Builds Moonshine - A Build Thread (11 Viewers)

[GLTHFJ60]

The challenge with running your small turbo wastegate signal off of compounded boost is that this signal will easily override your spring tension in both the fooler and the wastegate (something I've learned with our set ups).

Where is a better place to reference for the high pressure wastegate then? The intermediate charge pipe feeding the high pressure turbo? Meaning the wastegate is reacting to the atmospheric turbo boost level instead of it's own turbo's.

 

[boots4]

Great question, not sure it's a better location but the only two options are compounded boost (where you have it now or any spot down stream like the intake manifold), or off of the atmospheric turbo. It kind of depends what you want to achieve and how your turbo's work together. If you are not getting what you want it's potentially another variable to play with in the tuning/experimentation phase. Ultimately they both do the same thing just a little differently and the nuances can be a little more advantageous one way or the other depending on how these two turbos play together.

Side Note: This is true for the signal feeding the AFC housing as well and I've been playing with both signals to try and clean up my preboost fueling using this idea as one of my variables.

Thoughts:
Pulling it off of total boost is fine (that's how I'm doing it) it just means knowing that the springs in these wastegates and foolers were typically meant for single turbo boost levels. Knowing that helps in understanding that what seems too tight on the spring tension may not be enough to do what you want. So you may need to tighten up the fooler and the spring tension on the wastegate if you were aiming for the small turbo to do more of the work or trying to get it to produce more boost. In your setup, even though the signal might be tightened down the small housing on your big turbo may end up spooling it anyways. I'm interested to see how this works with your turbos.

Pulling it off of the big turbo will have your small react more to how your big turbo builds boost. So it does basically the same thing but it's more based on the big turbo's map and it's not as much psi so it could be easier for the wastegate to handle and potentially could allow a little better fine tuning.

This is where the gauges and the formula's can be helpful in seeing what each is doing/producing. The values get converted to pressure ratio (to satisfy the formula) and then back to psi (to speak our language). The turbo maps are in pressure ratio so if you were good at reading the maps (or can even find a map available for the Holsets) you could aim for certain PR's that are best for each turbo. I can read turbo maps but I wouldn't say I'm "good" at it. Cooler boost is more dense and can produce more power (Banks) and that can be achieved by tuning the turbos into their sweet spots.

The good thing is that you have some adjustability with the wastegates on both turbos that should give you room to experiment.

 

[Zjohnsonua]

We're on the same page, @GLTHFJ60. I did a pi$$ poor job of explaining myself.

Nvm my fuel pressure nonsense...too much time around P7100s had me forgetting that the VE uses an orificed banjo to regulate the FP .

Here's another vote for holding back more of that energy for the HP turbine....and then put more fuel in it .

 

[GLTHFJ60]

Adjusted the boost fooler full shut and the boost numbers didn't change at all, lol. I need to start doing pulls in 3rd, it's too fast to wind it out in 4th.

 

[The Phoenician]

Adjusted the boost fooler full shut and the boost numbers didn't change at all, lol. I need to start doing pulls in 3rd, it's too fast to wind it out in 4th.

Yea 3rd and 4th are where i see the boost gains. Mostly in 4th.

 

[GLTHFJ60]

Yea 3rd and 4th are where i see the boost gains. Mostly in 4th.

My RPM limit is ~3800rpm, and in 4th gear with my gearing/tire size, that's 107mph

I think I need to do another boost leak test (fix what i find), then use bailing wire to tie the high pressure turbo wastegate shut, then do another driving test.

 

[GLTHFJ60]

Wired the high pressure wastegate shut and this is as good as it got at about 3500rpm in 4th.

@Zjohnsonua had a good idea of moving the boost reference higher up on the intermediate charge pipe to see if there's a big pressure drop there. I'll do that this week.

 

[boots4]

Big: PR = (20 + 14.7)/14.7 = 2.36

Total: PR = (37 + 14.7)/14.7 =3.52
3.52/2.36 = 1.49
Small PSI: (1.49*14.7) - 14.7 = 7.2psi

Big turbo is making 20psi and the little turbo is making 7.2psi for a compounded 37psi total.

With your small wastegate wired shut (meaning it cannot open now, right?) it would suggest this may be as hard as the small can be driven with the current fuel settings (and timing). I know this is subjective but does it feel more powerful than last week's 26 total psi?

To get more total psi at this point (not adding more fuel in this initial experiment) it's playing with the big. As Zjohnsouna suggested to play with tuning on the big's wastegate by changing the signal reference or also by the spring tension on that wastegate. I suspect an issue is that by reducing flow on the wastegate for both the small and the big you should get more total psi (already proven with wiring shut the small's wastegate) but with both wastegates restricting flow (to drive the turbine sides harder) it will be hotter psi meaning your egts will go up because the exhaust cannot escape. You are still safe now with egts so I'd say now is the time to experiment with the big's wastegate. What this is doing is getting you familiar with how these two turbo's share the load and how they react to adjustments. This is good experience to gain with your set up. Once you start adding more fuel you will most likely need to rebalance these two turbos and now that you are gaining experience in how they react you will know what direction you may want to try to balance things out.

 

[GLTHFJ60]

Correct, I wired the hp turbo's wastegate shut (meaning it can't open under any circumstance). That last screenshot was at 3500rpm, so the hp turbo was almost certainly in choke with the wastegate wired shut. I did that as a test, but took the wire off so the wastegate can function again.

