[screamingchief]

If you wanna look at a more practical example to follow,go back over gtoroadracer's old threads/posts,as his GTO is about the most serious example of a road racing pontiac that one is likely to find.

Here is a post I made in a suspension thread that has links to get you started.

And FYI,his orignal engine was a 455 block w/4" stroke (440),so the oiling system info for that car directly relates to the discussion here,though he has since went to an LS based engine IIRC.

http://forums.maxperformanceinc.com/forums/showpost.php?p=5041196&postcount=9

Then go to the advanced search and put in his screen-name and the keyword "oiling" and I'm sure you'll find a bunch more reading material on oiling system design for this sorta deal.

HTH

Bret P.

[FrankieT/A]

Larger diameter main bearings have greater bearing speed by virtue of circumference.

[hurryinhoosier62]

Originally Posted by smokepedal

I don't understand what cintrifical force has to do with oil system and pressure.


A centrifugal pump uses the force generated by the mass of the oil to produce pressure. Oil enters the center of the pump and exits at the outer diameter of the impeller. We are basically using a positive displacement pump to force oil backwards through a centrifugal pump.

My oil pressure (prior to bad bearing) is about 50 cold idle, 25-30 hot idle, 80 at over 5000 hot.

high pressure oil washing out bearings... doesn't make a ton of sense how that can work. I'm pretty sure it's an old wives' tale.

I'm basically going to shim the spring to raise the pump discharge pressure by about 30 psi. I will lock the shaft and use compressed air to open the relief valve.

Did anybody look at the chart from the wallaceracing website? Comments? Why do larger diameter main journals require more pressure if my theory of why the rods are being starved is SOOOOO far off?

I agree with Screamingchief that there are other issues with the oiling system that could use attention. I am going to fabricate a larger (wider) sump on the pan and make sure it's baffled well.

What's wrong with plasti-gage to verify something that is supposed to be right already? I didn't use it to do machine work. I did it to verify machine work.

Plastigage gives you a RANGE, not a specific measurement. Can you tell the difference between .0018 and .0020 by looking at it? I'm a retired ASE certified master engine machinist and I CAN'T. That is WHY every engine clearance spec needs to be checked with precision measuring instruments. Plastigage is better than nothing, but it's not accurate. High pressure oil "washing out" bearings is a wives' tale, eh? Hmmm.....Clevite and Federal Mogul are passing along "wives' tales"? Every professional engine builder I've known is passing along "wives' tales"? I've seen it. It's NOT a wives' tale...........

[TransAm525]

Originally Posted by smokepedal

Why do larger diameter main journals require more pressure if my theory of why the rods are being starved is SOOOOO far off?

http://kennedysdynotune.com/oil-pressure-tech/

Originally Posted by smokepedal

I agree with Screamingchief that there are other issues with the oiling system that could use attention. I am going to fabricate a larger (wider) sump on the pan and make sure it's baffled well.

Stock oil pans are inadequate for for road racing. The factory baffle was designed to control the oil on a stock vehicle pulling relatively low cornering G's, not road course racing. Depending on your vehicle's cornering ability, and road course design, you may want to consider a high-volume oil pan with better baffling or even a dry-sump oil system (again, depending on the level or racing your doing).

Originally Posted by smokepedal

What's wrong with plasti-gage to verify something that is supposed to be right already? I didn't use it to do machine work. I did it to verify machine work.

It's kind of like measuring with a ruler vs dial calipers. Theoretically everything should be fine from the machinist, but for something running upward of 6500 rpm on a regular basis, I would personally verify everything using precision instruments. Trust, but verify.

[old66tiger]

Why such high pressures in the first place? I was skeptical about low oil pressure in my engine. 20 psi hot idle and 50 psi hot running as measured at the distributor. My engine has had several trips north of 6K and is still living. One would think that you would rather have nominal pressure and more flow to control heat in the bearings. What is your oil temps like?

[llwta76]

I shimmed my pump pressure relief too much years and years ago and right on start up on a hot day I ballooned the filter!

[hurryinhoosier62]

Originally Posted by smokepedal

One of the big problems with a gear pump is that unless they are helical cut, the pressure pulsations that they put out could significantly cause an increased torque pulsation beyond the theoretical torque if that makes sense. Maybe a small accumulator to dampen that would help.

How about shimming it to try for 110 psi? I am convinced that based on the table posted above, and the description on the wallaceracing website, 80 psi is on the edge of adequate.

