Excessive oil pressure

[CGT]

WOW

[wilson1970]

http://www.speedtalk.com/forum/viewtopi ... 35#p302626

Good reads!!

[Kevin Johnson]

I have both pumps on order from Jegs to double check. The standard one is in stock and ships today; the performance one will ship next week.

Okay, the standard pump ("1") came in shortly after I ordered it and I put it to the side. JEGS did not know when the backorder would be gone for the performance version ("2") so I found one from a GM parts dealer out West. The performance pump arrived today so I disassembled both and compared them.

IMG_0633.gif

The castings and gears were made at different times but otherwise appeared generally the same. I did not look at the relief springs. The difference that I found was in the casting that contains the relief valve. The performance pump ("2") had some very mild "porting" work done in a passage and I expect that this results in the flow capacity difference claimed by GM (high volume):

IMG_0646.gif

IMG_0647.gif

I invite others to confirm or refute these observations.

[cjperformance]

Were they actually porting that as such or removing dags left after drilling/machining? I think you would need to compare a few of the same to know.

[Kevin Johnson]

Were they actually porting that as such or removing dags left after drilling/machining? I think you would need to compare a few of the same to know.

I can see removal of small casting flaws by hand in several angles/shots of (1) but (2) has a qualitatively different appearance of smooth machining over a continuous surface. I am guessing a small jig and very basic CNC pass with a carbide burr.

The principle of charity suggests that the factory designated high volume pump -- marketed for many years as such at a premium price -- does show a difference over the standard volume pump.

[zums]

I have both pumps on order from Jegs to double check. The standard one is in stock and ships today; the performance one will ship next week.

Okay, the standard pump ("1") came in shortly after I ordered it and I put it to the side. JEGS did not know when the backorder would be gone for the performance version ("2") so I found one from a GM parts dealer out West. The performance pump arrived today so I disassembled both and compared them.

IMG_0633.gif

The castings and gears were made at different times but otherwise appeared generally the same. I did not look at the relief springs. The difference that I found was in the casting that contains the relief valve. The performance pump ("2") had some very mild "porting" work done in a passage and I expect that this results in the flow capacity difference claimed by GM (high volume):
IMG_0646.gif
IMG_0647.gif

I invite others to confirm or refute these observations.

Trust me, there is no "porting" if it came from GM or Melling, if the pump gear height is the same and inlet tube diameter and spring, there will be no difference
Tom

[CGT]

Were they actually porting that as such or removing dags left after drilling/machining? I think you would need to compare a few of the same to know.

Exactly. Ive looked at plenty of both of those pumps, like any cast part expect any cast part to be touched to deburr in a crude way by someone randomly.....or "ported" for flow like Mr Johnson claims

I'd buy the GM its obviously a high flow M155 thats been ported making it high volume.

[Kevin Johnson]

...

Trust me, there is no "porting" if it came from GM or Melling, if the pump gear height is the same and inlet tube diameter and spring, there will be no difference
Tom

Well, that is contrary to what is published and what I was told. That is why I performed an empirical experiment and purchased two brand new pumps to compare them.

Years back I used to think that connecting rods with matching serial numbers meant that the beam and cap were matched. I thought that right up until I found an in-situ counter-example that indicated the serial numbers were a desperate attempt to correct a manufacturing problem.

[Kevin Johnson]

I used to think that castings with the same part number were the same. I thought that right up to when I purchased a dozen die-cast sumps and found three distinct groupings of castings.

[CGT]

Well, that is contrary to what is published and what I was told. That is why I performed an empirical experiment and purchased two brand new pumps to compare them.

Your information came from a jegs rep. So.....

[Kevin Johnson]

Well, that is contrary to what is published and what I was told. That is why I performed an empirical experiment and purchased two brand new pumps to compare them.

Your information came from a jegs rep. So.....

Well, I put my money and time where my mouth is, so ...

[CGT]

Well, that is contrary to what is published and what I was told. That is why I performed an empirical experiment and purchased two brand new pumps to compare them.

Your information came from a jegs rep. So.....

Well, I put my money and time where my mouth is, so ...

And your 150.00 poorer and still trying to convince yourself of something thats not there. Btw Amazon lists it as standard volume....so that must be

[MadBill]

Since oil is essentially incompressible, I believe delivery per revolution depends only on the gear displacement. 'Porting' efforts could reduce internal pressure differentials, cavitation, etc. and possibly slightly lower drive power requirements.

[af2]

Since oil is essentially incompressible, I believe delivery per revolution depends only on the gear displacement. 'Porting' efforts could reduce internal pressure differentials, cavitation, etc. and possibly slightly lower drive power requirements.

That!!!!
The reason I run BB pumps in all my 2 to 3 builds a year. LOL

[racear2865]

No that is why they made a HV oil pump. More volume per revolution
reed