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Oil Pressure Spike on 1st start

Old 11-11-07, 07:20 PM
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Oil Pressure Spike on 1st start

I have a freshly rebuilt S5 NA engine with a GSL-SE front cover. The engine is a hand-me-down from a friend, so I do not know all the details that lay inside. I believe it has a T2 oil pump and probably a high pressure oil pressure regulator, but 100 psi on start up? Yikes, that is the top end of my gauge, what do you think causes this?

A problem with the bypass in the front cover?
Is the high pressure regulator supposed to keep it at 100 psi?
Some thing else?
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Old 11-12-07, 06:22 AM
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There are several regulator options:
stock FC ~60 psi
stock FD ~90-100 psi
competition ~110 psi

It is a common upgrade to use the FD regulator with a shimmed front cover bypass (to handle the high pressure). If you have a higher volume oil pump with a higher-than-stock regulator, you will see full pressure on startup. The pressure may be less at idle, but once you get the rpms up a little, it should be producing full pressure again.

If you start the car and rev to 3k rpms, what is your static oil pressure?
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Old 11-13-07, 04:59 PM
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I find that my oil pressure is around 110+ psi while cold, but as the engine warms, gradually falls to around 60 psi at idle. I think the higher than normal oil pressure is due to the thicker viscosity of cold oil. Otherwise it may be the oil pressure sender itself thats the cause of the spike. I wouldnt worrt about it unless it always was above 100+ psi.
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Old 11-13-07, 07:05 PM
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Ehh what's the big deal. ?
HIgh oilpressure is not a problem it's a luxury
At 100+psi the oil MIGHT seep past bearings but it WILL still lubricate, due to the seepage,oil temperature will be higher, but i've never had temps high enough to cause a concern.

On cold starts, high pressure (depending on sensor location) is a good thing, everything is "dry" and needs oil NOW, the rotary engine though IMHO could do with less than its piston counterpart as the stress on bearings are alot less.
High pressure due to thin oil viscosity implys fast lubrication of the rotating assembly, whereas thick oil viscosity MIGHT trick your OPG and show high pressure immidately after You let go the ignition key.

Either way, in the long run it might make a difference, but seriously who here on this forum has put very high milage on their engine HA HA No seriously I would love to see a sheet of SAE papers telling me that low Oilpressure in the first second of start-up will make a significant difference on a 30K To Be milage engine.
Sure, the rotary has less stress on the bearings and there will be wear, but still I doubt that low, LOL even high pressure will hae a measureable effect on bearing life in lets say 30K miles(expected tuned and punished rebuild) engine life.

Maybe I just totally misunderstood the topic, excuse me then, blame the redwine
Kim K. <-- Mn,I can't hardly wait to log on tomorrow.

*EDIT* and why the hell am I deleting previous letters when inserting new letters, but cut/paste still works?
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Old 11-14-07, 04:47 PM
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****, I wrote that ^^ ?
I should stay off the internet when drunk...
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