mega_stream

I've had 3 people now well known in the Scoob tuning world tell me that there is no such thing as an uprated oil pump

The term uprated, so I'm told, is merely a washer (unsure if its an additional washer, or a new washer) in an original oil pump, and this costs anywhere between £150 and £200

Whats the score with these?

David_Wallis

more likely a shim.

speak to mark mark@lateralperformace.co.uk

ChristianR

iTrader: (1)

roger clarke motorsport sell a modified subaru oil pump, both Bob and Harvey have them.

[Edited by ChristianR - 11/19/2002 4:12:26 PM]

Gez

They do indeed ChristianR, and im getting one.

Cheers

Gez

Pavlo

how much do they cost out of interest?

Paul

Deep Singh

Does anybody have any details of this ie how is it different to the OEM?

Adam M

they work out about £170.

They are not uprated as such as they do not necessarily improve anything.

they modify the oil pressure relief valve so that it is less likely to jam. this is an integral part of the oil pump.

There is not really any proof as such that the standard one jams of its own accord, as the consequences of bearing failure would cause it to jam anyway. Its kind of a chicken and egg situation.

there have been good reports of reliability from modified ones, with far fewer (if any) reported cases of these jamming, but I am not sure if these are proportional to the reduced numbers.

Prodrive do a mod to drop oil pressure a little, but I would not advise this personally, although oil pressure is not related to the strength of the oil film, just the flow of oil arond the engine, I still do not think it s a good idea.

Prodrive do it as the oil pump is parasitic on the power of the engine and runnign lower pressure will reduce losses on the engine. Since they rebuild all the time, always use fresh oil, and have modified oil pathways, lower pressure is less of a concern for them.

Adam M

On another note, it is not just a washer, but more of a machining of a piston to take a groove of metal out of its end. And yes it is expensive.

they do provide an exchange service I believe which is much cheaper

(like £30 or so) but the car will need to be off the road unless you have a spare anyway!

hypoluxa

The oil pump is driven directly off the crank so your pressure increases with revs. The standard relief valve is designed to dump excess pressure above 5bar... a shimmed one will be proportionally higher.

So basically the 'washer trick' doesn't up your base pressure (thicker oil or tighter tolerances will do that), it just allows it to go a little higher.

Adam, I think you have your wires crossed, Prodrive do raise oil pressure, but not as much as what they used too.
Due to oil cavitation, iirc.

StanS

iTrader: (3)

FWIW, mine was "uprated" when it had its engine rebuilt. Charged £20 for a shim job (mind you I did spend a largish amount with them !). After 5K miles hot oil pressure at tick over is about 60psi, runs at 95psi.
Stan.

DO'B

'Uprated' Oil pumps. Prodrive only modify the plunger on their oil pumps to make it a better engineering job and otherwise the oil pump on a WRC car is just the same as a standard pump on ANY EJ20 turbo motor. The delivery rate and pressure as standard are perfectly adequate for all types of use and in my experience when building these units, a 'modified one' is a complete waste of money.

The bearing failures these units exhibit is more to do with bearing wipe for a number of reasons not directly connected to oil pressure when running. Baffling the oil pan will help surge on track days, but as the engines are way out at their development limit at 280ps the part that takes the strain of the compression and detonation is just not up to the job over many miles.

You can fix it, but rest assured bearing failure WILL happen again in Uk driving conditions - maybe not for another 50,000 miles but happen it must.

Sorry to bring bad tidings but I see too many of these engines broken to be able to offer anything but reality.

mega_stream

What do you mean by "UK driving conditions"???

If its the fuel, surely this can be addressed by 98 and octane?

DO'B

It's not just the fuel, the general road speed conditions in the Uk mean that everythings working harder. Cars in Japan do short distances at relatively low speeds compared to almost anywhere else in the world. Therefore we need to consider all aspects of keeping the best parts of our cars looked after properly. AND you really should be using 'Optimax' It's the nearest thing you'll get off the shelf to a Japanese fuel Ron rating. NO I don't work for Shell. Gotta sign off now - back another day.