Walsh produced a stirring performance when he clocked a 2:03.82s lap in the Aston Martin V12 Vantage he is sharing with George Miedecke and Tony Bates.
The Amateur Class-entered Miedecke Stone Motorsport entry is using the same car which clinched a podium finish at the 2015 Bathurst 12 Hour when it was campaigned by Craft Bamboo.
“It was certainly the most committed lap that I've done in my life,” said Walsh, who will start from fourth on the grid.
“I wanted to go out there and obviously give it a pretty good crack and I knew that we probably didn't have the pace to be right up there.
“So I knew I had to have a committed lap to have a chance of moving up, and, I guess, last of all I just didn't want to hang it off the fence.
“You know there's a couple of times in the lap where I thought I was having a few moments, but in these cars you're so fast across the top that you have to be committed.
“It's nearly three-quarter throttle, the lowest point that you get between The Cutting and Skyline, so it's very fast.”
“I've been coming here for a number of years now and I think the (Bathurst) 1000 last year gave me confidence in myself, my ability and the track,” Walsh added.
“I like the challenge of it and I like the commitment that you've got to have across the top, coupled with the big stops and the technicality of that.
“So I love coming back here, (the 12 Hour) which is the first race for the year and I guess it couldn't be a better one.
Walsh said the aim for the Aston Martin was to qualifying in the top 15.
“It's always good to surpass your expectations, so I'll just be doing my best (in the race) as I tried to today
“And whatever happens from that, I hope it gets me some more exposure in some international racing because I'd love to do it.”