No, you need indexer clusters and search head clusters to have their own machines.
Indexer Clustering docs say no: http://docs.splunk.com/Documentation/Splunk/7.0.2/Indexer/Systemrequirements#Machine_requirements
Search Head Clustering docs say no: http://docs.splunk.com/Documentation/Splunk/7.0.2/DistSearch/SHCsystemrequirements#Hardware_and_operating_system_requirements
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