Oil temp and pressure problem ?

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Wolf_Tm250

Joined
Dec 18, 2004
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137
Location
Parma - Italy
Hello,

I'm Wolf from Italy.

Car is Toyota Celica GT four, engine is a modded 3SGTE ( 430 awhp - 588.2 Nm torque ).

According to my oil clearance ( 0.045 mm ), oil used is Motul 300V 10W-40.

Engine is newly rebuilt, 1500 kms old.

After 6 rounds in a local track ( ambient temp was 5 deg. C. ), I get 125 deg. C. ( 1740 F ? ) and a oil pressure of 2.5 bar above 3000 rpm ( sensor is in the head ).

For the temp, now I have the stock water/oil cooler plus a small air/oil cooler: it seems that I have to buy a bigger cooler and move it in front of the water rad ( now is behind the bumper, where there was the side-marker ).

For the pressure... isn't it too low ?
Talking with other high hp Celica owners, it seems to be a normal value, but it doesn't tranquilize me a lot...

At cold I'm getting over 6 bars at 2000 rpm.

Shimming the relief valve shouldn't change anything because at that pressure I think it's not open.

Lowering the oil temp will help me with the pressure ?

Any comment/advice ?

Thank you !
 
2.5 bar at just above 3000 RPM seems a bit low, but the dash gauge may not be accurate. 125 C (257 F) is not that high, considering you track the car.
 
Unmfortunately I didn't trust to go to higher rpms with this pressure.

I can tell you I was at 2.5 bar at 3000 rpm and going over the pressure increased slowly.. IIRC around 2.6 - 2.7 bat at 4000 rpm...

My redline is at 7400 rpm.

Thank you AEHaas.
 
Hi Moribundman,

My gauge is a Greddy one, and the sensor ius iun the head.

125 deg C.n is not that high, I agree, but it was after only 6 rounds, and with an ambient temp of 5 deg C., and I was thinking about italian summer temps...

Lower the temps will help me increase a bit the pressure ?

Thank you.
 
My Maranello and my Enzo manuals stated that 75 PSI at 6,000 RPM is sufficient. 5 Bar at 7,000 RPM would be OK, 6 would be the best number in my book and over 7 would be too high. Then a thinner oil would be needed for you application.

aehaas

PS Is Parma north and west of Firenze? I think I had lunch there once. Mangiare.
 
Very big difference between cold and hot pressure. I am used to pressure sensor in the block. It may be that having the sensor in the head gives the lower reading. Seems 2.5 bar in the head is pretty good. Would be interesting to move the sensor to the block and see what pressure you get. Bet it would be higher for hot, similar for cold. Just my wild guess. Otherwise, is a 20w50 needed???
 
AEHaas,

Do you think it's time for a THICKer oil ?
For example turning from my Motul 300V 10W-40 to the 15W-50 ?
PS: Yes, Parma ( italian food valley ) is 140 km north and west of Firenze... please whistle me when you'll be there next time !
wink.gif



TallPaul,

Yes, it could be a good choice to move it in the block...

I'm too amazed for the big differenze between cold and hot...
Mates, what could be the reason for this ?
I think that oil squirters work when cold too !

Thank you all.
 
My Toyota 7M-GE service manual states that oil pressure of 2.5-5 bar @3,000 rpm is acceptable. The pressure sending unit on this engine is tapped in right after the oil filter.

Have you looked up the specs for that engine?

Are you using the right oil pan and pickup for the installation, i.e, transverse versus longitudinal? Later model engines have a higher output oil pump, so that might be worth investigating.

What does "According to my oil clearance (0.045mm)" mean? Oil pump body/side clearance? Or main/rod bearing clearance?
 
The old rule of thumb is that you want 10 PSI for every 1000 RPMs. 14.2 PSI = 1 bar; 2.5 bar = 35 PSI which is right on for 3,000 RPM point.

125dC = 257dF which is "not that hot". "That hot" begins around 280dF = 138dC, and "too hot" begins about 150dC.

Oil looses viscosity as it gets hot. A 10W-40 oil should be in the 100+cSt range at startup, will be in the 12.5-15cSt range at 100dC and will drop to 5cSt range at 140dC. You pressure guage is seeing this drop in viscosity.

