Indianapolis 500: Ed Carpenter flies on rain-affected 'Fast Friday'

Carpenter, who won pole for last year's race, achieved a best average speed of 230.522mph on a day when the top seven drivers all went above 229mph.

Three-time winner Helio Castroneves was second-fastest at 220.843mph, with Marco Andretti, JR Hildebrand and Josef Newgarden rounding out the top five.

"When it comes to predicting what the pole [speed] is going to be, I think a lot of it will be figuring out what the weather is," said Carpenter.

"If it warms up enough and the air gets a little thinner, certainly I think 230s are realistic, even up to 232 and 233."

The day marked the first time that IndyCar teams could work with the higher qualifying boost levels, which are turned up from 130 kPa to 140 kPa from Friday through the two days of qualifying on Saturday and Sunday.

The engines, which deliver an estimated additional 40bhp in that spec, will then be returned to their previous boost levels for Carb Day and the race.

Jacques Villeneuve, who won the 1995 Indy 500, admitted that the poor weather had left him feeling ill-prepared for qualifying, but said that his priority is to have a car that works in the race.

"We have no idea what to expect for tomorrow," said the Canadian, who ended the day 16th-fastest.

"We were on old tyres in the few laps we got on Fast Friday and we hadn't trimmed the car out yet. I also had a little bit of a tow on those laps. We haven't even done a practice qualification run yet.

"We're not under any stress though, because we're not in the points championship. Qualifying is almost meaningless for us, so there's no point in us taking a risk with anything. What matters for us is the race."

Under the new Indy 500 qualifying system, Saturday's session will formally decide the 33 cars that will make up the grid.

On Sunday, the cars will return to the track to determine the starting order for next weekend's race.

Pos  Driver              Team/Engine      Speed    Time      Gap       Laps
 1.  Ed Carpenter        Carpenter/Chevy  230.522  39.0418s            8
 2.  Helio Castroneves   Penske/Chevy     229.843  39.1571s  +0.1153s  9
 3.  Marco Andretti      Andretti/Honda   229.419  39.2296s  +0.1878s  4
 4.  JR Hildebrand       Carpenter/Chevy  229.384  39.2355s  +0.1937s  8
 5.  Josef Newgarden     Fisher/Honda     229.276  39.2540s  +0.2122s  6
 6.  Juan Pablo Montoya  Penske/Chevy     229.205  39.2662s  +0.2244s  7
 7.  Scott Dixon         Ganassi/Chevy    229.062  39.2907s  +0.2489s  11
 8.  Ryan Hunter-Reay    Andretti/Honda   228.603  39.3695s  +0.3277s  7
 9.  Simon Pagenaud      Schmidt/Honda    228.544  39.3798s  +0.3380s  8
10.  Jack Hawksworth     Herta/Honda      228.176  39.4432s  +0.4014s  6
11.  James Hinchcliffe   Andretti/Honda   228.115  39.4537s  +0.4119s  8
12.  Martin Plowman      Foyt/Honda       228.036  39.4675s  +0.4257s  7
13.  Carlos Munoz        Andretti/Honda   227.938  39.4844s  +0.4426s  11
14.  Mikhail Aleshin     Schmidt/Honda    227.822  39.5046s  +0.4628s  8
15.  Takuma Sato         Foyt/Honda       227.741  39.5186s  +0.4768s  5
16.  Jacques Villeneuve  Schmidt/Honda    227.682  39.5288s  +0.4870s  6
17.  Alex Tagliani       Fisher/Honda     227.394  39.5788s  +0.5370s  4
18.  Oriol Servia        Rahal/Honda      226.387  39.7550s  +0.7132s  8
19.  Sebastien Bourdais  KV/Chevy         226.351  39.7612s  +0.7194s  7
20.  Sebastian Saavedra  KV/Chevy         226.137  39.7988s  +0.7570s  5
21.  Ryan Briscoe        Ganassi/Chevy    226.072  39.8103s  +0.7685s  5
22.  Will Power          Penske/Chevy     223.202  40.3222s  +1.2804s  7
23.  Kurt Busch          Andretti/Honda   217.145  41.4470s  +2.4052s  8
24.  Charlie Kimball     Ganassi/Chevy                                 2
25.  Graham Rahal        Rahal/Honda                                   2
26.  Carlos Huertas      Coyne/Honda                                   1

All drivers use Dallara chassis