Use a supplemental search engine with SWP_Query

gistfile1.php

<?php

/**
 * Use SearchWP's SWP_Query to perform a search using a supplemental engine
 */

$swp_query = new SWP_Query(
	array(
		's'      => 'coffee',    // search query
		'engine' => 'my_engine', // search engine
	)
);

if ( ! empty( $swp_query->posts ) ) {
    foreach( $swp_query->posts as $post ) : setup_postdata( $post ); ?>
        <div class="search-result">
            <h3><a href="<?php echo get_permalink(); ?>"><?php the_title(); ?></a></h3>
            <?php the_excerpt(); ?>
        </div>
    <?php endforeach; wp_reset_postdata();
} else {
    ?><p>No results found.</p><?php
}