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Old 03-31-2019, 06:48 PM   #1201
dvallis
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More good work today. Rob was up at dawn and installed the oil catch can. I like it. I can't find a definitive answer about needing a PCV valve between the cover and catch can or not. Seems to make sense you'd want the valve cover to vent, but not pull in air so the engine would maintain a better vacuum. Any comments?



We re-visited the boot control solenoid before cutting hose for install. In the diagram below, boost pressure comes from the compressor housing to a tee. Middle of tee routes to top of the boost control valve diaphragm. (It's upside down in the picture) Pressure works against the spring until boost exceeds spring tension and the valve opens. Other side of the tee routes to the bottom of the valve diaphragm. As boost PWM duty cycle increases, it adds pressure to the spring side via path 1-2. At 100% duty cycle, air pressure on each side of the diaphragm is equal and the spring holds the waste gate closed. As the boost PWM duty cycle decreases, pressure vents from the valve diaphragm via path 2-3. Makes sense.



Boost hose ready for the solenoid.



Solenoid mounting bracket with rubber for isolation. Solenoid vibrates at 50 Hz so you don't want it directly bolted to the car body or it will vibrate like a snare drum.



Solenoid mounted. Hard to see from this angle but it doesn't touch anything except the bracket and hoses.



Charge hose back in place. Nice clean install.



Finally, we did a compression test. Average for all 6 cylinders is 150 psi. Bentley's says spec is 142 - 156 psi. 1,3,4,5,6 are great. 2 is 6% low, which is Ok. 10% variance is the rule of thumb.

1:150
2:140
3:155
4:151
5:155
6:151



Last thing left is rewiring the ECU for boost control. i.e. pull the damn bulkhead. Oh joy. Gonna have to wait until Rob gets back as its a two person job.
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Old 04-01-2019, 06:47 AM   #1202
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Glad to see you are back at it.

We were worried about "our" car,
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Old 04-01-2019, 07:22 AM   #1203
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WTF does O/T mean in German?
oberer Totpunkt (top dead center)
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Old 04-01-2019, 01:36 PM   #1204
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For the crankcase vent, you want to have the catch can between the valve cover and a vacuum source if you want vacuum on it. The way you have it set up, it's just venting to atmosphere, which works, but having vacuum is best.

Often for a turbo setup, rather than just a filter, I will go from the valve cover, to catch can, to the pipe between the turbo and filter (not much vacuum there, but will have some) - or have even done a slash cut at the exhaust system to create a venturi effect.

So, in short, no, you don't need any kind of PCV valve.

Would have to read back at what camshaft you have in there, but 150 is a little low for a stock cam/compression. Just did a comp test on a 9.5:1 m20 with 272 cam here at the shop and it's 180 across the board (cam is also a few degrees retarded). Moreso, wonder why you got 140 on #2.
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Old 04-01-2019, 05:45 PM   #1205
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Hey 'Bird

Thanks for chiming in. We don't need no steenking emissions control so I'll leave the catch can as is, LoL.

Cam is a Schrick 284/272
---lift 11.4 mm intake / 11.0 mm exhaust
---EO -246, IO -32, EC 26, IC 252 deg
---Intake / Exhaust overlap 58 deg

I'd have to go back to my spreadsheet & see how those specs compare to stock. I'm guessing valves open longer could lower compression.

No idea on #2. Rings are new, maybe that cylinder is taking longer seating?
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Old 04-02-2019, 06:50 AM   #1206
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Yeah, your cam is bleeding pressure at low RPM, your cranking pressure is good if you have the stock 8.8:1.

PCV is not for emissions (originally), it was to bleed off positive pressure in the crank case (positive crankcase ventilation). In a running engine, combustion gasses leak past the rings and eventually fill the crankcase with pressure. This blows out gaskets as well as creating more resistance for the piston travel. If you think about how fast a piston moves up/down in an engine, air resistance gets serious. If you have perfect vacuum in an engine, then you eliminate said resistance. So, right now you have PCV, but, vacuum would be better.

There have been many trials for crankcase vacuum, here's a quick link from a Google search...

https://dsportmag.com/the-tech/quick...essure-part-1/

In the old drag racing days, slash cuts were used in exhaust systems, but once sound ordinances came about and mufflers were required, the back pressure limited the venturi effect, hence companies like Moroso developing belt-driven vacuum pumps.
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Old 04-02-2019, 08:31 AM   #1207
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Good post John. I get it. Will look at re-engineering the catch system.

I think it looks like this: Hose from valve cover to one side of catch can, then from other side of can to intake. No filter on the can. Will pull a bit of vacuum on the head, but catch any oil that wants to blow out to the intake.
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Old 04-02-2019, 09:07 AM   #1208
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In a turbo setup, you will want the hose going to the intake side of the turbo, or, have a check valve of some sort...otherwise you will send boost into the crankcase.
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Old 04-02-2019, 10:41 AM   #1209
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In a turbo setup, you will want the hose going to the intake side of the turbo, or, have a check valve of some sort...otherwise you will send boost into the crankcase.
Maybe he meant throttle body? I don’t know anything about turbo set ups and i get that the intake is pressurized, is there a throttle body?
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Old 04-02-2019, 06:57 PM   #1210
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No. He meant tap between turbo intake filter and turbo compressor to pull some vacuum.
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Old 04-03-2019, 08:23 AM   #1211
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I just added a catch can to my NA car and in my research it echo'd everything Bird said, a little vacuum helps the VC ventilation to work properly. But it will work ok vented to atmosphere.
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Old 04-04-2019, 05:54 AM   #1212
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I think it looks like this: Hose from valve cover to one side of catch can, then from other side of can to intake. No filter on the can. Will pull a bit of vacuum on the head, but catch any oil that wants to blow out to the intake.
Right. I meant "other side of can to intake between air filer & turbo compressor" not the intake manifold. Boosted catch can would not help performance LoL.
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Old 04-09-2019, 07:02 PM   #1213
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Finally got to the last bit before dyno time.

One inline fuse for the boost solenoid


Added a connector to the solenoid in case we have to swap it out


Turbo blanket on and boost controller wired up


Yeah. We really had to do this. Boost control solenoid gets wired into the Megasquirt option connector and a switched 12V supply


Fortunately we're good at it now. Bulkhead back together


And dash re-installed


Started it up and let the engine reach operating temp. Idles great, even without an ICV.

We're ready for the tuner. Going to drop it off on Friday.
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Old 04-09-2019, 10:09 PM   #1214
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Cant wait to see the results of the work!
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Old 04-10-2019, 07:21 AM   #1215
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Don't you just love those "third hand" clamps for soldering?
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