Variable Oil Pressure ... can it be done?

[bazeng]

NOTE: Measured at the oil filter housing....

 

[cheekychimp]

Yes, I have seen that before. What is involved in fitting it?

I also found this.

Canton Adjustable Oil Pressure Regulator

 

[bazeng]

Just pull off your rocker cover, pull off the original plate, install the new one!
Very simple!

 

[Barnes]

Quoting cheekychimp:
Porting the relief valve is a band aid and it's solving a symptom not the cause.



The cause is simple. Our oil pumps are too large without balance shafts in the engine. So unless you can figure out how to fabricate or swap in a smaller oil pump, the oil relief valve is the only solution to too much oil pressure.

 

[cheekychimp]

Barnes,

I accept that to a point but I have spoken to some guys that know a thing or two about the 4g61t engine. The pump on that engine (in fact on pretty much all the 4g engines) is essentially the same and it was intended to flow more than an NA block pump because it supplies a turbo. So I come back to this critical issue.

Do stock 4g61t blocks have these insane oil pressures of 100 psi and even 140 psi plus just because they don't have balance shafts?

And if not, why not?

 

[Barnes]

It almost certainly does. However unless someone sticks an oil pressure gauge on a motor and takes a reading we will never know for sure. The only other possibility I can think of is that the 4g61 comes with a much larger oil relief valve.

 

[Dialcaliper]

Someone might also point out that the factory oil is either 10W30 or 5W30. Most people seeing pressure problems are running at least 10W40, or more likely, 20W50 or thicker oil (Like anyone foolish enough to run straight SAE 50 "race" oil in an engine not designed for it). An oil that is too thick cannot properly "wet" and stick to the surface it is supposed to protect, it also cannot flow as well through small gaps. In short, tighter main and rod bearing clearances require thinner oil.

Quite honestly, if you are still having over-pressure problems after the engine warms up, you are simply using oil that is too thick for a) the clearances in your engine and b) your local climate.

Also, there is a huge variation in actual viscosity between oil brands and types that carry the same "SAE" Weight. It's the same story as with tire diameter, width and treadwear. Look around at some oil spec sheets, and you'll see that (for example) some 10W40 oils have higher true viscosity at certain temperatures than other 20W50 oils.

Just because the oil is thicker does not mean it protects "better" if it is producing extremely high oil pressures. If your engine is not running hot enough to thin 20W50 oil out to produce normal operating pressures, you don't need to be running it, especially with modern high end synthetics, which have come a long way.

I'd also like to point out that while porting the filter housing can fix pressure problems, it's also a sign that oil thickness is working doubly against you - not only does higher pressure mean you are getting less oil flow to the moving parts in the engine (think of fuel pump outputs at high pressure), the oil relief opening even further means a larger fraction of the pump flow is dumping back into the pan.

The easiest way to alleviate pressure problems is switch to a lighter oil. If the problem is only when the engine is cold and thinner oil ends up with lower pressures at operating temperatures, a synthetic oil with more viscosity modifiers (0W-XX or 5W-XX oil) will help to reduce the pressures.

 

[IncorpoRatedX]

I saw an aftermarket oil distribution block for the head posted above, reminds me I've seen some variations between those on 4G engines...

 

Quoting cheekychimp:
Barnes,
The issue is this, with the Balance Shafts in the engine removed people are seeing 100 psi on cold starts and up to 100 psi at WOT (7500 rpms). So whilst I think your idea might work to prevent cold start pressure surges, it will probably be worse for high rpms. I think I am going to have to port the oil filter housing relief valve and then experiment with different restrictors.
Paul.


I see you have been reading my thread lol