HELP!! - Gen V LT1 Build with Maggie 2650 False knock above 4000 on the dyno

[gman915us]

I think the tune file is what's missing - not the log. Just says it's translating it when I try to open it. Never seen that before.

It shouldn't be pulling that much vacuum on the can. Post some engine and under hood pics specifically showing the valve covers and where the ventilation hoses are going.

Look two replies up, I have the HPT file there. If it's still giving you fits, shoot me an email I can send it to directly if you're ok with that? Thanks

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[gman915us]

Forgot to mention, The dry sump has vacuum drawn from the CAI, and I'm running the MM restrictor to the SC to limit vacuum, so it doesn't pull air in the front main seal. It's a common problem with the 2650s on the Gen V LT cars apparently. But mine definitely had the issue.

[GHuggins]

Do you not have a valley port?

Normally, it's valley port to catch can, then catch can to behind TB in the SC. Then valve cover to intake pipe post MAF in the airflow measuring process. I honestly don't remember if the dry sump setups have the valley, but the way you have it, it's pulling "hard" vacuum on the crankcase with not really much of a chance of fresh air to go in other than the filter and orifice on the MM catch can - this is why you were hearing the whistle. This is also a roundabout vacuum leak.... When plumbed right, you shouldn't have super high vacuum on the crankcase as that can actually get into the territory of starving splash lube items.

[edcmat-l1]

If it's making the seal whistle there's no crankcase air "in". Simple as that. It's drawing vacuum on the crankcase. It's pulling air past the seal. That's what makes it whistle.

[gman915us]

Maybe I didn't clarify my statement, but yes, I had too much vacuum being pulled by the 2650 plumbed exactly the way the mighty mouse instructions wanted it and was getting the intermittent squeal only at idle. That's why MM makes the restrictor for the bigger superchargers between the 10AN wild catch can and the SC just behind the TB. I no longer have the squeal since adding the restrictor last fall. But I am concerned about the fresh air supply to the engine. Kaizenspeed had me kill the valley vent to the SC snout after the TB, and plumb each valve cover to the catch can to improve vacuum at idle to keep the BOV fully open. I additionally have the passenger side valve cover plumbed to the drysump tank the way it was stock, and the dry sump has a line that goes to the CAI that should be the fresh air side of the system.LT4 Dry Sump flow.jpg