post per page

I am trying to list only a certain amount of work porfolios on my front page, right now the code list all. I only want to list 6 so I am using posts_per_page but is not working. Any help would be appreciated.

Here is the code:

<?php
$args = array(
	'nopaging' => true,
	'post_type' => 'portfolio',
	'posts_per_page' => 6,
	'orderby' => array('menu_order' => 'ASC', 'ID' => 'ASC')
);
$wp_query = new WP_Query($args);
while ($wp_query->have_posts()) : $wp_query->the_post();
	get_template_part('loop', 'portfolio');
	endwhile;
?>