Suby Club

That's a good question Josh, i'd also be interested to find out. I wonder how much you can adjust the ECV without accounting for that change with ECV duty cycle and adjusting the timing of the changeover. If that makes sense?

You would think that if it's right on the verge of opening, just a little bit of vacuum may open it too far too quickly which will result in a rapid loss of exhaust pressure.

I just need to get your mods right in my head.
What are you using for boost control? factory re-tune?, MBC? or just stock programming?
what dump pipes/ intake are you running?

Sorry for not mentioning the boost control
Doing any mods to the intake/ exhaust or boost system really needs to have independent boost control of some sort, OR retune the factory system.
without it you're asking for trouble.

But we've done the mod to stock Gen3's before and had no issues

20PSI is a lot of boost to run on these high comp motors, and is far out of the efficiency range of these turbo's
you're really just making hot air.

What the mod is trying to do is this:
Allowing the ECV to open by itself simply due to the force of the exhaust gasses.
It needs to happen at a point that the primary can easily maintain the target boost level. 
So you can end up with the ECV partially open, while still on the primary.
this has the effect of getting the pre-spool happening, but using the ECV and secondary turbo's exhaust to bleed the extra exhaust gas, and not relying on the primary wastegate
(This actually has an effect or increasing engine VE by increasing exhaust flow, so you lower pumping losses from exhaust restriction)

Now, porting the ECV will help get more exhaust gasses through the secondary, preventing you from over-driving the primary.  
In NZ there have been a lot of primary turbo explosions over the years by using overly big dump pipes on the primary, Again, the exhaust gas will go through the primary with a big dump more easily than it wants to go through the 20c sized hole in the ECV, so when the secondary comes on and boost drops, the ECU lets off the boost control and it all goes through the primary, over-spinning it and the bearings just explode, front wheel ends up in your intercooler, intake, even bits of it go through the breather system, into the crankcase and you end up with blown big-ends.

That's a good question Josh, i'd also be interested to find out. I wonder how much you can adjust the ECV without accounting for that change with ECV duty cycle and adjusting the timing of the changeover. If that makes sense?

You would think that if it's right on the verge of opening, just a little bit of vacuum may open it too far too quickly which will result in a rapid loss of exhaust pressure.

^^ exactly the point of the adjustment and bypass.
When the lines and solenoids slowly accumulate gunk, the duty solenoid doesn't bleed off enough preuusre, so it blows open early

Taking that out of the equation lets the operation of the exhaust gas pressure and ECV adjustment provide the pre-spool, and when the ECU shuts the BPV, it fully opens the ECV (vacuum port) and then opens the ICV once the pressure between turbo outlet and ICV has risen sufficiently.

you can also manipulate the ICV opening by moving the "primary" side of the DPS to right near the turbo outlet where boost pressure is higher
What this does is have the BPV shut, but the ECV open for longer, helping to allow exhaust pressure to equalise from bank to bank before bringing the secondary in.

Ahhhhhhhhhhhhhhhhhh... interesting!

 

Mate I have 2.5" dumps, GFB T9000 BOV, the only intake mod is an in guard CAI with a SAAS pod (It joins to the standard filter box minus the stock filter so the Maf is in the original position).

HPF Tuned to 19 psi primary 20 psi secondary. Runs quite rich.

 

Never ever ever pings!

 

I've heard that before about turbos being out of their efficiency range at 20psi. The primary is running out of puff by 4k but with the secondary pumping it loves 20psi and consistently produces power all the way to redline @7500 rpm.

As far as I know the turbos & engine are unmodified.

 

I'm going to change it back to the standard vac plumbing this arvo for my drive home and see how it runs with the EVC adjusted the way you described for the mod.

I'll asume that is the way you generally adjust an ECV.

OK I think I'm wrong about the ECV adjustment.   It's a specific setting to suit this mod yes?

Ahh, good.

