What is the proper amount of oil needed for this setup..?

[x98boardwell]

here is what I am working with.

1) 1.5 or slightly more Peterson oil tank (6-7 quarts total), dimensions... 15.5" x 7".
2) In-line Peterson 400 series oil filter
3) 2.4 liter 6 cylinder 1973 911S motor
4) 550 Spyder tribute.

What kind of volume did this system have back in 73 and what do you think is adequate for this dry sump tank and motor. I had 6 quarts in, then I added another and can't seem to find how much is appropriate.

NOTE: I am not sure if the capacity of 6 or 7 quarts in this system is total volume of tank or what amount of oil it can handle. There is baffles inside that channel the oil downward... the entire tank is never filled with oil.

The motor has been smoking lately and i did a compression and leak-down test with all decent numbers listed below. Before I say that my valve guide seals are bad I wanted to rule out the fact I may just have too much oil in there.

Cyl #1 - 185/10%
Cyl #2 - 185/5%
Cyl #3 - 190/3%
Cyl #4 - 185/4%
Cyl #5 - 180/5%
Cyl #6 - 185/4%

Any help with this Peterson oiling system would be great.

[Quicksilver]

The way to tell what oil quantity is needed is to get a sight line on the side of the tank so you can see where the oil level is (or some other gauging method that gives accurate continuous readings). You need to ensure that the oil level in the tank never drops to the point where the oil doesn't have enough depth to allow the air to settle out of it before it is drawn out of the bottom. You need to add cornering forces into the arrangement as that will stack the oil up in the side of the tank.

If it is really a 6 to 7 quart tank then it is inadequate. When people add non-stock tanks they are generally talking about systems that require 18 or more quarts. A minimum would be a tank with 9-10 quart fluid capacity with additional vertical air space at the top to allow for air/oil separation and to make sure oil doesn't slosh out of the breather under braking/cornering forces.

Basically You want to be certain there are a minimum of a couple inches of standing oil covering the tank outlet when the car is fully G loaded on the skidpad when you are at high RPM and the oil temperature is low. That is worst case because the higher RPM pumps more oil out of the tank and when it is thicker it takes longer for it to drain back to the pump to get pumped out of the engine. Note that you must take account of which side of the tank the sight line is located as the G forces can load it full of oil or drain it. (You need to know what you are measuring...)
At the same time the tank needs to have enough reserve that when the oil temps are higher and going slower the tank doesn't overfill when scavenging is more efficient. (That is where the taller the better dry sump tank comes in.)

[Elombard]

I always assumed that 911s smoked when over filled because oil slopped into the fume recirculation hose/vent hose that leads into the intake (different locations depending on the type of induction). It looks like your set up vents to the atmosphere, so the oil smoke is not coming from that problem.

The only thing I can think of that might be an issue is the height of the oil tank on your car. Could it be draining back into the sump and filling it up on shut down? Seems like this could cause lots of issues.

just guessing here, hopefully some one will chime in with more direct experience.

[McLaren-TAG]

Is the rotation of the Bridgestones in you pic on backwards?

[x98boardwell]

Quicksilver, I think the amount of oil is adequate. The motor never gets too hot even on a hot day at idle. The oil tank is baffled and circulates the oil properly from the top when it returns to the tank. When you look in the tank you can't see that far down do to the internal channels and baffles in the tank so tough to tell where the oil level actually is. I do agree that it would be helpful to have a window so you could see into the tank but it doesn't and I won't be doing that.

Elombard, I do agree with your statement about oil sloshing around on a normal 911 but I just am not familiar with this type of oiling setup (even though very similar). It is just different enough to make me question it. The oil shouldn't be too high in the tank. On the bottom it feeds directly into the engine the same way it would from a standard oil tank. Mainly just different measurements on the tank.

McLaren-Tag, yes, the tires were on backwards. This is an older picture from when I bought the car and someone else had did that. Nice catch.

Any other ideas or input on this systems appropriate capacity?

Happy Turkey Day,
Bryan

[x98boardwell]

Update, removed a quart from the tank. 6 total in the system.. minus what was in the cooler and lines before so maybe 7 total. Car barely smokes at all. Only on WOT for a quick second and doesn't barely smoke in any other situation except an occasional gear change.

My other issue is I just bought a CB fuel pump from our host. It is at 3.5psi when I start it up but as soon as it warms up it is at 2 or even 1 PSI.. I need to return the pump and actually spend some money on a legitimate one with a Holley pressure adjuster to keep at a constant 3.5psi. Not sure how the low fuel pressure is effecting my motor since the carbs are basically gravity fed once they fill up. I do know this is not good long term as well.

Went for 70 kilometer ride and it was a blast. Any thoughts on the oil and carbs?

[x98boardwell]

Pics from today... Thx for all the help.

[Quicksilver]

The complete volume of a 7"dia x 15.5" tall tank is right at 10 quarts. You can't fill this thing up because you need room for the air to settle out. I would say a minimum height of a 7" dia tank on a 911 engine should be 20". That will give you a little over 13 quarts of volume so you can have at least 1/3 of the tank for air settling room. If I was sizing this thing for myself I would look a 22" to 24" tank.

I find it weird that a custom system would be designed with a capacity so much smaller then the stock system and that anyone would except that.

[x98boardwell]

Wayne, thanks for the help. Not sure why either? I know the motor does not have any heat issues with 7 quarts in there... not saying that is all that matters. Henry at Supertech is the one who sorted out the oiling issues. PO had smaller hoses and some lines routed incorrectly.

It wouldn't seem to me that the 2.4 liter motor had much more than 9 quarts in total volume in a 73 911S... would you agree? If so, with no oil lines traveling up front and a much more open motor.. maybe this is completely adequate.

Can someone confirm what a 73 911S had for oil volume in the system with lines, coolers, tank, motor, etc?

Thanks,
Bryan

[Quicksilver]

Total volume didn't really change until they did away with the aircooled motor. There is about 10 quarts that drains out and 3 quarts that are left behind.

If Henry is working on it then that is a good resource. I would ask him directly if what you have is what he would recommend. I suspect he is trying to make what you have work as opposed to making an optimal solution. If Henry is comfortable with it then it is probably ok.