IMSA Really Messed Up Their Balance Of Performance At Sebring This Weekend

I really hate discussing Balance of Performance in motorsport, but it’s a fact of life these days, and it’s an integral part of the endurance racing subject. BOP is effectively the means by which the series officials try to level the field on lap time; adding ballast, adjusting pit stop refueling times, and fitting various diameter engine air restrictors. In a pro racing, as IMSA’s top flight Prototype class, the point of BOP is to make the race about things like strategy, driver capability, and luck instead of team budgets. 

Back at the 24 Hours of Daytona, I filed a complaint that IMSA had completely hashed their BOP in the GTLM class, but had done alright in Prototype and GTD. A little over a month on, and another endurance race done and over with, it seems that they’ve figured things out pretty well in the GTLM class, and GTD is still alright, but they’ve completely screwed over some teams in the Prototype category with horrible BoP. Speaking to, United Autosport driver Paul di Resta called it an “embarrassing waste of time.

Image: IMSA

As early as Friday’s qualifying session, it was pretty clear that something wasn’t quite right. The Prototype class is made up of manufacturer supported Daytona Prototype International entrants from Cadillac, Nissan, Acura, and Mazda, as well as FIA WEC specification LMP2s with a shared spec Gibson-built V8 engine. You can see immediately that the top 10 qualifiers are DPi entries, while the international LMP2s make up the bottom six of the grid.

Paul di Resta, quoted above, drives for the United Autosports team, which qualified last in the Prototype class, more than two seconds slower than the pole winning time. By IMSA’s own admission, their BOP efforts are aimed at creating parity between the LMP2 and DPi entrants, so why should this huge qualifying delta exist?

Image: IMSA

Speaking frankly, di Resta went on to describe racing against DPi cars “totally impossible.” United Autosport team owner Zak Brown echoed his concerns, saying his LMP2 team is “racing with the hope the DPi cars are unreliable,” expounding by saying they “cannot currently compete,” and that the DPi contingent “are in another category.” It’s not as though he’s wrong, either, as during the race, the DPi cars put in fastest lap times that were a second per lap faster than the best of the LMP2 teams. di Resta and United Autosport finished fifth overall, and still on the lead lap of the race, but were never properly in contention for the overall victory.

To Brown’s point, both Penske-entered Acura DPi machines fell out of the race with engine issues, one of the fastest Cadillacs crashed hard just after nightfall, one Mazda had a lengthy pit stop for braking issues that dropped them out of contention, and the other Mazda was fighting for the victory until clutch issues dropped them to sixth. All of those cars with failures were faster and higher up in the rankings than the United Autosports Ligier-Gibson LMP2.


BOP is intended to be a seamless and largely invisible process. By giving the DPis such an advantage on that baseline, IMSA have effectively thrown the race in favor of the factory-supported teams, or at the very least given them a huge advantage which they had the strategy, driver capability, and luck to take full advantage of.

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Bradley Brownell

Jalopnik contributor with a love for everything sketchy and eclectic.