Here's a bit of lucidity.......The Detroit Series 60 575 develops 575 hp and 1,850 ft/lbs. of torque. The main saddle bore is 3.594-3.595; main journal diameter is 3.3450-3.3460. The suggested oil clearance is .0016-.0046. The NORMAL running oil pressure is 50 PSI. IF a 14 liter engine producing the same hp and 3 times the torque only needs 50 PSI, WHY then do you need 110 PSI? Your problem ISN'T a lack of oil pressure.

[Formula8]

Originally Posted by hurryinhoosier62

Here's a bit of lucidity.......The Detroit Series 60 575 develops 575 hp and 1,850 ft/lbs. of torque. The main saddle bore is 3.594-3.595; main journal diameter is 3.3450-3.3460. The suggested oil clearance is .0016-.0046. The NORMAL running oil pressure is 50 PSI. IF a 14 liter engine producing the same hp and 3 times the torque only needs 50 PSI, WHY then do you need 110 PSI? Your problem ISN'T a lack of oil pressure.

Really? Are you going to seriously compare a motor that tops out @ like 1500 RPM with the OP's 6500 RPM motor? Not that I disagree with you that there is no need for 110 psi, nor a lack of pump pressure is the dudes problem, just the analogy is absurd.

[hurryinhoosier62]

Originally Posted by Formula8

Really? Are you going to seriously compare a motor that tops out @ like 1500 RPM with the OP's 6500 RPM motor? Not that I disagree with you that there is no need for 110 psi, nor a lack of pump pressure is the dudes problem, just the analogy is absurd.

The 60 Series 575 has a main saddle bore and main journal not much larger than the 455. While the OP is turning his engine much higher (WHY is he turning a 455 @ 6500?), the oil demands of the Detroit are actually HIGHER. Don't know much about diesels, do you?

[Tim Corcoran]

There seems to be a lot of theory and speculation being thrown around in this post. There are people here that have been doing this long enough to know what works and what does not. I can tell you eliminating your pressure valve in your oil pump would have less than desirable results so if you decide to do this we all would be very interested to hear your results. I also am curious why your spinning up a 455 so high unless you have some serious airflow and a pretty big solid roller. I suppose your power is already dropping off past 5500 RPM. As soon as you mentioned plasti-gage many here will question the credibility of the engine build for high performance use. As long as you have 10 psi for each 1,000 RPM you will have enough pressure to properly lubricate your engine provided everything else is correct. It could be that your bearings are hitting the larger radius of the Eagle crank and that could cause oil starvation or your bearing clearance could be too small for proper cooling of the rod bearing. Pontiacs were designed by the factory to have small heads with high velocity big torque at a low RPM, under square bore to stroke ratio with long and rod big rod and main journals to make it last a long time. When you start turning the Pontiac motor into a race motor you need to open up bearing clearance and the factory oil pump will be adequate up to around 7,000 RPM with a 3" main and a 2.2 rod journal.

[screamingchief]

So far for me this is a no-brainer,the stock oil pan should have never been part of the plan here from the get-go,even H-O racing (the guys that came up with that pressure chart on Wallace racing) preached that deal back in the day,and their bread & butter was selling parts to address that shortcoming like the OE pan baffle kits and oil accumulators and such.

Even the "good" oil pans will start dropping pressure on hard right hand turns,just ask the guys here who've BTDT (like ho428,gtoroadracer,andyleonard,bigger is better,455-4+1,et-al) as all those guys have worked thru their own issues here and the info is there for the taking if one will just spend a little time looking for it.

So those two items (proper oil pan & oil accumulator) are'nt remotely optional in my mind for any "cornering" oriented pontiac application.

And changing a bunch of things @ one time is also a very bad idea too,as doing that one will never know for sure what is helping the problem,and what may be compounding the problem even further yet,plain & simple that is hot rodding 101,always,always,change one thing @ a time.

I dunno,I kinda expect these words may fall on deaf ears when it comes to the OP,his mind seeems made up on this deal from his first post,but hopefully for someone else these words may actually sink in and save them some frustration some day down the road.

I'm not saying the OE designed bypass is w/o it's flaws,all I said from the begining here is I honestly dont think it's responsible for this bearing failure.

Like I said earlier,if you dont like the OE bypass,disable it and use the Peterson external bypass like gtoroadracer did,as that's really the better moustrap,because the bypass is external,it can be adjusted to what-ever pressure floats your boat,also it does'nt return the oil to the pump inlet like the OE oil pumps do,so the potential for aeration/cavitation is largely eliminated as well,only "catch" is that it requires some external plumbing,but honestly a deal like this should already have a fair amount of that (remote filter[s],oil cooler,etc).

