
Joined
·
1,272 Posts
Just like Juiced46 said...the boost controller bleeds off boost through the vacuum line to "trick" the wastegate into thinking its not under boost. But exhaust pressure alone can open the wastegate valve if the spring is too light. I think I just explained it the same way juiced did!...LOL
 

·
Registered
Joined
·
1,272 Posts
......thats why people use C02 to keep the gate shut! Sometimes even running a heavy spring, the gate can open. You can shim the spring to add pressure also!
 

·
Moving on up...
Joined
·
4,776 Posts
Discussion Starter · #15 ·
I understand what you guys are saying. BUT, if that was true, then a BC is always struggling to keep the gate closed no matter what spring you run. 18 psi is 18 psi, so when your BC is "tricking" the gate into staying closed, with that same logic, it would still be struggling with a 10 or 15 pound spring too. 18 psi > 10 psi

PLUS + If you ran say a 20 pound spring and you wanted exactly 20 psi and you ran a boost controller, it (BC) would be useless because it wont be controlling the gate at all. A spring does nothing more than augment a BC. It's job when running a BC is to keep the gate closed long enough for any boost pressure to build, once it does, the BC takes over. I can see a problem with running like a 1/2 pound spring (which doesn't exist) keeping the gate shut. But when your boost is building, your BC will always have boost pressure + spring pressure to keep the gate closed. Boost pressure + sping pressure > exhaust pressure.
 

·
Registered
Joined
·
1,272 Posts
I dont understand what you mean...boost pressure+spring pressure=exhaust pressure? Anyways, if you were to run a 20lb spring and only wanted to run 20psi like you said, you wouldn't need a boost controller! Some people just run off the spring. Bottom line, you can try putting a 3 lb spring in but believe me the gate will open with just the exhaust pressure alone before you hit max boost....and even if you think it isn't...believe me, it is.
 

·
Registered
Joined
·
4,454 Posts
I will guarantee that if you put a 3psi spring in there and try to have the controller run 20+ PSI just like Twin57cobra said, the spring will open from the backpressure and you may have other issues with spiking, creeping, and inconsistent boost pressures. The more boost you are going to run the higher # spring you want to run in there then have the controller compensate for more. You want the most spring pressure possible when running higher boost.

If you want to run 9#s then put a 9# spring in there run it off the gate with no controller and call it a day. .

CO2 is used for this as well. Ever hear of an AMS 1000?
 

·
Registered
Joined
·
261 Posts
Again, my instructions outlined this during the install and setting of my greddy profec b spec 2. The controller will only make twice what the spring is. I have a 9lb spring in there now and can only run about 19lbs.
 

·
Moving on up...
Joined
·
4,776 Posts
Discussion Starter · #19 ·
Again, my instructions outlined this during the install and setting of my greddy profec b spec 2. The controller will only make twice what the spring is. I have a 9lb spring in there now and can only run about 19lbs.
I run the same controller. So whe I put a 3.5 pound spring in, you're saying I won't see more than 7 psi, even if the controller is set to 100%? I definitely want to see if that's true.
 
1 - 20 of 24 Posts
Top