Vagitarian

Hey guys, Im wonderring what is the best source for my wastegate, I am getting a 5psi flutter (20-25psi) when I try and run my manual boost controller.

If I run off just wastegate spring, with the source vacuum line for the wastegate going straight from the compressor housing to the wastegate, I get steady 18psi. But if I add in my manual boost controller to try and run 22-23psi I am getting that 5 psi flutter.

I only know Im "fluttering" based on watching my boost gauge which is getting its vacuum/boost from the back of the intake manifold. So Im assuming its safe to say thats what my engine is seeing?

Would I be better off to give the wastegate a source from the intake manifold?

LTCxD2B

Intake manifold

Dark_Teg

I have always had better luck using the manifold.

wantboost

iTrader: (2)

The intake manifold is the best spot for consistent boost control.

The problem with using the compressor housing is the air is moving at a very high velocity and it's very turbulent air... So there's a large amount of pressure fluctuations and pulses that can wreak havoc with boost control.

Also using the intake manifold will give you a slightly higher pressure level since you're reading after the intercooler pressure drop. So say if you were running a 15psi spring. If you had the signal line before the intercooler you'd see a lower pressure reading due to the pressure drop across the intercooler. Using a signal line after the intercooler means you'll see 15psi at the intake manifold since boost pressure will be higher before the intercooler to compensate for the pressure drop.

If you're insisting on using a signal source pre-intercooler then you could tap the charge pipe between the turbo outlet and intercooler, closer to the intercooler. This would allow time for the airflow and pressure to stabilize before you're reading pressure levels.

Vagitarian

thanks guys, I will relocate the source to the manifold

riceball777

I have read that it is better to get your boost source for your watergate or boost controller from before the intake manifold because it is bad or you don't want your waste gate to see vacuum. You only want your boost controller and waste gate to see boost and not vacuum.

Runnerdown

Yes, riceball has it correct. A pressure tapping location on the charge pipe before the throttle body is the ideal location, vacuum introduced to the gate is highly advised against by the WG manufacturers.

sleepencivic

Pressure source has to be before the throttle plate unless noted by wastegate manufacture! Can always use a quick tap in a coupling....

FTG-QuickTap-CompHSG : atpturbo.com

OneBadTurboCRV

LOL... there have been multiple threads on this as well. It's exactly as 3 guys above me have stated.

wantboost

iTrader: (2)

I've run my wastegate on a source after the throttle body with no issues. Under boost the gate can't see vacuum, it is physically impossible

Vagitarian

Im nervouse now I dont know what to do. I dont have any spots pre manifold other than the compressor housing. Do you guys think the compressor housing is whats cuasing the weird flutter and moving it to a better location should help?

I dont want this vacuum on the wastegate deal to cause an issue, I like trouble free turbo Honda so far

OneBadTurboCRV

What about out of boost? How about when you down shift and deceleration? Tons of vacuum there unless your engine is in severe need for a rebuild.

I have always used the compressor cover for my boost reference and have never had flutter from 5 to 25 psi... How exactly are you hooking it up OP? What is your complete setup?

wantboost

iTrader: (2)

The amount of vacuum seen between shifts is irrelevant. On decel no boost is made, making wastegate operation also irrelevant. Anytime you're in these conditions the whole system doesn't see pressure.

OneBadTurboCRV

LOL... dude, are you serious? Think about everything you just said real hard. It's all good, I'll back out.

wantboost

iTrader: (2)

Also when you are at part throttle cruise the whole system is under vacuum, including the wastegate, regardless of where you have the signal location for the wastegate... The system still operates as it should under those conditions.

It's physically impossible for the wastegate to not see vacuum, unless you're talking about a turbo diesel motor, they never produce vacuum. Hence why they all have some form of vacuum pump.

Runnerdown

Pre throttle body as they should be hooked up is not seeing any sort of significant vacuum. Hooking it up to the intake manifold may "work" but it's not where they are suppose to go. End of story.

Vagitarian

It flutters from 20-25psi. I have it setup coming off the compressor housing, to the bottom of my MCB, out the side of the MBC to the side of the wategate. If I run simply off wastegate spring, so line right off the compressor to the side of the wastegate it will hold 18psi steady with zero flutter. Its doing it after I tap in my MBC to try and up the boost that few more psi.

But if moving the boost source to after intercooler will gain me a few psi as opposed to having it sourced from the compressor, Id be happy running 22psi just off w/g spring but I doubt it would get me there But I wanted to be able to run 24-25 at the track...

