There is a 30k character limit to post questions on all Stack Exchange sites; Code Review's is over 65K.
If it fits into one question, then you may absolutely ask it. Otherwise, perhaps you will find a way to split it up into two questions, or ask about a particular part in your application.
For applications of this site however, it is very important that you include a lot of explanation and context about what your project is about.
I have myself asked questions on Code Review about quite big code projects, see for example:
- Analyzing Minesweeper ProbabilitiesAnalyzing Minesweeper Probabilities
- SudokuSharp Solver with advanced featuresSudokuSharp Solver with advanced features
Explaining a lot about your code in plain English really helps reviewers to better understand and review your code.