What are the general weaknesses of the LD9's stock oil system? Is it mainly lack of good flow to the head at higher revs or is there more?
12.6 @ 114.6 MPH
It cavatates the oil above 5800 RPM and it includes the balance shafts, which adds 6 lbs of rotational mass..
Matt, I would run an oil pressure gauge and see when your oil pressure starts to drop. Mine is good till 6500ish before it starts dropping. I agree a lot start cavatating around 5800rpm, but not all.
2.3 oil pump swap is a great idea for any higher revving LD9.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
I haven't had the cav out in a while. Been pretty busy finishing some body work on it so I can finally paint. I'll have to pay attention to that next time I have it out. I've got a gauge right on my dash for that, but I usually only have it displaying the turbo's supply line pressure (I have 2 senders on a positional switch for the gauge; one engine, one turbo).
So loss of pressure seems to be it? Wouldn't a larger pan (more oil) stop the cavitation issue? Cavitation is usually caused by a pump sucking more than can be supplied, no?So the head in particular is no more of a weak link than the rest of the engine in terms of oiling?
12.6 @ 114.6 MPH
i meant the stock pump starts cavatating the oil at 5800 rpm. and removal of it would also remove the balance shafts, losing 6lbs of rotational mass.... lol i re-read what i wrote and failed to associate the pump with my statement..
I recommend the 2.3 oil pump swap to anyone who plans to build their motor and especially to those who drop HO cams (or bigger) in.
The 6 lbs of roational weight is an increase in 15-18 hp without the one balance shaft slowing down the crank. Plus the whole assembly weighs 20 lbs. Actually it'll idle better and have less stress on the crankshaft. They are only used for the 4th harmonics, which are in the higher rpms of the engine. The Harmonic Balancer is used to cancel out the 1st, 2nd, 3rd harmonic vibrations and the crankshafts twisting and bending forces with its rubber elastic band. Not really necessary on a 4 clyinder, yet still helps longetivety of bearing life.
I agree removing the balance shafts is a big plus...you will feel the difference.
If you drive an LD9 I strongly recommend having an oil pressure gauge and using Lucas oil additive
GMR has got nothing on this
honestly nobody has ever really PROVEN whats weak.. the oil pump or the block passages, etc.
the pump itself quite honestly could be adequate but since its driven by a stupid biycycle chain and has a @!#$ty ratio its held back, really.
i would swap ANY LD9 to the 2.3 style. stock or otherwise. ...just to be safe.
and dont worry about the "harmonic balancer". the stock 2.4 system has proven more dangerous to "bearing life" than any aluminum crank pulley ever used on any quad 4 family engine ever has.
Edited 1 time(s). Last edited Tuesday, March 13, 2012 3:13 PM
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Quote:
Wouldn't a larger pan (more oil) stop the cavitation issue? Cavitation is usually caused by a pump sucking more than can be supplied, no?So the head in particular is no more of a weak link than the rest of the engine in terms of oiling?
My .02 cents from what I have read over the last 8 years or so on this forum:
The cavitation is caused by the pump spinning at twice engine speed. The type of pump, iirc its a positive displacement pump, starts to spin too fast around 12,000 rpm and since they are driven twice engine rpm thats 6,000 on your tach. At that point the pump outruns itself resulting in it caveatting and aerating the oil. As Brad said its not really the pump, just the gearing/speed GM has it run at. Its all speculation but seems to fit pretty well with the common LD9 failure point, #3 rod bearing and I read somewhere that is the first bearing that gets oil from the pump so it makes sense if the oil is aerated that bearing will fail first.
PSN ID: Phatchance249
I WENT DIGGING!
SweetnessGT wrote:SpeedRacerZ wrote:The pump itself might not be the sole reason, but the pickup, balance shafts, chain...... the whole oiling "unit" is a POS. At higher RPMs, how fast is that little 2.4 oil pump spinning? I checked tonight, the 2.4 cank to balance shaft gear is a 1:2 ratio, while I believe the 2.3 is 1:1.
as far as weights, someone forgot to weigh the chain, gear, tensioner, bolts....... I just tore a balance shaft assebly off a 2.4 tonight, heavy POS! lol
Where is Chris (SunFighterGT?) with all the 2.4 oiling answers? I remember him saying he spent hundreds of hours and dollars (canadian) researching the 2.4 oiling system for his build.
