what is you take on oil persure to much for bareings ect what s the idea amonte of persure for the 7mgte
Too high of oil pressure cons and plus
- Thread starter NashMan
- Start date
Ive herd it can hurt them kind of the same way a water jet works. Alot of pressure washes away the bearing surface. Im sure theres some type of fancy word for it, ive seen IJ talk about it.
Also theres more resistance on the oil pump at higher pressures bogging down the motor. probably not measurable but its there still.
Also theres more resistance on the oil pump at higher pressures bogging down the motor. probably not measurable but its there still.
Bearing Wash is what i have always called it.. Usally rule of thumb is you need 10 psi x 1000 rpm... So at say 6000 rpm 60 psi would be good.. at 2000 rpm 20 psi is fine...Why they made the 7mgte with such low pressure i have no idea....but it is a high volume low pressure system...... Im fixing to plumb my remote oil filter and cooler.... I used a 3/8 ball bearing in the Relief spring on pump.. Hope it puts it were i want it.. :}
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HommerSimpson;915631 said:
I dont understand the idea about toyota making high volume low pressure system. Doesnt that just mean all the bearing clearances are larger and flow more/hold less pressure? If thats the case why couldnt you fix that by running the kind of clearances you want? If im totally wrong, my question is, what exactly about the system lowers the pressure and increases the flow?
i think it's the other way around. the high volume low pressure system is for the tight bearing clearances
Adjuster
Supramania Contributor
The stock oil pump has a pressure bypass that dumps any oil pressure at the pump over about 40psi back into the oil pan/engine.
It just "leaks" the oil out v/s sending it anywhere else.
There is a second "leak" system on the stock 7MGTE. It too also leaks about 40psi.. (So not much oil really ever goes to the stock oil cooler if you think about it.. but there must be quite a bit of flow as we have found out, because if you shim the pump bypass about 5mm, and delete the cooler bypass, the oil pressure on the 7MGTE improves 100% in my opinion.)
SO with two designed in leaks, the oil that is not dumped either back into the pan at the pump, or through the stock cooler, is all the engine needed to run fine for thousands of miles.
I would think with the oil mods done, rod bearing wear should be avoided better, as clearly there would be more oil pressure due to the increased volume of oil not bypassed in the system anymore.
Oil erosion of the bearing material is not going to happen at even 130psi. Besides, this engine has so many leaks and places to bleed off volume/pressure, it's not going to stay there as the oil warms up. (And as indicated by a few of us with modified oil systems.)
130+ psi on start up is not uncommon. I have my oil pump shimmed perhaps 7mm? It does not open up much to bypass, and when the oil is cold, the oil pressure is very high.
When fulled warmed up, the oil pressure is between 60 and 80 most of the time, and drops to under 20 at hot idle.. (Sucks, because this is where my accusump kicks in, and dumps every time I come to a stop light and the engine rpm drops to where the oil pressure drops under 25psi, the "start" point for opening up the valve...)
I need to adjust, or replace my pressure switch for one that will not dump the oil at a hot idle. For now, I only turn on the sump when I'm going to play around. The rest of the time, I just have it switched off, and then turn it on just before shut down, fill up the sump, turn it off and keep that pressurized oil for prelubing the motor before I start it again.
Personally, I don't think the 7MGTE pump is capable of causing oil erosion damage to your bearings even if you completely blocked off the pump bypass. This is not a good idea however, and I'm not going to try it out. I did shim the crap out of the bypass though.
It just "leaks" the oil out v/s sending it anywhere else.
There is a second "leak" system on the stock 7MGTE. It too also leaks about 40psi.. (So not much oil really ever goes to the stock oil cooler if you think about it.. but there must be quite a bit of flow as we have found out, because if you shim the pump bypass about 5mm, and delete the cooler bypass, the oil pressure on the 7MGTE improves 100% in my opinion.)
SO with two designed in leaks, the oil that is not dumped either back into the pan at the pump, or through the stock cooler, is all the engine needed to run fine for thousands of miles.
I would think with the oil mods done, rod bearing wear should be avoided better, as clearly there would be more oil pressure due to the increased volume of oil not bypassed in the system anymore.
Oil erosion of the bearing material is not going to happen at even 130psi. Besides, this engine has so many leaks and places to bleed off volume/pressure, it's not going to stay there as the oil warms up. (And as indicated by a few of us with modified oil systems.)
130+ psi on start up is not uncommon. I have my oil pump shimmed perhaps 7mm? It does not open up much to bypass, and when the oil is cold, the oil pressure is very high.
When fulled warmed up, the oil pressure is between 60 and 80 most of the time, and drops to under 20 at hot idle.. (Sucks, because this is where my accusump kicks in, and dumps every time I come to a stop light and the engine rpm drops to where the oil pressure drops under 25psi, the "start" point for opening up the valve...)
I need to adjust, or replace my pressure switch for one that will not dump the oil at a hot idle. For now, I only turn on the sump when I'm going to play around. The rest of the time, I just have it switched off, and then turn it on just before shut down, fill up the sump, turn it off and keep that pressurized oil for prelubing the motor before I start it again.
Personally, I don't think the 7MGTE pump is capable of causing oil erosion damage to your bearings even if you completely blocked off the pump bypass. This is not a good idea however, and I'm not going to try it out. I did shim the crap out of the bypass though.
CyFi6;915708 said:
You can run larger clearences, I have, on the bearings. Which means to me that you have more oil in those areas as long as you mod the oil pump and anything else you can do to keep oil to the bearings. Somebody please correct me if I'm wrong.
