Lb7 wastegate tuning

N2BRK

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I’m just playing around tonight in the garage and I wanted to see what the little PPE valve actually does. I was pretty surprised, maybe everyone knows what I’m about to share and I’m just catching up, lol.

The valve ALWAYS leaks boost. There’s a small orifice that leaks boost immediately. I turned my regulator down to a Lb and it was immediately leaking. I didn’t expect that.

The stock setup has the wastegate creeping open as boost rises. The valve seems to bleed off until break over and then it activates the wastegate slowly. I expected more of a blow off effect, so that was a surprise too.

I have videos if there is any interest in seeing this as it happens.
 

2004LB7

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Dec 15, 2010
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I always thought those things were just a restriction that delayed the opening of the wastegate.
 

Chevy1925

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Nope, they release the pressure to the spring so it makes it take longer before the spring/diaphram sees pressure and starts to finally move the wastegate. Its main purpose is to up the boost level. It does help boost peak out quicker vs the spring kinda giving a more tapered off affect as it nears peak boost but not massive.

It’s an old school trick for internal wastegate turbos. Gas guys use 1 way check valves to do the same lol.

If you really wanna have boost come in quick and peak fast, a dual port waste gate and 3 or 4 port electronic boost valve makes a big difference
 
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N2BRK

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ok, so here's some videos. One is no valve and shows opening of the wastegate, another is valve with higher pressure showing the wastegate opening slower than low pressure without, and the last is just 1 psi showing leakage from the valve orifice.
 

darkness

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My ‘02 had the ppe boost valve when I bought it from Sean. I too was surprised to find out it bled boost off. I took it off and put a needle valve in. Same as I used on my ‘04.
 
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Bdsankey

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Yeah, they've always been just a bleed. It's like drilling holes in the wastegate reference line which turbo gas guys have been doing for decades. It requires more pressure/flow to achieve wastegate actuation.
 

N2BRK

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That doesn't sit right with me. If they were just a bleed, then why are they labeled as directional? There should be a ball and spring in there. I'll air up tonight after work and see :)
 

Bdsankey

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It is a smaller orifice on the turbo side. It also allows the air to come in, hit that "chamber", then bleed. It makes perfect sense from a fluid dynamics sense (air is modeled as a fluid).

There are some check-ball style devices out there, Kennedy makes one that comes to mind.
 
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N2BRK

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as a fluid, there would be a drop in pressure within the tube from the orifice... but the direction of the tube wouldn't matter. So either the direction of flow through the tube matters or else they put the marks on there to make the consumer think there's more magic inside. LOL
 

Bdsankey

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as a fluid, there would be a drop in pressure within the tube from the orifice... but the direction of the tube wouldn't matter. So either the direction of flow through the tube matters or else they put the marks on there to make the consumer think there's more magic inside. LOL
It's a measurement of flow. The incoming flow (from the turbo compressor housing outlet) is a larger size than the outlet side feeding the wastegate. This creates a "backup". I have not measured one in awhile but I'd be curious to see if the mass flow of air is equivalent (IE how the two outlet holes compare to the inlet hole). So yes, there is a drop in pressure from the orifice but it is a bit more to it than that.

Their logic and design does work and works well. They followed the KISS method which I enjoy.
 

N2BRK

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Ahh, ok! So if there's an internal taper, then that makes sense now! Burnoulli - if you installed it backwards, then the orifice would draw IN and not push out! Got it! Thanks
 

Bdsankey

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Ahh, ok! So if there's an internal taper, then that makes sense now! Burnoulli - if you installed it backwards, then the orifice would draw IN and not push out! Got it! Thanks
It would likely never draw in air as that would mean the compressor outlet is under vacuum. It would still push air out of the orifice under pressure, it would simply be less effective.
 

N2BRK

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Good call. Once the diaphragm opens, there’s a brief moment of filling, and like you said it wouldn’t be significant.

For S&G I did hook it up both ways. Backwards it blows through without much resistance. In the right direction it directs more air out the orifice and much less comes out the end. So the people making their own with a piece of small pipe and an orifice are not getting the same performance as the PPE offering.
 

TheBac

Why do I keep doing this?
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I wonder what Jon is doing nowadays? I think I still have his number in one of my old phones, but damned if I know which one or where it is.

Remember when he was pushing Absinthe way back when, or when we'd have "chat nights" on yahoo? My God, he and Mike were Abbot and Costello.

The whole sheep thing started when he referred to sending "Wellingtons" to Mike. It all went to hell after that. :ROFLMAO: