The 48 propane burners use 11in WC which comes to about 0.4 psi.  It puts out enough BTU's (120K) to keep me going around the track without loosing steam pressure.  At first, the problem was with the flame being sucked out when under load (going uphill) and the throttle was opened a bit too much.  Sure glad I have those electric starters.  I experimented with a couple blast nozzles making them larger, but this just made the problem more tolerable but didn't eliminated it.

The original fuel setup used two propane regulators, a high pressure which reduces tank pressure to about 30psi and a low pressure regulator which further reduces the pressure to 11in WC.  Wanted to see if boosting the gas pressure on the low pressure regulator would give me a stronger flame more resistant to being sucked out.  Couldn't find any variable low pressure regulators anywhere.  Did find a 1 psi low pressure regulator and tested it out.  Before it was installed, this picture of the flame using the 11in WC regulator was taken.

After replacing the 11in WC regulator with a 1 psi unit, here is what the flame looked like.

It's not easy to see with these photos, but the flame using the 1lb regulator was much fuller and higher than the lower pressure regulator.  Draft was also increased to keep the flame blue.  The same amount of draft with the 11in WC regulator would have sucked the flame out.  Not with this regulator.  I may not get the same number of hours on a tank but I don't think I will be running the burners at full blast all the time like I used to. 

Here's the regulator setup.  The high pressure regulator has the red knob.  The 1lb low pressure regulator is blue.

After these modifications were made, the Daylight was taken out for a test run.  It took only 30 minutes to get 120psi of steam.  With the original regulator it took over 45 minutes.  The next thing noticed was the flame was no longer affected by how hard the engine was working.  No more flames being sucked out!  The third thing is that the safeties kept popping when all burners were on.  In order to avoid that, the outer burners were turned off most of the time and turned back on when under load going uphill.  Even though I am burning more fuel with the higher 1lb regulator, I don’t run all the burners all the time like I did with the 11” WC regulator.  I also moved the blast nozzle all the way up to the bottom of the petticoat.  This also helped reduce the vacuum in the smokebox which helped eliminate the flame being sucked out.

UPDATE AS OF 2022

After adding two steam powered air pumps to the engine, I began having problems maintaining steam pressures to run the engine and all the pumps.  The plan was to increase the propane pressure from 1psi to 2 psi to see if that helped.  A Rego LV340TR regulator was used for the first stage which lowered the tank pressure to 10 psi.  A  Rego 596FA was used for the second stage which had a range of 1-15 psi.  

  The QCC connection to the tank was also upgraded from 200K BTU (green) to 400K BTU (red).

  The regulator and QCC fittings are overkill for the BTU's needed but I wanted top make sure I don't run into capacity problems again.