General Motors V8 Discussion Discussion relating to getting the most out of your LSx or other GM-based V8 Miata's engine

Oil pressure fluctuation in an LS1

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Old 06-15-2015 | 10:16 PM
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charchri4's Avatar
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Jim Stainer
 
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Default Oil pressure fluctuation in an LS1

I've never noticed the gauge move around so much on power. It's the top gauge right of the wheel, is is the flickering at :08, :45, etc normal?

https://youtu.be/jybZwgVPpyQ

I found a clip from last summer and the gauge did not move around then. BUT the engine was considerably cooler and it was a single run up to 130 not the repeated hammering of the track.

http://youtu.be/CnPPGl5srMc

No idea why these videos are not embedding. Working on that!

Last edited by charchri4; 06-16-2015 at 11:28 AM.
Old 06-18-2015 | 03:37 PM
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Jim While I'm not a professional engine builder, I have built several LS engines and have many laps at HPDE and based on my experience the fluctuations of the oil pressure gauge is an issue with the gauge. My experience with oil pressure lose on an LS has been due to bearing failure, the symptoms are a 10 to 15 psi drop at first followed shortly ( within days of normal driving) of another pressure drop and a loud noise from the engine.
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Old 06-18-2015 | 03:59 PM
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Jim Stainer
 
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Thank YOU! I think you are right. I had a great response on the video from a guy that really knows gauges and he said the same thing. He suggested a little restrictor in the line as close to the pump as I can get to smooth it out. He was concerned that repeated hammering like it was doing would rupture the gauge and make a big mess.

So I'm going to put the oil cooler that has been sitting on my bench for 2 years in the car and look at a little restrictor for the line as well. I'm thinking a slight squeeze of the vice grips on the copper line should fix her right up!
Old 12-21-2015 | 09:06 PM
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Jim did you ever put the oil cooler on you car? I'm getting close on my NB build and im thinking about a cooler but im worried it might drop my oil pressure. Did you see any pressure drop with yours?

Thanks
Old 12-21-2015 | 09:47 PM
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I see flickering oil pressure gauges on older LS based vehicles all the time. (suburbans, silverado's etc..) My truck does it and had for thousands of miles. I'm really not concerned with it at all. Never have had any indication of bearing wear or anything.
Old 12-21-2015 | 10:43 PM
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Jim Stainer
 
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Yeah I had the cooler on it in that video at the track. It settled down after a trip or 2 to work and in the last 3000 miles has not bounced a bit. I have not been on a road course with it either though...
Old 12-22-2015 | 12:04 PM
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is that a manual gauge? or electric?

Originally Posted by Jerryg
Jim did you ever put the oil cooler on you car? I'm getting close on my NB build and im thinking about a cooler but im worried it might drop my oil pressure. Did you see any pressure drop with yours?

Thanks
you can pick up psi with an oil cooler. route the boss from the front of the motor to the back of the oil in line. it's good for +5psi
Old 12-26-2015 | 11:19 PM
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Manual gauge and I ran the car 2 years with no cooler then put the cooler in and no change at all in the pressure.

The 1st law of fluid mechanics says that fluid under pressure in a contained space transmits that pressure equally in all directions. Adding a cooler can't drop the pressure. Perhaps you are thinking about flow because it will usually slow it down as it flows through it due to the size of the cooler compared to the lines but the pressure reading would remain the same. The only way a cooler would increase the pressure is if it had a restriction in it and if it did I sure wouldn't want to use it.
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Old 12-28-2015 | 12:39 PM
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Originally Posted by charchri4
Manual gauge and I ran the car 2 years with no cooler then put the cooler in and no change at all in the pressure.

The 1st law of fluid mechanics says that fluid under pressure in a contained space transmits that pressure equally in all directions. Adding a cooler can't drop the pressure. Perhaps you are thinking about flow because it will usually slow it down as it flows through it due to the size of the cooler compared to the lines but the pressure reading would remain the same. The only way a cooler would increase the pressure is if it had a restriction in it and if it did I sure wouldn't want to use it.
might have some air in the line to the manual gauge.
Old 12-31-2015 | 04:32 PM
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There's always air in the line.... not sure if trolling.
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