The endoflame now has a ceiling of 16000 ticks (how much blocks of coal burn for) of how long it can burn a single item for. Items that burn for longer can still be burnt but only last that long.

src/main/java/vazkii/botania/common/block/subtile/generating/SubTileEndoflame.java

@@ -28,6 +28,7 @@ import vazkii.botania.common.lexicon.LexiconData;
 public class SubTileEndoflame extends SubTileGenerating {
 
 	private static final String TAG_BURN_TIME = "burnTime";
+	private static final int FUEL_CAP = 16000;
 	private static final int RANGE = 3;
 
 	int burnTime = 0;
@@ -50,7 +51,7 @@ public class SubTileEndoflame extends SubTileGenerating {
 
 							int burnTime = stack == null || stack.getItem() == Item.getItemFromBlock(ModBlocks.spreader) ? 0 : TileEntityFurnace.getItemBurnTime(stack);
 							if(burnTime > 0 && stack.stackSize > 0) {
-								this.burnTime = burnTime / 2;
+								this.burnTime = Math.min(FUEL_CAP, burnTime) / 2;
 
 								stack.stackSize--;
 								supertile.getWorldObj().playSoundEffect(supertile.xCoord, supertile.yCoord, supertile.zCoord, "botania:endoflame", 0.2F, 1F);