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yae i am at the point were i am improveing the oil system i don't plan to use accsump thou it be bad ass thou
i do plan to drill the block and run larger fitting and the pump as well and get rid of the stock releaf vavle and just just thread into the side of the block and run remonte oil relocation but the thing is what size to pick i wa thinking of -8 insaid deamder full out
or what ever the stock rx7 oil was ?
but sinc ei just incressed the size of every thing will this affect my persure and drop it some more and if so how much to shim or not to shim ???
i all so have rx7 oil cooler but the thing i not sure about is does the rx7 oil cooler have bypass in the t state or am i going to have to do this at the oil filter
plus at this point i just going to lower the sump closer to the pan since i whould have just incressed the voume of oil by alot
on my old system i just ran a larger oil cooler to try to keep shit coole cuase of the stuiped releaf vavle worked great thou
well this is where i am at
i do plan to drill the block and run larger fitting and the pump as well and get rid of the stock releaf vavle and just just thread into the side of the block and run remonte oil relocation but the thing is what size to pick i wa thinking of -8 insaid deamder full out
or what ever the stock rx7 oil was ?
but sinc ei just incressed the size of every thing will this affect my persure and drop it some more and if so how much to shim or not to shim ???
i all so have rx7 oil cooler but the thing i not sure about is does the rx7 oil cooler have bypass in the t state or am i going to have to do this at the oil filter
plus at this point i just going to lower the sump closer to the pan since i whould have just incressed the voume of oil by alot
on my old system i just ran a larger oil cooler to try to keep shit coole cuase of the stuiped releaf vavle worked great thou
well this is where i am at
Doward;915617 said:Pressure is resistance to flow.
Any where I can have increased flow, I'm down for
Exactly
The reason a bump in pressure is seen as beneficial is you are actually increasing flow, pressure being a byproduct of resistance to that flow. Flow is what protects your bearings, not pressure, and an increase in pressure is NOT directly proportional to an increase in flow. Pressure will rise faster then flow.
Don't ever run without a pressure bypass, you will shear the oil pump!
good read on oil if anyone is interested:
http://63.240.161.99/motoroil/index.html
QWIKSTRIKE;915817 said:
Why is that? If you run a little larger clearence then you would have more oil to those areas. In modified motors you would want more oil in the critical areas, rod bearings in the Supra's case. Of course you have to make sure you still have the volume and the pressure. And run a heavier oil.
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475rwhp459torq an climbin
I just shimmed the oil pump, and put on the na adapter with a billet inlet and outlet, and then I am using an inline billet themostat with a Monsta oil cooler from an Australian comapany. The cooler is 13x2x6, and cost $109.00 delivered. The cooler is an equivalent of an Earls cooler for less. I am using a dual Billet.ams oil filter mount which both hold about 2.5-3 quarts of oil. I use 10 quarts of mobile1, and a mobile1 M301, and M403 oil filter. I used to use the B&M 70266 oil cooler, and I believe that although they worke well they may be a little to constricting of flow. I got everything in billet because the cast aluminum pieces were of inferior quality, and was always cracking.
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AJ'S 88NA;915849 said:
I personally don't believe in running loose clearances on the rods or main berings, but if you feel man enough to do it don't let me stop you. I belive the looser the clearance the less the oil pressure wll be I am getting higher oil pressure with tight clearnces. I usually find the more loose the clearance the more problem you have for knock collision inevitability. 7M's need tight clearances around the mians, and rods. this is done by sending the block and the crank with the main and rod berings to a good machine shop to have each journal done to the tightest clearances.
QWIKSTRIKE;915873 said:
Well I am man enough to do it as I have and still disagree with you. If you run too tight a clearence what happens to that little bit of oil you have running on the bearings when you really have the motor spinning at high RPM? Especially the heavy weight you run. You're getting pressure but not volume.
Adjuster nailed it
Nash - Run -10 piping/fittings if you can and shim the pump ~5mm.
Quick - I agree, mid to tight on the bearings are what this motor likes. I don't agree with your choice of oil brand/grade. I can see running a heavier oil with larger bearing clearances (and other oil mods), but not when running the clearances tight.
A Grp IV or V syn oil is best for a high HP turbo motor (Mobil 1 is neither)...if you run a lighter weight oil, you'll get better flow through the bearings. The link Calculated posted above is a good read (and his comments too)...a bit long, but worth it.
AJ - If you run a lighter weight oil with bearings on the tight side, you'll get plenty of flow. If you run them loose, I'd go with a heavier weight, but realize it will cause other increases in pressure due to restriction in other areas of the system. The pump def needs to be shimmed in this case. Keep in mind, hydrostatic open bearings (rod & main) are like a water ski...the flow is there to cool AND keep the surfaces from ever touching.
Nash - Run -10 piping/fittings if you can and shim the pump ~5mm.
Quick - I agree, mid to tight on the bearings are what this motor likes. I don't agree with your choice of oil brand/grade. I can see running a heavier oil with larger bearing clearances (and other oil mods), but not when running the clearances tight.
A Grp IV or V syn oil is best for a high HP turbo motor (Mobil 1 is neither)...if you run a lighter weight oil, you'll get better flow through the bearings. The link Calculated posted above is a good read (and his comments too)...a bit long, but worth it.
AJ - If you run a lighter weight oil with bearings on the tight side, you'll get plenty of flow. If you run them loose, I'd go with a heavier weight, but realize it will cause other increases in pressure due to restriction in other areas of the system. The pump def needs to be shimmed in this case. Keep in mind, hydrostatic open bearings (rod & main) are like a water ski...the flow is there to cool AND keep the surfaces from ever touching.