an egg wheigts about 50 gram - so I'd calculate the original relation between dry ingredients and liquid ... than you can easily calculate (rule of three) how much liquid there should be in with more bananas.
I mean that's what I guess 
but in the other hand, maybe not the liquid is the thing to consider. more bakingpowder/soda is necessary to rise up the heavy banana?
My mom uses a basic yellow cake mix from betty crocker and just adds mashed bananas to make it into a banana cake. She does not reduce the number of eggs and it looks and tastes fine.
Personally, I make my own banana cake and it's very easy. So, let me know if you want that recipe and I will gladly send it over 
I am really sorry i did not post earlier. Things got very busy with thanksgiving and relatives coming over.
The recipe has been slightly modified from the the recipe in the betty crocker book. I love it!
2 1/2cups all purpose flour
1 1/2cups mashed ripe bananas (the bananas that go all dark and ugly work best...so, it is a perfect way to use them up...hehe)
1 1/4 cups sugar
1/2 cup water
1/2 cup butter
1 1/2 teaspoons baking soda
3/4 teaspoon baking powder
1 cinnamon powder (use less if you don't like it too much)
Pinch of salt
2 large eggs
-Preheat oven to 350 degrees.
-Mix all the iingredients until you have a smooth mixture. No creaming is necessary.
-Pour into greased/floured pans. The cake does rise quite a bit so i usually use two pans.
- Bake for 45-50 minutes .
There you go. Hope you like it
_________________________
http://www.cakewhiz.com
I am really sorry i did not post earlier. Things got very busy with thanksgiving and relatives coming over.
The recipe has been slightly modified from the the recipe in the betty crocker book. I love it!
2 1/2cups all purpose flour
1 1/2cups mashed ripe bananas (the bananas that go all dark and ugly work best...so, it is a perfect way to use them up...hehe)
1 1/4 cups sugar
1/2 cup water
1/2 cup butter
1 1/2 teaspoons baking soda
3/4 teaspoon baking powder
1 cinnamon powder (use less if you don't like it too much)
Pinch of salt
2 large eggs
-Preheat oven to 350 degrees.
-Mix all the iingredients until you have a smooth mixture. No creaming is necessary.
-Pour into greased/floured pans. The cake does rise quite a bit so i usually use two pans.
- Bake for 45-50 minutes .
There you go. Hope you like it
_________________________
http://www.cakewhiz.com
Cake_Whiz
That's 1 what on the cinnamon powder? The rest of the measurement didn't come through.
Theresa
It should be 1 teaspoon as that is what is in most recipes. HTH
evelyn
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