Mailing List flyrotary@lancaironline.net Message #63245
From: <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: fuel system peer review
Date: Fri, 24 Mar 2017 13:58:54 -0400
To: <flyrotary@lancaironline.net>
The racer has one Setrab 44 row cooler in the pressure loop and two 44 row Setrabs in the scavenge loop'   Before sponsor money appeared, We used air conditioner cores from big GM cars as oil coolers. Fill with water and TIG on the dash 10 or 12 fittings.
 
Multiple smaller coolers my provide more latitude of design in small spaces. A bit more than 1/3 of all engine heat escapes through the oil. Make up cardboard box replicas of proposed coolers for fit up before buying.
Lynn E. Hanover
 
In a message dated 3/24/2017 12:48:29 A.M. Eastern Daylight Time, flyrotary@lancaironline.net writes:
Steve,
 I find two versions of the Fluidyne DB 30618 oil cooler........One call a "Single Pass" Thermo HX Nascar version ($460.00)
and a DB-30618 ($380.00) which may be a two pass (Does not Say)........Which are you using ??...........

Kelly Troyer

On Thu, Mar 23, 2017 at 10:29 PM, Steven W. Boese <flyrotary@lancaironline.net> wrote:

Dave,


The oil thermostat and bypass is internal to the oil cooler.  Removing the thermostat would allow the oil to always bypass the core no matter what the temperature of the oil is.  The pressure at the inlet to the oil cooler would not be as high at lower RPM but still reach 150 psi at high RPM.  Without oil being forced to flow through the core, however, the cooling effectiveness would be greatly reduced.  I have not set up the oil cooler this way.


It is also possible to remove the oil thermostat and block off the bypass with a bolt and nut.  This prevents the hot oil from flowing through the bypass and mixing with the oil cooled by the core.  Only the cooled oil will exit the oil cooler then.  The pressure at the oil cooler inlet would reach 150 psi at lower RPM with this set up.  I've tried this setup but didn't make pressure measurements on it.


I've converted the RX7 oil cooler to single pass instead of double pass by welding a -10 fitting on the tank at the opposite end of the normal connections and removing the thermostat.  The inlet pressure reached 150 psi at about the same RPM (2800) as with the unmodified cooler with the thermostat installed.  This demonstrated the restrictive nature of the RX7 core.


Steve Boese
RV6A, 1986 13B NA, RD1A, EC2



From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of hoursaway1 <flyrotary@lancaironline.net>
Sent: Thursday, March 23, 2017 6:52 PM

To: Rotary motors in aircraft
Subject: [FlyRotary] Re: fuel system peer review
 
Steve, Dave Cook here, have you tried looking for that same pressure build-up pre Mazda oil cooler with the temp by-pass removed/by-passed, I'm thinking that is the cause of the restriction. David R. Cook  RV6A Rotary ,MI


From: "Steven W. Boese" <flyrotary@lancaironline.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Thursday, March 23, 2017 12:11:21 AM
Subject: [FlyRotary] Re: fuel system peer review


Andrew,


A Fluidyne DB-30618 is the oil cooler I ended up with in the plane.


When a pressure gauge was installed in the line between the front cover outlet and the RX7 oil cooler inlet, the pressure rose with increasing RPM to 150 psi at 2800 RPM.  Increasing RPM above 2800 resulted in a steady pressure at 150 psi.  Since the oil pump is a positive displacement pump, additional oil flow above 2800 RPM passes through the relief valve into the sump.  At 5600 RPM half of the oil pumped by the oil pump never flows through the oil cooler.


With the Fluidyne oil cooler, the pressure at its inlet never reaches 150 psi so all of the oil passes through it.


An archive search for 25 Feb 2014 should find a description of various oil cooler configurations that I tested.


Steve Boese




From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Andrew Martin <flyrotary@lancaironline.net>
Sent: Wednesday, March 22, 2017 8:40:08 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: fuel system peer review
 

This thread has perfect timing and great info for me.

I was thinking of ditching my setup and simplifying it, but it looks like every system is a compromise.
I just mounted a belly radiator which entailed moving the pumps & sump tank. As other local pilots had commented on how complex my fuel system was I thought it opportune to address it now. After following this thread though I'm inclined to stick with this setup now as I know it works. and just not let anyone else on the controls.
Only problem I have is I cannot tell the fuel level in the sump tank. Need some sort of warning that I've drained a tank dry or have a vent or feed problem. Am thinking of putting a sight glass in the return line from sump to fuel selectors for a visual clue.
I like this setup as it allows me to feed from any or all tanks. not needed but usually leave 1 transfer pump on. if both transfer pumps happened to fail the fuel return path gives a free flow path from tanks to sump also.
I have managed to empty the sump tank once when flow testing the system but there was no back pressure on the system so regulator was not circulating fuel. I guessed the tank vent lines (1/4") are just to small when fuel flowing at 180l/hr and it vapourized in the sump.

Steve. I'm interested to know the model No. of your fluidyne oil cooler. I started with these mods because I couldn't control my oil temps, so new belly radiator installed to give oil cooler all the cowl air, but I never thought that the mazda cooler may be blocking oil flow. Whats the clue that the front relief valve is opening?

Andrew





--
Kelly Troyer
Dyke Delta_"Eventually"
13B_RD1C_EC2_EM2
Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster