Advanced Engineering Tech - sparatic oil pressure drop under load, lots of information given..need advice!!!

ok for starters i'm going to post up the mods list of the motor that i'm dealing with in particular.

2000 f-body ls1
asa cam, .550 lift
beehive springs
oem lifters
manley pushrods
c5r timing chain
melling 10296
probe pistons
eagle rods
chevy mls hg
arp mains
clevite's "race" bearings
gto front sump pan setup
3qt. high pressure accusump with manual valve

thats about it as far as parts that could be related to my problem minus some of the valvetrain parts...

i'm gonna type this up the best i can but no promises this is gonna make sense...

stage 1 with my motor, it spun a bearing at a drift event in st. louis, i replaced bearings on track, spun the bearing(s) again. done for the weekend, time to go home.

get home and have it rebuilt, at this point i pull all the stops and use eagle rods/probe pistons/full MLS gasket setup/arp mains/melling 10296/rollmaster dual chain (previously installed)/ cam and springs. engine shop sends me spec sheet and its right on point with all the research i had done. mains are .0023/.0025 and rods are .0025/.0027.

now, this setup had problems from the get-go. the melling 10296 was nowhere NEAR close to fitting. we did the typical housing machining but it just wasn't close at all. if you trimmed the timing chain cover or the oil pump cover down enough to where it fit you'd either hit a passage or put a hole in the timing chain cover. this was 2 nights before an event, so of course we got creative. we took the new gear from the 10296 pump and put it in my old 10295 housing after having it precision machined down to the .0001" of the width of the old 95 gear. from there assembly went great as did startup. motor built pressure correctly and temps are good as were the hg seals, no mixing. However, when we went to do our break-in test drive i notice my oil pressure stumbling. it wasn't consistent, had nothing to do with temps...or gravity. it was when the motor saw load or a hard punch in 2nd or 3rd, oil pressure would stumble down to around 36 psi then catch right back up. it didn't seem to mind 1st gear so much, more-so 2nd and 3rd...i haven't gotten to rip on the car much beyond that. we figure, totally shitty non-detergent break-in oil was the cause, so...new synthetic oil and filter in...same business.

so we've put the car aside while i order a new pump to eliminate the possibility of the gear we milled down being faulty. ANOTHER 10296 and a single row c5r chain to guarantee its fitment. We put it together this weekend with all new gaskets and o'rings and got fresh oil in. same exact problem right off the bat. i'm so lost, this pump was primed properly and installed properly and torqued to spec. we were careful not to pinch the pickup tube o-ring, i pushed it in carefully by hand before i tightened the bolt. so we step back for a minute and look at the big picture. motors built to spec, new pump, problem CANT be internal. i was told when i very first built this car which sides were in/out on my canton filter relocation kits. never thinking to double check (since a reputable shop had told me) i just installed it how they said. turns out this was my configuration all along...

engine out to oil cooler in, oil cooler out to remote filter "out" port, accusump being fed off "in" port of remote filter and finally oil filter "in" going back to the engines "in" port

yeah, it was incredibly wrong, i know. so we figure from there lets redo the AN line configuration. I got it all 100% based on quadruple-checking canton's site. SAME THING. accusump is more responsive now, as-is oil pressure. but the numbers didn't change much. then i eliminated the oil cooler thinking it MUST have bearing pieces and break-in bearing material in it. that didn't change anything. then i eliminate the accusump and the remote filter, put an 04 gto filter right on the pan. again, this was with the thought process that my accusump is probably ruined from having 3 sessions of serious catastrophe's on it with unfiltered oil the whole time. we bumped the oil weight up as well and went to 20w-50. first time i went out to drive it, nothing! the defi's recorded remarkably responsive pressure with just a little stumbling (but i feel this is from the cars stiffness as my tach did it a tad as well). i finally decided its time to take the car for a bit longer of a test drive, about a mile and a half to be exact. got on it a little harder and drove a little faster/gave the car different conditions. everything seemed fine. but the problem is, now my cars doing the exact same thing! oil pressure dropping as i'm giving it a certain percentage of load. only...its doing it more now!

none of the oil has shown any signs of extreme wear or any bearing material minus the break-in oil change which had the usual amount. when we first noticed the psi drop issue we immediately went to mechanical gauge which reflected exactly what my defi gauge did, so i know thats exact. we are sourcing our oil pressure from the oem location with a remote mounted sensor being fed from a -4 AN line.

I need realistic answers, I've been checking my oil levels constantly, I've done all my tests with and without my accusump on. I don't have a podunk oem gauge sensor feeding some obdII reader, everythings been exact readings (minus the ability to datalog, only record and playback on my gauge setup). Please don't leave me with generic answers. I am going to TRIPLE check my oil pump pickup tube o-ring this weekend, but beyond that...everything not internal or bearing related has been checked to the best of my knowledge. I'm running out of ideas and I need more opinions towards this particular situation.

