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

[gman915us]

After my winter build project of a brand new LT1 Forged 1000HP build (C7 Z-51) with the below parts; all balanced down to 1 gram by our local top race engine machine shop (Moffit and Bratton). We are getting what we believe is false knock at higher RPMs on the dyno that is pulling all the timing (10-12 degrees). Car sounds and runs great, but we are having this constant knock issue. They chased the usual long tube header issues, looked for anything loose or touching, changed plug wires, inspected spark plugs, changed out fuel to Sunoco 260 + only to eliminate bad fuel or octane issues, and started to desensitize the knock tables for the LT1 (currently at 12.9). Please help!

My Build:

Magnuson Corvette LT1 TVS2650 Supercharger System with the 103MM throttle body (90mm upper w/DSX 15% lower 9.25)

Nick Williams 103 MM Throttle Body

RotoFab Big Gulp 5-inch C7 Z06 CAI

ARH Long Tube Headers 2 inch into a 3-inch X-pipe with high flow cats. Kept the NPP setup

Mighty Mouse catch can crank breather Wild -C7 10B.R Wild 10AN

NGK LTR7IX-11 Spark Plugs gapped at .28

Hinson 2500-degree Spark Plug wire boot protector for LT

BTR Gen V 180* Thermostat SD180LT1

GPI Drop-in Forged 10.25:1 Diamond Pistons with 6.125 Callies Compstar H-beam rods (CSC6125DS2A2AH)

Clevite - MAHLE Main Bearing Set GM/Chevy 2014+ Gen V 6.2L (L86/LT1/LT4) with Standard Size (Coated)

ACL ? H-Series Standard size rod bearings (Calico Coated) GPI-8B663H-STD

BTR Supercharged Stage 2 Cam Grind BTR227-354-242-348-15+6 +38%FL

BTR LT1 .660 Platinum Spring Kit with Titanium Retainers SK007/0560/BB

BTR trunnion upgrade kit for LS7 and Gen V LT1/LT4 A6200+24200-16

Chromoly One Piece Pushrods, 3/8' diameter, .080' wall, 7.850' length

LT1 DOD Delete Gen V DOD delete kit, Oil block off plugs, GM performance head gaskets, valley cover gasket, Johnson 2110R lifters set of 16P header gaskets, lifter trays

LME solid timing gear conversion with billet chain damper and billet timing cover. Removes VVT

Katech C5R HD Timing Chain

ARP HD Head stud kit 234-4343, ARP HD Main Stud kit 234-5802, ARP HD Flex Plate Bolts 234-2902 ARP HD Cam Sprocket Bolts 134-1003

OEM GM LT4 high pressure fuel pump (12694529) 12711668

OEM GM LT4 fuel injector (19420801 kit)

DSX Tuning low side fuel system for C7 Corvette 255 GPM Pump DSXC7AFPK

DSX Flex Fuel Sensor for C7 LT1 to run E-85 DMS-C7STINGFFK

OEM LT4 Engine Oil Pump - GM (12686435)

GM ? Chevrolet Performance GEN V LT4 Multilayer Head Gaskets 12654622

GM ? Chevrolet Performance GEN V LT Valve Cover Gasket 12619787

GM ? Chevrolet Performance GEN V LT1 Exhaust Manifold Gasket 12657093

GM ? Chevrolet Performance GEN V LT Water Pump Gasket 12657430

ATI Super Damper 917315 Dry Sump

DSX LT4 Lower Pully 235MM (9.25-15% OD)

GRIP TECH Upper 90MM

Harding Performance Billet Valve Covers with coil relocation. Dry Sump

TSP 10MM 30 OHM per foot Spark Plug Wires (Red) with heat boots

HD Tuners RTD (from Magnuson) with two Credits for ECU and TCM Forced induction GM calibration, 8L90E Transmission Calibration

[GHuggins]

A lot of things cause knock retard on a 5th gen. Without a tune it's hard to say anything. Basically if injection timing is too close to spark, it'll cause it. If the torque model isn't right - it'll cause it. If timing is too low, it'll cause it and on and on. Put a stethoscope on the engine - electronic - and do a pull. Do you hear anything? No - go from there. Hate to say it, but something could have been measured or set up wrong during the assembly, but if you don't hear anything..... Plus why did you delete the VCT? Big mistake on that one for this build unless it's just required for that particular cam

Also hate to ask this, but does the shop doing the tuning actually know what they're doing?

