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More oil system woes

60K views 94 replies 50 participants last post by  BBF Newbie 
#1 · (Edited)
More oil system woes, with pix

We have been dyno testing a 598” Boss 9 hemi, and seeing some strange oil system behavior.
Engine data:
4.6” x 4.5”
Our Boss 9 Hemi heads…. (The set from our 2009 Engine Masters 511” entry), Ported
Unported 4500 Kaase intake
1150 dominator carb, by Dale Cubic @ CMF
13 to 1
282-288, .457” lobe, 112 CL Comp Cam
Wet sump pan with our pump
Best power, 1100 HP @ 6900, 875 Ft/Lbs at 5500
This engine is built for a friend to take to Maxton, NC , for the 1 mile speed runs

This has been a great engine, except for the oil system. It has a Moroso road course oil pan. The pickup is ¾ toward the rear, in a 4” x 4” trapdoor box. There is directional screen over most of the bottom. The pan is mostly flat, front to rear, with a trapdoor divider half way back. During a dyno pull, it loses oil pressure, 5 to 10 lbs or more. We tried jacking up the front of the engine to help more oil get to the rear. We tried thinner oil, Mobil 1 0-W50. We tried more oil. Started with 8, then 10, then 12. Then I really got pissed and threw in another 4 Qt, total of 16. Didn’t hurt the power much, but didn’t help the loss of oil pressure. It would start at 60 psi, and go down to 48. When we ran it from 4500 rpm to 7000, the oil gauge would nose dive at 6500 and over. 6200 to 7000 and it still fell at 6500, 4000 to 7000 and it still fell fast over 6500. The length of the dyno run didn’t seem to matter, it was when it reached 6500 rpm and over that the oil pressure went to hell.
The block is aluminum, which has lower head oil drains, so the heads don’t hold much oil in the valve spring area. The lifter lines are restricted. We took it off the dyno and pulled the pan. Bearings were OK.
Because we needed to know whether the problem was the pump or the short block, or the pan, we decided to change pans to my EngineMasters pan and pickup. It’s a 12” deep front sump with no baffles or screens or covers anywhere. Just a big, deep, open pan.
Well, we ran it today, and it was perfect. Even when the oil was hot. It started at 72 psi and would gain a pound or two at 7000. The pressure gauge was perfectly steady, where with the other pan it would bounce a little. We only had 7 qts of oil in the pan!
So, the oil pressure problem was obviously the oil pan. I think most people would have blamed the pump. I had my doubts about it. Now we have to figure out what’s happening in the customer’s pan and fix it. There is a square hole in the screen for the pickup to fit through when the pan is installed. I think maybe all the windage and pulses from the pistons above are disrupting the oil around the pickup.
Next week we’ll work on the pan, and I’ll post some pictures and dyno sheets here.... Kaase
 
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#28 ·
Jon, How high (or close to the crank) does 12 quarts of oil get in that pan. Have you filled it with 12 quarts and observed the depth or closeness to the crank? It looks awfull shallow to me for 12 quarts. And running lower volumes looks like it would starve the pickup box. Too shallow and close to the crank for my liking, especially for a big stroker.

Hats off to the meaness of that 598. That is serious!

Bret
 
#29 ·
I had always wondered if there might be a flow problem with those type of pans that have the slosh "dam" around the pick up. I'm thinking that it wouldn't be hard to empty the area inside when there is alot of oil elsewhere in the motor and the level in the pan is low and not able to flow over the sides of it....especially at those flow #'s.
Rob
 
#30 ·
More Oil System Woes

Hi Jon
Have you ever made the transition from the pick up into the tube a smoother transition ? I also have often thought also about using a bigger pickup tube. I never liked any restriction on the inlet of any pump. I could be wrong but I think that a bigger pickup tube would offer less restriction just like making the radius on the bends bigger.

Gary
 
#31 ·
I have seen when using a small block Chevy, WET SUMP, road race pan, almost the same phenomina however, using a WET SUMP pan WITHOUT the "box", under hard braking and turning a corner the oil pressure would go down to "ZERO" so, under those circumstances choosing the least of two evils was the alternative.
Back then we never played with windage tray designs and that might have solved both problems.
 