Thanks in advance for your help!

http://www.gmhightechperformance.com/tech/0608htp_ls1_engine_build/index.html
http://www.gmhightechperformance.com/tech/0701gm_ls1_engine_build/index.html
http://www.gmhightechperformance.com/tech/0609htp_stroker_build/engine_covers.html

oil galley barbell restrictor would be my first guess, replace it with a new one.
the links above may help.

you mentioned you used non-detergent motor oil for break-in, what brand/weight of oil did you use? was it API-SB rated? what was the rationale for using non-detergent oil?
for oil, the smart thing is to not use a synthetic, i'd say 50% of the reason is for piston ring seal (has nothing to do with your oil pressure issue) and the other 50% is cost. Synthetic will gain you nothing in protection during break-in. During break-in, the engine conditions are controlled, you won't be overheating or overloading it, and you won't be starting it in -20F weather. what you do want to happen is wear between the piston ring and cylinder wall, and synthetic is believed to prevent wear more so than conventional oil. The other thing is cost, you'll be changing the oil 1 or 2 times right away so why spend the money on synthetic when you don't need it.
As for non-detergent oil, which all i am aware of is API-SB rated stuff on store shelves, unless you bought some uber high-end brand stuff that's specifically formulated for break-in, an API-SB rated oil is not for modern engines, it's typically marketed as non-detergent but that rating also means it falls far short on anti-wear additives like ZDDP which is paramount in break-in... that's what GM engine oil supplement is and is used for engine break-in (primarily for flat-tappet camshafts which you don't have). So using a non-detergent oil, unless it was something else i don't know about, certainly isn't helping things.

only other thing i can think of and i'm not that knowledgable about accumulators or what you have and how it is set up, is when you say pressure drops to around 36psi then catches back up, is the valving on the accumulator being faulty or maybe not working right, it sounds like the accumulator is filling- that'll be an empty space so your pressure will drop as that 3 quarts or whatever fills and pressurizes equal to the 50+ psi or whatever you were running, but you say you have the problem without the accumulator so that throws this thought out the window. could you explain better how the oil cooler and accumulator is plumbed in, where do you pipe into the oiling system on the engine? Is it the fitting on the block right above the oil filter? And how is that oil returned to the engine?
also, when you say you eliminated the oil cooler thinking you had bearing "pieces" in it, break-in should not generate pieces of anything. Any wear material will be so small that the oil filter won't catch it, which is why it is recommended to do an oil change, and also to use a "detergent" oil (a.k.a. regular motor oil these days API-SL/SM). The detergents keep that microscopic material in suspension in the oil so when you drain the oil that material leaves the engine, as opposed to not being in suspension and laying on internal parts like the cylinder head, bottom of the pan, etc. I doubt the non-detergent oil was your problem, unless you had enough hours on it to where you started generating enough wear and contamination and if the oil got hot enough started leaving sludge, possibly causing the barbell restrictor to stick maybe, just speculating. these would be specific things to look for when you tear into the motor. other than that, only other thing i can think of to cause a pressure fluctuation is the oil pump, either air entering the pump if the pickup is not low enough or not enough oil in the pan, or the o-ring not sealing and drawing air in there.

I don't know if this helps. My shop told me not to run Oem lifters. They said they had oiling issues. There not the best for build ups. Maybe when you combine the Oem lifters with certain after market mods you get problems out of them. I'll ask them today.
If you think about it when you cold start some factory 6.0 it knocks until it's warm or when the motor is under load. I never cared about it before I thought it might have been spark knock. Maybe the motor is starving for oil.

thanks very much for the in depth information 1 FMF! we're going to look into that barbel and for sure swap in a new one when the block comes out. before we pull it we had planned on measuring the pickup location (height) once the pans off and checking the oil pump pickup o-ring as well, what would you particularly like to see if you were measuring the clearance between bottom of pickup screen and pan? The pump is new as of saturday and the non-detergent oil was only in the motor for mayyybe an hour of break-in...if that. we referred to a more abusive heavier load break-in style so we knew it'd be for a very short period of time, hence the cheaper oil. its a shame that we cannot simply pull the transmission to get to the barbel, the 240sx tranny tunnel is very very compact and requires a good bit of hammering.

rundeep66, i have also heard the same. i was planning on tossing in caddy lifters for the time being but couldn't find anyone local with them in stock before the motor had to go back together. i now feel like i should've waited as that could've definitely eliminated one of our oil loss possibilities!

