Hi Doc,

What oil pump would you recommend for your special "Treatment?" I was under the impression that most mild builds would do just fine with the 5/8" pump as far as volume was concerned.

CJ

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Part of Tyrde-Browne Racing

The factory die cast aluminum 5/8th impeller pump works fine for most stock Slants with good bearings. These pumps can run a bit low on hot idle oil pressure, especially on loose engines running thin oil.

The after market cast iron "5 bolt" pumps (7/8 impeller) also work well, just keep the pressure at 50 - 55 psi
DD

Sorry to hi-jack the thread CJ but you have me thinking of something I have forgotten.
On a turbo engine, what if any extra considerations need to be addressed with oil pumps? If there is a low idle issue it may not hurt the engine but the turbo will have issues wont it?

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Chris'
Autobody
Restoration
Service

When ever there are extra oil demands, I use a thicker impeller pump.
I have gone as far as installing the thicker impellers into die-cast pumps housings in order to save weight.
DD

So the 7/8" pump won't tend to run the sump dry at the end of a 5000 rpm blast?
Humor me, I just don't know how well this application will respond to a high volume pump.
Do you recommend installing baffles in the pan?

CJ

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Part of Tyrde-Browne Racing

The only time you will run the oil pan sump "dry" on a SL6 is when you never add oil to the engine. Oil return is pretty good on a SL6 so that is not a worry.
I do add baffels to the oil pan as a general rule. That is done to control "slosh" in such a large pan / sump... you don't want the oil pick-up to suck-in air during a hard stop or tight corner.
DD

Thanks Doc! Time to do more searching on this subject.

_________________
Chris'
Autobody
Restoration
Service

For what it is worth, the hot oil pressure on a stock turbo Buick with 10w-30 oil is very often as low as 5 - 10 psi. It concerns just about everyone, but I have never seen or heard of it hurting the turbo. Going to a heavier oil will raise the pressure a little but it does that by lowering the volume that goes thru the system. The turbo bearings will actually run hotter. Low running pressure tends to hurt rod bearings first. As long as you can maintain correct pressure for the engine, the turbo will be fine. I would feed right after the filter, not off the end of a galley.

With those cars it is common to boost it with a plate that helps limit internal leaks in the pump or a kit with larger gears and a spacer.

In the last build I did on mine I modified the oil system in the block and timing cover much like Doug Dutra outlines for the slant, reaming passages and radiusing intersections. I also went with a pump kit. I ended up with too much oil pressure and had to use a stock spring and shim out the retainer. It was ok but right at the high limit.

My point is, I would not overlook blue print type procedures like cleaning up the oiling system. They can be all the difference that is needed with no downsides and only cost a little of your time.

You can hand lap the pump rotors so they match and then lap the pump housing to minimise the end play as well. This not only helps the volume some but the pump will prime much faster if it gets air in there.