you need a program that allows you to select which mathematical formula to use when resizing - something like Photoshop or GIMP.
Then you need to select "nearest neighbor" (or something similiar named, different from program to program) as the method for the 400% resize.
Be warned that this will only be without blur as long as you keed resizing to full multiples.
It is technically almost impossible to resize without blur because that blur in reality is averaged pixels which cannot be circumvented if you don't have full multiples (the resize x1.5 from Ace to MV is one such example that will never be without blur, you can only minimize the effect).