Stronger standing erection ?

It seems like an odd question, but although I can get an erection in any position, my erections are always strongest when I'm sitting down in a certain position; namely, when I am slightly hunched over. In my finite knowledge, I assume this to be due to blood circulation, but I'm open to other evidence. I would just like to know how it would be possible to achieve a maximum erection in any position, instead of that particular sitting position. Thank you in advance for your consideration!