Will changing from a touring bike to a racing bike improve my energy level? I'm 50 and have been cycling for years, but only 25 mile rides and indoor training. I've been training for 8 weeks, adding 5 miles a week to my big ride, but at 60 miles it is taking me 4:20 and I can't seem to improve my average! 

I am on a touring bike but really seem to struggle with energy. I only eat once half way but drink regularly. At my rate 100 miles is going to take me about 7 hours. I don't think I can ride for that long. 

Would a racing bike make that much difference? I am cycling about 110 miles a week currently.
I think the times you're posting for the distances you're riding, especially on a touring bike are pretty reasonable. Professional athletes, or racers, will ride quicker, but for an amateur aiming for a century your times are fine. On a longer ride, you need more time for rest stops and food and nature breaks.

A road bike will make you a little quicker, especially when you're riding into a headwind. It will also make the time spent more comfortable because you have more options to vary your position.

Make sure you keep up your fluids, electrolytes and carbs. Sports drinks, energy gels, sports bars and glucose lollies can really help when you hit the wall, or 'bonk'. On long rides, you need to keep eating regularly, even if you don't feel hungry (sometimes even when you're sick of eating sugary foods). It's amazing the pick up you can get from eating some good fuel.

Keep riding, keep training and the distance and time on the bike will be more achievable and comfortable.