Full Flow Cover with Pressure Relief Valve

[gimmesomeshelter]

I see that WW is offering a full flow cover with a pressure relief valve.

http://www.wolfsburgwest.com/cart/DetailsList.cfm?ID=111115141ffp

I already have a repro full flow cover from Speedwell USA.

How beneficial is a pressure relief valve, anyway?

Cheers,

Paul
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By my understanding the oil with those csp/ jaycee style covers is that when the oil in the oil pump is at a certain rpm the oil pump will foam the oil and the oil from the oil galley is not 100% oil flowing .so with those csp/jaycee oil covers have a build in piston well I know the jaycee one does don't know if that csp one does but anyways it has a piston and spring so when that rpm is reached and starts to foam in the oil pump the piston/spring open and allow the foam to flow threw there and back to the case ..i think there a great upgrade since a 36hp is a single relief any other relief piston for the oil galley is good .. that's my understanding ..

[TomSimon]

In my experience, oil pressure relief covers are too risky.

Most people don't understand how a acvw's oiling system works to begin with. A word of caution; If you're that guy, either study up and figure it out, or be very careful making any modifications.

The oiling system is the 'life blood' of your engine, understanding modifications is very important if you are going to make changes. A good oil system won't make it go much faster, but plumb or put it together wrong, have a pressure relief valve or bypass valve stick in the open position, and your engine is screwed.

Here's a diagram on Jack's website of a dual relief set up for a T1 that is helpful

http://www.jayceevw.com/store/p106/JayCee_Full_Flow_Extension_Adapter.html

When I say 'too risky', what I mean is if it malfunctions, oil pressure can fluctuate (bad) go down (worse) , all the way to zero (disaster). I personally know of 4 different people, along with myself, who have had external oil pressure relief valves stick open, cause low or no oil pressure, and ruin parts starting with the end of the oil system chain, the poor over worked and under paid connecting rod bearings.

Race and very high performance engines use big rod bearing clearances, to promote oil flow, cooling the journals and keeping the bearings from buring at high load and high rpm. That requires a lot of oil volume (big pump), and oil pressure. Big oil pumps take HP to drive, and if you aren't using all of that volume, the excess needs to be dumped back into the sump, to keep the pump from working harder than it needs to, oil pressure going so high it bursts the filter, and robbing hp.

One of the problems with a dual relief case T1's stock oil system is the excess oil volume gets bleed off near the flywheel, via the rear stock oil pressure relief valve, and dumped back into the engine, into the #3 exhaust pushrod tube. Many engine builders believe that dump port is partially responsible for filling the 3-4 valve cover with oil, an Auto Craft 910 race head and aftermarket pushrod tubes hold 2 qts of oil. I want that 2qts in my sump, covering up the pick up tube, thank you very much.

Oil pressure relief covers come in two types, one that is intended to bleed off oil volume, return it to the low pressure side, at the oil pump (Berg, CSP, others). The other, bleed off oil volume by dumping it back into the sump via a metal tube (JayCeeIt takes force, and hp, to turn the pump, move the oil thru the engine and dump exceed flow near the #3 exhaust pushrod tube. Bypass covers return it at the pump, reduce frictional losses of pumping oil through the holes, orifices and channels only to dump it.

Simply put, bypass oil pump covers dump excess pressure at the pump, instead of later in the system. In theory at least, the pump should be doing less work that way, taking less power to drive. But wait, there's more...

Sometimes bypass covers aren't assembled right, are a poor design, made with substandard components, and stick open, partially or fully. Sometime intermittently, and it barely shows on the gauge. For that reason I don't like them. I've fixed more than one race engine with low oil pressure by just bypassing the external bypass. I've later bench tested the cover on one, w/air and a regulator only to find out it opens and closes as intended, almost every time. I lapped the seat, assembled and re-assembled, called the manufacturer. Wait... almost? If you are saying to your self about now "almost every time?... how about it needs to work every time? Whisky Tango Foxtrot, over?" like any thinking man should, you now understand why I hate those things.
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2-time NASA Pro Racing Champion, Bonneville 130 Club and 150 Club Memeber, BRS Pro Gas racer