Melling 10778 oil pump question
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For anyone who might care, here's my take on oil pumps, pressures and volumes. It's all about supplying the engine, mainly bearings, with enough oil to get the job done. There are a lot of factors in this but the biggest one is bearing clearances. Second being what oil you run, and clearances and oil go hand in hand. Engine usage, rpm, HP, oil temp...all play in considering clearances and type of oil. IMO volume and pressure are directly related. If you don't have enough volume to supply enough oil, then you need more volume, not necessarily pressure. This would be basically when bearing clearances are more than standard clearances and a standard volume pump isn't going to do the job. How will you know? It won't make or maintain enough pressure. Increasing pressure in a standard pump without enough volume may or may not solve the problem. Most likely not, so the next step is a high volume pump. Again, you need more oil, not more pressure. What is enough pressure? Lots of "formulas"...the oldest one in the book is 10psi for every 1000 rpm but I know too many pro level engine builders who say that doesn't work. A lot of them rate their oil pressure by HP...10 psi for every 100 hp. but that would mean for a 1200 hp build, you'd need 120 psi of oil pressure and I don't believe that either. IMO, and this is just over years of observation, in most of these sorts of marine apps if you're running a consistent 55-60# hot, WOT, full load and full oil temp, you should never have any issues. Some may like a alittle more just for insurance but remember...it takes HP to turn an oil pump and I'm never one to just throw away free HP. More pressure also increases oil temp @ the pump. To that, run whatever it takes to get whatever pressure you're comfortable with. Stock pump might be fine on a 400 hp 454. 1200hp blown wet sump with added coolers and remote filters will probably take all the oil pump you can throw at it. The more additions you have to the oil system, the more you tax the pump, and the further away these additions are from the pump, the more the pressure drop will be. A good quality pan, good oil drain back, and good, high quality full synthetic oils will also help. Keeping the oil temp under control will help and of course, good general building practices like deburring oil passages, blending entrances and exits, proper clearances and making sure the oil system is problem free will all go a long way to keeping oil pressure under control.
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I was very scared when I increased oiling to rockers and opened up my lifter bores I think the higher then normal pressures really helped me, and I also run really big main clearances... I am a fan of high pressure and volume because it sucks to spin bearings!!
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I`ve lost about 15 psi with spring oilers , 50ish psi wide open (have high volume melling pumps) . Bearings look fine but I get some anxiety when the pressure falls below 18 psi @ hot idle.
Looking into going with Schumann pumps this time around , or titan but those are some $$
Looking into going with Schumann pumps this time around , or titan but those are some $$
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mains average .0032-.0035 with a .0040 rear, rods .0025-.0028 average, with Eagle it's all over, you remember the findings when we talked I am sure, I would have used Scat if I knew Eagle was like that at the time..
lifters are .0022 across the board.
I never see less then 25 at idle no matter what, always shows 70 when running with oil temps in 220 range
lifters are .0022 across the board.
I never see less then 25 at idle no matter what, always shows 70 when running with oil temps in 220 range