Stupid boost spike.

[Kinkstaah]

Hi Folks

Has anyone ever seen anything like this before with boost spiking?
Below is 4 small traces from 4 pulls.

Run 1 was done with a vacuum line running from the compressor housing to the wastegate.

Run 2, 3, and 4 were done running the line through the (Borg Warner) 3 port boost solenoid with it ENTIRELY UNPLUGGED ELECTRICALLY.

I can only surmise that the boost solenoid itself acts as a restriction. In run 4 I stayed on the gas longer and you can see it does drop to wastegate pressure.
Note: I've had issues similar to this with:

a) 4 port boost solenoid (MAC, very old, replaced)
b) 3 port boost solenoid (MAC, literally fell apart and returned)
c) Borg Warner EFR boost solenoid

If something else can cause this, what could it be? The gate was/is a 50MM Progate single.
I am assuming the wastegate is fine, as a hose directly from pressure source to wastegate works as expected. I have had (briefly) a MBC which also works as expected sitting in the line in the past. I have replaced all hoses and shortened them to no effect.

Is there anything else to check? I'd love to run between 10 and 20psi, but it really looks that if I hook up any boost solenoid I'm going to be dealing with at least a 20psi spike before settling down to whatever boost I specify (that part does in fact work).

[Dose Pipe Sutututu]

try dumping your wastegate to atmosphere and see how you go, i.e. remove the plumb back.

And why not 20psi? even stock cars run that now

[Kinkstaah]

Too much power. Stock cars may run it but Skylines sure don't like living that long up there. 12psi is more than enough, 10 is okay but I'd love a little more than that, but really what I want is electronic control to actually hold the line flat instead of it falling off which is what you'd expect from a MBC or just a line to the gate directly. (12psi is 330rwkw)

Can't see how removing the plumb back would affect this? The plumb back is a 2inch piece of exhaust that is well over a meter long before it joins with the exhaust again, which would be unused when the gate is shut, I can't see how adding a solenoid in the line would affect it.

[Ben C34]

No way would a correctly functioning and correctly plumbed valve be a restriction.

are you super sure you have it plumbed correctly?

[burn4005]

yea, check you can blow through the pressure supply port of the solenoid with it de-energised/unplugged, and it is blocked with it energised.

[Kinkstaah]

1000000000000000000000000000000000000%

It's pretty easy to see, blow air in one side, see where it comes out. Attach hoses inline with that flow, considering it's unplugged and all... did check to see if its leaking using the same scientific test and doesn't appear to be.

 

 

[Kinkstaah]

Here is a (blurry) picture of it plumbed in. The electrical connector was disconnected further up the chain. When I join the two hoses I've labelled together with a straight barbed connector, I get no more spikes.

The BW provided hose to the compressor looked a little kinked, so I replaced it with exactly zero effect.... on either configuration (plumbed into solenoid or past it straight into the gate).

[KiwiRS4T]

3 hours ago, Kinkstaah said:

Here is a (blurry) picture of it plumbed in. The electrical connector was disconnected further up the chain. When I join the two hoses I've labelled together with a straight barbed connector, I get no more spikes.

The BW provided hose to the compressor looked a little kinked, so I replaced it with exactly zero effect.... on either configuration (plumbed into solenoid or past it straight into the gate).

My set up: drilled and tapped nipple in compressor housing going to mac valve controlled by Link through to Synapse 50mm wastegate. Result pretty flat boost curve (attached). Can you swap out your wastegate to test it?

[Dose Pipe Sutututu]

Maybe use a normal MAC valve, can't imagine that BW valve being any good. 

[Guilt-Toy]

nothing wrong with the borgies products,   you know what they say about the mechanic who blames his tools?  lol

Moving right along.

Kinksta:  you are using an external wastegate right ?

[Kinkstaah]

Yep, this is running a (genuine) 50mm external gate.

I can get the thing to hold boost fine for 20psi, similar to KiwiRS4T posted just above, the problem is I may not want to run 20psi, I may want to run 15psi or 12psi in the fashion that was posted above, or 17 psi etc. Or say pull 5psi boost per gear in 1st, none of which really has much effect if I'm spiking to 20psi semi-controllably.

I just found it astounding that the spike happens when the device is plumbed in, even with the solenoid is unplugged. The logic that air has to do a 90deg vs not is the only real difference here but I just can't see that causing this oddity!

[infomotive]

On 2/7/2018 at 11:45 AM, Kinkstaah said:

Hi Folks

Has anyone ever seen anything like this before with boost spiking?
Below is 4 small traces from 4 pulls.

Run 1 was done with a vacuum line running from the compressor housing to the wastegate.

Run 2, 3, and 4 were done running the line through the (Borg Warner) 3 port boost solenoid with it ENTIRELY UNPLUGGED ELECTRICALLY.

I can only surmise that the boost solenoid itself acts as a restriction. In run 4 I stayed on the gas longer and you can see it does drop to wastegate pressure.
Note: I've had issues similar to this with:

a) 4 port boost solenoid (MAC, very old, replaced)
b) 3 port boost solenoid (MAC, literally fell apart and returned)
c) Borg Warner EFR boost solenoid

If something else can cause this, what could it be? The gate was/is a 50MM Progate single.
I am assuming the wastegate is fine, as a hose directly from pressure source to wastegate works as expected. I have had (briefly) a MBC which also works as expected sitting in the line in the past. I have replaced all hoses and shortened them to no effect.

Is there anything else to check? I'd love to run between 10 and 20psi, but it really looks that if I hook up any boost solenoid I'm going to be dealing with at least a 20psi spike before settling down to whatever boost I specify (that part does in fact work).

It sounds like you have a leaking WG diaphragm or hose to the top of the gate. Suck on hose to the top of the gate and suck on it and ensure it holds vacum.

 

Jason

[Guilt-Toy]

I will send you a PM mate.  Should be able to sort this out.

[Kinkstaah]

Update:

 

Plumbing the lines like this fixed it. 

Seems that it really didn't like being in the simplest possible method.

Bit of playing with PID and start duty afterwards, now right as rain.

[Guilt-Toy]

Glad its all sorted mate

 

another example of the dunning kruger effect.

 

 

[GTSBoy]

Haha.  When did you discover the D-K effect?  About 2 hours ago on PF?

[Kinkstaah]

Strange, I would have thought that plumbing one line directly to the bottom of the gate should be the most spike resistant/basic way to set up the gate especially if looking for low boost, like how most IWG's run.

It still makes no sense to me how this can happen by adding the solenoid in the middle of the vacuum hoses, when connecting the hose directly does not have this spike, with the solenoid unplugged, doing literally nothing.

Is it an example of the Dunning Kruger effect when you:

1) Try something, then get stuck
2) Ask for help
3) Take that help on board, get the problem sorted
4) Post up results so other people can find it?

[infomotive]

1 hour ago, Kinkstaah said:

Strange, I would have thought that plumbing one line directly to the bottom of the gate should be the most spike resistant/basic way to set up the gate especially if looking for low boost, like how most IWG's run.

It still makes no sense to me how this can happen by adding the solenoid in the middle of the vaccum hoses, when connecting the hose directly does not have this spike, with the solenoid unplugged, doing literally nothing.

I'm assuming that setting it up in the pictures I posted above means that that line to bottom of the gate is always 'pressurized' and not going through anything (i.e the solenoid) and no more spiking.

Is it an example of the Dunning Kruger effect when you:

1) Try something, then get stuck
2) Ask for help
3) Take that help on board, get the problem sorted
4) Post up results so other people can find it?

 

The way you now have it plumbed is the normal way of plumbing a three port for most applications.

Edited February 14, 2018 by infomotive
Quoted wrong

[GTSBoy]

1 hour ago, Kinkstaah said:

Is it an example of the Dunning Kruger effect when you:

1) Try something, then get stuck
2) Ask for help
3) Take that help on board, get the problem sorted
4) Post up results so other people can find it?

No, he was hanging shit on Dose Pipe.

[KiwiRS4T]

A lot depends on the design of the wastegate.  The Synapse wastegate  has four ports - two above and two below the diaphragm and different combinations can get close to the desired boost levels leaving the Mac valve and ecu with just a trimming job. i saw a wastegate a while back with no springs and a solid piston instead of a diaphragm so it was all done with the balance of the air supplies (with a mac valve and ecu).