High performance oiling mods for 500 inch motor

["Cadillac Kid" Greg Surfas 15364]

As anyone who has actually seen the insides of a 472/500 inch motor the size of the rod and main crank journals are very generous. They should be capable of much more horsepower than the Engineers ever intended and they are.  The oiling system likewise is sufficient to keep these motors (if the oil is up to capacity) running for several hundred thousand miles without failure.
The oil pump too is more than sufficient.
When, however modifications to the motor are made for high performance that allow higher motor speeds (this motor was designed to run at a maximum of about 4600 RPM) over 5000 RPM the seemingly singular pitfall becomes apparent.  Due to the oil circuitry where oil is fed first to the passenger side gallery which serves the lifters, cam shaft, rods and mains and then fed (via the crossover passage) to the drivers side gallery, the "end of the line" where the oil pressure sensor is is also where the rear main and crank throw bearings reside.
The short version is that it is not uncommon for #7 and/or#8 rod bearings to be destroyed with an extended 6000 RPM "jaunt".
Folks in the esoteric Cadillac high performance arena have tried several remedies without much success but have found that by running an auxiliary oil lone from the factory plugged high pressure port just above the pump around to the back of the motor and tapping into the galleries through existing plugged gallery plugs oil is distributed equally and the inherent short fall is overcome.  You ask how I found the short fall? 6200 RPM.
Anyhow my motor is going back together and I have included a couple of shots of the oil system plumbing. 
I know this is purely academic for most of you but some might find it interesting.  I wonder what Robert Templin would think?
Greg Surfas

[wrench]

Greg, thanks for the info...First question is why you went with rigid tubing instead of flex lines?

Are the lines steel or aluminum?

["Cadillac Kid" Greg Surfas 15364]

Jim,
The lines are Steel.  Flexible lines are intended when there might be relative movement between the two ends of said line.  There should be VERY LITTLE movement between the front and the rear of the block.
Greg Surfas

[DeVille68]

very interesting! On my engine the #8 connecting rod bearing failed (spun), however I certainly never drove the car with rpms over 4500. During the rebuild I have not found the reason for the failure.

["Cadillac Kid" Greg Surfas 15364]

Nicholas,
#8 is "at the end of the line" in the oiling system, so anything that effects oil delivery such as a weak pump, plugged filter, excessive leakage elsewhere (excessive lifter/bore clearances), or debris in the oil galeries will get to #8 first.
Greg Surfas

[DeVille68]

Nicholas,
#8 is "at the end of the line" in the oiling system, so anything that effects oil delivery such as a weak pump, plugged filter, excessive leakage elsewhere (excessive lifter/bore clearances), or debris in the oil galeries will get to #8 first.
Greg Surfas

Ok, maybe there was left over debris from a previous rebuild. However, I was not sure how much debris was from the recent bearing failure. The bearing where already oversized.
I understand that the pressure sensor / gauge is also at the end, so could one check the pressure readings?

Would you need move the location of your pressure sensor because it is not at the end of the oiling system anymore?

["Cadillac Kid" Greg Surfas 15364]

Doesn't show in the picture but the blue fitting in the rear that is shown going into the oil pressure sensor tap has a female pipe thread on the side here pressure sensor and gage wll go.
Greg Surfas

[The Tassie Devil(le)]

Would you need move the location of your pressure sensor because it is not at the end of the oiling system anymore? 

You always want your pressure sensor at the end simply because it will show any pressure loss throughout the system.

Having it at the pump will only indicate a pump failure.

BUT, the big thing is to actually monitor the gauges and not simply forget about them.

The best thing is to include a warning buzzer to immediately alert the operator that something is not right.  Lights are good, but the buzzer is instantaneous.   As long as it is louder that the rest of the noises within the car, or without the car.

Bruce.

["Cadillac Kid" Greg Surfas 15364]

Bruce,
Simply put there are 3 actual "end of the circuitry" points in the 500 inch motor's oiling system.  The location of the pressure sensor on the stock motor is a compromise and it is possible to have low oil pressure at several points without it activating the sensor at (I believe it is) 8 psig.  You are correct also in a "Warning system", and that consists of a big b right red light just opposite the shift light on my dash.  Buzzer? You have to be kidding. Ambient sound at 6000 RPM with open headers and 110 MPH is something approaching 120db.
Remember this is not a modification necessary for a 500 until you get somewhere into the 500 HP and 6000+ RPM.
Greg Surfas 

[TJ Hopland]

Most of the classic American engines have pretty similar oil paths and systems don't they?    What was the setup on the V-12 WW2 aircraft engines?   Those had some pretty big pistons to throw around and I assume ran at a pretty high rpm especially considering their size. 