My setup is a d16 non vtec vitara setup, zex cam, cast manifold, 38mm w/g, garrett 57 trim .60/.63, 3" from the turboback, agency power bov, backdoor intercooler w/ 2.5" steel piping

boosted94gsr

Why exactly is it bad for the WG to see vacuum? Does it stress the diaphragm in some way?

I guess I will switch from intake manifold to compressor housing for my boost source when I switch from my MBC to a Mac solenoid for boost by gear...

Runnerdown

Wastegates are designed to have only positive pressure applied to the bottom side and not vacuum. Like others have mentioned, it will work off the intake but why stress the **** out of the diaphragm all the time? From pressure to vacuum constantly gives it quite the work out. Good thing they are built well.

Ask a company like tial that actually does r&d and engineering what they recommend. I can asure you they will not advise the intake as the source.

Tony the Tiger

Most wastegates have slight leakage at the stem of the valve either from its design or regular wear and tear. Having it under vacuum will actually pull exhaust gases into the engine, as you can see traces of carbon at the vacuum lines over a period of time.

The most ideal spot to take the pressure source is after the intercooler and right before the throttlebody for maximum spool.

If the turbo setup is prone to spiking, then taking it off the compressor housing is more ideal.

Vagitarian

Well, I guess Im pulling my charge pipes off tomorrow and threading in a brass barb fitting after the intercooler

Fvckers always making me do it the hard way! lol

boosted94gsr

More like the right way lol. I gotta do the same **** now haha! Learn something every day.

wantboost

iTrader: (2)

I can see the validity to not wanting to have the wastegate see substantial vacuum, in theory... However I have first hand experience with running a post-throttle body signal with no effects on the wastegate. Everything from 200hp stock sr20s to 500hp+ Hondas, an 800awhp Audi TT, R33s, R34s, even a couple 1000+hp supras. Not once was there ever an issue with the wastegate seeing vacuum, systems worked fine and we never had a failure. All cars ran some sort of boost controller from MBCs to ecu and standalone EBCs.

However lets get back on topic...

Vagitarian, can you elaborate on your boost controller a bit more?

Info like brand, ceramic or steel ball, spring strength, signal line length and diameter, mounting location, etc.

I've witnessed MBCs that use a ceramic ball have problems with flutter at high boost levels. Mostly due to the mass of the bearing causing the spring to oscillate. Also sometimes an MBC with a stiff spring can also suffer from flutter.

Depending on how fast your setup builds boost occasionally the MBC will "overshoot" target pressure and depending on things like spring tension, bleed hole size, bearing weight, etc. It can go from overshooting to just under target pressure depending on how fast the MBC can bleed off pressure. This ends up putting the system into a rollercoaster of flutter.

Sometimes line size can affect performance but I've seen it be more related to the bearing.

Have you tried removing the MBC and just running off the wastegate? If you run a line directly from your signal location to the wg and the issue is still there it could indicate an issue elsewhere, most likely involving the turbo. If the problem goes away after the test I would disassemble the MBC and make sure everything is in working order.

Sometimes the springs weaken over time and can sag or break. Occasionally I'll find a small piece of debris obstructing the bleed hole and a few times I've seen evidence of the bearing wearing the inner diameter of the MBC which can cause issues as well.

Anytime I take an MBC or any type of low temperature valve (bov for example) I like to put a small amount of light grease and/or liquid Teflon lube on any surfaces that move or contact each other. It can eliminate friction/stiction allowing slightly better response, reduces wear, and so on.

All joking aside I use the DuPont multi use Teflon lube spray on everything.. I don't touch pb blaster or wd40 anymore. It'll break loose 10yr old exhaust bolts in less than 5 minutes, frees anything sticking instantly, reduces friction considerably, and it lasts forever on whatever you apply it to.

I would test without the MBC just to see what happens. Did this just start or has it always done it? With the weather cooling off lots of little gremlins like to pop up a lot.

sleepencivic

taken from Tial's website:

Make sure that you are using only a boost pressure source. This can be found anywhere between the turbo compressor housing and before the throttle body. Do NOT have the boost pressure line plumbed in to the intake plenum. The intake plenum has both boost pressure and vacuum at different points. Vacuum can damage the diaphragm in the wastegate housing.


Again just use this !! Intercooler pipes are not thick enough to tap for threads, so you would have to weld a block on the pipe for threads or just use the quick tap.

FTG-QuickTap-CompHSG : atpturbo.com

OneBadTurboCRV

Damn, sleepencivic beat me to it. Oh well haha. Thanks for your input as well Tony as that was my next rebuttal. You are doing the right thing by relocating it Vag...