FWIW

Bret P.

[tom s]

maybe this would be served better in the race section?Tom

[gtofreek]

Originally Posted by smokepedal

yeah, the oil pump pressure is lower than the amount of centrifugal force it must overcome in order to push oil to the center of the crank in order to supply the connecting rod bearing. the clearances were correct when I assembled the engine. I don't think that I will have a ballooned filter. I don't expect to see much above 100-110 psi.

This is not why you lost a rod bearing. I have built hundreds of engines and never had a bearing failure. Many others have ran these pumps as is with no problems.

Do you understand that with the pressure bypass plugged in the pump, it will make unlimited pressure the higher you rev it. That will not be good. Find out why the rod bearing failed, and don't blame it on the bypass valve. That needs to be there.

I've had pumps make 110 PSI with a bypass and spring in there.

[gtofreek]

When you tear down the engine, check the failed rod bearing to be sure the upper half is in the rod and the lower half is in the cap. Maybe they got mixed up. They are stamped on the back for upper and lower.

[hurryinhoosier62]

Originally Posted by screamingchief

So far for me this is a no-brainer,the stock oil pan should have never been part of the plan here from the get-go,even H-O racing (the guys that came up with that pressure chart on Wallace racing) preached that deal back in the day,and their bread & butter was selling parts to address that shortcoming like the OE pan baffle kits and oil accumulators and such.

Even the "good" oil pans will start dropping pressure on hard right hand turns,just ask the guys here who've BTDT (like ho428,gtoroadracer,andyleonard,bigger is better,455-4+1,et-al) as all those guys have worked thru their own issues here and the info is there for the taking if one will just spend a little time looking for it.

So those two items (proper oil pan & oil accumulator) are'nt remotely optional in my mind for any "cornering" oriented pontiac application.

And changing a bunch of things @ one time is also a very bad idea too,as doing that one will never know for sure what is helping the problem,and what may be compounding the problem even further yet,plain & simple that is hot rodding 101,always,always,change one thing @ a time.

I dunno,I kinda expect these words may fall on deaf ears when it comes to the OP,his mind seeems made up on this deal from his first post,but hopefully for someone else these words may actually sink in and save them some frustration some day down the road.

I'm not saying the OE designed bypass is w/o it's flaws,all I said from the begining here is I honestly dont think it's responsible for this bearing failure.

Like I said earlier,if you dont like the OE bypass,disable it and use the Peterson external bypass like gtoroadracer did,as that's really the better moustrap,because the bypass is external,it can be adjusted to what-ever pressure floats your boat,also it does'nt return the oil to the pump inlet like the OE oil pumps do,so the potential for aeration/cavitation is largely eliminated as well,only "catch" is that it requires some external plumbing,but honestly a deal like this should already have a fair amount of that (remote filter[s],oil cooler,etc).

FWIW

Bret P.

Bret,
I agree with you. It's oil starvation, not a lack of oil pressure.

[hurryinhoosier62]

Originally Posted by Formula8

Really? Are you going to seriously compare a motor that tops out @ like 1500 RPM with the OP's 6500 RPM motor? Not that I disagree with you that there is no need for 110 psi, nor a lack of pump pressure is the dudes problem, just the analogy is absurd.

More lucidity just for you. The crankshaft out of a Series 60 575 weighs 350lbs. The total rotating mass is just shy of 550 lbs. Do you think it's EASY on the oiling system to keep proper oil cushion for a rotating mass of that weight @ 1800 rpm while producing 575 hp and 1,850 ft/lbs. of torque? Additionally, the oil has to be able to help cool the engine (diesels operate at far hot operating temps the gasoline engines do). The OP's standard oil pan holds 5 qts of oil. The Series 60 575 hold 11 GALLONS of oil and has TWO oil filters to keep the oil as clean as possible. IF Detroit Diesel can keep an engine with those loads properly lubricated with 50 PSI, 110 PSI is totally insane.

[smokepedal]

Originally Posted by hurryinhoosier62

Here's a bit of lucidity.......The Detroit Series 60 575 develops 575 hp and 1,850 ft/lbs. of torque. The main saddle bore is 3.594-3.595; main journal diameter is 3.3450-3.3460. The suggested oil clearance is .0016-.0046. The NORMAL running oil pressure is 50 PSI. IF a 14 liter engine producing the same hp and 3 times the torque only needs 50 PSI, WHY then do you need 110 PSI? Your problem ISN'T a lack of oil pressure.

