Change the excerpt length on search results only. Requires Generate Blog to be enabled.

gistfile1.php

if ( ! function_exists( 'generate_excerpt_length' ) ) :
	add_filter( 'excerpt_length', 'generate_excerpt_length', 999 );
	function generate_excerpt_length( $length ) {
		$generate_settings = wp_parse_args( 
			get_option( 'generate_blog_settings', array() ), 
			generate_blog_get_defaults() 
		);
		if ( is_search() ) :
			return 100;
		else :
			return $generate_settings['excerpt_length'];
		endif;
	}
endif;