pickup screen to oil pan clearance is traditionally been 1/4" to 3/8", fairly tight. Up to 1/2" is generally acceptable and 3/4" is the most amount of clearance you would want to ever run. This is on a SBC, I'd imaging the LS1 is no different. Most of it has to do with the pan depth, and how high the oil is in the pan when engine is running and also when in turns or under acceleration. What just occurred to me since you mention this is you have a high volume oil pump, if you have too high a pickup tube (not close enough to the bottom of the pan) and don't run a full 6+ quarts in the stock pan it may be possible under certain conditions to suck air. don't know if you can do it now, but idle the engine at 2000-3000 rpms then shut down and quickly check the dipstick, if it's low then you may be sucking the pan dry.
Someone correct me if i'm wrong but general practice on a stock LS1 is to overfill it to 6-7 quarts to prevent oil starvation if on a road course and the engine is seeing high lateral g's. The reason for locating the pickup as far down as possible, not so much so the oil level never drops below it, but there can be air in the oil, or may be air on the upper layer of oil sitting in the pan as the oil drains back down, so the lower the pickup is from the surface of the oil the less chance it will suck tiny air bubbles, which will definitely cause pressure fluctuations because the air is compressible. It may be that the combination of non-detergent oil if it were lacking in anti-foam additives which is likely, and too high a pickup to pan clearance, was causing aerated oil to be sucked into the pump under certain conditions. would the fluctuations happen only when you accelerated, as in rpm rapidly increased, meaning the oil pump quickly draws a larger volume? or would it happen at a constant rpm, say 3000 rpm steady going down a straight level road?

acceleration is when it was happening, particularly under higher load situations...much like a 2nd or 3rd gear "punch." at first it didn't seem to mind lower rpm's, now the problem is increasing and happening at lower and lower rpm's and load levels. i've had to abide by the ls1 overfill method due to the fact that this is a drift car and oil slosh/starvation is and can be a big issue for us, so my oil levels were always spot on (1-1.5 qt's high). the non-detergent oil acted identical to all the synthetics, minus the 20w-50...which held up for a bit longer (probably due to its viscosity) but once it broke down it mimic'ed the other oils perfectly in failure patterns.

i apologize in advance, i don't have any fancy data-logging capabilities. but i did video record playback on my gauges, i tried to show all conditions, temps at 70c-80c, then i focused on tach and psi gauge which reads in bar, it rarely ever goes below 3 bar, or ~42 psi. but if you watch after 0:45 you'll see that with acceleration comes drops in oil psi and how its reacting to throttle. also, if you want to watch it from start to finish (1:45 minutes) you'll notice that at first its not as bad which i assume is due to the oils viscosity.

http://img.photobucket.com/albums/v338/kidnrg/new%20batch/th_SDC10612.jpg (http://smg.photobucket.com/albums/v338/kidnrg/new%20batch/?action=view&current=SDC10612.flv)

Question? Do you have a evac pump on the car. Next your pump could be sucking your oil pan dry. It makes since. You had your pump upgraded to work better. So now it's working better. Looking over the post I would get a stock GM pump have it cleaned up in the inside. Get a stock tining chain cover and put that on. If you still hae the same problem then you know it's not the pump or cover. Think about it the tighter the clearences in the motor the more oil pressure you have.

I would try the easy stuff first.But try it one at a time.

Do a brake torque in your drive way to see if the pressure frops. If it doesn't then atleast you will know that it's not due to a hard launch. I know your shop guy checked the crank thrust. I'm just throwing a few things out that it may be.

the easiest check for us right now is to pull pan and measure the pickup height and quadruple check that o-ring. thanks to the motor plates its super simple to pull the pan, but to do anything else on this motor i've gotta pull it so i need to have all my ducks in a row so i can fix any and every possibility. we've been slowly learning about the up's and down's of the new GM lifter design. i knew all along they had redone the shitty ls1 design and replaced with ls7, but i was UNAWARE of the pushrod length difference. we didn't replace all of our lifters, just the one that wouldn't bleed out. should i be suspect of this one lifter/pushrod assembly possibly causing this issue? the pushrods i currently have are manley chromoly oem length, nothing special.

I came across this I thought it may help.

http://cgi.ebay.com/ebaymotors/GEN-III-and-GEN-IV-LSX-engine-girdle-for-Pick-up-tube_W0QQcmdZViewItemQQ_trkparmsZQ7c301Q3a1Q7c293Q 3a1Q7c294Q3a30QQ_trksidZp4634Q2ec0Q2em14Q2el1262QQ hashZitem3ca2118684QQitemZ260417095300QQptZMotorsQ 5fCarQ5fTruckQ5fPartsQ5fAccessories

wow thanks for the heads up on that part, purchased!

let me know if it works out.

shit, o-ring is still in really good condition. it wasn't cocked at all. time to pull the motor, AGAIN :mad:

just so i've got everything lined up for the swap out. whats the place you guys would most recommend to snag some caddy lifters and if my block used the brown barbell, is it ok to put gm's revised white one in?

Call Scoggin Dickey talk to Tim. 8004560211. Maybe he can help. I usually get my stuff cheap. Not as cheap as whole sale but i don't have an account setup with them yet. They may have a little inside info. Can't hurt

i'm gonna need a lot more than that now :( we disassembled the motor to make sure we were still working with a fresh palette. 1 mile of driving and break-in combined...2 is generous, and all of my bearings are trashed. too much went through the motor. while we were looking at the mains, i asked my builder if he removed the front gallery plug next to the oil pump mating surface to help all the trash leave while cleaning the motor and he admitted that he did not. ugh, how much stuff could've gotten stuck there?? anyways, back to the drawing board.

on a side note, i've dealt with scoggin dickey before and was very pleased with their service! i'll gladly deal with them again.