I used to work on diesel engines in the navy that would produce 20,000 horsepower on 60 psi oil pressure. Low rpm. 2 foot main bearings.

The Detroit you are talking about revs out at 2200 rpm or so.


Never mind, this was addressed.

[smokepedal]

So, the #3 rod bearing was pretty hammered. I only have edge on pics for now of that and the #4. I will take some more today when I tear the engine down the rest of the way.

I am going to shim the oil pressure relief valve a little bit but not significantly. You guys have talked some sense into me.

The #4 bearing was down to the copper too, I don't have all of them disassembled yet. I didn't have a very good clean place to do everything. I work as a mechanic for a trucking company and pulled the engine in the shop at night. I didn't have my engine stand down there and didn't want to get too carried away.

I think that one of two things was the problem.... oil starvation at high rpm because the pump lost suction, or predetonation. I am running 11.2 to 1 compression (4000 ft zero decked with flat top pistons and closed chamber heads).

I am recurving the distributor. The springs I had in it were the stiffest ones for an HEI. I am running a points style distributor (pertronix pickup) I had to grind the weights to keep the advance from coming in until about 4400 rpm. It basically ramped from 5 degrees at idle to 28 at 4400 but I think the springs got weaker when the engine was hot and was letting it come in by about 3500. I have a moroso points kit now.

I don't do road racing. I just drive like an asshole once in a while on the street. I don't know if any of you have ever been young and single, but a muscle car with a 455 revved out to 6500 rpm is kind of exciting for girls. We know what exciting translates to. (I don't understand why he's........)

I have one question about an accumulator. Is it usually orificed or valved at all to control oil flow in and out?

I am going to modify the oil pan. I am going to put a wider sump on it. I don't want to go deeper because ground clearance is already limited. I might put some hinged baffles in it.

I am going to put a 6500 rev limiter on it.

As far as the personal judgement goes, I am asking for technical advice. I am not stupid or ignorant. I was an engineman in the Navy. I have worked on all types of engines. Ones that HAD to run 24/7. They weren't any fun. This is a fun hobby. I am a college senior in chemistry now. Science doesn't escape me. I can do theoretical math based on the density of oil and the induced pressure gradient that is experienced on a 1.625 column of liquid. The ad-hominem ("lucidity for you") comments are not productive. I don't need lucidity, I can think in complicated terms.









Except apparently I don't know how to attach pictures!!!

http://forums.maxperformanceinc.com/...p?albumid=1408

This should be a public album and the pictures I have so far are in there.

[hurryinhoosier62]

Originally Posted by smokepedal

I used to work on diesel engines in the navy that would produce 20,000 horsepower on 60 psi oil pressure. Low rpm. 2 foot main bearings.

The Detroit you are talking about revs out at 2200 rpm or so.


Never mind, this was addressed.

Did the Navy teach you how to figure bearing loads? The bearing loads in a diesel are hellish, yet they survive on 60 PSI or LESS of oil pressure. WHY do you think the oil systems on diesels have the capacity they do? The Series 60 actually produces max hp @ 1800, not 2200 as you allege. I will reiterate....your problem is NOT too little oil pressure. 6,500 rpm on a STREET 455......WHY? There are many guys here that have built street 455s that produce 500+ hp and torque that NEVER see the high side of 6,000 rpm. Hope you have a VERY significant saving account. You're going to need it, IMO.

[smokepedal]

Originally Posted by hurryinhoosier62

Did the Navy teach you how to figure bearing loads? The bearing loads in a diesel are hellish, yet they survive on 60 PSI or LESS of oil pressure. WHY do you think the oil systems on diesels have the capacity they do? The Series 60 actually produces max hp @ 1800, not 2200 as you allege. I will reiterate....your problem is NOT too little oil pressure.

The bearing loads are supported by an oil wedge from the moving bearing, and not from pump pressure. They have the sump capacities they do in order to absorb chemical contaminants without changing properties significantly, leading to extended change intervals.

http://www.marinediesels.info/2_stro...ubrication.htm

The oil wedge that supports the bearing loads is very strong and high pressure. With a 4.125" piston, and 150 psi above the piston, you have over 2000 pounds of pressure against the rod bearing. That is cranking compression. I know that pump pressure could never support an oil film against that kind of pressure. Most of us here understand the basics.

I just think that I was getting an interruption to oiling. I will figure it out. I will NOT plug the oil pressure relief valve. I will shim it to 100 psi and make sure the other problems are addressed.

Question: are accumulators designed for engine oiling valved in any way?