Amid

Got a solution for this on the german forums:

<?php
if ( 'portfolio' == get_post_type() ) {
	$this_post_id = get_the_id();

	$args = array(
		'post_type' => 'portfolio',
		'post_status' => 'publish',
		'posts_per_page' => -1,
		'fields' => 'ids',
		'order' => 'ASC',
	);
	$the_query = get_posts( $args );

	$key = array_search( $this_post_id , $the_query );
	$key++;

	$published_posts = wp_count_posts( 'portfolio' )->publish;

	echo ' ' . $key . ' / '. $published_posts;
}	//end if post type ?>

range … didn′t know that one … thanks alot @girlieworks

Yeah I saw that one, but it seemed overly complicated to me.
First doing an extra query to get all IDs?
WTF … then i could directly do one query to get the posts.

Is there really no easier way to do this seemingly simple query?

Yeah I know all that, but what when I don′t want my upload folder cluttered with image sizes I don′t need in my theme?