#32 ·
Today we did a visual test on the pan and pickup area while flowing oil in a loop circuit. We ran the oil pump with a drill at first, but could flow only 5 gal/min. No drill in the shop would spin fast enough. The only way we could get 10 gal/min was to hook the oil pump drive up to the Bridgeport. Don't laugh, it worked great. At 850 rpm, we had 10 gal/min and could watch the pickup and the oil level in the trap door box. The oil was returned in the front of the pan. (hose in the front cam bearing hole and then down) With the same oil as the engine was runnung, 8 QT, the oil level never went down more than 1/4" inside of the pickup box. Even with cold oil, it flowed through all the trap doors easily. So, the only possible reason for the oil pressure loss has to be the pulsing and windage about the pickup area. In the pictures you can see the pickup box looking down the bore. ... Kaase
 
#36 ·
For what it's worth, we ran the 598 yesterday to test oil filter screw in adaptors. The 7/16" hex type, and one that we reamed out to the same size as the block and radiused. The 7/16 hex has about the same area as a .460 round hole but probably has slightly less flow. The block is machined to .530, so that's what we reamed the adaptor to. The result was that the bigger adaptor had 2 PSI more oil pressure at 7000 rpm. Below 6700, it was the same. Check out the pictures. ... Jon
 
#39 ·
I know its easy to have all the answers when i'm only sitting here in my computer chair, not having to do any of the work, but i'm wondering if its possible to pull the pins on the trap doors and pull the flaps off leaving the slots open. would that correct the low pressure, but still hold enough oil when cornering in a car?
(it looks as though is possible to do that but i'm not 100% sure)

are there eddycurrents in the oil around the pickup at high rpm to shut the doors at least to a point and cause the pressure problems you're seeing?

I'm grasping at straws i know. :D
 
#40 ·
when we ran the pump and watched the oil in the pan, it was well behaved and you couldn't see any fast oil flow or movement around the pickup or through the trap doors. It's the hurricane from the crank and pulsing from the pistons pumping the air up and down above the oil sump that causes the problem.
 
#42 ·
Might be totally off track here, but this is an issue I have seen with my engine. The support strap off the main cap for the rear pickup cracked and broke. The pickup actually sucked itself to the base of the pan. There were two 1/4 inch stand downs on the pick up so that the screen would not suck from the very bottom of the pan, but this still did not allow enough oil into the system. The stand downs on the pick up screen left obvious dents in the 3mm sheet aluminum sump? The datalogger showed a drop from my normal 85psi down to 40psi from about 6800rpm up. I had over 10 litres in the sump , so oil starvation was not an issue. We then changed the stand down to 1/2 inch and no problems.???

I have since gone to a Peterson external pump , but maybe this experience may add to the clues?

John
 
#44 ·
im having similar oil psi problems with a billet titan pump with 2 #12 p/u lines and the p/u is

2-4 inch in a jeff johnston drag chassis pan with screen windage tray.remote sys 1 filter.1-

90deg / 2-45deg and 1 straight in remote oil system.oil inlet on the block was drilled out to

9/16.

Jon Kasse ill keep looking on here for your diagnoses and if you come up with a tray that

cures the problem ill take one or if you need a quinney pig with a approx 850 hp low 9 sec

3300 lb ride.
 
#49 ·
JOHN
i have heard rumor that some of my fellow racers in dirt track are using a five stage dry sump system as a vac pump and a oil pump. i was told they seal the motor up no vents.only vent is on the tank. is that possible? on a nother note.. i had this same oil pressure problem on 466. i had a stock pan dual sump,and before it was said and done i made a 15qt pan.never did find the problem. always thought it was sucking air from some where.when the motor broke a rod i tore it down all mains and rods were perfect. that was a 466 on a 275 shot of th happy juice.oil pressure would start at 70psi drop to 45 warm and bounce between 45 -55 when you raised the rpm. anyway thanks for your time.
 
#54 ·
Being in the marine business, we have had the same experiances with Ford power and the Milodon jet boat pan. The Chev.powered boats and the Milodon pan seems to work o.k. for us. We believe the problem is the pickup tube to the front sump Ford pump. We try to talk our Ford customers to use their modified Milodon pan with a rear sump collector and fitting to an exterior belt driven pump. (somewhat expensive but cheaper than an engine loss).
 
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