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DPis Slowed in Pre-Sebring BoP Adjustments

Three of four DPis slowed in latest round of Balance of Performance adjustments…

Photo: Rick Dole/IMSA

Cars from three of the four DPi manufacturers have been slowed ahead of next weekend’s Mobil 1 Twelve Hours of Sebring, in IMSA’s latest Balance of Performance adjustments ahead of the second round of the WeatherTech SportsCar Championship season.

Both the Acura ARX-05 and Nissan Onroak DPi face power reductions, while the Rolex 24 at Daytona-winning Cadillac DPi has been given a 10kg weight increase.

The adjustment for the Cadillac DPi brings it up to a minimum weight of 950kg, ten more than any other Prototype class competitor.

The pair of Acura Team Penske entries, meanwhile, face a turbo boost decrease across all power levels as well as a 1-liter fuel capacity reduction, with the Nissan DPi getting power reductions between 6000-7600 rpm.

Mazda’s RT24-P is the only beneficiary from the BoP changes, with the Multimatic-built prototype receiving a 2-liter increase in fuel and aero adjustments to its rear wing.

BMW Given Additional Breaks in GTLM

Following its turbo boost increase post-Daytona, the BMW M8 GTE has been given further concessions for Sebring, with the car getting a 20 kg weight break and additional power boost at the 5000-7500 RPM levels. 

The BMW, along with Porsche’s 911 RSRs, will also have a 2-liter increase in fuel capacity.

GT Daytona sees changes primarily to the Mercedes-AMG GT3 and Lexus RC F GT3, which both gain a 1mm larger air restrictor, but offset by a 20kg weight increase for the Mercedes.

IMSA has also confirmed the minimum full tank refueling times for Prototype (30 seconds), GTLM (34 seconds) and GTD (40 seconds) as previously announced last week.

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. tracer

    March 7, 2018 at 5:04 pm

    Looks like sensible changes all around… will be interesting to see the state of play in GTLM though on a track that isn’t custom built for the Fords.

    • juneracer

      March 8, 2018 at 6:46 am

      the Porsches finished really strong last year when they showed late, but had pit issues or would have won it easily. the Corvettes have a lot more power then last year, they can be out front. the Fords dominated early but struggle late with tires. tires have changed for them. BMWs keep getting power. its all about who wants to show. Ferrari is in a similar condition to last year, still poor straight line performance.

    • Sir Skidsalot

      March 8, 2018 at 9:53 am

      The Ford GT was custom built for Le Mans and Daytona, not the other way around, DUH!

    • Andy Flinn

      March 8, 2018 at 12:25 pm

      Tracer, Sebring appears “custom built” for the Corvettes (competing for their fourth consecutive GTLM win next weekend).

  2. JG

    March 7, 2018 at 6:26 pm

    The Maxda’s AER needs another increase in restrictor size…

    • Haskellb

      March 7, 2018 at 7:57 pm

      No it needs an increase in displacement size. Or better yet a not AER replacement.

    • Slicks in the wet

      March 8, 2018 at 4:44 am

      Bright side….2 more litres of fuel should make for a better outhouse fire on track.

  3. JG

    March 7, 2018 at 6:29 pm

    …actually it just needs the restrictor removed completely. Swap that AER for an unrestricted R13b 4-rotor.

    • Larry

      March 7, 2018 at 7:04 pm

      That would make it a 26B. 🙂

      I would love it.

      Got to see the 767B at Daytona in 1989 and that 4 rotor sounded so sweet on the banking.

      • j_c

        March 7, 2018 at 10:50 pm

        To be pedantic, the 4 rotor in the 767B was called the 13J.
        Doesn’t make sense to me either.
        R26B was used in the 787/787B.

        either would be better than this AER lump.

        • Larry

          March 8, 2018 at 11:05 pm

          Actually, the 13J was in the 757 and early 767s. Later 767s had 26Bs in them as well as the 767B, 787 and 787B.

          It was the 26B that won LeMans.

  4. Bob

    March 7, 2018 at 11:15 pm

    Goddamned BMW and their public whining strategy. We’re already approaching M6-levels of BoP imbalance compared to the rest of the category and it’s only the 2nd race.

    • Chips O'Toole

      March 8, 2018 at 7:47 am

      Yep. They’re claim of a BOP disadvantage is fairly disingenuous since leading up to Daytona they publicly admitted they were approx. 5 months behind on development. Once they showed up at Daytona their BOP spin campaign was in full effect. Almost every interview with a team representative (crew, driver) mentioned a BOP disadvantage.

    • Gene in Florida

      March 8, 2018 at 2:30 pm

      Sooo…. post Daytona BMW gets a BOP break.
      And before the next race is even run, they get a SECOND BOP break?

      This is almost comical. IF they suddenly have significant race pace – every team should fire their engineers and hire media consultants/public speakers since this is apparently how you make the car more competitive.

      • Tim in Virginia

        March 8, 2018 at 6:37 pm

        Yes. It is called gathering data. That is what the official series tests are for. Everyone just needs to quit crying and let IMSA do their job to get all cars in a competitive window. And I wouldn’t consider it a ‘break’ if you see how far off IMSA was at Daytona with the BOP. It is simply a step in the direction of getting everyone where they should be.

    • TF110

      March 8, 2018 at 6:53 pm

      The BMW was kinda screwed over when it was developing the M8 GTE. They had to change something dealing with the roofline being too low for another GTE competitors tastes and had to go back and redo it. That’s why they’re behind on the car. It’s not their fault really that everyone was cool with their concept then changed their minds. So right now the car isn’t what it can be. Maybe in a couple months it will be and the BOP can change to a less favorable one.

  5. Mart

    March 8, 2018 at 5:32 am

    BMW should base their car on the M4 instead of this whale of a car…

    • KW

      March 8, 2018 at 7:48 am

      True. Marketing beats Engineering.
      Funny: BMW has a bottom-up approach fielding a big touring car and complaining about BoP until that elephant gets allowed wings instead of ears. At the opposite end, Ford has a top-down approach filding a downsized LMP1 car. Seems the only “true” GT cars in GTLM are Porsche, Ferrari and Corvette.

      • Tyler Sanders

        March 8, 2018 at 10:15 am

        You know the Ford GT is larger than LMP1 cars but i get you’re point.

      • E Greveb

        March 8, 2018 at 11:44 am

        The M8GTLM is smaller than the M6.

      • Mike

        March 8, 2018 at 4:31 pm

        > Seems the only “true” GT cars in GTLM are Porsche, Ferrari and Corvette.

        Except for the whole reality that the M8 perfectly fits the definition of GT as a luxury, powerful vehicle built for long haul driving and relative comfort. BMWs are probably the truest remaining GTs in the literal sense left, and have been since the Z4.

  6. Kurt

    March 8, 2018 at 2:50 pm

    The Mazda looks to also have a lambda change, I’m guessing the fuel capacity has more to do with that, then stint length. Stint lengths seemed equal at Daytona on average.

  7. Jeff Wagner

    March 9, 2018 at 7:12 pm

    Wouldn’t it have been WAY easier to leave ALL three P2 BOP’s alone not slowing them down, and instead just increasing the Mazda/Joest’s pace with the BOP even more?

  8. GimmeShelter

    March 14, 2018 at 3:54 pm

    Hey, Ford GT fans (all 6 of you)

    get ready for some pain…

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