Delete the OP Relief Valve and DIY Baffle

#1

I got to looking my uninstalled the TC Motorsports baffle and it annoyed me the way the OP Relief Valve (OPRV)interferes with any attempt to baffle the right side of the oil pan. A couple guys at e30tech.com experimented with removing the OPRV and plugging it’s port. They unsurprisingly had high cold oil pressure but the case for higher hot oil pressure was mixed.

Pics of the TCMotorsports baffle here: http://www.spece30.com/forum/46-oiling-system/66226-poor-mans-tc-baffle-project

My perception is that the OPRV’s spring limits OP to around 70psi with cold oil and with hot oil the pressure limit is a matter of the flow resistance of the oil system. Tight tolerances everywhere means high pressure. Once loose tolerance and hot OP suffers.

The OPRV can also be a failure point. One of my engines a couple yrs ago had low OP and Chuck Baader fixed it by replacing or fixing my OPRV.

I’m told that the E30 M3 does not have an OPRV. That needs to be confirmed tho.

The oil pump also has a pressure relief valve. I think the purpose of that valve is to protect the oil filter, not set cold old pressure for the whole system.

OPRV plug. A common oil pan bolt in 20mm x 1.5 available at your local autparts store.

OPRV in place.

DIY baffle that really does seal the right side, as opposed to leaking around the OPRV.

#2

Basically what I have been running for two years but with a PP pan and a full length windage tray. cB

#3

What kind of windage tray? M50?

#4

Please point me to the rule wording that allows the removal of the oil relief cable?

#5

I am pretty certin the S14 has an OPRV. it is built into the oil pump. There are many trends on shimming the spring for increased pressure. This is how the EVO oil pumps were from the factory.

#6

What kind of windage tray? M50?[/quote] Yes, but cut a second one around the OP…no windage tray.

Michael, the M20 actually has three. One on the filter housing, One on the oil pan rail, and one in the oil pump. What we are talking about is the fact that the one on the pan rail is problematic and 99% of the time is the problem with low oil pressure, especially at higher oil temps and lower rpm. Chuck

#7

So has it been determined that plugging the oprv on the oil pan rail doesn’t cause any problems? And is class legal?

I’m getting ready to baffle my oil pan and this information would be beneficial.

#8

You can’t just remove the PRV…you must also modify your oil pump so the poppet valve acts as a PRV. The stock spring will give cold OP of around 95psi on 10W30 oil. YRMV. Chuck

#9

[quote=“Dizzle” post=69369]So has it been determined that plugging the oprv on the oil pan rail doesn’t cause any problems? And is class legal?

I’m getting ready to baffle my oil pan and this information would be beneficial.[/quote]

Send your oil pump and a check to Chuck and he’ll modify the oil pump’s relief valve for you. Not legal tho. I’ve been slow to put together my rule change requests this year. Might get to it yet tho.

#10

Chuck, how much do you charge and what is your typical turn around time?

#11

According to the rules, hoses/lines are free. The OPRV is part of the hoses/lines. Somewhat intorturated gray area but it will make your motor happier and allow a full baffle on the right side of the pan. I charge $75.00 plus return shipping. Chuck

#12

Sorry, takes a couple of days here. CB

#13

Thanks, will PM when I get closer to removing the engine.

#14

Hey Chuck, PM sent.

#15

I don’t think of this as a commonly accepted problem that needs to be part of everyone’s build process. Oil pickup in left corners and braking is a universal problem and my pump was a major problem. After fixing those and adding a accumulator my op stays between 65 and 75.