Compound turbo build and other updates

Maybe your primary is just too big? Maybe some tighter housings or two 360's would have better characteristics?
 
Seems to be a secondary issue though? Smaller primaries would definitely spool better.


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Gate looks fine, everything is sealing well still. Must be the housing, unless the gates cracking open slightly at low boost.

I'm thinking I might need to just downsize all the chargers. Whats the use of triples if they spool crappy. I have a lot of hours into building this though, would be nice to not have to redo a bunch of piping.
 
After a WOT blast the secondary charge pipe into the head was about 150*. Don't know how accurate that is though, and how much of that was just from radiant heat off the engine.

A housing swap or maybe just a smaller secondary is in order I think. I think it just lost velocity with the true t4 .91 housing, the .83 had those t3 sized volutes.
 
Pretty tough to get a decent reading that way. While the charger is heating the air the engine compartment is cooling it at the same time.

The real lack of drive pressure where you want to see it is suggesting the hotside is a bit fat.
 
Joesixpack said:
You need to use a quality regulator that does not creep. I've got hours on my build on the dyno using shop air as the supply and they bang on hold the pressure they are set at. I'm using a 60mm Tial dual port gate and it works very well with regulated shop air. I put about 40psi to the top of the gate to max out my build. I set it to 40 psi and it exactly stays there.


Now the OP's regulator being right in just about the hottest part of the engine compartment needs some more thought.



I was using a Parker brand regulator that came with my 50mm gate from Engineered Diesel. I thought it was supposed to stop at the set pressure, so I installed another, locally sourced unit from my local heavy truck shop. Same exact results, so I assumed my findings were accurate. Did you have a brand in mind or one you prefer?
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zfaylor said:
I think everybody understands that pressure will still equalize and be the same on both sides of the valve if the air has nowhere to go. However, I know myself and many many others successfully control gates using what is essentially just a ball valve. Hints why you can use a basic "boost controller" or boost elbow and take a factory charger from gating itself at ~23psi to ~40psi. Something most do with an unmolested truck from the get go to make them something worth driving.
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I can certainly see a guy using a manual, spring and ball boost controller to be able to adjust the opening pressure of a stock, turbo mounted gate. Makes for a much enhanced driving experience, lol. I just haven't seen a regulator stop at the set pressure as JSP describes, without the outlet side being allowed to flow. I could be wrong, or exposed to junk regulators, possibly...

I would also say that my ED gate will slam open with 25-30 psi on the gate against both springs in it, so I would also assume that if shop air or 40 psi was applied to the gate, it opens fully, period. what about adding 5 or 10 lbs, to the top, to help the spring, but only a little? This is where I had issues, trying to find a tuning window between one spring and two. Either the regulator was open or it wasn't. Sounds like what you've found, also?
 
A proper functioning regulator should be able to be hooked up to shop air and you can turn flow off completely. If it is still hissing it is leaking.

Think about the regulators on oxy/acetylene tanks. You can set the pressure against the dead head and they hold. If they didn't your oxy line would explode.

There are some cheap ass regulators out there, I know there was a crappy plastic one here that was leaking. Zero spring was still hissing.

The **** about those ED and that other brand that escapes me with the orings is the damn things are prone to leak. Pressure will get past the rings and screw with your equilibrium. The TIAL gate I'm using has a diaphragm.

Relieving type regulators would help with this a bit.
 
That sure don't seem that horrible being a 12V. Am I seeing right your up to 20lbs boost and your primary stage is still flat?
 
Yeah. I don't remember exactly when the primaries start moving but it takes a bit.


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I agree, the regulator should be able to shut off completely, yes. And the ones I have, probably 6, all work the same, just like the one on my spray guns. The pressure out goes to the pressure in unless it's flowing. Pull the trigger to spray and you get a big high pressure blast, then settles down to the set point. I like the piston/o-ring style gate that JGS makes when using boost on the gate to operate it. Never had the O-rings leak a bit, even with shop air on them. The regulator for my argon tank on my tig welders also have a high pressure "dump" when I strike an arc, then fall to the low pressure it is set to. Interesting, I need to do more research on the regulator's function.... JSP, How do you set your regulator at 40? with it hooked to the gate? where is the gauge mounted, before or after the regulator? Using it to open the gate or hold it shut? This has troubled me for some time, very interested.....
 
Man I don't know what to tell you, the regulator for our paint guns also works exactly the way I describe. When its dead headed you can set the pressure and its stays bang on and does not creep to supply pressure. When you operate the gun you see a little drop from set point but not much.

The way mine is setup is with a relatively weak spring in the gate and use a pressure setpoint in addition on the top. I have no need to limit boost and have no reference to it. All I care about is drive pressure and more or less using the air on top as a variable spring + mechanical spring. Now if I was trying to limit boost set point I'd need both sides of the gate. 40 Psi sounds like a lot on top but its a pretty big gate and the working pressures are up there.


As to the OP's I did a little math and there's no reason why even 67mm compressor's shouldn't be coming online at where you boost braked to. Which makes me think the primary's hot side is just to fat.

Tightening that up though is not going to make the secondary more responsive.

I'd like to see a video of the boost gauges + rpm rolling into it around cruise if for nothing more than my own education if your up to it.
 
Seems pretty simple here. IMO, the secondary having to both draw through (compressor) and push through (turbine), such lazy primaries, is slow to respond and creates heat which is NOT being cooled due to lack of high pressure side IC which further exacerbates the issue.
 
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