For what it's worth - nearly identical built lt1 with variable cam timing and less boost. This was before dialing in the density table and was running lean up top after it got hot. Would hit around a 13afr at this point while targeting 12.5ish. Only recommend doing that with forged internals... Otherwise let off quick.

[gman915us]

I'm fully forged and at 10.25:1 compression. The BTR Stage 2 Supercharger cam requires phaser lockout, so I did the sexy LME front cover with the LS3 seal and solid pinned timing gear. If it's not a chassis or exhaust rattle that the knocks are picking up, then I'm thinking there might be a little too much preload on the LT4 HPFP or the slop in the timing chain with the LME billet timing chain guide. How much did you have to desensitized your knock sensors after your Maggie build?

[GHuggins]

That was a customers car that vengence, lsxperts and 2 others had already worked on and couldn't get right for the guy. Nearly identical build to what you listed changing a thing here and there.

Highest knock setting was 8 on all cylinders except for cyl 1 which was running 6.5 It's running lsxperts ground pounder cam or whatever they called it.

[DannyC]

I am no way an expert tuner but I'm learning. I had some false knock with the Magnuson 2650 and after talking with some tuners I reduced the sensitivity of the knock sensors, just a little. Apparently, the SC adds some harmonics the knock sensors pick up.

[gman915us]

I am no way an expert tuner but I'm learning. I had some false knock with the Magnuson 2650 and after talking with some tuners I reduced the sensitivity of the knock sensors, just a little. Apparently, the SC adds some harmonics the knock sensors pick up.

They reduced by 12.9 percent already which is a lot. This car is loud with the long tubes, but the engine is smooth (no ticking)

[gman915us]

So they finally used a stethoscope and found the engine is just fine. The false knock is coming from somewhere else, so they will use the PLEX knock sensor to tune the car to be safe. If anyone else has delt with the false knock at higher RPMs please share. I still need to track down what is vibrating. lol
Attachment 130313

[Camaro6]

You will see false knock for airflow tables not correlating, tq tables being improperly messed with, airmass numbers exceeding your allowable parameters, improper iat2 temp reading, there are a slew of things that will limit the vehicle and pull timing to get it into a safe parameter (as the tune is making the ecm do this). Remember, its just a computer and doing what its being told to do. Knock sensor parameters need to be raised in these vehicles as well with consideration to what is installed. I would dump the NGK plugs personally and run Brisk RR12S gapped at .020-.024 You can DM me the tune and log for review.

[gman915us]

UPDATE: I went and picked the car back up and readjusted the pushrods, HPFP lash and found where the high flow cats were still rubbing the belly plate. Kind of disappointed in the performance shop that gouged me on the exaggerated 10 hours of labor looking for it, putting my car on the rack 3 separate times yet found nothing; I found it in less than 30 minutes of looking and it wasn't hard and fixed it myself. I took it out yesterday to log for the shop and only saw a small brief knock at 4K of 2.5. Car is still on their safe tune with Sunoco 260 to ensure we have no detonation due to octane. Also, I'm trying to see why my oil pressure seems a bit low. I'm currently using Driven BR10-40w until it's broke in (still less than 100 miles at this point), then onto the 0-40 Mobile 1. Bearing clearances are as follows for my DD: Mains, .016, rods .021, end play .006. My oil pressure stayed around 30 psi most of the time, but would jump under harder acceleration, then drop right back down while accelerating. Once the car was hot and I pulled up to a light, it dropped to 20 briefly then came back up.

How do you attach a log file in here?

[GHuggins]

To attach files - Go Advanced - Manage Attachments. As long as you have good internet it should work. Otherwise if a file is too big you'll have to trim it down in the scanner and save the trimmed file and attach that. To trim a log file - export log file - hp tuners - visible field. Then whatever you have highlighted will be saved under your new file name and able to load from that point as long as it's small enough.

You sure about those bearing clearances? That's WAY too big. Sure the decimal place is right?

