7M-GTE track oil pressure to low?

[Blackmk3]

Hey guys so just finished a track day in my supra today and got a question about the oil pressure.

The engine specs are
Rebuilt motor (not sure of clearances re builder did it). Oil squirters, full flow relocation setup with a 19row oil cooler and a 86c oil tstat
New toyota oil pump shimmed 6mm
Hard pipe oil pump mod thinge (no banjo setup)
Custom winged and gated sump 9 liters capacity

But anyways during the race the oil temps got up to 120c
I'm running a penrite 5w-30 oil full synthetic that's pao based racing spec high zinc etc etc
But what I noticed is that at 4000rpms it was making 300kpa oil pressure 43psi and by redline 6200rpms it had only increased to around 320kpa 46psi


When the engine is cold the relief system works perfectly, i have a Greddy gauge that's a digital stepper motor and very sensitive, the pressure at startup shoots to 500kpa 72psi then the relief must open it causes pressure to instantly drop back to 420kpa 60psi which is normal when cold pressure?

At normal oil temps around the streets the temperature sits around 80c the pressure is prefect and rises around 10psi per 1000rpms and has done ever since the the engine was first started.

Its just when the oil is at track temp 120C that the pressure wasn't getting as high. I understand how the viscosity changes at temperature and even more so at race temp, i wanted to know if that pressure around 40-45odd psi is enough when at the track? or do i need to step up to a thicker grade?
So my question really is at track temps is the 5w-30 that im running that's making 45psi of pressure enough to protect my 7M-GTE?


Thanks!

[dnegative]

There are no hard and fast answers, I wouldn't be overly concerned with 320kPa, it sounds a little low but you dont need 120psi oil pressure for a bearing to survive;
None of the diesel engines I work on really run over 400kPa and they handle stupid amounts of sustained load for eons.

What do other 7MGTE's seem to run at?
Your going to lose a fair amount of restriction when your oils 120c, if you could get it 20c cooler your going to pick up a decent bit.

[crownman]

Hi I raced 7MGTEs for years used 20x50 always . get operating temps for 30 mins before boost KEEP BEARINGS and keep your head gasket.

regards Steve CROWN PARTS FOR SALE 0412 711 481

[maj]

No idea regarding pressure, but I know that oil (since it is a proper racing oil) will not shear at 120c, so you are okay on that front. But agree with dneg the closer you keep it to 100-110c, the better.
It really does come down to whether that viscosity is suitable for the clearances in your engine when it was rebuilt. I feel you should probably be running their RACING 15W-50 or 20W-60, but again this is just general advice.

You are on the right track though using a racing oil and logging pressures vs temp.

[Daddio]

Just out of curiosity, did you have the piston oil squirters replaced when the engine was rebuilt? These do wear and can cause a drop in pressure....

[Blackmk3]

Thanks for the reply's everyone its starting to make me feel abit happier about it the last thing i wanted to do was damage a rebuilt engine.

Yeah the oil squirters were replaced, the engine has wiseco 20thou over pistons with eagle rods i wanted to keep the oil squirters for there cooling ability as i figured even tho a forged piston dosent require the cooling but that heat has got to go someware and oils can take more heat easily than putting more load on the radiator cooling system.
The oil cooler is currently tucked behind the FMIC the car as a full under cover on it and factory viscus fan for the radiator but im still planning on relocating the oil cooler and tstat to get direct airflow, Hopefully that will see a drop in 10 or so degrees, Hopefully more!

Maj - why do you think such a thick oil?
My mentally with the thinner oil was i would rather have the flow getting into the bearings, rather than a backlog of pressure trying to squeeze thicker oil into the gallery's.

[andrew_mx83]

Agreed get the oil temps down and I'd want to see a bit more pressure than that if it were my engine. That oil is a bit thin IMO, I've found 7ms to be the happiest on 15w40
Aside from rod & main clearances you also need to consider cam journals which do wear and will drop pressure.
Another possible issue would be an internal leak at any of the hard pipe fittings.

My view is that squirters can eat a dick, I'll keep the oil for my bearings thanks. Ceramic coat the pistons/valves/etc and keep the heat in the combustion chamber.
Along the same lines I now modify the aux shaft to run a ball bearing at the rear rather than the plain bearing which originally steals oil from #3 main.

[maj]

Maj - why do you think such a thick oil?
My mentally with the thinner oil was i would rather have the flow getting into the bearings, rather than a backlog of pressure trying to squeeze thicker oil into the gallery's.

It really depends on the tolerances the engine was rebuilt with. I'd imagine a factory engine would be 15W-40, a worn engine rebuilt they usually find factory tolerances on the tighter side so rebuild on the safer side to ensure even wear on the surfaces, rather than a tighter tolerance and developing hot spots etc.

Flow might only be an issue on a cold engine, but considering you are using a race oil anyway, cold start protection etc. Goes out the window and you are targeting a specific temp and pressure whilst under load.

It's always best to talk to your engine builder and get their advice. They are the one that will know what the engine is capable of and what it will run best with.

[RACINROLLA]

Have you tried using a different weight of oil?

Maybe it is thinning out too much with the heat........Maybe try a 10w60 to give you a better heat range.

Cheers Matt