So i have a d15b2 and have a y5 head laying around i put it on and everything but timing belt is too loose. What timing belt would i be able to use? I already tried a y5 timing belt aswell

 

Even if you find a timing belt that fits, it's unlikely you will be impressed by the Frankenstein engine that you created.

 

Y5 I believe is the vtec-e head. The B2 pistons I believe are like the B7 with flat top design. I think the Y5 pistons are dished for lower compression.

I think you will have some serious running challenges with any stock ECU as the compression will be totally different than any stock setup. Even tuned it may not operate efficiently as the lean burn may not have the right conditions much of the time due to the changes.