ive been playing seriously 4 2 yrs grade 4.how many years b4 your realy good and what hours practice would u suggest

Learning is a lifelong process. It`s almost impossible to answer your question. Well, by the standard` good`? What do u mean by good? As a concert pianist? As a good enough student? And if that`s so, what grade or level are we talking about here?
Or u mean good in general-as in complete mastery or at least decent control of the instrument?
Then, I think at least 20 years.
5 years for the basics-foundation.
Another 3yrs to know.
Another 2 yrs to understand.
Another 5 years to explore and experiment... this is perhaps the most crucial stage in learning an instrument. Here`s when u do technical developments ...Chopin/ Kreutzer ... or other etudes etc...
Another 5 years to get use to the physical keyboard and establish a reliable stage prescance.
There goes your 20 years.
And it really doesn`t stop there.

I never consider myself really really good but consider myself good enough to at least teach and pass my knowledge along to others.

Remember back in college seeing people in the practice rooms for 6 hours on hand just to practice to be great musicians.

As long as you don`t wear your self out and hate to play....well your on the right track.