Featured Images In Post

I need to increase the size of the featured image on the single post page to the full size of the image. I have tried using the array/string (array (w,h)) on the content.php here:

<?php if( is_single() ) : // Only display Excerpts for Search ?>

<div class=”entry-content”>
<?php cyberchimps_featured_image(HERE); ?>
<?php the_content( __( ‘Continue reading’, ‘cyberchimps’ ) . ‘ <span class=”meta-nav”>→</span>’ ); ?>

and also in the loop i.e.
<?php
if ( has_cyberchimps_featured_image()) : cyberchimps_featured_imagel(‘full’);
endif;
?>

Nothing seems to work, please advise.