Which oil pump

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megacab

megacab

Leglhi
Joined
Jul 11, 2008
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Nipomo California
Hey guys whats up?Had an oil pump question.When i had this motor apart last month i replaced the oil pump.I previously had a standard volume with a high pressure spring.When i pulled the engine apart for a knock(camshaft)i ended up remachining the whole block.I replaced the standard with a high volume melling.My clearances are now back to standard as they should have been.I run 40 wt VR1.When i start the car the pressure is at 80 at idle.If i whack the gas it will go to 100.After a run,its about 40 at idle and will go to 70 or so when i get on it.After the motor cools all the way down,the pressure goes back to 80 at idle ect.Should i not have run a HV pump?Thanks again for your help as always.
 
Stock clearances=stock volume pump in my book. Your wasting HP spinning that HV pump and also creating alot of heat from the oil bypassing.
 
When the oil gets hot it tends to thin down (lower oil pressure) and goes back to normal when it cools. I use the Mellings HV oil pump in my 440 and it idles @ 85 ish with Mobil 1 20-50W fully synthetic, have never seen it drop below 70 PSI though. Also I use the Fram HP-1 oil filter it has the anti drain back valve and filters down to 18 microns and has heavy duty construction. The Fram oil filter cost more and when used with the Mellings HV oil the 20-50W oil I use probably robs at least 10 HP but for me I like cheap insurance and have never had any kind of engine failure with it.
 
fishy68 said:
Stock clearances=stock volume pump in my book. Your wasting HP spinning that HV pump and also creating alot of heat from the oil bypassing.
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When you compress oil it gets HOT, the more, the HOTTER.

I use stock pumps in my 340 and 410 strkr that have 2 thou'ish bearing clearances.
Your just using up HP turning it to the tune of 20'ishHP@ 6000rpm
 
Thanks guys.Thats what i was worried about.Well if the engine comes out again,hopefully not for a while,i'll change back.That 20 hp i might be losing might get me closer to a 9 second pass,but as long as its not bad for it i'll leave it as is.
 
I have read a few tests from different mag's and that HP number is high from what I read. If your racing the car, I think the extra HP for the oil and protection on a Race engine is the least of your problems.
 
rumblefish360 said:
I have read a few tests from different mag's and that HP number is high from what I read. If your racing the car, I think the extra HP for the oil and protection on a Race engine is the least of your problems.
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Thats based on around a 400hp engine, it obviously differs per engine output.:read2:
 
Try 10W-30 oil. I've seen noticable differences when trying different viscosities. They also flow faster on initial start-up. Straight weight oils take more HP than multi-weights. Even with a 10w-30 in my engine, it can go way over 100 when revved dead cold.

Not sure of the clearances my engine builder put in, but I use Amsoil 5w-20 Dominator series with a standard volume/standard pressure pump.

BTW, if you are concerned about zinc content, Amsoil has several with lots in it! https://www.amsoil.com/dealer/techservicesbulletin/MotorOil/TSB MO-2007-08-08 Flat Tappet.pdf

Amsoil source & info: www.thelubepage.com
 
More damaging than the hp loss is the heat. Oil as as much of a cooling agent as the water system. What I've read is about 5-10hp more lost beyond 70psi. Thats above and beyond the parasitic draw of the usual below 70psi. There is no reason to use a HV pump unless the clearances are set up loose such as an endurance or high rpm engine. That being more than .0025" on the mains and .003 on the rods. Even then, unless it's running up past 7K there's little reason to use one.
 
Thanks for the input.I was just going by what i read in the Big inch small block mopar book.If im using a straight 40,what would be a good weight to go to?Stock clearances.I have been shifting at 6900,but Ryan at Shady told me to try shifting at 7200.Thats where they shift their W headed smallblocks at.So next trip, next week will be a trial for that.And im going to be bumping the timing from 32 degrees to see what happens,good or bad.
 
If you've had no issues with the rpm yet, I'd keep the clearances. But if I was building an engine for you I'd be going .002 on the mains and .003 on the rods for that rpm. I terms of oils, I'd run mineral oil 15/40 or synthetic 5/30.
 
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