legacycentral bbs

So i recently installed a mechanical oil pressure gauge w/ a SS line for leakfree goodness. Its a metric gauge for kg/cm^2 (1 kg/cm^2 = 14.22 PSI).

Upon cold startup it will rise to ~6kg/cm^2 and as it warms up it will slowly work its way down to 2kg/cm^2 and at full temp 1.6kg/cm^2. When its warm and i rev it from idle it will go up to ~4-5kg/cm^2 @ 2.5k rpm. All of this seems to be within the specs i have seen.

Now my worry comes from when im driving it. If i am starting in 1st and presenting a load on the motor it will go from ~4kg/cm^2 to ~6kg/cm^2 but while i hear the turbo starting to spool i can see it jump down to a little less than 5kg/cm^2 for a second and then jump back up past 6 as i start making boost. This jump directly coincides with a chugging sound ive been hearing from the turbo area and temporary lack of power. Sometimes it will flutter between 4-6kg/cm^2 before it kicks back to a solid 6.5 and boost is level and performance is smooth again.

When i let off throttle from a constant speed it will float at 6 for few seconds past when the RPMS have dropped to idle level before it will drop. Is this the turbo spinning still or what?

Anyone have any idea what could do this? Does 6.5kg/cm^2 (92 psi) seem high to anyone else?

warm idle= 20-25psi
cold idle= 75 psi

warm 3000rpms=80psi
cold 3000 rpms =100 psi

that close to what you have?

yeah i mean its not terribly off. It just seems a bit high since the relief valve is supposed to be at 75psi and i would think it shouldnt go much higher than that. Its also reaching this pressure at 2k when its fully warmed up.
My concern is what can cause the rapid fluctuation down and back up in pressure when there is a constant increase in RPM.

Where did you tap the oil pressure gauge in?

As for the pressure drop....assuming everything mechanical is good.....the first thing that comes to mind is the oil squirters kicking in. I do not know the pressure they kick in at, but they will obviously kick in at some pressure, and you will have pressure loss through all the oil galleries, so the pressure at the squirters will probably be less then what you're reading.

Makes sense. For now i have totally replaced the sender as i only had one BSPT to NPT adapter. I havent decided the method of making a T to the sender. I would rather have the oil light on and know my exact pressure over having the light come on when its too late @2PSI.

http://www.wrxtra.com/

check the sandwich adapter.

works great!

Threshld1 wrote:Makes sense. For now i have totally replaced the sender as i only had one BSPT to NPT adapter. I havent decided the method of making a T to the sender. I would rather have the oil light on and know my exact pressure over having the light come on when its too late @2PSI.

You could ground the contact that the oil pressure switch went into and not have the oil light on.

Legacy777 wrote:You could ground the contact that the oil pressure switch went into and not have the oil light on.

Did it and no result. It requires (atleast with my experimenting) it to be open circuit and then grounded before it will turn off. I was thinking of rigging up a timed relay upon ignition but im lazy.

Yeah that would work.....don't be lazy

so... hard... not... to when i want to smash the car into a wall with this damn hickup problem ive had since i got the car a year ago