JasonC SBB

Anyone noticed a drop in oil pressure?

With 82*C oil (180*F), I only get
16-17 psi at idle,
28 psi at 3000 RPM, and
38 psi at 6000 RPM.

With stone cold morning oil (50 *F) it's 65 psi at idle and tops out at 75 psi, so I know my oil relief valve is working.

neogenesis2004

iTrader: (12)

Maybe it needs to be shimmed.

TravisR

iTrader: (9)

There is a reason they increased the size, the oil pumps are designed at exactly what they need to be to create the proper flow in the engine. 38 PSI sounds very low to me, I'd be worried about your bearings. There is a reason why I recommend 70-90 PSI for my customers! All that extra flow affords a lot of protection.

JasonC SBB

Neo shimming won't help because 38 psi is below the bypass opening pressure.

Would thicker oil for higher pressure help? This won't improve flow though.

TravisR

iTrader: (9)

No, the thicker oil won't do anything for you. What you need is flow!

Flow is what actually keeps the surfaces apart. You can drop a fork into a 5000psi body of water and it'll sink at the same rate as one at atmosphere. The high speed movement of the fluid pushes the metal parts apart doing the bulk of the work.

Ideal would be dynamic viscosity being low, and pressure is high! 0w-20 @ 90 PSI!

Faeflora

iTrader: (2)

Argh PSI is dictated by other things as well including various restrictions etc. I thought what you wanted with the oiling system was massive flow, not pressure.

BTW FWIW Y8S and I, with VVT heads never see more than 45psi or so at 5000RPM. VVT will **** with the oil pressure too.

JasonC SBB

Fae,

Which oil pump do you have?

JasonC SBB

BTW Travis,

If 100% true, why not use 5w-20 oil and get more flow despite less pressure? (for those with lots of pressure)...

Reverant

iTrader: (10)

Oh I definitely have more than 50psi at or above 5000rpm, albeit this is a stock VVT engine, not a built one.

Faeflora

iTrader: (2)

mz-bp4w-14-100A

I have no clue what year that pump is from. It is an old miataroadster billet OPG assembly. It would be nice if I could find out :{


How much more? 50psi @ 5000RPM is about where mine tops out at.

Reverant

iTrader: (10)

60 to 65.

miata2fast

iTrader: (2)

Does that not rob horsepower to have oil pressure at a high PSI?

Faeflora

iTrader: (2)

OK NM

The MZ-bp4w-14-100A is the oil pump that was standard through '99. A "non VVT oil pump".

Faeflora

iTrader: (2)

Why is all the PSI necessary? If there's a film of oil, there's a film of oil right? Doesn't matter what the PSI through the system is does it?

JasonC SBB

All else being equal more oil pressure means there's more flow too.

Now if you're in the middle of the acceptable ranges, is thinner oil for more flow better, or thicker oil for more pressure?

JasonC SBB

Arrrgghhh!!! I'm not getting significantly higher oil pressure with 5w50 oil

How do I change the oil pump without pulling the motor?

Anyone want to buy billet OPGs blueprinted in its housing, for a non VVT application?

Reverant

iTrader: (10)

Can be done but you will need to raise the car up enough to work under and then prepare to break your back several times. I would rather pull the engine out.

shuiend

iTrader: (24)

Pulling the motor is the easiest way to swap oil pumps. So what gears are you using? I am using a 94 OP with the BE billet gears on my 94 block with the VVT head and oil pressure has been fine so far. I will look tonight to see what my oil pressure is at idle, but I do not think it is anywhere near as low as yours?

Faeflora

iTrader: (2)

Jason, before pulling the motor do an oil analysis. That's what I'm doing at the next oil change.

shuiend

iTrader: (24)

Warmed up I sit right above 30psi and cruising at 45mph in 5th I am a little below 60psi. When VVT kicks in oil pressure does drop a little. I am still using the stock oil pressure sender from my 94 with the stock gauge.