Nah, the ECV adjustment itself isn't specific to the plumbing mod, it can be done on a bone stock car to smooth or change the VoD range.
One of those thinbgs where it works well on one car, but not on others, some like a tighter rod,
it all comes down to the little differences in airflow and pressures through the solenoids and actuators and the diaphragm/ spring stiffness, etc

I would say that the adjustment IS 100% necessary after doing the bypass mod though.
 

It's just setting the ECV to be on the verge of opening. Lengthen the rod til it rattles, then shorten it a little to make sure it's sealed at rest.

Still don't understand how the exhaust can overcome the spring in the ECV and open it to prespool with the mod. That's a pretty stiff spring in there and gasses will always take the path of least resistance.

Awesome, cheers.

It's just setting the ECV to be on the verge of opening. Lengthen the rod til it rattles, then shorten it a little to make sure it's sealed at rest.

Still don't understand how the exhaust can overcome the spring in the ECV and open it to prespool with the mod. That's a pretty stiff spring in there and gasses will always take the path of least resistance.

typically you'd be seeing a pressure differential of around 2:1 across a turbo
i.e exhaust pressure vs boost pressure.

so we're talking about the ECV needing to hold back 30-40psi

Fair enough. If it works, it works.

I guess by the time it is overcome by exhaust pressure, primary is up to it's boost target and the wastegate is doing its thing so you never really notice it.

This is some seriously good reading, yet still a nightmare to understand.

BTW, what does this guy do? (referring to the solenoid) Because it sits under the engine cover, i've overlooked cleaning it.

 

OMG TIM!

I was only thinking about this not more than an hour ago.
Weird!


I have no idea.

It would have to be something to do with manifold pressure

I changed back to standard from the ECV mod this arvo.
Took it for a spin...... No good.

ECV MOD is here to stay for now.

Now I need to find time to do some fine tuning.
Much smoother and powerful with the mod at changeover but at 4500rpm it doesn't liKe WOT unless you have planted it from low rpm.

According to Sean it does jack all. The nipple broke off mine last week so it took it into SNJ to see if it was important. He said just to bypass it. I repaired the broken nipple anyway for my peace of mind.

Certainly wierd kong!

 

Manifold pressure you say? that's interesting. Another lead to the cause of the issue i'm having post rebuild. I'll check it out tonight and see where the lines lead. The top line obviously heads into the manifold.

 

But basically, my car won't hold boost without a one way valve inline with the MAP sensor (line 11 on mine) so that it only ever sees vacuum. Without the one way valve, it will boost for a second and sends a signal way early to the ECV to open which then causes the loss of all exhaust/boost pressure. I'm told the secondary stage begins when the ECU detects injector duty cycle is high i.e. under load - it seems like this is what it's trying to do.

 

When the cause of this is found, it will be a huge accomplishment which will be recorded in the TT history books. 

He said just to bypass it.

 

Ahh great, back to square one.

that's the purge control solenoid for the charcoal canister.
you NEED to feed the line from the canister to the manifold, but with a one way valve so it can only suck the nasty fumes from teh canister under vacuum.
if you pump boost into it you get a nasty fuel smell.

 

KONG: as fort the 4500rpm WOT issue, what's happening?
what is boost doing at the time?
Are you just cruising along at 4500rpm and then mashing the pedal?

4500 is right on that changeover point
so it could be the ECV is a little too loose and blowing open with the sudden rise in exhaust pressure when you hit WOT.

TIM:
yours has some serious issues.
what boost level are you trying to run?
i would be bypassing ALL boost control and just running a line from compresor outlet to wastegate actuator.
this will rule out or in the ECU opening the wastegate or ECV.

Do you still have the ECV Top-Port Mod in place?
If not, I suspect a duty solenoid/ pressure feed issue.
Same problem as happened to my car before i got it, boost would rise, top port would be fed too much pressure due to a missing restrictor, and the ECV would blow open too early and bog down when going into sequential staging.
Bypass mod fixed it for good

I know this is the tech thread not the for sale but i have a top nick B4 intercooler available for $80 plus some odds and ends and tips for extra HP. from past experience