Oil Pressure For Higher Redline
 

I have a 2003 VVT built head and engine and redline set to 8400. The oil pressure is stable in the low 50s psi up to redline with a VVT pump with Boundary gears in the pump. I need to take the front subframe and transmission out anyway, and I have the shim kit from Boundary sitting on the bench. The rule of thumb according to random people on the internet is 10psi/1000 rpm. By that logic the engine needs more like 85 psi than 55.

The question is, is it worth taking a non-leaking oil pan off to shim the pump to a higher pressure? At what pressure do people start having problems with blowing out seals?

The shims promise 66, 72, 78, 84, or 90 psi, although I'm sure there's a tolerance on those numbers. If I shim it, I'm leaning towards the 78 psi one. This is primarily a street car.

What are you using for oil?

Amsoil 10w40

I would not recommend removing the pan in the vehicle, especially if it is not leaking.

The main concern is the rod bearing supply since it is the last oiling point and the increased inertia from the higher RPM. The 10psi/1krpm is an old rule of thumb and more applicable to older v8's which have a longer stroke.

IMO The output from the oiling systems on the BP engine is a bit low for max performance applications. Feeding the VVT and a turbo at high RPM is asking a lot. On my next build I'm going to do more clean up on the oil galleys and pump.

Adding shims isn't going to help bring up oil pressure at high rpm, it's only going to increase initial pressure when the engine is cold on startup. It's more about volume than actual oil pressure and the vvt pump is the best you can currently get. You might not even be making power at 8400. My redline is 7500 and I rarely need to take it up there anyways

This assumption would only be true if the bypass was completely closed at the max rpm. The pressure relief is a bypass system which reduces the output volume to control the pressure. There are two issues to contend with, the first is the restrictive passages to the filter and the second is, if that is improved would it drain the pan. The filter also has a bypass that might be set too low (15-20psi) to offer good filtration.

IMO the oil passages need to be improved. I would also consider a better filter like a system 1 etc. and then increase the oil volume. Maybe running one extra qt could work, otherwise it would require increasing the sump of the pan which might also need cross member mods.

The volume is directly dependent on engine RPM, so volume flow increases as the engine speeds up. More shims should increase the RPM and pressure at which max PSI is reached

Yes volume increases as engine RPM climbs, but so does consumption.

However, judging by the fact that you say pressure stable in the low 50s and the lowest shim option is ~66psi, you're probably pushing enough volume and pressure to be opening the stock relief valve which is causing pressure to level off in the 50s. Ergo, you could probably shim it up to a higher pressure if you wanted to. But again, I don't know that there is a reason to do so. You could always get an oil sample analysis and then make a judgement call based on whether there is a significant amount of bearing metals present in the sample. If not, I'd leave well enough alone.

I have a boundary stage 2 with 72psi shims. At redline with 15w50 m1 I see maybe 60psi at most. These engines just don't make high pressure like a Honda does. Adding shims will not increase pressure once the engine is at operating temp from my usage. Never had any issues with the lower pressure my older BP that I built had similarly lower oil pressure 50-55 at redline with a oem pump.

This has been my experience as well. Stock pump, boundary pump, boundary VVT pump and i have seen minimal differences in pressure between them. I run vr1 and generally see about 60psi on all of them, a bit less on the VVT setup i used to run. When i went to the BP4w head my oil pressure ticks just over 60 on the stock gauge at WOT.

My engines were built by the gun builder here, and he put a new higher mark put on the dipstick to increase the oil volume in the sump - maybe an extra litre or so, I can't remember now. He also did work on the baffles and (I think) the windage tray, that may or may not have been to deal with the extra oil. No idea any other work on oil flow.

I really don’t think extra capacity is needed. The pumps don’t move that much oil and the heads drain well. You’re probably losing some efficiency from windage with that much more in the sump.

That's interesting. Anyone else around here have experience with shimmed pumps and whether they hit the target pressure? Seems kind of strange that Boundary would advertise higher pressure if it never actually happens in real life

I still maintain (like others here) that you really don't need any more pressure than it makes already. Check out this article, specifically the subsection about pressure: https://www.enginebuildermag.com/201...iling-systems/

They recommend around 3-5psi per 1000rpm for a performance application. Modern oils are far better than when the "10psi per 1000rpm" adage was born, and its just costing you efficiency and robbing power to push that much pressure anymore.

That's what I'm telling you, the shims will not increase pressure when the engine is warm. Trust me I've been in the Miata game for over 20 years.

I actually just logged a 20 mile drive home to look at an oiling issue I'm having with my EFR. Theres a lot of extra data, but the 5th graph down in green is oil pressure. I have a boundary stage 2 VVT pump with 2 shims, so "72 psi". Actually hits some peaks above 100psi while the oil is still cold, and after that, anywhere you don't see green means it's below 72psi. It does still get to 72psi, but at idle when warm, I've got just under 30psi. This is Total synthetic 5-40.
https://cimg1.ibsrv.net/gimg/www.mia...2357dcf5b6.jpg

5 and 6 together tell the full story, on my reading.

What brought IAT up in the latter stages Curly?

Seems to correlate with lots of idle time, I’d wager just heat soaking in traffic. Once RPM is consistently up again it drops back down

What he said. Fairly consistent heavy traffic, what should be 5 minutes from my house but ends up being 20 minutes every day. That's what happens when a freeway, highway, and frontage road all converge onto a one lane bridge into the city, with multiple lights on the other side.

This has triggered a fan upgrade however, as you can see my coolant temps creep up too. Currently using only one side of a MSM fan shroud.

Seems like the shims work as advertised, hitting over 72 when engine RPM is high. Do you have any issues with seals or anything from the higher pressure?