:Some remarks: 
 :*สิงห์ is sing (RTGS), with สิ (si), ง (ng) and ห์ (ha, in fact an 'h' with implicit vowel 'a'), where the diacritic above the 'ha' means silent. RTGS is a kind of simplified IPA (phonetic), so what is silent, is not transcribed. At the entrance of the temple compound we see WAT PHRASINGH, which is not according to RTGS. 
 :*Anglicization is the source of transcribing วิหาร as viharn. It is not clear why วัด is transcribed as wat and วิหาร as viharn, both start with the same ว! But probably its origine 'vihara' is an explanation. Furthermore in (stiff upper lip?) English an 'r' is not really pronounced, but it makes the vowel in front of it sound longer. This is what must be done with the 'a' in wihan (RTGS transcription of วิหาร). But of course Americans DO pronounce the 'r' in viharn! 
 :*In fact Woramahawihan is not a single word, but 3 separate words: Wora Maha Wihan. For me it is strange that วร is transcribed as 'wora'. The rule about implicit vowels says an open syllable gets an implicit 'a', and a closed syllable gets an implicit 'o'. So, if วร is a single syllable word, it would be 'won', but as a double syllable word it would be 'wara', not 'wora'! 
 :So, in Thailand you can see many different transcriptions for the same Thai text. On the English Wikipedia pages about Thailand a decision has to be made about the transcription to be used. RTGS is a more or less official system, described in a document. Choosing RTGS would implicate renaming the page to Wat Phra Sing. 
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