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DPis Slowed for Fourth Consecutive Race

DPis slowed for fourth consecutive IMSA WeatherTech SportsCar Championship race…

Photo: Rick Dole/IMSA

DPis have been slowed for the fourth consecutive race, as IMSA works to achieve parity with LMP2 machinery in the WeatherTech SportsCar Championship.

The sanctioning body released Thursday an updated Balance of Performance table for the Prototype class ahead of next weekend’s Acura Sports Car Challenge at Mid-Ohio, which sees all four DPis hit with power reductions.

The turbocharged powerplants inside the Acura ARX-05, Mazda RT24-P and Nissan Onroak DPis will all have slightly less top-end boost, with the Cadillac DPi-V.R getting a 0.6 mm smaller air restrictor. 

Associated two-liter fuel capacity reductions have been made to each of the DPis as well.

The 30.4 mm (x2) restrictor on the Cadillac DPi is 1.8 mm smaller than than the configuration it ran in January’s Roar Before the Rolex 24, and has seen seen reductions made in each race, outside of the Mobil 1 Twelve Hours of Sebring.

Sportscar365 believes it equates to roughly a 40-50 horsepower difference since the start of the season.

The changes come in the wake of a dominant start to the season for DPi machinery, which have swept the opening three races.

Only a single LMP2 car, the No. 54 CORE autosport Oreca 07 Gibson, has managed to get on the podium so far, in the Rolex 24 at Daytona. 

Per its agreement with the ACO, LMP2 cars are not subject to BoP adjustments in the WeatherTech Championship, meaning IMSA has had to continuously work to reduce the performance of its flagship platform. 

John Dagys is the founder and Editor-in-Chief of Sportscar365 as well as the recently launched e-racing365 Web site for electric racing. Dagys spent eight years as a motorsports correspondent for Channel, and contributes to other publications worldwide. Contact John



  1. George 917-30

    April 27, 2018 at 8:21 am

    This is not going to look good for the series if they’re slower at Watkins Glen (my home race) than they were last year. There is no lmp2 team currently in IMSA that compares to the factory teams. There has to be a better solution than this constant dumbing-down.

    • Tom Sawyer

      April 27, 2018 at 8:33 am

      I think they’re running on a new tire this year also, so I don’t think they’ll be slower. But only time will tell I guess.

    • Alexx

      April 27, 2018 at 9:11 am

      That’s exactly right. The current LMP2 teams are nothing more than PC teams trying to compete against pro teams. IMSA should just make the DPi a separate class and stop all this nonsense. The LMP2 cars have the fastest straightline speed now as it is, so if these current teams can’t compete even though they already have the best top speed, why dumb down everyone else who has proper teams and drivers?

      • Pete

        April 27, 2018 at 9:42 am

        Man, it’s almost like top speed doesn’t determine who’s the fastest in road racing…

      • daedalus

        April 27, 2018 at 10:12 am

        If the pace defect was purely down to drivers then when the pro drivers in LMP2 get in they should be at the pace of DPI but that is NOT the case.

        Gustavo Yacamán,James French and Sebastián Saavedra are all capable pro drivers and they were all off the pace compared to the DPIs at all the races so far. Even the F1 champion alonso and DTM champion Paul di Resta could not match them at daytona or sebring.

        The fact of the matter is that the DPI teams use their large resources to constantly improve their pace but the LMP2 teams can not because of Homologation which means they can’t change or improve any parts at all, its all set in stone. As a result IMSA needs to keep pegging DPI back to offset their improvements. The problem is that IMSA are always one step behind so the DPI always end up having a pace advantage.

        • Jack

          April 27, 2018 at 10:17 am

          James French is not pro pace. He was on average 1 second off of pato on the average laps for Daytona and Sebring.

        • Frank

          April 27, 2018 at 9:12 pm

          James French is a silver. Alonso wasn’t even as quick as Lando Norris in the same United Autosports car at Daytona.

        • Mike S.

          April 28, 2018 at 12:16 am

          You are correct to race in the entire world homologation of P2 it’s basically spec. I think Dagys is right let the DPi’s go into their own class and develop with their own class BoP and lep the P2s have their class. It will be same as in ALMS. DPi’s will blow out expenses leaving a few teams and cars left after exploding budgets and repeat.

        • John

          April 28, 2018 at 11:53 pm

          That’s basically what Cheng of JCDC said after Sebring.

          It’s more than just the engine and aero; the works DPi teams are free to and have the money to develop the whole car, including parts like the dampers, while spec P2s are limited by their homologation. He lamented how much better Penske’s Oreca took the bumps vs. their Oreca. The P2s needed to be closer to the limit to achieve comparable lap times, and that’s where the driver factor is amplified.

          The current situation probably doesn’t make anybody happy, and that’s something IMSA needs to reconcile.

    • kv

      April 27, 2018 at 1:58 pm

      BoP will not hurt manufacturers .until reliability is compromised ,then manufacturers will withdraw support !

    • kv

      May 4, 2018 at 10:22 am

      BoP is working on all DPi,so the hi reving Gibson is at a disadvantage to boosted or torqy engines !P2 CARS NEED A 50 LB REDUCTION IN WEIGHT,TO have a chance to be competitive !

  2. Andrew

    April 27, 2018 at 9:01 am

    how much of this has to do with the relatively bush league driver lineups the LMP2 teams are fielding? Core manages the results they do because Colin Braun is one of the few drivers on an LMP2 squad that is in the same league as the DPI drivers. BOP really needs to be set with the same human being behind the wheel. (I know that will never happen)

  3. Marc

    April 27, 2018 at 9:21 am

    Let’s not forget the last half of last season when LMP2 cars were able to compete made the last several races quite exciting (especially Watkins Glen, CTMP, Laguna Seca & Road Atlanta). Even though we hate seeing these continuous BOP adjustments, its for the good of the series and the on-track product. This is a BOP class after-all.

    Looking at fastest lap times at the 3.7 miles Sebring circuit, LMP2s were off 1 second. At the 1.9 Long Beach circuit, LMP2s were about 0.5 seconds off. It looks like IMSA is going in the right direction. Hopefully, this change will be the sweet spot.

    • Max

      April 27, 2018 at 9:50 am

      Indeed. From my peanut gallery/armchair quarterback level POV, I think JDC-Miller’s move to a two car team may have disrupted their momentum and their results aren’t what they could have been.

  4. Matt

    April 27, 2018 at 12:00 pm

    A real shame that P2 teams race with this POS Gibson engine with no torque. It would be great if they could get a better engine.
    I’d also love to see IMSA tell the ACO to **** off with the new P1 regs and make DPi a seperate class where manufacturers can run with legitemently powerful engines. 600hp is not that much in today’s world where road cars easily have that much.

    • Sergio Serrano

      April 27, 2018 at 1:03 pm

      You’re comparing apples to oranges. 600HP in a prototype is more like 1000HP when you take into account power to weight ratios.

    • Lesspowers

      April 28, 2018 at 10:53 am

      DPi is now around 520hp with these reductions. They started at 580 per…. IMSA

  5. Chips O'Toole

    April 27, 2018 at 2:13 pm

    Lol. A P2 with a better engine is a DPi.

    • kv

      May 4, 2018 at 10:32 am

      The ACO/FIA KNOWS DPi is the answer but manufacturers do not want to see multi million dollar investment in HYBRID, GO DOWN THE TUBES !

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