The team fast-tracked some new components through the manufacturing process and will be running them in both Las Vegas and at the season finale in Abu Dhabi that follows.
The items were not expected to improve the performance of the A523 in Las Vegas.
The team struggled for pace in FP2, with Gasly 15th and his team-mate Esteban Ocon only 16th after a change of chassis following his incident in FP1.
"So far it's been pretty tricky," said Gasly. "On my side of the garage, we're doing some experiments for next year's car, so we're trying different set-ups and trying to get some answers and direction for next year.
"Interesting, not the most comfortable so far, but hopefully we can get something out of it."
Gasly said he was prepared to take a hit in Vegas if it helps for the long term: "I think we're not really looking at this track specifically, so we're probably compromising a little bit this weekend.
"But we know it's for a bigger purpose and mainly for next year. Trying to optimise as much as we can with what we have. Today has been a little tricky."
While not divulging any details, Alpine technical director Matt Harman indicated that the test items could have a significant impact on next year's design.
"We got some experiments that we're going to be trying this weekend," he said. "And they're all around some work we've done recently that informed us on a certain direction that we'd like to take.
"We've had some components made over the weekend by the factory, which was a great response by the factory, because I wanted to try something particularly different at this event. And I'm excited to see it.
"You're not going to see in lap times, but we're going to see in data.
"And I think it's another one of those things that will help us with the aerodynamic direction, the sensitivities, the weightings of our aerodynamics on the car, but also some of the mechanical systems at the rear of the car that really do control how these cars can operate through corners, which is important."
