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

[GHuggins]

You say you have a 10.25:1 compression ratio - is this dynamic or static? Either way timing is way too low in that log where it's showing knock and I'm almost willing to say that as long as you have all of the rattling taken care of that the low timing is your problem. It looked like you were only running 5 to 8 degrees in that area before timing was pulled.

I haven't been into a lt4. Do they still use the restrictor plug in the back of the block and was this reinstalled after machining? Unfortunately the engine would have to come out to even check this, but your bearing clearances are showing that it should have that pressure and slightly more on 30 weight.

Simple enough you can always drain and change the oil to see if it's full of metal - if not then most likely somethings missing or bleeding off.

[gman915us]

You say you have a 10.25:1 compression ratio - is this dynamic or static? Either way timing is way too low in that log where it's showing knock and I'm almost willing to say that as long as you have all of the rattling taken care of that the low timing is your problem. It looked like you were only running 5 to 8 degrees in that area before timing was pulled.

I haven't been into a lt4. Do they still use the restrictor plug in the back of the block and was this reinstalled after machining? Unfortunately the engine would have to come out to even check this, but your bearing clearances are showing that it should have that pressure and slightly more on 30 weight.

Simple enough you can always drain and change the oil to see if it's full of metal - if not then most likely somethings missing or bleeding off.

GHuggins,
First and foremost, thank you so much for your help and expertise on this. After digging deeper I found that I may have been chasing nothing after all with the oil pressure. The LT4 minimum specs are 6 PSIG @ 1000RPM, 18 PSIG @ 2000 RPM, and 24 PSIG @ 4000 RPM. I cut open the filter to look for metal shavings and it still looks new (only minimal normal break in metal). I disconnected the oil pressure control solenoid on the front cover and it immediately jumped to 52 PSIG and stayed; this was read cold. It will bleed off 10 PSIG when hot, but I found 90 percent of this issue is attributed to the 2110R Johnson lifters. Many others are experiencing the same thing, with a 6 to 10 PSIG drop in oil pressure when they use the Johnsons. I called Johnson to talk about it and they said they never bleed down, but forum after forum states otherwise. In hindsight, the LS7 lifters would have been a better option for my daily driver. Since I don't want to crack open this motor again, I'm just going to install the Katech performance dry sump pump and be done with it. It runs about 20 PSIG higher at all RPM which will give me a better piece of mind. It should be here tomorrow and I'll keep you posted on that front.

Your comments on timing is concerning me with my tuner. The 10.25:1 is the static from the GPI kit (https://gwatneyperformance.com/produ...n-rod-package/) For your restrictor comment, are talking about the dumbbell that is installed at the rear of the oil galley? If so, it was installed with new. The last log file I sent was on sunoco 260+. This one is their next tune file for pump but I saw knock again. I'm on 91 Chevron with Lucas oils 3 point octane booster and am seeing knock in the 3800 to 4200 range only under spirited acceleration. I fixed the exhaust rubbing on the belly plate (well more like grinding on the belly plate), readjusted the push rods, and relashed the HPFP to minimize the false knock. Can you please take a look at the log and tell me what you think I should do?

[GHuggins]

There's one place in the middle of the log where you're tipping in at 3800 rpms and only running 6 degrees of timing - it automatically senses knock and starts pulling timing. It may even be overly rich here - I don't see a wideband - not sure how they're adjusting fueling without one? Then lets take a look later in the log - 4300, you're hitting boost - 10 to 9 degrees of timing - no knock. Too low of timing and too rich can just as easily cause knock and timing pull as running too much timing. You should be down around high 9's with dynamic compression and I don't see a reason why you shouldn't be at least in the very low teens timing wise just for dialing things in. You should only see single digit timing numbers at full boost less than 22 or 2400.

The filter really needs to be pulled apart, but it looks good. I wouldn't worry about things coming apart. Sounds like you figured it out with the lifters. Don't believe I've seen them cause that much of a pressure drop, but anythings possible. Timing is best to dial in on the dyno - thought they already did this? Several things can cause timing to be pulled as previously stated by many, but the low timing is the big one standing out right now.

[gman915us]

There's one place in the middle of the log where you're tipping in at 3800 rpms and only running 6 degrees of timing - it automatically senses knock and starts pulling timing. It may even be overly rich here - I don't see a wideband - not sure how they're adjusting fueling without one? Then lets take a look later in the log - 4300, you're hitting boost - 10 to 9 degrees of timing - no knock. Too low of timing and too rich can just as easily cause knock and timing pull as running too much timing. You should be down around high 9's with dynamic compression and I don't see a reason why you shouldn't be at least in the very low teens timing wise just for dialing things in. You should only see single digit timing numbers at full boost less than 22 or 2400.

The filter really needs to be pulled apart, but it looks good. I wouldn't worry about things coming apart. Sounds like you figured it out with the lifters. Don't believe I've seen them cause that much of a pressure drop, but anythings possible. Timing is best to dial in on the dyno - thought they already did this? Several things can cause timing to be pulled as previously stated by many, but the low timing is the big one standing out right now.

Before I head back to the dyno, I'm changing out the Johnson lifters for the LS7, and the oil pump to a Katech to give my nerves a break. lol I'll let you know how everything goes.

[GHuggins]

Only seen it once, but make sure nothing under the blower is touching too

[gman915us]

Thanks.....Supercharger has nothing that can touch under it (been off 3 times in the last 60 days lol). Which wideband do you recommend? I have the ARH 2" with high flow cats so 4 total O2s are currently on it. Should I place it in the spare single bung, or in one of the current O2s?

[GHuggins]

As long as the spare is precat use it. I always recommend the aem OBD 2 wideband.

