oil pressure question

[Johns]

The manual says 40 to 50 lbs during cruise for a 2180 aerovee. Wondering what people are actually getting. I have a 2300 and am getting low 30's at about 2900 - 3000 rpms. Oil temp is at 208-210, but engine it is still breaking in. Am using Valvoline 20w 50w racing oil.

John

[lutorm]

Our oil pressure is rock steady at 43-44psi at any appreciable RPM on the rebuilt engine, even with oil temps up to 220. (Idle pressure at those temps is ~10psi.) That's with both 10W-30 oil and straight SAE30. Cold start pressure is the same, with either oil. The pressure control valve seems quite effective. The new engine has quite tight clearances, at least for the big end bearings.

Before we rebuilt it we had way low pressure, <10psi at 3000 rpm/ 210F oil temp, with 20W-50 oil. But that was with severely worn bearings and gigantic oil clearances.

The VW guys have a rule of thumb of "10 psi per thousand rpm" for the lowest recommended.

[Johns]

Thanks for the reply, at least I have the 10 lbs per thousand. I do have a pressure adjustment on the rear relief valve, I just didn't want to mask something else going on.

John

[magicpilot]

Hi,
I just ran my aerovee Turbo for the first time - it runs it’s amazing !!

But here is one concern - my oil pressure is roughly at 5 psi at idle and about 15 at 2000 rpm - I didn’t dare to go more on the throttle on the first day. Any body with numbers from turbo engines with that duplex oil pump? Or any information tipps or tricks to help me out in this matter is appreciated.

Regards,
Juergen

[NWade]

Hi,
I just ran my aerovee Turbo for the first time - it runs it’s amazing !!

But here is one concern - my oil pressure is roughly at 5 psi at idle and about 15 at 2000 rpm - I didn’t dare to go more on the throttle on the first day. Any body with numbers from turbo engines with that duplex oil pump? Or any information tipps or tricks to help me out in this matter is appreciated.

Regards,
Juergen

Have you double-checked to make sure you have both oil pressure plungers installed in the proper location, with the proper orientation, and with the correct spring underneath them?

--Noel

[magicpilot]

Yes - confirmed!

But I just discovered that inside the duplex oil pump are 2 openings which allow crossflow between the 2 pumps. One is/was blocked of out of the box the other one is open and allows probably to let the pressure just to be relieved via the short turbo return line from the secondary pump to case line.
Of course there is nothing about that topic in the assembly manual.

Can anybody confirm my theory?

And thx Noel for your response.

Juergen
N69YX
WXB0017
Aerovee Turbo

[Sonerai13]

But I just discovered that inside the duplex oil pump are 2 openings which allow crossflow between the 2 pumps.

The duplex oil pump for the AeroVee turbo is actually converted from a "dry sump" oil pump, as might be used on a Formula Vee racing car or similar. For the AeroVee turbo, the pump is converted to run as two separate oil pumps, one providing pressure to the engine, and the other providing scavenge from the turbo to return the turbo oil to the engine (via the tube leading from the oil pump to the rocker cover).

As a part of this conversion, the two "crossover" passages that tie the two pump halves together are blocked, and the pump drilled out so that each of the two pumps has an inlet and an outlet individually. There should be NO open passages between the two pump halves internally.

[magicpilot]

Thank you! That’s what I thought.
One of the openings was not blocked as provided by Sonex also there is no Instruction in the Assembly Manual from Sonex....

Thanks again ! Should have a lot more oil pressure after I receive the hardware to block this opening.

[mike.smith]

The manual says 40 to 50 lbs during cruise for a 2180 aerovee. Wondering what people are actually getting. I have a 2300 and am getting low 30's at about 2900 - 3000 rpms. Oil temp is at 208-210, but engine it is still breaking in. Am using Valvoline 20w 50w racing oil.
John

I used to have the same numbers. It turned out to be a sticking oil pressure plunger. Your numbers are perfectly OK for a VW and mine ran with those numbers for two years, but if you get the opportunity to polish the oil pressure plungers and the orifice they are in, I'll bet you get better pressure.

[Johns]

Thanks Mike, makes me feel better. I do have a oil pressure adjustment on the rear relief valve I will be playing with. Hope to be in Keene this year!!

John