My current grow box is about 2'x2'x2' lined with tinfoil and reflective tape.

I'm running 2 27w CFL daylight bulbs and 2 42w regular white CFL bulbs about 14 hours a day.

It's great because I get lots of red wavelengths from the regular CFL bulbs and some blue from the daylight ones.

I also suppliment about 5w of blue LED lighting inside right after germination.

First 11W is not equivalent to 60W, it is 55W at best. This type of bulb also takes anything from around 30 seconds to 5 minutes to reach full brightness, so you should wait a while before taking readings. Lastly it is very difficult to compare total light output from a bulb radiating in all directions with a spot type since it will be brighter in some directions but dimmer in many directions.

In my experience the total light output from the spirals compares well to an incandescent of about 5 times the power, but that light output decreases by maybe 10% in the first thousand hours or so and by more than 20% over its lifetime. Partly because of this, regulations in the US only allow these compact fluorescents to be marketed as equivalent to an incandescent roughly 4 times the power since that is what you'll be getting for the majority of the lifetime of the bulb.

By eye, you may just be able to spot the 10% difference between a 60W incandescent and a new fully warmed up (warm white) 11W spiral if you have them side by side. Any significant difference suggests there is a fault with the bulb. This would be very hard to judge with a spot, even compared to a 60W incandescent spot since the beam patterns will be different.

Thanks Arcygenical. You are confirming the view of 20 to 30 watts per sq ft - though you level at 34.5 is quite high.
Shrubs n Bulbs. I am pleased you have confirmed that a fluorescent gives the same light as an incandescent of 5x the power. I think there is a serious flaw in my light meter. It was showing several times more light from the incandescent, even when the fluorescent had fully warmed up and was at the optimum angle. All my fluorescents gave the same reading. It is possible that cheap light meters also pick up heat effects - but to the eye there was not much differance in light.

As a result of your help, I have changed my design to use ordinary 3 foot tubes. Its a shame because the spotlight type coiled tubes should have benefited from the excellent built in reflector.

Now, I could be completely off base, but... 11 watts of CFL is not nearly enough. I have 2 CFL's per square foot, which is excessive, but the plants seem to like it. One is a 42 watt at 5200K for a blueish light and the other is a 30 watt at 3000K for a more reddish light. They are suspended no more than 6 inches from the tops of the plants. I also have two, 2 foot standard fluorescent tubes. They put out roughly the same amount of light as one of the CFL's, but the light is distributed over 2 feet rather than at a point, so the light dissapation is faster. I would go back to CFL's, after upping the wattage. They are by far the most bang for your buck.