SBC oiling system revisited

[Tony]

OK, I started working on the Cig again and this whole oil pump setup is still bugging me. Last year I had two fresh small blocks built from the ground up by a local very reputable engine builder who builds everything from drag racing to tractor pulling engines. He has done half a dozzen high HP marine engines for some friends of mine and they now swear by this guy.

My dilemma: He was insistent on using high pressure oil pumps, I explained to him that I would be running no bypass valves anywhere in the remote routing and large -12AN fittings and lines through an HP6 size filter (yes I know its overkill). I ran the setup on a drill primer @640 RPMs and was seeing a little over 60psi on a mechanical guage @70 degrees with 50w oil.

Is it just me or is oil pump just plain wrong for the application? Seems to me like there is going to be a tremedous stress load on the pump and distributor gear.

Thoughts?

 

[Chris]

You are absolutely correct. The small block does not need alot of pressure. You need good volume and cool oil. High pressure might be nice for a drag race engine but it not only does nothing for you in your endurance application, the additional strain is going to be tough on your timing chain and at higher RPM that pump load is going to give you spark scatter from all the funky things the load is doing on the back of the cam.

 

[skaterdave]

first off why straight 50 w? try running 15 -40? second off, trying to figure this out by just running it by priming isn't going to tell you that much. the oil needs to be 180 to 220 degrees. once your up to temp it will probably go down to around 60 and thats right were it should be.

the bypass in some of the non-race filters and in the normal oil filter on the block are questionable? do you want to starve your motor for oil if the filter gets clogged or do you want to have the bypass and have what ever came part in the bottom end of your motor thats clogging your filter get bypassed back into the motor? most race setups don't run a bypass. have an idiot light on the oil pressure and this will let you know if something is wrong ( low oil pressure).\

something else, since your running a remote fliter setup put a stainless steel screen type oil filter in the system as soon as it comes out of the motor or even better after the cooler. this way if there is any debris in the oil you will see it when you change the oil, either from the motor or the cooler. not to many peolpe cut open and check there filters. with a reusable screen filter see would be able to see some problems before they end up really big problems

 

[Tony]

The builder reccomended 20w50. The block filter adapter w/bypass is in the trashcan, I opted for the Hamburger female AN adapter plate instead. I plan on rigging some sort of low oil pressure ignition cut out for a safety margin.

I guess I need to pull an oil pump off and look at the size of the discharge port in comparison to the size of the port in the block that it mates to.

 

[Mrhorsepower1]

I will disagree about the fact that a small block does not need a high volume/ high pressure pump. When engineering an oil system, bearing clearance, oil line size, oil galley sizes, capacity, ect ALL play a very important role in RELIABILITY! All of my high performance engines, whether a small block ford, chevrolet, Big Block Chevrolet, ect.... I set the engines up with high volume melling oil pumps. Are bearing clearance is adjusted for a heavier weight oil ( 25W50 Pennzoil racing GT Performance) and higher oil pressure. I run may oil clearance probably wider than anyone would ever even think possible from experience not books. You need volume and pressure to keep the engine alive. Even on a brand new Dart or Merlin cylinder block, we do extensive oil galley modification for more volume. Oil line size is increased also. When you add more volume you need more pressure to compensate for pressure drop. With all of these mods we perform we also will shim the high volume pump to increase pressure. Higher oil PSI will never hurt you. I like to see 80-85 cold, 80-85 at WOT, and no lower than 40 PSI at idle after a hard run with the oil at temp. I hope this helps.

 

[PatriYacht]

Running no oil filter bypass is a good idea. Just route the oil pressure gauge to a place on the block after the oil filter. That way, if the filter starts to clog, you will see your oil pressure drop. However, I've been running mine with no bypass for 4 years now, with normal oil changes, I've never seen a drop in pressure. Nothing but filtered and cooled oil gets into the engine.

 

[Raylar]

Dean is right on here!
There are two jobs for oil in an engine, one is to lubricate, the other is to remove heat! A higher horsepower engine will make more heat and with looser clearances it will need more pressure from the pump and volume to keep the oil flowing correctly and with enough pressure to overcome the higher volume flows. You really can't have to much volume of oil for a performance engine, ie dry sump tank and system sizes!
We also use special Melling high volume high pressure oil pumps in all our 496 and LSM marine high performance engines and we also try to set clearances that will keep pressures at about 60-65lbs cold at idle, 65-75PSi at WOT under load and hot about 40-45lbs at idle. Most oil bypass systems open with a 15-30psi pressure increase across the valve and the oil system should still deliver its set operating pressures as this bypassing normally only bypasses the oil filter and coolers connected and not the oil delivery to the engine oil galleries, otherwise every time the bypass opened you would shut oil pressure and delivery off to the engines galleries and systems needs.

Best Regards,
Ray @ Raylar

 

[TomZ]

X2

TomZ

 

[Ratickle]

I know I'm not in the league you guys are, but I always used the rule of thumb, 10 lbs pressure per 1000 rpm. Is that wrong for a safe amount?

 

[FULL FORCE]

Dean is right on here!
There are two jobs for oil in an engine, one is to lubricate, the other is to remove heat! A higher horsepower engine will make more heat and with looser clearances it will need more pressure from the pump and volume to keep the oil flowing correctly and with enough pressure to overcome the higher volume flows. You really can't have to much volume of oil for a performance engine, ie dry sump tank and system sizes!
We also use special Melling high volume high pressure oil pumps in all our 496 and LSM marine high performance engines and we also try to set clearances that will keep pressures at about 60-65lbs cold at idle, 65-75PSi at WOT under load and hot about 40-45lbs at idle. Most oil bypass systems open with a 15-30psi pressure increase across the valve and the oil system should still deliver its set operating pressures as this bypassing normally only bypasses the oil filter and coolers connected and not the oil delivery to the engine oil galleries, otherwise every time the bypass opened you would shut oil pressure and delivery off to the engines galleries and systems needs.

Best Regards,
Ray @ Raylar

I agree also, I had issues last season with lower pressures and volume, wiped mains on each engine, went with Melling HV/HP pumps and shimmed them for extra pressure, I get 78-80 cold at idle, same WOT and 35-40 at idle after a run with 454's temps at 200-220

Tony, make sure you are good, you know what I went through....