From my point of view, it looks like the #3 is the first to receive oil, and therefore the first to receive oil airation or cavataion.....
please excuse my spelling errors, for some reason my netbook doesnt point out my errors, and my iphone always fixes mine for me..... I'm lazy and tired.
Clearly I don't read through this forum as thoroughly as I used to! Sorry for missing this Brian... Oh and it's SweetnessGT now. 
Quality control by GM is a huge issue and detriment to this block... a lot of the issue is in how they cast it. Chamfering the passages helps a lot if you can get in there... this is something I had done that took a considerable amount of time.
I sectioned a stock block to see it for myself (a fun process in itself) and the passages are questionable - that's for sure. #3 sees oiling first as Brian said. The block I cut also had questionable casting to #3 as well as #1 bearing.
I stuck with the 2.4 setup running with Mev's JBP pump. It has a different gear that increases volume which is a help but I have proven through two engines it provides almost zero pressure benefit over the stock setup. I still see around 10 psi at hot idle and 35 psi at 3500 rpm which is exactly what I've seen on two of my other stock LD9 setups. Bear in mind this reading is from the head where everybody else gets it... the pressure is much better when tested at the block with a snap-on gauge as we had to test it in multiple spots to ensure good oiling after 1500 km.
The biggest issue was mentioned by Brian - the gear ratio. The LD9's stock pump spins at twice the cranks rotation so at 7000 rpm the pump is rocking a solid 14000 rpm which it's just not up to handling, even if you overfill the oil.
In all honesty had I trusted Mev to do the 2.3 swap and taken the time to find the swap parts I would have done it, and to this day wish I had. Maybe down the road I'll pull the engine again and do the swap. The engine has been torn down multiple times and I can say the chamfering of the oil passages helped quite a bit but considering I wanted this engine to go to 7500 rpm give or take and I have a pump in there that runs at a 2:1 ratio I don't feel 100% safe doing it.
C'est la vie. Live and learn. That's all the info I have for you, take what you'd like from it.
My current mostly stock LD9 doesn't see over 3500 rpm on a daily basis and even when run low on oil has been fine. I don't dare abuse it though.
-Chris-
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
-MD- Enforcer wrote:I WENT DIGGING!
SweetnessGT wrote:SpeedRacerZ wrote:The pump itself might not be the sole reason, but the pickup, balance shafts, chain...... the whole oiling "unit" is a POS. At higher RPMs, how fast is that little 2.4 oil pump spinning? I checked tonight, the 2.4 cank to balance shaft gear is a 1:2 ratio, while I believe the 2.3 is 1:1.
as far as weights, someone forgot to weigh the chain, gear, tensioner, bolts....... I just tore a balance shaft assebly off a 2.4 tonight, heavy POS! lol
Where is Chris (SunFighterGT?) with all the 2.4 oiling answers? I remember him saying he spent hundreds of hours and dollars (canadian) researching the 2.4 oiling system for his build.
From my point of view, it looks like the #3 is the first to receive oil, and therefore the first to receive oil airation or cavataion.....
please excuse my spelling errors, for some reason my netbook doesnt point out my errors, and my iphone always fixes mine for me..... I'm lazy and tired.
Clearly I don't read through this forum as thoroughly as I used to! Sorry for missing this Brian... Oh and it's SweetnessGT now.
Quality control by GM is a huge issue and detriment to this block... a lot of the issue is in how they cast it. Chamfering the passages helps a lot if you can get in there... this is something I had done that took a considerable amount of time.
I sectioned a stock block to see it for myself (a fun process in itself) and the passages are questionable - that's for sure. #3 sees oiling first as Brian said. The block I cut also had questionable casting to #3 as well as #1 bearing.
I stuck with the 2.4 setup running with Mev's JBP pump. It has a different gear that increases volume which is a help but I have proven through two engines it provides almost zero pressure benefit over the stock setup. I still see around 10 psi at hot idle and 35 psi at 3500 rpm which is exactly what I've seen on two of my other stock LD9 setups. Bear in mind this reading is from the head where everybody else gets it... the pressure is much better when tested at the block with a snap-on gauge as we had to test it in multiple spots to ensure good oiling after 1500 km.
The biggest issue was mentioned by Brian - the gear ratio. The LD9's stock pump spins at twice the cranks rotation so at 7000 rpm the pump is rocking a solid 14000 rpm which it's just not up to handling, even if you overfill the oil.