Since you are seeing 6 bar cold, this indicates the blow-off valve on the oil pump is popping off at 6 bar which is completely in line with a 7,000 RPM redLine. Even with hot oil, you should be seeing something in the 5+ bar range at redline with hot oil. Are you?
 
The thing about "old rules of thumb" is that they're "old" and "rules of thumb". NASCAR engines typically run with no more than 50 psi of oil pressure at 9,000 rpm.

There's a reason for the range of pressures in the specifications. Namely to account for changes in viscosity as the oil heats up.

If you changed the plumbing of a stock oiling system and added significant additional restrictions, all bets are off.
 
quote:
427Z06 wrote:

My Toyota 7M-GE service manual states that oil pressure of 2.5-5 bar @3,000 rpm is acceptable. The pressure sending unit on this engine is tapped in right after the oil filter.

Have you looked up the specs for that engine?
Click to expand...
Unfortunately there are no specs for MY engine... let me explain...
this is a 3SGTE that I rebuilt with TTE-WRC parts, so I cannot follow the Toyota specs for the original engine...

So I asked for general specs for racing engines...

I think I'll have to buy the WRC oil pump... oh yes, it gives 5 bar at hot idle... but it costs 1800 euros !!!!

BTW for the longevity of my engine I can do it
wink.gif



quote:

Are you using the right oil pan and pickup for the installation, i.e, transverse versus longitudinal?
Click to expand...
Yes...


quote:

What does "According to my oil clearance (0.045mm)" mean? Oil pump body/side clearance? Or main/rod bearing clearance?
Click to expand...
Sorry, main/rod clearance.


quote:

If you changed the plumbing of a stock oiling system and added significant additional restrictions, all bets are off.
Click to expand...
I added an air/oil cooler ( MOCAL ), a sandwich adapter (MOCAL), a thermostatic valve (MOCAL), 2 meters in total of -10 ss braided teflon lines, 2 straight + 4 90deg + 2 180deg. hose ends....

Did my pressure finish here ?

Thank you.
 
Mitch Alsup wrote:


quote:
The old rule of thumb is that you want 10 PSI for every 1000 RPMs. 14.2 PSI = 1 bar; 2.5 bar = 35 PSI which is right on for 3,000 RPM point.
Click to expand...
Ok.
But problem is at 5000 rpm I was not at 50 psi....


quote:

125dC = 257dF which is "not that hot". "That hot" begins around 280dF = 138dC, and "too hot" begins about 150dC.
Click to expand...
Ok.
But I had those temps in a 5dC day and after only 6 laps, that's why I think I'll have to change something in the system...


quote:

Oil looses viscosity as it gets hot. A 10W-40 oil should be in the 100+cSt range at startup, will be in the 12.5-15cSt range at 100dC and will drop to 5cSt range at 140dC. You pressure guage is seeing this drop in viscosity.

Since you are seeing 6 bar cold, this indicates the blow-off valve on the oil pump is popping off at 6 bar which is completely in line with a 7,000 RPM redLine. Even with hot oil, you should be seeing something in the 5+ bar range at redline with hot oil. Are you?
Click to expand...
No, I think here is the problem...

Thank you.
 
I wonder if a super high quality oil like Redline or Motul would make up for the lower pressure? Cheaper than the revised oil pump.
 
The oil temperature is not helping your problem that is for sure. You need to get that under control a little better. Somewhere around 220-230 F Max would be much better for a road race type car.

Have you checked the oil pressure gage with another one of high quality to verify it is correct?

When the motor was rebuilt, was a new Toyota oil pump used?

When the motor was rebuilt, was the oil pickup checked with clay to make sure it was .375 to .500 inch off the the bottom of the oil pan with gasket??

If you can get to 50 to 55 psi with a reduction in oil temperature is should work fine in your Toyota motor.
 
Assuming 7gpm flow the 2 meters of -10 ss braided teflon lines present about a 4 psi drop. You'll have to look up the pressure drop for the other pieces.

.0018" clearance is probably on the upper end for that engine. 125C(257F) isn't anything a good synthetic couldn't handle.

Hmmm...try TallPaul's suggestion and try to get a oil pressure reading right before the oil line enters the engine.
 
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