Following a low-key first practice for both Penske Acura ARX-05s, three-time Indianapolis 500 winner Castroneves moved the #7 car to the top of the times 25 minutes into the one-hour session with a 1m37.283s.

The Brazilian later improved to a 1m37.036s, ending FP2 four tenths up on the best time produced by Mazda Team Joest driver Rene Rast in the opening session.

Second-fastest was Nicolas Lapierre in the #22 ESM Nissan DPi, the Frenchman setting a 1m37.360s amid a late flurry of improvements prior to the red flag being shown with five minutes remaining.

Filipe Albuquerque was the quickest of the Cadillac drivers in the #5 Action Express car, 0.025s down on Lapierre, while best of the LMP2s was the #54 CORE autosport Oreca driven by Colin Braun in fourth.

After topping the first session, Mazda was fifth-fastest courtesy of Jonathan Bomarito in the #55 car, ahead of defending race winner Jordan Taylor in the #10 Wayne Taylor Racing Cadillac.

Fernando Alonso's #23 United Autosports Ligier JS P217 ended up 12th, with Lando Norris setting the car's fastest time of 1m37.960s - two positions behind the sister car driven by Bruno Senna.

The two United cars were split by the #37 Jackie Chan DC Racing Oreca of Robin Frijns.

Porsche led the way in the GT Le Mans class as Patrick Pilet put the #911 entry on top in the latter stages of the session with a 1m43.902s, edging out Jan Magnussen's #3 Corvette by 0.068s.

The two Ford GTs led the way for much of the running, but were demoted to third and fourth places, with Richard Westbrook giving the Ganassi team a best time of 1m44.057s in the #67 car.

Alvaro Parente topped the GT Daytona division with a 1m46.790s in the #86 Michael Shank Racing Acura NSX.

Second practice results (top 10):

Pos.	No.	Drivers	Chassis	Time	Gap
1	7	Helio Castroneves Graham Rahal Ricky Taylor	Acura DPi	1'37.036
2	22	Pipo Derani Johannes van Overbeek Nicolas Lapierre	Nissan DPi	1'37.360	0.324
3	5	Christian Fittipaldi Filipe Albuquerque Joao Barbosa	Cadillac DPi	1'37.385	0.349
4	54	Loic Duval Romain Dumas Jon Bennett Colin Braun	ORECA LMP2	1'37.613	0.577
5	55	Harry Tincknell Spencer Pigot Jonathan Bomarito	Mazda DPi	1'37.616	0.580
6	10	Jordan Taylor Ryan Hunter-Reay Renger van der Zande	Cadillac DPi	1'37.695	0.659
7	2	Scott Sharp Ryan Dalziel Olivier Pla	Nissan DPi	1'37.699	0.663
8	77	Oliver Jarvis René Rast Tristan Nunez	Mazda DPi	1'37.711	0.675
9	31	Mike Conway Eric Curran Felipe Nasr Stuart Middleton	Cadillac DPi	1'37.771	0.735
10	32	Bruno Senna Paul di Resta Will Owen Hugo De Sadeleer	Ligier LMP2	1'37.924	0.888