In all honesty had I trusted Mev to do the 2.3 swap and taken the time to find the swap parts I would have done it, and to this day wish I had. Maybe down the road I'll pull the engine again and do the swap. The engine has been torn down multiple times and I can say the chamfering of the oil passages helped quite a bit but considering I wanted this engine to go to 7500 rpm give or take and I have a pump in there that runs at a 2:1 ratio I don't feel 100% safe doing it.
C'est la vie. Live and learn. That's all the info I have for you, take what you'd like from it.
My current mostly stock LD9 doesn't see over 3500 rpm on a daily basis and even when run low on oil has been fine. I don't dare abuse it though.
-Chris-
My stock LD9 sees high rpms everyday. It has over 212k and it leaks so much oil I stopped changing it a while ago because it is constantly low. Im kinda waiting for it to blow up and it wont. I do however have a replacement for it, which is the reason I don't particularly care about it. It is a 96 which is supposed to have worse oil passages than later years. Point being some cant handle the abuse but some can. Guess it depends if they were assembled/casted on a monday or friday
Could you not change the gear ratio slightly? Like 1.75:1 or something?
- Your not-so-local, untrained, uncertified, backyard mechanic. But my @!#$ runs
Oedwards wrote:Could you not change the gear ratio slightly? Like 1.75:1 or something?
Technically, yes, you could have a different gear cut. But why, when swapping to the older 2.3L setup costs roughly $80-$100 with USED parts.
IT's cheaper, it's safer, and it's been used, to much success, on several high horsepower/higher revving cars on this site. I honestly don't see a reason for anyone to continue to use the stock oiling system.
You have to have the engine apart and redrill passages for the swap, don't you? I never did anything with the oil system when I rebuilt (stupid me), but am not going to pull the engine and rip it apart again just for that.
12.6 @ 114.6 MPH
Just as a note, I pulled apart a motor this week that had a severely damaged 2nd rod bearing,#3 was fine as well as the other 2.
"Oil Leak ? What oil Leak ? Oh, Thats Just The Sweat From All The HorsePower!!"
Gents, as a hydraulic systems instructor, I can possibly help to crowd source more information on this situation. As far as pumps go, the speed of the pump in a positive displacement style (non-turbine) pump does not actually interfere with its operation as it climbs higher into the RPM range. Positive Displacement pumps are exactly that, "positive displacement." They do, however, require a larger volume of fluid in the supply/reservoir/tank as their RPM increases. This is due to the fact that they will soon overrun themselves by putting more fluid into the "system" than is available left in the supply to feed the the suction side of the now screaming pump. When a pump tries to put out more than it can take in is when you have cavitation problems. I am of the opinion that the oil supply for such a large 4 cylinder is inadequate. I have been considering the possibility of adding a remote oil supplementary tank, much like the radiator reservoir, to see if my hypothesis is correct. The added benefit to this would of course be more oil and less oil duty cycle. Restrictors are also commonly used in hydraulic systems immediately after the pumping mechanisms to help prevent exhausting the fluid supply. I am not sure how to factor this in to the LD9 engine, just some of the things I have learned about fluid dynamics in pressurized systems over the past 9 years. Maybe someone can take this information and practically apply it... I guess it can't hurt!! Best of luck all!!
SweetnessGT wrote:-Z Yaaaa- wrote:honestly nobody has ever really PROVEN whats weak.. the oil pump or the block passages, etc.
the pump itself quite honestly could be adequate but since its driven by a stupid biycycle chain and has a @!#$ty ratio its held back, really.
i would swap ANY LD9 to the 2.3 style. stock or otherwise. ...just to be safe.
and dont worry about the "harmonic balancer". the stock 2.4 system has proven more dangerous to "bearing life" than any aluminum crank pulley ever used on any quad 4 family engine ever has.
I made a huge post about this with my findings and how I came to my conclusions about 3-4 weeks ago in another LAD9 oil system thread, actually. Nobody noticed.
-Chris-
Om hoping i can get a reply i am having issues with a 2.4 right now and i noticed rod 1 and 3 journals pretty beat up i want to switch the pump for the 2.3 but am in aware of the parts needed i can look it up in the forums but i am new here and i will take me some time maybe but Om going to try any ways
The swap isn't that bad, and there are a few ways of doing it.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
