Shiels won the GCG Open Class at the weekend's Yokohama World Time Attack Challenge with a scorching shootout lap time of one minute and 28.114 seconds.

It was anything but smooth sailing for Shiels and his garage across the course of his event, with mechanical issues and unfavourable racing conditions coming into the picture, but he saved his best for Saturday's crucial shootout drive.

Shiels said the atmosphere at the track was electric.

"It's the biggest event of the year at Eastern Creek. There was a huge crowd there," he said.

"You're racing in front of thousands of people while driving as fast as you can. It's amazing."

Shiels said, given the nature of the cars, the challenge can often provide teams with their share of mechanical headaches.

"We had a few problems over the weekend, which can be common for that type of racing because the cars are so highly strung. You only get a lap at a time out of them," he said.

"In our first session on Friday we blew a disc. At Sydney Motorsport Park the track suffers from the heat a lot so your fastest times usually come in the morning. Blowing the disc in those nice conditions meant we didn't get a lap in.

"When it first happened we weren't too sure initially what it was. I'd come onto the straight to start my fast lap and I heard a bang and lost all drive.

"I was worried it was a gearbox issue when it happened, which we didn't have a replacement for, but when we got it back we saw that it was just a rear dif which we've got spares of. It was an easy fix."

The team identified the issue and were able to get the Skyline back on track for the next session, where the news was much better for the Bathurst driver.

Despite missing out on the optimal session Shiels still drove a 1:28.2 to jump to the top of the standings.

His chances of bettering that effort were quashed on Saturday morning.

"Just as we were waiting to go out the class before us dropped oil across half the track, so we again missed that ideal window," Shiels said.

"We weren't getting the speed out of the car that we should have. We actually went faster at testing a few weeks earlier, but everyone was in the same boat."

His 1:28.2 from the previous day was still enough to book a place in the top five shootout.

A strong headwind and scattered showers turned up the degree of difficulty going into the crucial session.

Shiels knocked a tenth off the time to finish ahead of Matt Longhurst's Nissan R34 Skyline GT-R (1:28.736) and Rob Nguyen's Nissan S15 Silvia (1:29.174).

He beat 18 other competitors to take home the open class title.

Shiels had made an impressive debut for the team earlier in the year at the Australian Time Attack Challenge in July with his outright win.

The fastest overall time of the event belonged to Barton Mawer and his RP968 Porsche 968 with a 1:19.277, just short of his pro class lap record.