Mailing List Message #65343
From: Finn Lassen <>
Subject: Re: [FlyRotary] Re: Renesis oil pressure
Date: Fri, 15 Nov 2019 18:54:24 -0500
To: Rotary motors in aircraft <>
Thanks Matt.

No clue why I assumed the OMP got the oil before the cooler. So, would have to insert some kind of adapter between engine and cooler. Right now it's the 10mm (?) to AN8 fitting and a 12" run to the 25-row cooler under the engine.

Main reason I wanted to also monitor pressure before the cooler was to see what kind of pulses it's exposed to. But if it's only 80 psi I'm not as worried.  I have no idea what year or series engine it is. How do I tell? It's a NA 4-port. It does have the rear (same end as oil filter pad) regulator. When I had the regulator out to dill/tap the PSRU oil return hole in the rotor housing base, I did not notice if it was possible to shim it.

Definitely will want before/after oil cooler temps to see how well the cooler works.

Same with before/after radiators. Any clue what temperature drop is from fluid to outside of alum or brass fittings? If negligible it'll be easy to glue/strap a TMP36 to fittings.


On 11/15/2019 3:47 PM, Matt Boiteau wrote:
Based on racing beat's page, the first series of RX8 is 80psi. The second series does away with the rear pressure reg and is rated to 115psi.

Finn, it's a good idea to tap the oil pan to get it's temperature. It usually is around 30F hotter then incoming oil, then you get a true reading of how hot the oil is. The OMP pressure will be after the regulators, so no point going there. The stock location to get oil pressure is @ #8 in the picture below. Where it goes out to the oil radiator (just above #9) would be your best spot for a pre-cooler pressure, but I don't think that pressure is worth knowing anyways. 

Those sensors from Ebay look to be the same I am using. S.S.,1/8npt and comes with pigtail. Can't beat the price, and they seem to be working well so far.

- Matt Boiteau

On 2019-11-15 12:20:27 PM, lehanover <> wrote:

Any early regulator can be shimmed to over 100 PSI. We ran 100 PSI with Redline 40 weight.  RX-8 came stock with 110 PSI. Early valves can be dismantled  and shimmed to anything you want. RX-8 valves are welded shut. Most racers have a drawer or box of early valves. Check your local SCCA for member help.
Lynn E. Hanover

In a message dated 11/15/2019 10:36:08 AM Eastern Standard Time, writes:


Anyway, thank you all for your replies. Sounds like a 150 psi sensor will be the safest.

I have no plans to tear down the supposedly brand new Renesis, so for now no modifications.

Thinking about a before cooler pressure sensor too. I suppose the only (easy) option is to drill and tap the oil metering pump supply hole (which I've already plugged)?

I would like to also have a before oil cooler temperature sensor. I guess I need to find a spot in the oil pan?

I suppose a 30 psi sensor is adequate for water pressure (assuming I don't go with Evans non-pressurized system)?

Trying to source sensors, I looked in the places I had purchased them decades ago (Newark, DigiKey, Allied) and was dismayed at the availability and prices. In my original RV-3 I had used the solid state MPX-5999 with barb from NXP USA.

A Google search finally lead me to a posting which led me to Aircraft Spruce and a "Swift" pressure sensor. That led me to eBay where there now is a wide selection of 5V (amplified) solid state sensors with 1/8-27NPT housings.

These solid state sensors have (amplified) output voltages from 0.5 to 4.5 volts with a 5 volt supply (they even come in 12V (10-25V) supply version for a bit more).
Yes, your engine monitor has to subtract (offset) the bottom by 0.5 volts (0 psi = 0.5 volts).ⓂmTKFrDgAsPLl-bZmKbUTKgQ

When searching note that oil pressure switches are often called sensors too.


On 11/15/2019 7:36 AM, Bobby J. Hughes wrote:
Thermal pellet and carb jets with racing beat race regulator. Idle at 28 warm and 88-92 psi at 4800-7000 rpm.??


Sent from my iPhone

On Nov 15, 2019, at 2:43 AM, Matt Boiteau <> wrote:

I installed an RX7 rear regulator and shimmed the front reg with 2 washers. Also installed thermal pellet and weber jets in the e-shaft. Average around 110-115psi during cruise, so I went with an 150psi sensor.

- Matt Boiteau

On 2019-11-14 11:53:30 PM, Neil Unger <> wrote:

Fin,?? My renesis starts cold at 150 PSI.?? I let it idle at 2200 rpm
until after a few minutes it settles to 80 psi (plus).


On 11/15/2019 10:45 AM, Finn Lassen wrote:
> I'm starting to look at engine monitor sensors for my RV-4.
> In his Renesis report, Tracy mentioned 100 psi oil pressures. Not
> clear if they dropped after the engine got some hours on it.
> What kind of oil pressures are you seeing?
> Should I go with a 150 psi or a 100 psi pressure sensor?
> Finn
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