-------------- Original message --------------

Hi John,

 

Don't have my REW FD engine manual here at home (Don't want to quote figures off the top of my head). However,  60 PSI seems OK at those revs (4,000).  What do you get up around 5,500 - 6,000 RPM?  That's the critical issue. Anyway,  will get back to you when I have consulted the manual.  (Anybody else got an FD workshop manual handy?). 

 

It's not really the pressure that matters so much as the ability of the pump to supply sufficient volume. The FD pump is quite big,  and has the capacity to pump enormous volumes of oil.   As somebody else said,  it's designed to feed two turbos,  so it shouldn't have a problem feeding one turbo plus the PSRU.

 

I'm currently running in a Series V turbo engine.  It is mild ported,  and has a tricked up early model dismantleable style regulator.  It will produce 100 PSI above 6,000 RPM,  but it has about the same PSI as you have at the lower RPM ranges,  once the engine is warmed up. Again,  I don't have any of my manuals here so I can't tell you exactly what to expect from the different stock reguilators.

 

Apart from a leaky pickup gasket,  or if the bolts were left finger tight (you have to be REAL careless to have this happen)  it is possible to have a fractured oil pickup pipe (rare but it can happen),  I've also seen blokes leave the oil pump bolts loose (again usually finger tight!),  or not stake the oil pump shaft lock washer (just carelessness),  or the Woodruff key wasn't located correctly (Ed's issue! - REAL easy to do - happens to me about every second or third engine).  Sometimes it takes two or three goes to get it in. They are real small & fiddly You must ALWAYS double check - use strong light or a torch to make sure that you can see the key is in the correct place once the sprocket in on on the shaft,  before fitting the nut & lockwasher. 

 

I also assume you used the white nylon backup ring that goes with the O ring on the outlet from the front housing to the front cover??  I also assume that you used the correct O ring??  Early (pre '85) engines just has the O ring and the gasket.  I've had these blow out at times ( usually with tricked regulators in race engines). I developed a technique where I stopped using front cover gaskets for this reason.  Just a much thinner O ring and RTV sliastic.  Never had a failure since. But all this is a thing of the past with "86 on engines.  Mazda got smart,  and used the nylon back up ring to contain the O ring,   instead of just the gasket material.

 

One operational thing we have found in race cars is that if the sump is overfilled,  and/or we are not using a baffle plate (a sheet of alloy that goes between the sump & the bottom of the motor),  the oil can get whipped into a "milkshake" (emulsion) by the front counter weight.  The emulsified oil will cause the pump to cavitate,  and then you get fluctuating/dropping oil pressure.  So make sure you have the correct length dipstick,  and the sump is not over-filled. 

 

I think all aero engines should have an alloy baffle plate.  During descent,  the engine is still turning at reasonable RPM,  even though the throttle might be nearly closed.  Oil in the sump will tend to migrate up into the front cover (just like a car under brakes).  If the counterwieght gets a chance,  it will take great delight in making a caramel or chocolate (depending on how clean the oil is)  milkshake out of your lubricant.  If you happen to need to get back on the noise in a hurry,  you might just have oil pressure problems.

 

Anyway,  there's my baker's dozen or so Brass Razoos for today.

 

Cheers,

 

Leon

----- Original Message -----

From: John Slade

To: Rotary motors in aircraft

Sent: Thursday, January 06, 2005 1:26 PM

Subject: [FlyRotary] Acceptable oil pressure

Leon and anyone else who cares to comment...

 

The remaining question with my installation is whether the oil pressure is acceptable, or whether something actually wrong.

Everything has been triple calibrated now, so I'm pretty sure of the following readings.....

 

Start-up at 70F ambient gets me 80 - 85PSI.  Once the oil gets hot I'm seeing about 15 or so at idle, 25 PSI at 2000 rpm, 45 PSI at 3500 rpm, and maybe 60 PSI at 4000.  Talking about today with Tracy he felt it was marginal, and was wondering if this might be normal with a combination of a turbo and a redrive both taking pressure.  Other possible causes he suggested were Ed's spinning shaft syndrome or air being sucked by a leaking oil pickup.

 

I hate to remove the engine (again) to check these items.

 

What do people think? Anything else I can check?

 

John (no more soot on the prop)