[silverbullet08]

Interested in hearing your findings after swapping the lifters. I had a different experience with my personal car with the Johnson lifters. I had LS7 lifters in a fresh build and had no oil pressure problems, swapped to some aftermarket heads and new cam so decided to swap to 2110r at same time. Didn't have any issues with oil pressure then either. One of the heads had a crack in the exhaust runner so I pulled them and came across a steal for a set of the ST2126LSR tie bars, figured I would be turning it harder and may as well go for the best. With the tie bars oil pressure was lower by about 8-10psi. It did maintain about 34-38psi idle and made 65-68psi at wot. After the tie bars it idled at 26-32psi and peaks 58psi at wot but holds about 52-54psi during a run.

It would be nice to be able to log the DC to the oil pump control solenoid. Would also be nice if we could have control of when the ECM commands high/low situations. May be beneficial to some of the more dedicated track vehicles or more wild engine builds running heavier/lighter weight oils and different block materials.. hmmm

[gman915us]

Interested in hearing your findings after swapping the lifters. I had a different experience with my personal car with the Johnson lifters. I had LS7 lifters in a fresh build and had no oil pressure problems, swapped to some aftermarket heads and new cam so decided to swap to 2110r at same time. Didn't have any issues with oil pressure then either. One of the heads had a crack in the exhaust runner so I pulled them and came across a steal for a set of the ST2126LSR tie bars, figured I would be turning it harder and may as well go for the best. With the tie bars oil pressure was lower by about 8-10psi. It did maintain about 34-38psi idle and made 65-68psi at wot. After the tie bars it idled at 26-32psi and peaks 58psi at wot but holds about 52-54psi during a run.

It would be nice to be able to log the DC to the oil pump control solenoid. Would also be nice if we could have control of when the ECM commands high/low situations. May be beneficial to some of the more dedicated track vehicles or more wild engine builds running heavier/lighter weight oils and different block materials.. hmmm

After talking to Joe Lewis from Johnson and some concerns about running the 2110SLRs with a cam above .630 lift, (apparently they can come out of the trays or turn in them) I decided to play it safe. I remove the trays all together and went with the 2116SLR link bar lifters, and a Katech Dry Sump pump to keep pressure up. I'm at 33PSI at idle, and over 70PSI above 2500RPM. Now back to the dyno.

[gman915us]

Made 800.3WHP on 91 Pump and 654WTQ. The torque seems a bit low for a Maggie 2650 but it may do to the hub dyno vs the rollers.
Small Dyno Results 2016 C7 Z-51.jpg

[will_974]

I havent followed this fourm close

But there are Noise Threshold Knock Tables Per Cylinder that exist.
EFI live has them defined.

I have located them, and can provide xdf files forthem if desired.
As well as adjust them to LT4 values.
I do not know if it will fix the issue, but The LT4 Tables are much different in expected noise levels than the LT1 vehicles from the factory.

On my setup, I was able to remove the false knock i was getting under boost using the LT4 values on the noise threshold tables.
I can locate them for you

[gman915us]

Thank you for your help. The false knock in my situation was being introduced two ways, one through the ARH 2" into 3" xpipe that was hitting the belly plate with the green cats, and the driven rotor rattle in the Magnuson 2650b which both have since been fixed. So, thankfully I no longer have any false knock.

[GHuggins]

Might not be a bad idea to have those updated especially if they just killed the other settings again. That way at least you have some protection.


Did magnuson rework the blower for the rattle?

[gman915us]

GHugginsd,
Yes, it went back to Magnuson and they put in a new rotor set. Since then, I was chasing what sounded like a belt chirp at idle that turned out to be excessive vacuum from the TVS-2650 that was pulling in air from the front crank seal. Once I got the 6AN restrictor/adapter from MM, that went completely away, but now I have an intermittent surge at idle when your foot is on the brake and you put the car into gear (A8). It dips RPMs then tries to correct itself and makes a surging sound once or twice then settles back to a normal idle. You can watch the BOR on the Maggie open then close when it happens.surging hard 10 september.hpl

[GHuggins]

You really don't want to hear what I have to say about that log, but the torque model for one, VE is 20 to 40 % overly rich, O2's go through some sort of failure when the rpms settle and they stick 20 percent too rich and your density table and/or open loop tables are off not to mention it'll need some idle setting finessing. From what I've been seeing they'll use the open loop tables for added fueling on top of the density tables fueling until O2's past their test. Makes it harder to dial in as you have to dial the open loop tables in off of each initial start when you know the density table, VE and MAF are right, but it is possible.

Crankcase vacuum shouldn't exist if it was plumbed correctly, so that's a little confusing. Best to post a pic of hoses on that one.

[gman915us]

8 April 2024 Surging.hplTerryGullickAugust2023-V10.hpt

Sorry GHuggins, was chasing one thing after the next on here for the past 6 months. Squeal turned out to be the Mighty Mouse catch can pulling too much vacuum through the front main seal that a restrictor from MM fixed. But then my idle started to surge because of vacuum issues. I just ordered VPMs low vacuum BOV to try to fix it, but what do you think I can do with the tune to clean it up? I finally have the HPT file pulled and one of the latest logs that has the surge. Vacuum goes down so low the spring in the BOV overcomes it and closes causing the surge. Car smells rich too. All issues are at idle. Everywhere else it runs fantastic.

[gman915us]

8 April 2024 Surging.hplsurging hard 10 september.hpl

[GHuggins]

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 underhood pics specifically showing the valve covers and where the ventilation hoses are going.

[Camaro6]

One look at that log and willing to bet anyone that it's tune related. That surge issue I see all too often. Look at your timing drop so far because the tune isn't correct. If you put your foot on the gas pedal ever so softly and apply throttle little by little (VERY LITTLE), it will idle steady correct?

[edcmat-l1]

If vacuum is causing a seal to whistle then there is no crankcase air "IN".