He will aim for a time of nine-and-a-half to 10 hours at Taupo.
"That will be a oncer too. After that it will be time to move on to other challenges," Sillars said.
The first Triathlon Hawke's Bay competitor in Sillars' event, Bram De Boeck, finished sixth with a time of 4hrs08m59s.
Hot favourite for the overall women's title which she also won in the inaugural event in 2017, Taupo's Samantha Bradley, won in 4hrs.14m.37s. The 48-year-old Bradley (nee Warriner) has represented New Zealand in triathlons ranging from sprint distance up to full Ironman. She was second at the 2006 Commonwealth Games in Melbourne, third at the 2008 ITU world championships in Vancouver, won the 2008 ITU World Cup and collected bronze in the 2007 ITU World Cup.
Triathlon Hawke's Bay committee member and Sport Hawke's Bay board member Naomi Fergusson, 40, did the best of the host club members with a seventh overall placing and a third in her 40-44 age group. Her time was 4hrs28m and this included a four-minute drafting penalty.
"Without the penalty I would have finished fifth overall and my age group placing didn't change. However because one of the competitors in my age group was from overseas I got silver," Fergusson explained.
Although she qualified for the Netherlands the Hastings District Council communications adviser and mother of two won't be going.
"That event will involve a 3.8km swim and 180km cycle and requires a big training commitment during our winter. I wouldn't be able to fit the training in between work and family commitments," Fergusson said.
The weekend's festival attracted more than 360 competitors and also included a middle distance triathlon (2km Ocean swim from the beach at Perfume Point, a 95km cycle which took in the Tuki Tuki Valley and a 21.1km run) and the Aquathlon National Championship which involved a 1km swim and 5km run.
Wellingtonian Lucas Duross won the overall male title in the triathlon with a time of 4hrs26m59s. Graeme Buscke was the best of the host club members with a fourth overall placing in a time of 4hrs42m13s.
Buscke, 38, who has been doing multisport events for 10 years tackled the Harbour to Hills event for the first time as he had been out of town when the previous three events were staged.
"While it was tough I enjoyed it and will be back again next year," Buscke said.
He used the festival as a training day for the Taupo Half Ironman in six weeks.
Aucklander Nikkola Mathews won the overall women's title in the triathlon with a time of 4hrs56m20s. Claudia Weidekamm did the best of the Hawke's Bay starters with a second overall placing, an improvement on last year's fifth placing.
Triathlon Hawke's Bay general manager Bruce Richardson was thrilled with the success of the festival.
"The 168 volunteers we had spread out from Napier to the back of the Tuki Tuki Valley did a phenomenal job. It was well managed and because of the heat we put in extra aid stations on the course and we had plenty of recovery pools at the finish."