["Cadillac Kid" Greg Surfas 15364]

What is the question in there TJ?
Greg Surfas

[TJ Hopland]

I was just wondering how someone would design the oiling system of a big engine that you planned on spinning fast and I was assuming the WW2 V12 plane engines would qualify as big and fast so I wondered how they did it.   

Also wondered if any of the car makers ever did anything significantly different oil path wise or if they were all more or less the same?   I assume some of the other 'big blocks' from the 500 era were expected and rated to spin pretty fast how did they more or less survive?

["Cadillac Kid" Greg Surfas 15364]

TJ,
Engines such as the Allison 1600 and the RR Merlin as well as the high output  radial engines were dry sump oil systems.  That means that the designers could introduce oil through external lines to the points that they thought most needy.  That said, 3000 RPM was the "war emergency" red line for these motors and they were only expected to last something like 300-500 hours before replacement. Most of these motors were extremely complex and so were there oil circuitry.
 
Regarding other (than Cadillac) manufacturer's V-8 oiling systems, many feed the crankshaft directly (first in line) from the pump or have multiple parallel oil galleries.  That means they feed the cam/crank directly off of a gallery and the lifters/valve trains off their own supply gallery. 

The galleries in the Cadillac depend upon a cross-over between the two galleries which is just aft of the second cam bearing to feed the drivers side valve train and the rear main and rear crank throw.

This oiling system is more than adequate for all "Normal" expected operations of this motor, but when pushed into the 500+ HP and 6000+ RPM the shortfall is the last main/crank throw.
Greg Surfas

[TJ Hopland]

Thanks for the info.   I didn't know that 3k was redline for those aircraft engines but it does make sense.   Its got to be some of those pesky laws of physics that make it difficult to make a big mass reciprocate really quickly and survive. 

If you have the answers and don't mind more questions.....

When you put an engine under more stress like in this case are you just trying to get more oil to the bearings?   What happens to the oil that is there when its under stress?   I assume its multiple issues.  Does the increased pressure on the bearings from compression stroke and the force of changing directions just mash the oil out so to speak?  Or the extra heat break it down?  Getting more oil there helps both cool things and replace what was go squished or thrown out?

[DeVille68]

Interesting! I kinda had the same thoughts but you outlined them nicely!

["Cadillac Kid" Greg Surfas 15364]

Lubrication and rotating bearing lubrication is quite a complex combination of viscosity, temperature, clearances, relative rotating speeds, unit area loading, metallurgy, and a myriad  other factors. Aircraft engine speed as the WW II motors were designed is limited by propeller speed or rather propeller tip speeds.  They worked backwards with motor design to maximize output at the propeller speed they were intending to use.
Greg Surfas

[Barry M Wheeler #2189]

I have resisted looking at this thread since it's been up, but finally did so. I know just about enough to be like Penny on Big Bang. I could follow what you guys were talking about and understand it pretty well. I don't have a car with one of these engines, so my interest is moot, but I certainly appreciate having people at hand that can explain (and work out the fix) in such an interesting way. Good job! I've learned something new today.

(My dad worked on the V1710 engine at Allison plant three during WWII and kept some of his manuals, but I never knew that War Emergency Power turned relatively slowly.)

["Cadillac Kid" Greg Surfas 15364]

Barry,
"war emergency" power settings increase the blower boost, add a few hundred RPM to the engine speed and engage the "water" (water/methanol) injection.
Greg Surfa

[The Tassie Devil(le)]

Barry,
"war emergency" power settings increase the blower boost, add a few hundred RPM to the engine speed and engage the "water" (water/methanol) injection.
Greg Surfa

And probably saved many pilots when they really needed the extra grunt to escape.

Bruce.

["Cadillac Kid" Greg Surfas 15364]

Did a mock up and the oil line seemed a bit close to the header. Re routed  the line and put it in an insulated jacket. Might wrap the headers also.
Greg Surfas