Hi C.,
Sounds like your little guy is on the same schedule mine is and was at 24 mos (he'll be 4 in June). He is just not that into sleeping. He'll go down for about 9 hours at night and take a nap for 1.5 - 2.5 hours. You may want to try adjusting when he has his nap to curb the evening crankies.
I must also respectfully disagree with Donna's post. Everything I have read (and I read A LOT) says naps DO count (total hours slept matters). It's great to think your child could get 12 hours straight at night but if that is not his body's rhythm you can't make his sleep that long. My son has always been on this schedule for a long time and he is developing just fine, mentally and physically.
Here is some info from BabyCenter.com:
"How much sleep does your child need?
As a new parent, that's probably one of your biggest questions. Below are some general guidelines as to how many hours of sleep the average child requires at various ages. Of course, every child is different — some need up to two hours more or less sleep than others.
Age Nighttime Sleep Daytime Sleep * Total Sleep
2 years 11 2 (1) 13
* number of naps in parentheses"