Very good read, how to reduce rod bearing inertia? - Performance Forum

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Very good read, how to reduce rod bearing inertia?
Monday, May 15, 2006 12:35 PM
Well after experiencing a CRBF (connecting rod bearing failure or fu*k-up, lol) Im starting to be alot more wary of it in my new car (99 fire GT). A few things im doing is making sure the oil is always topped off (with premium grade oil) and changing it every 3000km. However, im still afraid of higher rpms with the LD9's...specifically, passing 5000 rpm.

**While browsing on the net, I read something real interesting which might be useful. Its all about connecting rod bearing "inertia". Now my question here is, what is causing a CRBF "specifically", in the LD9s. I understand this topic has been covered numerous times, but the only reason im askng this is because the people that rebuild their LD9's might need to invest in something extra that wouldnt really extinguish their pockets ("clevite" bearings) relative to a 2.3 oil pump.

So heres the deal, is it just the bearings that GM engineers did a half ass job on (used @!#$ty parts), in other words, by getting clevite bearings, could this virtually eliminate the CRBF problem on LD9's? Or regardless of any bearings I use on the, will it always screw up someday unless I get the 2.3 oil pump?

Or is it really the oil not getting to the right place (the bearing I guess), when the piston is in TDC while in combustion, which has been proven to have the most tensile (pulling effect: visualize pulling the piston from the rod bearing) inertia on the rod bearing.

So after reading the above, and learning a bit through my little summary, is it better to replace the bearings with clevite bearings or do the 2.3L oil swap? Obviously both is better, but money is limited! Feel free to add your insight on anything related!



Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 12:40 PM
from what i understand its the oil pump in the LD9 thats crap and its not giving the bearings enough oil i may be wrong though i am not a LD9 person but if i recall thats what i thought it was... pump issue.. not enough pressure or something....



Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 12:51 PM
forgot to put a really nice quote in...lol "7000 rpm can develop connecting rod bearing inertia loads greater than 4000 pounds, thats like a jbod with pounds of rice sittin on your rod bearings!
(rice is whatever you interpret it to be)


Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 5:20 PM
Wrong - so wrong. Ahh...

I'll let one of the .org experts handle this one, since apparently I'm not qualified enough.

-Chris-



-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 5:32 PM
What part is wrong so I can get smarter?


N2O + Bolt-ons = 220Hp/250Tq

Coming Soon:HpTunersPro, EagleConnectingRods, WiescoPistons, 13sec2200
Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 5:37 PM
Chris, just want to clarify i was not talking from my personal opinion, if you want me to cite it properly, see below. Since you have a 2.3 pump your definetly not ignorant when it comes to talking about oil remedies. But please, that little read is logically sound in my head.

Maximum boost: designing, testing, and installing turbocharger systems. (1997). Retrieved May 15, 2006 from
Website:http://www.amazon.com/gp/reader/0837601606/ref=sib_fs_bod/104-8599097-1704712?%5Fencoding=UTF8&p=S009&checkSum=kR3n9bXqGLeKOZsUGeuZbjypgTMMl%2B6Dcp08VTsmHKk%3D#reader-link


Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 6:31 PM
ya know, im not sure, im thinking its all on maintance, 90k miles original bearings, and drive my LD9 pretty hard, every now and again up to 6k, still no issues yet. I think its all on how one takes care of their oiling system.


Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 6:49 PM
Ya I know that, but is what I found about inertia really wrong?


Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 6:58 PM
The LARGEST issue is not having the fluids topped off. It has nothign to do with the bearings, its all in the oiling. The oil pump on the 2.4 operates on extremely low pressure, and the oiling passages are tiny. I am in LOVE with the 2.4, but seriously...the thing has some serious oiling issues, and any1 that does some major modding on the LD9 without doing something about it...is plain and simple retarded, IN MY OPINION. Many people will come here and say...I am boosted with no oiling modifications blah blah blah....yea...you are one of the lucky ones. If you keep the oil topped off....you may be alright for a little while. But...in my opinion, go with the JBP oil pump, get passages widened, and cross drill the crank, and use good synthetic oil. You can put the best bearings possible in there, but even the best arent going to last long with no oil getting to them. I am deff. on the LD9 side when the debate comes up between ECO and LD9, but I have to admit, the Eco kicks the LD9's ass in the part of the field. Get Chris back in here, hes very knowlegable when it comes to this topic.
Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 7:04 PM
Cody, thanks alot bro, thats the kind of anwser I was looking for. I hear rumours of the JBP oil pump which hinders me from using it. I understand Chris is probably a role model to the pro's with respect to the LD9's, but really wish he had put his insight in aswell. I guess Ill invest in a 2.3 pump.


