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Dyno result for the risky business Porsche

General engine tech -- Drag Racing to Circle Track

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ptuomov
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Mon Jul 13, 2020 8:13 pm

Proof of life:

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Re: Dyno result for the risky business Porsche

Post by ptuomov » Thu Jul 16, 2020 8:07 pm

Engine bay mostly buttoned up:
A9182D31-445E-4D1F-B9BF-9677CE004224.jpeg
5D653E38-D208-4549-B5BB-849599C2C91C.jpeg
17CD9FAE-E30C-4980-8495-ABECDA7D400F.jpeg
AC9BE2E6-0FA1-41AC-B3E1-6ECE7358761E.jpeg
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Re: Dyno result for the risky business Porsche

Post by vannik » Fri Jul 17, 2020 2:52 am

Looks really great!

Do you have a blow-off valve on each side?
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Fri Jul 17, 2020 7:34 am

vannik wrote:
Fri Jul 17, 2020 2:52 am
Looks really great!

Do you have a blow-off valve on each side?
Yes, every version of John’s kit has had two recirculating bypass valves. It’s a blow thru MAF system for many reasons and the recirculating happens upstream of the MAF.
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Sat Jul 18, 2020 1:13 pm

Nikasil break-in:

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Re: Dyno result for the risky business Porsche

Post by ptuomov » Mon Jul 20, 2020 4:53 pm

Six hour shakedown on the dyno starting tomorrow, says John Kuhn. Here’s a shot:
61F2B3B9-0E33-4DFC-A9D7-2BAAC775DF43.jpeg
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Re: Dyno result for the risky business Porsche

Post by vannik » Sat Aug 01, 2020 3:02 am

ptuomov wrote:
Fri Jul 17, 2020 7:34 am
vannik wrote:
Fri Jul 17, 2020 2:52 am
Looks really great!

Do you have a blow-off valve on each side?
Yes, every version of John’s kit has had two recirculating bypass valves. It’s a blow thru MAF system for many reasons and the recirculating happens upstream of the MAF.
How does he prevent the bypass valve and the wastegate from interfering with each other? Seems to me it can lead to an unstable situation and possible overspeed of the turbo.
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Sat Aug 01, 2020 3:28 am

vannik wrote:
Sat Aug 01, 2020 3:02 am
ptuomov wrote:
Fri Jul 17, 2020 7:34 am
vannik wrote:
Fri Jul 17, 2020 2:52 am
Looks really great!

Do you have a blow-off valve on each side?
Yes, every version of John’s kit has had two recirculating bypass valves. It’s a blow thru MAF system for many reasons and the recirculating happens upstream of the MAF.
How does he prevent the bypass valve and the wastegate from interfering with each other? Seems to me it can lead to an unstable situation and possible overspeed of the turbo.
Can you elaborate on the problem scenario that you have in mind?

Throttle closed, the intake manifold sees a vacuum. That signal closes the wastegate. This helps maintain the turbo speed even though the exhaust flow is minimal. The throttle closed and intake manifold vacuum opens the cold-side bypass valve. The compressor circulates air with atmospheric conditions in the inlet, including thru the intercooler, but without having to push against high pressure, therefore doing work and slowing down but not too fast. The turbo slows down but doesn’t stop. What’s the concern?

Pre-compressor throttle would probably maintain the turbo speed better, but with that arrangement you could potentially over speed the turbo because the compressor would be operating in vacuum. We don’t have that.

Or is the concern about running two sides and twin turbos? The two turbos are tuned to run at almost exactly the same speed at all operating conditions, so the system behaves just the same as half of it would.
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Re: Dyno result for the risky business Porsche

Post by vannik » Sat Aug 01, 2020 7:45 am

I misunderstood that the BPV was used for boost control on top of the wastegate but you make it clear that it is to stop compressor surge during closed throttle running. Thanks.
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Re: Dyno result for the risky business Porsche

Post by ptuomov » Fri Aug 07, 2020 12:19 am

Dyno shakedowns continue

Here is one dyno shakedown graph. This is with the new short block and valve springs set up a little tighter. At 0.8 bar (12 psi) and 6200 rpm, valve spring setup change doesn’t enter the equation, so for practical purposes the only change is the short block.

The new short block seems to be running very well so far:
37BC835C-8D95-4E57-B631-E3371A3B2C0D.jpeg
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