diff --git a/Engine/engIO360C.xml b/Engine/engIO360C.xml
index c3a3fbe98..01ab49040 100644
--- a/Engine/engIO360C.xml
+++ b/Engine/engIO360C.xml
@@ -9,7 +9,6 @@
   IDLERPM:       minimum RPM when the engine is running
   MAXTHROTTLE:   maximum throttle setting (as before)
   MINTHROTTLE:   minimum throttle setting (as before)
-  SLFUELFLOWMAX: maximum fuel flow (as before; units unknown)
 -->
 <FG_PISTON NAME="IO360C">
   MINMP             6.5
@@ -20,6 +19,4 @@
   IDLERPM         900.0
   MAXTHROTTLE       1.0
   MINTHROTTLE       0.2
-  SLFUELFLOWMAX     8.7
 </FG_PISTON>
-
diff --git a/Engine/engIO470D.xml b/Engine/engIO470D.xml
index a6e7b0489..d99364d53 100644
--- a/Engine/engIO470D.xml
+++ b/Engine/engIO470D.xml
@@ -9,7 +9,6 @@
   IDLERPM:       minimum RPM when the engine is running
   MAXTHROTTLE:   maximum throttle setting (as before)
   MINTHROTTLE:   minimum throttle setting (as before)
-  SLFUELFLOWMAX: maximum fuel flow (as before; units unknown)
 -->
 <FG_PISTON NAME="IO470D">
   MINMP             6.5
@@ -20,6 +19,4 @@
   IDLERPM         900.0
   MAXTHROTTLE       1.0
   MINTHROTTLE       0.2
-  SLFUELFLOWMAX     8.7
 </FG_PISTON>
-
diff --git a/Engine/engIO540AB1A5.xml b/Engine/engIO540AB1A5.xml
index 9d4a0e676..ca46793a4 100644
--- a/Engine/engIO540AB1A5.xml
+++ b/Engine/engIO540AB1A5.xml
@@ -9,7 +9,6 @@
   IDLERPM:       minimum RPM when the engine is running
   MAXTHROTTLE:   maximum throttle setting (as before)
   MINTHROTTLE:   minimum throttle setting (as before)
-  SLFUELFLOWMAX: maximum fuel flow (as before; units unknown)
 -->
 <FG_PISTON NAME="IO540AB1A5">
   MINMP             6.5
@@ -20,6 +19,4 @@
   IDLERPM         900.0
   MAXTHROTTLE       1.0
   MINTHROTTLE       0.2
-  SLFUELFLOWMAX     8.7
 </FG_PISTON>
-