Re: Very good read, how to reduce rod bearing iner
Monday, May 15, 2006 9:05 PM
To be honest with you, I cant get any CLEAR directions to give the machine shop to do the 2.3 oil pump swap...so that is why I chose to go the route I did. But something HAS to be done regardless, and it all starts with keeping it topped off.

Re: Very good read, how to reduce rod bearing iner
Tuesday, May 16, 2006 10:02 AM
Boosted or not.... run a 2.4L with low oil and it won't last very long. I know people who've killed them after 8,000 km's. (You know, back when the 2.4L was new!)

The bottom line is... check your oil on a regular basis.... even more so if you beat the hell out of your motor.





Re: Very good read, how to reduce rod bearing iner
Tuesday, May 16, 2006 11:10 AM
I wander if there is a member on the org with a 2.3 pump who still had the rod bearing issue?


Re: Very good read, how to reduce rod bearing iner
Tuesday, May 16, 2006 4:08 PM
John Lenko wrote:Boosted or not.... run a 2.4L with low oil and it won't last very long. I know people who've killed them after 8,000 km's. (You know, back when the 2.4L was new!)

The bottom line is... check your oil on a regular basis.... even more so if you beat the hell out of your motor.


i guess 182k everything original ocassionally beat on it isnt very long at all




Re: Very good read, how to reduce rod bearing iner
Wednesday, May 17, 2006 12:29 PM
Pressure vs. Flow.....
http://www.melling.com/support/bulletins/bulletin-2nd.htm

Some people need to do some reading on these issues. The 2.4 pump has a problem with both, the pump itself is small, so FLOW is pretty low. In the upper RPMs, PRESSURE also drops off with the 2.4 pump..... that is the bigger problem (poor pickup design). FLOW to the bearings is fine........ oil gets there to do the job....... its that the PRESSURE isnt there to support the load put apon the rod/bearing/crank. Drilling the oil passages, making them larger, is going to LOWER the PRESSURE...... but will increase the FLOW (which will DO NOTHING if it doesnt have PRESSURE behind it)

Installing the 2.3 pump increases the FLOW (larger rotor) and will support higher PRESSURE, solving 2 issues, also as the article states, make sure everything is with in clearence tolorances.




SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Re: Very good read, how to reduce rod bearing iner
Wednesday, May 17, 2006 12:36 PM
Also from their site:

Quote:

Common Misconceptions on Oil Systems

1. OIL PUMPS PRODUCE PRESSURE. Oil pumps produce flow and the resistance to that flow produces pressure. The pressure relief valve limits the maximum pressure but does not do anything until the pressure has reached that point.
2. THE INLET SCREEN WILL KEEP DEBRIS OUT OF THE PUMP. Some of the new ones will but the majority have a 1/2" ID valve in the center or they have eight 3/16" X 1/2"slots around the edge of the screen. The valve or slots are there to allow cold thick oil into the pump. If you use thick oil with the new screens, you have a good chance of starving the engine of oil and ruining it.

3. I HAVE LOW OIL PRESSURE SO I'LL PUT IN A HIGH PRESSURE PUMP.The low pressure is usually caused by a leak or excessive wear in the engine. If the original pump has a 50 psi bypass and the engine will not get over 30 psi, then putting in a pump with a 75 psi bypass will not change a thing. You will still have 30 psi. You have to fix the leak or rebuild the engine.

4. SAME AS #3 EXCEPT I'LL PUT IN A HIGH VOLUME PUMP. The high volume pump does increase the flow so you will have some increase in pressure. However, you still have the original problem of a leak or worn out. The high volume pump just delays fixing the real problem. High volume pumps are for increased demands on the oil system such as higher RPM usage, racing, remote filters and or coolers, etc.



Copyright © 2003 Melling Engine Parts


JBP offers a 'High Pressure' Pump...... as far as its been reported, its nothing but a stock pump with a stiffer Pressure Relieve Valve Spring........ kinda falls under #3.

The 2.3 pump is a Higher Volume Pump...... it also sports a Higher Pressure Relieve Valve Spring.



SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Re: Very good read, how to reduce rod bearing iner
Wednesday, May 17, 2006 12:38 PM
damn spell check turned my 'Relief' into 'Relieve'.......




SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Re: Very good read, how to reduce rod bearing iner
Wednesday, May 17, 2006 4:39 PM
ha, I talked to the rep at JBP and he said that the pump was comparable to the 2.3 pump, but i guess not.
Re: Very good read, how to reduce rod bearing iner
Wednesday, May 17, 2006 7:26 PM
I have not had 'hands on' experiance with the JBP pump, but thats what I have heard from a couple sources.......

....... untill someone buys one, and takes pics compairing the pump guts to a stock pump, we'll never know (kinda like 'how many licks does it take to get to the center of a tootsie roll pop')




SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Re: Very good read, how to reduce rod bearing iner
Wednesday, May 17, 2006 8:29 PM
Brian, thats the kinda anwser I was looking for. But I have a question, this might sound stupid, but until I ask it...ill always be skeptic. Why is pressure more important than volume? You noted that the volume is there, but theres not enough pressure, im kinda skeptic, is the oil pump virtually "spraying" oil onto the mechanics of the motor.


Re: Very good read, how to reduce rod bearing iner
Wednesday, May 17, 2006 9:18 PM
I read the article and kinda had the above question anwsered, but I still dont understand this:

Quote:


If the original pump has a 50 psi bypass the engine will not get over 30 psi, then putting in a pump with a 75 psi bypass will not change a thing. You will still have 30 psi. You have to fix the leak or rebuild the engine.



Does this infer that until the oil pump senses pressure of 50psi it will than open the relieve valve. What does that valve do, does it allow more volume? I wouldnt think it has much do with pressure, since the pressure is controlled by the resistance of the bearings, etc? Preferably Brian, but someone explain the purpose of this valve, im really thinking of buying the JBP pump.



Re: Very good read, how to reduce rod bearing iner
Thursday, May 18, 2006 1:13 AM
First..... Flow/Volume..... this aspect is how much oil you can move in a given amount of time. While the stock pump doesnt flow a ton, it does get oil to all ends of the engine. The size of the pump itself is matched to the area it covers. The pickup for the pump is poorly designed, causing the pump to starve out under higher speeds. The pump flows X amount of oil per rotation, as the pump spins faster, it still flows that same X amount, just faster. This causes a suction, that draws oil up into the pump, restrictions found in the pickup will cause a shortage of oil, and the pump now cant flow the same X amount per rotation Its at higher RPMs that cylinder pressure increases, and the load placed apon the bearings multiplies...... this is when the pressure needs to increase to support those loads. The 2.3 pump flows more oil per rotation, and has a better pickup design. With the 2.3 pump you dont suffer from the same starvation problems you get drawing oil threw the balance shaft assembly.

Second..... Pressure..... this is dictated by restrictions in the system....... bearing clearances...... oil passages....... The pump has a Relief valve built into it, that restricts the MAX pressure the pump can put out. This keeps from going to high, and causing leaks or other damage. If the stock relief is 50psi, and your Hot Idle pressure is 15psi..... putting in a Higher Pressure pump will not raise the pressure. If you put a Higher Flowing pump in, the restrictions in the engine will help raise the pressure since there is more oil trying to occupy the same space (as long as the engine is mechanically sound).

Think of your oiling system in the same way as your fuel system. It has a reservoir (fuel tank/oil pan), a pump, restrictions (FPR/bearing clearances) and a return (return line/oil drain backs)....... In the fuel system the pump picks up the fuel, and uses the fuel lines to transport it to the engine. The size of the line has an effect on how much fuel flows to the engine (combined with the pump). On the fuel rail is the FPR. This is what regulates the pressure in the rail and line. You can raise the pressure in the rail and line only so much, since raising the pressure will lower the actual Volume of fuel the pump pumps. Now increasing the size of the line and rail will allow more flow, it will cause the pump to work harder to build the same pressure. If you where to run 1/2" fuel lines, and a larger fuel rail...... and all you did was keep the stock pump, and turn up the pressure with the FPR, the pump will burn out in no time.

Now in the oil system, the 'lines' are the oil passages. Drilling them out will increase flow, at the cost of pressure. The stock pump just isnt large enough to supply the increased flow at the same pressure. Running a pump with a higher Pressure Relief pressure will do nothing to solve this, since its just a control for the MAX pressure. It just wasnt designed to supply that amount of oil with enough pressure to support the opposing pressure from the rods/pistons. In this case the Bearings will be what fails.

Did I confuse you yet? Cause I sure confused myself.....




SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

Re: Very good read, how to reduce rod bearing iner
Thursday, May 18, 2006 3:54 AM
The only question that I haven't seen answered is why #3 bearing? If it's pump starvation, then all bearings take the hit. If it's passages in the block then you'd simply open the passage supplying the main connected to #3 rod and it will perform as well as the rest of the bearings.

Rods are not in enpugh tension to cause problems during TDC on the compression stroke. Rods are in tension between TDC and BDC on the intake stroke. In 3 out of 4 cycles the rods are in compression. In a turbocharged engine the tension on the rod is greatly reduced under high engine loads thanks the positive intake charge pressure. Turbo engine rods are less likely to fail from tension fractures than NA rods.

The oil has a 3 part job to do at the crank. It acts like a cushion between the rod bearing and the crank. It provides cooling to remove heat from the rod or main and the crank. And it washes any loose particles out of the bearing face. As a fluid is subjected to more pressure, it becomes warmer. This is one of the tradeoffs in hydraulics. If you create more pressure with the oil pump, you increase the heat created , by friction, as the oil is forced through the engine. If you create more presure on a bearing in a connecting rod due to more pressure between the rod and crank, you increase the temperature of the oil only at the rod bearing. As oil becomes hotter it can support less pressure. The change isn't liner... the hotter the oil gets, the faster it loses it's ability to support the rods. But here's the thing. Because it's only at one rod, oil temperatures may not go up that much on a gauge. The gauge is measuring the average temperature of all the oil, not the temp of oil at the one stressed rod.

While increased pressure caused by the pump can cause slightly higher oil temps, the fastest way to increase engine oil temp is to advance the timing too much. Compared to 50 or 100 psi pressures generated by the pump, the amount of pressure generated as combustion occurrs is huge. The closer the piston is to TDC the more vertical the angle between the connecting rod and the crank. It's like driving a nail with a hammer. The crank has no way to turn all the pressure on the piston into motion, and something has to absorb the unused force. So it gets transferred through the rod, through the bearing, through the oil cushion at the rod brg, through the crank, and then into the block through the mains. If you continually ask one rod brg to support excess amounts of load the rod big end and the crankpin it's attached to will heat up more than the parts around it. This hinders the oil's ability to support the load even more. Eventually the oil fails and there's metal to metal contact.

Oh, and engine oil pressure is not what dictates how much load the bearing can support. If you think about this it's really apparent that it's the oil itself which does the job. Why do I say this? Consider a rod bearing. No matter how wide the bearing is, there's only a very small amount of material which is directly vertical from the piston at any time. The rest of the diameter of the rod does not support the force of combustion. It's kind of like hangfing a rod by a wire. So even with a 1" wide bearing you're looking at a fraction of a square inch of bearing surface to support combustion. So if we raise oil pressure to 75 pounds per square in, and multiply that number by a way too big 1/2 square inch, we find that the oil pressure generates an upward force of 37.5 pounds. And on the piston side if we multiply 1000 psi combustion pressure * a 3" diameter piston we find a downward force of 3000 lbs. I guess we need a bigger pump, eh? Think about the commercials which show an engine drained of oil and the car runs for some crazy amount of time. It's not a miracle that it happens. It's because they keep the loads down and use a chemical binder which holds an oil film on the crank .

HTH
-->Slow
Re: Very good read, how to reduce rod bearing iner
Thursday, May 18, 2006 8:32 AM
#3 is the thrust bearing.





Re: Very good read, how to reduce rod bearing iner
Thursday, May 18, 2006 10:48 AM
you made some good points slowolej....... I had over looked the heat vs pressure aspect. As for being the #3, its not always the number 3, but it is the most common one. Alot of your post deals with the oil itself, the composition of it. Its ability to hold together under heat and pressure. One would assume that most oils on the market could deal with 'OEM' conditions found in the 2.4........ I do remember those oil commercials...... what where they, Castrol?

If I had to pick out, or put the blame on, one componant in the 2.4 oiling system, it would the be pump/pickup/balance shaft assembly....... having things that spin while submerged in oil is never a good thing....

I think the #3 bearing just happens to be the closest to the pump, meaning it has the least amount of resistance, and that it will be the first to recieve what ever the pump sends it, or doesnt send it.........

again...... I'm by no means an 'expert'....... and I'm always open to input anyone wants to share.





SPD RCR Z - '02 Z24 420whp
SLO GOAT - '04 GTO 305whp
W41 BOI - '78 Buick Opel Isuzu W41 Swap

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