Yes, there are few Search engins who are completely dedicated to Blog searchs. In this post i am going to tell you regarding those Search engines. In this category the first one is

Amatomu - Amatomu is a blog search engine and article aggregator, focusing on blogs published in South Africa. It was founded by local web entrepreneurs Matthew Buckland and Vincent Maher in March 2007, while working for one of the country's largest news websites the Mail & Guardian Online. According to an article in Finweek, the site was still in its early testing phase with a select group of users when someone not in the test group leaked news about it and it was deluged with bloggers looking to use the service. The site ranks bloggers and provides charts and statistics for their blogs. It also has the ability to track trends and monitor keywords in the local blogosphere via buzzgraphs.
Amatomu organizes bloggers by topic and lists blog keywords.

Bloglines - Bloglines is a web-based news aggregator for reading syndicated feeds using the RSS and Atom formats. Mark Fletcher, former CEO of ONElist, founded the site in 2003 and sold it in February 2005 to InterActiveCorp. On July 23, 2007, Bloglines released an iPhone version of their site. On August 27, 2007 the company released a public beta version of their site, with new features such as drag-and-drop feeds in the feed tree and a customizable start page. Bloglines offers an application programming interface that can be used to write software that can read feeds, search its database of feed entries, and ping the service when a blog has been updated.

BlogScope - BlogScope is a search engine for the blogosphere with advanced analysis and visualization technology. BlogScope is outcome of an ongoing research project at the University of Toronto. As of Apr 2009, the system is indexing over 725 million blog posts. The BlogScope project has led to creation of Sysomos, a Toronto-based social media analytics company. Sysomos develops two products, Media Analysis Platform (MAP) and Heartbeat, based on the intellectual property created by the BlogScope project.

IceRocket - IceRocket is an Internet search engine specialized in searching blogs.IceRocket is backed by Mark Cuban and headquartered in Dallas, Texas.

Sphere - Sphere is a blog search engine. The Sphere search engine delivers blog posts based on algorithms that combine semantic matching with authority factors to deliver results relevant to the search query. Sphere also organizes bloggers by topic.

Technorati - Technorati is an Internet search engine for searching blogs. By June 2008, Technorati indexes 112.8 million blogs and over 250 million pieces of tagged social media.The name Technorati is a portmanteau of the words technology and literati, which invokes the notion of technological intelligence or intellectualism. Technorati was founded by Dave Sifry and its headquarters are in San Francisco, California, USA. Tantek Çelik was the site's Chief Technologist.