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Discussion Starter #1
what would happen if the oil bypass spring in a melling m55HV got stuck so that it made full pressure 100% of the time?

And is this possible how would it happen?
 

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Discussion Starter #3
is you're oil pressure going over 100psi ?
Hot
55 @ idle
80 @ Wot 2500and up

VDO pressure gauge ends at 80
so i dont know if it is going past 80!!!
 

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If the pressure was too high at high rpms then I would say it could be the spring, but if it is too high all the time I think you have a bigger problem.
 

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Tad- Did you log the pressure readings during the 2007 dyno runs?
 

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Oil Pump Bypass Failure

In March of 2008, as part of a rebuild, I installed a Melling M-99HV-S oil pump in my LT1. Moments after start-up, I discovered a 4 quart lake of oil under the car. The oil filter gasket had failed. With the engine off, my 100 psig liquid filled oil pressure gauge now read approximately -10 psig instead of zero.

The pump was returned to Melling (without disassembling) and word came back that the bypass was found to be faulty. I received a replacement pump and some $ meant to cover the cost of a replacement oil pan gasket. No significant $ to cover labor or gauge replacement though.

I checked the engine bearings from under the car and no damage was found.
 

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Discussion Starter #8
what did you set you're bearing clearances at
motor has been in since late 2006
oil pressures were tamer b4 I change the oil lines
 

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Discussion Starter #9
If the pressure was too high at high rpms then I would say it could be the spring, but if it is too high all the time I think you have a bigger problem.
Dwayne do tell
pressure is fairly high all the time...
 

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Discussion Starter #10

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Only time I used that oil pump was in the last gen 1 350 i built, I put the high press. spring in and that thing would get right at 100 psi at 2500 rpms or above on cold morning's...It scared the crap out of me the first time I saw that ! Car never did have an issue for the 5yrs after that I had it.
 

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A SBC can be oiled sufficiently with an oil can. There is no need for HV or ultra HP pumps. Anyone that states that it is necessary
is motivated financially by the sales of such pumps. The more builders try to over-engineer/over-build the oiling system by inducing unnecessary volume or pressure the more likely they will experience problems. Leave the HV crap for engines with less efficient oiling circuits. This also applies to unnecessary HP as well. The more knowledgeable people become the less likely they will attempt to redesign the system.

Be more concerned with keeping the oil itself flowing through the bearings (for lube yes, but especially heat removal) with no pump or pickup cavitation issues.
 

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Discussion Starter #13
I video'ed and documented detailed oil pressure info in my exhaust post.

I wonder if 110PSI of main line oil pressure is worth some HP?

would that make the lifters hold the plunger all the way out
not displacing oil for the pushrod?
 

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Discussion Starter #14

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A SBC can be oiled sufficiently with an oil can. There is no need for HV or ultra HP pumps. Anyone that states that it is necessary
is motivated financially by the sales of such pumps. The more builders try to over-engineer/over-build the oiling system by inducing unnecessary volume or pressure the more likely they will experience problems. Leave the HV crap for engines with less efficient oiling circuits. This also applies to unnecessary HP as well. The more knowledgeable people become the less likely they will attempt to redesign the system.

Be more concerned with keeping the oil itself flowing through the bearings (for lube yes, but especially heat removal) with no pump or pickup cavitation issues.
exactly what my engine builder said... he doesnt like HV oil pumps for the SBC. In my engine he said MAYBE we would use a pump with a MAXIMUM of 10% over stock volume because I now have 2 turbos to lube/cool and my engine wont be spinning very fast so it wont turn the pump too much.

He also pointed out that when using a HV pump the pressure relief valve is in by-pass mode most of the time anyways, so you're just heating up the oil for nothing.
 

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Where are you getting your oil pressure reading from (clean side or dirty side)? Have you thought of bypassing your remote oil filter with one in the stock location to remove any suspisions? Do you have an oil cooler and if so, does all of the oil go through it or only a little like the stock system?
 

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motor has been in since late 2006
oil pressures were tamer b4 I change the oil lines


"b4 I change oil lines".?? What did you change? Oil line/cooler changes do have a direct impact on oil pressure. For what it's worth my oil pressure is about what you have originally described: 40-50 idle and 80 at WOT warm. Rule of thumb is 10 psi per 1000 rpm (or thereabouts).
 

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exactly what my engine builder said... he doesnt like HV oil pumps for the SBC. In my engine he said MAYBE we would use a pump with a MAXIMUM of 10% over stock volume because I now have 2 turbos to lube/cool and my engine won't be spinning very fast so it wont turn the pump too much.

He also pointed out that when using a HV pump the pressure relief valve is in by-pass mode most of the time anyways, so you're just heating up the oil for nothing.
Hi Guillaume-

The problem is suspect marketing can do an effective job of screwing with the minds of the consumer, or in this case the auto enthusiast. It should be pointed out that marketing/advertising has one primary goal, and that is to sell a product. That is why mfrs.
pay for that service. Whether or not the consumer really has a need for the product is of little concern to the mfr.

I'm not stating the HV pump does not have a place, as it does, it just is not in the traditional SBC/LTx. By that I am purposely excluding the LSx engines, as I am not that familiar with the peculiarities of the OEM pumps.

While it is true add-ons that require oil fed from the parent system may alter the pump flow and/or pressure requirements, in most cases with a pump that is not marginal to begin with, alterations/replacements are not necessary. Pressure monitoring should confirm that. While not easy to determine, more oil is by-passed in the OEM system than many realize.
 

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Discussion Starter #19 (Edited)
"b4 I change oil lines".?? What did you change? Oil line/cooler changes do have a direct impact on oil pressure. For what it's worth my oil pressure is about what you have originally described: 40-50 idle and 80 at WOT warm. Rule of thumb is 10 psi per 1000 rpm (or thereabouts).
I change out the spliced factory lines for 1/2" Eaton Weather head lines.
In the process the restictive double barb fittings went away.
Also a small increas in inner diameter and smoother strighter hose path.

Where are you getting your oil pressure reading from (clean side or dirty side)? Have you thought of bypassing your remote oil filter with one in the stock location to remove any suspisions? Do you have an oil cooler and if so, does all of the oil go through it or only a little like the stock system?
oil pressure is at the remote spin on filter pre filtrations & pre cooler.
On this last test I pulled the Mobil1 M1-301 filter for inspection
and installed a Fram PH-8A in its place.
 

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Discussion Starter #20
I no longer use these red Napa hoses to connect to the stock lines
but this is the black Canton distrobution block that seats to the engine block


this is the current spin on filter base and lines
the empty port on the inlet is were I'm measuring pressure from.
 
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