[gman915us]

Here are the attached files. The false knock is significantly less now. Just want to make sure on the oil pressure. If I stab it a bit it jumps up then comes right back down. But when hot it dropped to 20 at idle. Should I be concerned?

[gman915us]

Sorry, screwed up the decimal places. Mains = .0016, rods = .0021, and the end play was .006

[GHuggins]

You might want to call your engine builder. Seems low to me, especially if those are your real clearances and not just some that were made up... Majority of oil pressure actually comes from cam bearing clearances - I assume new bearings installed there too?

I'm almost questioning everything the shop did at this point. If a stethoscope was installed, it would have picked up the knocking as sound travels as could be seen by the sensor picking it up.

[GHuggins]

Just for more reference. Pretty sure that nearly same built engine in the log above was running 30 weight - it was building 51psi in that log. Had about the same at idle, but more with rpm which yours running 40 weight should be doing more than that. He "may" have had 40 weight, in which case it would be within 6psi for the most part to his... Either way, you might want to talk to your engine builder just to be sure.

[gman915us]

My oil pressures were within spec on initial startup, and the dyno shop (Kaizenspeed) just wanted to up the oil weight to build a bit more pressure because they thought it was a tad low for their taste, but told me there nothing to worry about. It's a brand new OEM LT4 pump. Yes they should have used a stethoscope to isolate the noise immediately when it was on the Dyno in Washington for a week, but I got it sorted out. I built the engine myself less the machine work which was done by a reputable shop; I documented everything during the build filling a 4 inch thick binder and have literally thousands of pictures of the build. Was trying to attach them earlier for you. Did you get a chance to look over the attached log files?

[jlaudio11]

My oil pressures were within spec on initial startup, and the dyno shop (Kaizenspeed) just wanted to up the oil weight to build a bit more pressure because they thought it was a tad low for their taste, but told me there nothing to worry about. It's a brand new OEM LT4 pump. Yes they should have used a stethoscope to isolate the noise immediately when it was on the Dyno in Washington for a week, but I got it sorted out. I built the engine myself less the machine work which was done by a reputable shop; I documented everything during the build filling a 4 inch thick binder and have literally thousands of pictures of the build. Was trying to attach them earlier for you. Did you get a chance to look over the attached log files?

Has the oil pressure dropped from initial start up? Did you properly align the oil pump when installing?

[gman915us]

It's about the same. It's a brand new LT4 pump so to my understanding, you don't need to use the alignment tools. They are needed for a used pump to ensure it goes back to the way it exactly was for the wear patterns.

[gman915us]

Someone @ TSP had mentioned that it's either the DOD plugs or the o-ring valley cover that goes in during a delete, but not both; or it can bleed off pressure. I currently have both in; I just drilled a recess into the valley cover to have both the o-rings and DOD to make sure it sealed. Has anyone else ran into this issue? Thanks

[gman915us]

I'm so lost with this stupid car......

I pulled the SC for the third time now and inspected everything in the valley. All DOD plugs are still in and I even added a smaller O-ring inside of the new oil pressure switch for a tighter seal. On first startup, oil pressure is at 34.8, but when the temp hits 200+ it drops considerably down to 24 psi. And sometimes when the car comes to an idle, it drops to 20psi briefly then comes back up; I think that's the idle dropping low for a second. But it doesn't maintain a high boosted oil pressure when you get into it. It just spikes to 40+ then comes back down even if you are still in it. Should I put 15W15 in instead of the 10W-40, or just pull the damn motor and swap out the brand new LT4 pump? Here is a log from the free way on the 91 tune with Lucas oils octane boost; maxed the knock again and oil pressure is still scary low for my taste. I rolled into it pretty hard from 80 mph to 115 mph. Please take a look at the log and tell me what you think. The MAP pressure hit 176.4 with 14PSI of boost which I think seems way too high possibly creating the knock; the VCM software gage maxes at 110. Is that a tuning issue to drive it up that high? My IATs were somewhat crazy this time. I bled the lower Cordes heat exchanger to where it?s only fluid coming out, but my IATs are really high now. How do you bleed the TVS2650 up top with no valve? Can anyone determine anything from the log?

[gman915us]

Log