INDIANAPOLIS (AP) — Chevrolet engines have powered some of IndyCar's biggest wins over the last six years.

Their drivers have won three of the first five races this season, four straight series titles and claimed the top four starting spots in Sunday's Indianapolis 500.

So why is there so much chatter about Chevy vs. Honda in Sunday's race? It's the one mountain Chevy continues to try and conquer.

"We have more horsepower at the top end but race running's going to be different because you're not going to be flat out," 2016 series champ Simon Pagenaud said. "You're going to have to manage your tires, you're going to have to lift a lot and reaccelerate, and the Honda is really strong at that. So I think it's going to equalize the race and I think there's a good chance it will show, which is fantastic."

Pagenaud knows both engines well.

He spent his first four seasons in the series working with Honda teams before switching to Roger Penske's powerhouse Chevy team in 2015.

Yet as dominant as Chevy has been over the years outside Indy and as good as Penske's team has been on Indianapolis Motor Speedway's 2.5-mile oval, Honda continues to have the upper hand in the 500. Their cars have driven to victory lane 12 times over the past 14 years, including a run of nine straight (six coming when Honda was the series' sole-engine manufacturer).

Chevy has two 500 wins since returning to the series in 2012. But the engine battle is becoming far more competitive even at Indy where the disparity from the top qualifier to the last qualifier was cut from 11.083 mph in 2017 to 5.198 mph this year.

Drivers have already noticed a difference on the track and casual fans who only watch the 500 might pick up on the changes, too.

"It's certainly exciting for the fans, for us, for the teams," said three-time Indy 500 winner Helio Castroneves, a Chevy-powered driver for Penske. "It's all about the end. Right now, we happen to be competitive so let's see what happens in the race."

Last year, Honda grabbed four of the top five spots and powered two-time Formula One champion Fernando Alonso to the race's rookie of the year award. The problem: Three Honda engines blew during the second half of the race and those still on the track worried they would face the same fate.

This year, some of those same questions could return after Marco Andretti blew an engine just hours before the start of the IndyCar Grand Prix. Still, Andretti has been fast and qualified 12th for the race.

The new aero kits have drivers complaining about handling and passing on Sunday. Practice and qualifying speeds haven't provided many hints about what to expect, either.

The practice session Monday was the first time everybody worked heavily on race setups and attempted to run in traffic.

The result: Chevy and Honda each had five cars among the top 10, in practice led by 23-year-old Sage Karam at 226.461 mph in a Chevy. Ryan Hunter-Reay, the 2012 series champ and 2014 Indy winner with Andretti Autosport, was third-fastest at 224.820 — and No. 1 among the Honda teams.

Chevy, however, posted the top three non-tow speeds with rookie Kyle Kaiser leading the way at 221.107. Marco Andretti wound up fourth at 220.407 and was the top Honda car the list.

Four-time series champion Scott Dixon has learned not to read too much into all these numbers. The Chip Ganassi Racing star qualified ninth and is one of only two Honda drivers starting in the first three rows Sunday.

Last year, Honda took six of the top nine starting spots and had four of the top five cars at the finish line.

"I think there's a lot of good Honda cars. Hopefully this one is one of them," the 2008 Indy 500 winner said. "It showed pretty good, I think, in practice. But again it doesn't guarantee you anything. You've got to give it your best, put in the effort and work hard."

And hope for the best.

"I believe, even last year, even though the Hondas were really strong, we were able to fight in the end," Castroneves said. "It's all about being a good, balanced car."

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