I have already tightened the wastegate spring on the low pressure turbo one turn from fully closed. If it is opening, it can't open more than a blonde one. That was the first step after my first drive, thinking it wasn't spooling at the time.

Can't say for sure if it was more powerful with the wastegate wired shut. She's already got more power than with the single turbo, that's for sure, issue is only that it's not 2x the power like I was expecting.

Got a punchlist I'm working through today, and should have data by the end of the day to see if my intermediate charge pipe is causing a large pressure drop.

 

[boots4]

The good thing is that there has already been some improvement so that's a good thing.

My belief is that when we choke the exhaust flow we won't be able to make as much power as we could when we are able to get the exhaust out so that new air with more fuel can make a bigger boom. It's that dang balance and compromise thing. This is why I'm concerned with the size of your big turbine housing, but hopefully with a dialed-in wastegate setting that won't be a problem. I mean that turbo came off a bigger engine that made more exhaust.

 

[GLTHFJ60]

The good thing is that there has already been some improvement so that's a good thing.

My belief is that when we choke the exhaust flow we won't be able to make as much power as we could when we are able to get the exhaust out so that new air with more fuel can make a bigger boom. It's that dang balance and compromise thing. This is why I'm concerned with the size of your big turbine housing, but hopefully with a dialed-in wastegate setting that won't be a problem. I mean that turbo came off a bigger engine that made more exhaust.

Exactly my thinking, and the reason why I put the larger turbine in the lp turbo. Figure if that can make 350+ hp on a 6 cylinder with good egts, it should be plenty big enough for a 4 cylinder.

 

[GLTHFJ60]

Ran through a big list today.

Boost leak test, boost fooler was only leak, so I eliminated it. Also it was opening at 17psi or so fully closed.

Borescoped the hot side of the intercooler to make sure nothing was in there, and it looked good.

Head gasket appears to be leaking oil on the ds side, so that's not great.

Adjusted the hp wastegate six turns in and moved its reference to the intermediate charge pipe. Also moved the lp turbo boost gauge reference to the top of the intermediate charge pipe to see what the pressure drop in that pipe was.

Changed the lp turbo drain gasket as it was leaking pretty good.

Added a stainless gasket between the hp turbo turbine housing and the hot pipe flange.

With all that, went for another rip and got this screenshot. Not apples to apples as the last pull, as this was only about 3000rpm, but it does not appear to have a big pressure drop in the intermediate charge pipe.

With this data, I think the next step is to move to larger injectors, then re-evaluate, but as always, open to other suggestions. Not much else to check/change at this point without injectors though.

 

[GLTHFJ60]

Torn down to replace the lp drain gasket.

Hot pipe gasket

Back together with new lp boost gauge reference.

 

[GLTHFJ60]

Today's test drive screen grab.

Have a new whine that started on the last pull. Not sure what it is, but when inspecting I found one of the intercooler top hold down brackets broken. Weird because it's been on there for years.

 

[The Phoenician]

Dude, I think you're doing everything right, but I think this may be your real problem. It's too restrictive.

When I had the snorkel box on my truck, I could not get it to go above 14 or 15 psi. When I deleted it, I could easily hit 30. This was before the compounds. I just think that you're not able to move enough air with that.

 

[GLTHFJ60]

Measuring pressure at the inlet like I did today disagrees with you. That's why I did that. Even with 16psi feeding the hp turbo at 3000rpm that should compound above 40 easily. Can't push it higher than 37 at the manifold currently.

It's possible that the air cleaner is a restriction now, but it wasn't before.

 

[The Phoenician]

Measuring pressure at the inlet like I did today disagrees with you. That's why I did that. Even with 16psi feeding the hp turbo at 3000rpm that should compound above 40 easily. Can't push it higher than 37 at the manifold currently.

It's possible that the air cleaner is a restriction now, but it wasn't before.

s***, I hope I'm wrong. I really want to see Moonshine become more of a beast!

 

[boots4]

Big: PR = (16 + 14.7)/14.7 = 2.09

Total: PR = (37 + 14.7)/14.7 =3.52
3.52/2.09 = 1.68
Small PSI: (1.68*14.7) - 14.7 = 10psi

Big turbo is making 16psi and the little turbo is making 10psi for a compounded 37psi total. So same total boost as before but EGTs are down and the little turbo is doing more work.

You are still stepping in the right direction so there has still been improvement.

I bet the broken bracket is due to the twins. Weird things happen because of twins.

 

[StevoJonesFJ60]

Before getting the new injectors it might be worth modifying your atmospheric input, I have to agree with @The Phoenician , it looks pretty restrictive at that point.
Do you have rough dimensions of the custom connector to the atmospheric turbo?
Just in terms of fluid dynamics, short 90* fittings and other pieces that neck down add quite a bit of theoretical length to the system. is there any way you could add more radius to the part that you tapped for the port? something like this?

I just see those hard angles right before the big turbo which are definitely making quite a bit of turbulence before entering the turbo. Since its mild steel it shouldn't be too hard to radius it a bit which will improve the airflow, its amazing the difference laminar vs turbulent flow makes in pressurized systems.

I work as a duct system engineer, and have seen some funny results from turbulent air.

 

[GLTHFJ60]

Sure, it's possible. I'm just not convinced the juice is worth the squeeze to do that yet.

The restriction point is at that bottom point of your mspaint. To improve that, which would be ideal, would require a full rebuild of the part. If I decide to do that, I'll make the upper portion more sweeping to appease y'all