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Dyno result for the risky business Porsche

General engine tech -- Drag Racing to Circle Track

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vannik
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Re: Dyno result for the risky business Porsche

Post by vannik » Wed Jul 10, 2019 1:56 am

That is interesting, as well as the change to a Y-connection. I see in the simulation of this setup that with the junction box it is very difficult at lower rpm values to speed up both turbochargers because one has enough capacity to generate the required boost. Then the wastegates open to control the boost from one turbocharger and the other one does not speed up. It can even see reverse flow. The Y-junction goes a long way in resolving this but also where you get the wastegate control signal from is important. I know it is "only" a simulation but it seems to point at what is being done now.
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Wed Jul 10, 2019 5:47 am

vannik wrote:
Wed Jul 10, 2019 1:56 am
That is interesting, as well as the change to a Y-connection. I see in the simulation of this setup that with the junction box it is very difficult at lower rpm values to speed up both turbochargers because one has enough capacity to generate the required boost. Then the wastegates open to control the boost from one turbocharger and the other one does not speed up. It can even see reverse flow. The Y-junction goes a long way in resolving this but also where you get the wastegate control signal from is important. I know it is "only" a simulation but it seems to point at what is being done now.
The motivation for going from the plenum box to Y-pipe was reducing high-rpm high-load pressure losses there. Doing this was possible because we went from a single MAF after the box to dual MAFs upstream of the box.

Are you concerned about part throttle, low rpm operation or full throttle, low rpm operation? Both wastegates stay completely shut until about 2500-3000rpm, depending on the boost program. With manifold vacuum, the bypass circuit opens and recirculates air from the boost pipe to air filter box upstream of the compressor inlet.

We've got a MAF, pressure differential sensor between compressor outlet and inlet, and turbocharger speed sensor, each, on both sides. Therefore, we can observe whether the system is symmetric or not. Both turbos start spinning slowly already at idle, not making any boost, of course. The turbocharger speeds track each other fairly closely regardless of the conditions, and the MAF sensors indicate similar mass flow from both sides.

We've seen one situation in which the system was imbalanced and that was when one of the wastegate signal lines had popped out...

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Re: Dyno result for the risky business Porsche

Post by vannik » Wed Jul 10, 2019 11:41 am

With dP over each compressor and each compressor speed there should not be any imbalance problem. I saw it only when using purely mechanical control with MAP in the center pipe.

Your system has the required sophistication to correctly control the wastegates.
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Wed Jul 10, 2019 11:48 am

vannik wrote:
Wed Jul 10, 2019 11:41 am
With dP over each compressor and each compressor speed there should not be any imbalance problem. I saw it only when using purely mechanical control with MAP in the center pipe.

Your system has the required sophistication to correctly control the wastegates.
We’re actually running a very simple control logic and 30 year old computers, but I agree that we can verify balance effectively with the sensor suite.

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Re: Dyno result for the risky business Porsche

Post by ptuomov » Wed Jul 10, 2019 9:08 pm

What Porsche rubber turns into under high heat and 1.5 bar boost:
14D6DA91-EB9B-42EB-BD52-43A8C0940F77.jpeg
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Re: Dyno result for the risky business Porsche

Post by MadBill » Wed Jul 10, 2019 11:09 pm

Is that a recent part or an ancient one?
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Thu Jul 11, 2019 3:22 am

MadBill wrote:
Wed Jul 10, 2019 11:09 pm
Is that a recent part or an ancient one?
This is a new one. We swapped it in a couple years back, while you’re there and for no good reason. The original 30 year old part is still intact and will be going back in now.

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Re: Dyno result for the risky business Porsche

Post by MadBill » Thu Jul 11, 2019 9:35 am

A close comparison of quality and durability might be in order. It wouldn't be the first time that the old OE part was better than a new replacement one...
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Thu Jul 11, 2019 10:27 am

MadBill wrote:
Thu Jul 11, 2019 9:35 am
A close comparison of quality and durability might be in order. It wouldn't be the first time that the old OE part was better than a new replacement one...
I would say never and nowhere as true as with the 1987 928 S4, that at the time was fastest and probably also among the most expensive production cars. The 30 year old original parts were made from best materials and held to highest tolerances. Not so with the current replacement parts.

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Re: Dyno result for the risky business Porsche

Post by ptuomov » Sat Jul 13, 2019 1:43 am

Air filter:
CE9035DC-ADA1-45CA-BE8E-20DC1CB28ADB.jpeg
69C6238D-7AC5-445D-84A0-2D5E3BF3811F.jpeg
799B12FC-6A1A-4273-90C6-8519FCBE04CD.jpeg
2B854681-1FBB-4F69-804A-531A30DCA9E4.jpeg
E72BB04A-634F-4E31-AE35-3B5057384596.jpeg
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Sat Jul 13, 2019 1:46 am

Dual MAF plumbing:
1F2F1709-F1FD-42B5-AA4A-1FC84BC537AC.jpeg
30DABCF8-F1D3-493C-AC17-E780188C9BF2.jpeg
99F24185-DEE3-4538-9EE6-728C1890C683.jpeg
C2D4416C-1148-4970-953E-552D4A09EA99.jpeg
44520E07-DBB8-4AA0-8B16-AA626A7F4141.jpeg
D2918D2F-3B5A-451F-B7A6-25A51A4B3325.jpeg
EF325E09-7899-41EF-8708-794B187C046F.jpeg
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Re: Dyno result for the risky business Porsche

Post by n2xlr8n » Sat Jul 13, 2019 5:58 am

Nice work!

It looks like you guys could definitely stay busy.

Would you mind sharing that filter PN? I had trouble finding an air filter that would flow enough for my application and still fit the available space; I'm certain that would work for me.
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Sat Jul 13, 2019 8:01 am

n2xlr8n wrote:
Sat Jul 13, 2019 5:58 am
Nice work!

It looks like you guys could definitely stay busy.

Would you mind sharing that filter PN? I had trouble finding an air filter that would flow enough for my application and still fit the available space; I'm certain that would work for me.
It’s a standard part, don’t know the part number. The big non-standard portion of the filter is that it has two 3” inch holes and flared pipes bonded into them.

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Re: Dyno result for the risky business Porsche

Post by ptuomov » Sat Jul 13, 2019 10:47 am

Actually, a custom part but based on RU1500 cross section.

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Re: Dyno result for the risky business Porsche

Post by ptuomov » Sat Jul 13, 2019 11:03 am

Some photos of the filter looks with the cover on:
61D8DA2B-469F-4AF0-805E-D1780FE15581.jpeg
E86E71C7-444D-4647-913E-BD4AE696E74D.jpeg
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