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IMSA Set to Release DPi Constructors Manual

IMSA releases DPi constructors manual to manufacturers…

Photo: John Dagys

Photo: John Dagys

IMSA is set to take a further step towards the finalization of the DPi regulations with the imminent release of its constructors manual to manufacturers.

Sportscar365 has learned that the manual, which details the engine, bodywork and other associated regulations to transform a base LMP2 car to DPi specification, will be released next week.

“It’s the evolution of the philosophy documents that have been issued since August of last year, to the OEs and the four constructors, once they were chosen,” IMSA’s Director of Racing Platforms Mark Raffauf told Sportscar365.

“On our side, we’re pretty comfortable, both with what the constructors and the OEs need to know to build one of our cars; they know what the process is on how we’ll verify their car; they know the process on how we will balance that to the standard [LMP2] car.

“All of those processes are in place and ready to go.”

Despite previous reports of IMSA potentially moving further away from the FIA and ACO’s global LMP2 platform, Raffauf said there will be no changes to the the ACO-homologated suspension, gearbox, floor, splitter, diffuser, wing, cockpit or shark fin.

“The basic principle is that you take the core of the LMP2 car, you skin it and engine it,” he said. “There are certain deviations in the bodywork that’s allowed.

“There are certain deviations that will be needed to have different engine installations fitted to the same kind of chassis, and they have to be tuned with each OE as we go, because they’re not the same.”

Raffauf said that engine manufacturers must run the same gearbox that will be homologated to each LMP2 chassis, although the gearbox will be the choice of each constructor.

DPi cars, meanwhile, will be permitted to make changes to ancillary components, such as exhaust routing and cooling for turbocharged engines, as well as possible changes in electronics.

However, in order for the cars to be compliant at the 24 Hours of Le Mans, Raffauf said they will need to be operating in the final ACO-homologated configuration electronically, as well as with the standard LMP2 bodywork.

“In principle, that car combination/engine has to run to their rules to Le Mans,” Raffauf said. “We’ll obviously help [assist the ACO] with engine information.”

IMSA has also detailed a schedule for the DPi evaluation and homologation process, which will begin ramping up activity shortly.

Raffauf said the process will begin with virtual model testing, followed by physical, 40 percent scale model wind tunnel tests by mid-May and full-scale testing by late summer.

Three wind tunnel validation tests at Windshear have been scheduled for September, November and December, with IMSA-sanctioned on-track tests at Daytona set for November and December.

All new DPi and LMP2 cars will be exempt from IMSA’s testing restrictions, with Raffauf expecting the first on-track tests to begin in August, prior to the final homologations.

“The object is to get them out there, test them, figure out what you need to work on and not to work on, in that sense,” he said.

“Even if they have a pretty good design in theory in design in the tunnel, with the scale model, and it doesn’t pan out, they aren’t stuck with that. They have five more months to tune that.”

In terms of DPi interest, Raffauf said four manufacturers have been working diligently with them since last fall, with a few others potentially waiting in the wings should their programs get the go-ahead.

“It just seems to be getting better,” he said. “Whether they all hit their marks for Jan. 1 or not, that’s not easy to say.

“Whether they all get their final approvals is not easy to say. I can say we’ve had pretty steady dialogue with a solid four [manufacturers].”

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. vanillachinchilla

    March 18, 2016 at 9:30 am

    can we stop kidding ourselves with the le mans thing? we barely ever saw a P2 team do le mans, and when they do its usually with an entirely different chassis. It doesn’t make much sense to keep the car close to aco spec just for that. this is like a prototype indycar

    • Joe

      March 18, 2016 at 10:02 am

      I don’t think the chassis comment is really relevant. Some LMP2 teams would lease another car for Le Mans back in the ALMS days, but the fact that they ran the same car during the ALMS season is what made it reasonable (the closer the machinery the better in terms of data transfer).

      Also, I find your comment particularly odd since a number of teams have come out (some here on Sportscar365) indicating their interest in Le Mans (Shank who is going this year and Racing recently announcing interest). Finally, here are a list of teams from ALMS days in LMP2 that went to Le Mans since you think we barely saw them. Note that in most of those years, ALMS had all of 3 LMP2 competitors, so to have a presence at Le Mans at all speaks to interest:

      2013 – Level 5 Motorsports
      2012 – Level 5 Motorsports, Starworks*
      2011 – Level 5 Motorsports
      2010 – Highcroft Racing

      *Starworks of course was not an ALMS team, but they ran a P2 that whole year in WEC, and obviously, they are relevant to this conversation here, so that’s why I list them.

    • Bakkster

      March 18, 2016 at 12:45 pm

      It was definitely rare, but there’s still value in keeping the bulk of the equipment identical to reduce costs. But that’s also why it seems they’ll allow custom electronics here, for the OEMs who need it to compete here and have no interest in Le Mans. A very reasonable solution.

  2. Nate

    March 18, 2016 at 9:49 am

    So if an engine supplier wants to work with one of the approved chassis manufacturers and has to produce bodywork that represents one of their production cars they have to have a scale model ready by May designed to specs they still haven’t seen? Full scale by late summer? Hah!

    Way to go IMSA, you really know how to win the hearts and minds of the people who prop this series up.

    • Christian

      March 18, 2016 at 10:21 am

      You do know those engines mentioned are all FIA GT3 engines in which all have been tried and trusted, yeah?

      • ShiftingLanes

        March 18, 2016 at 11:39 am

        And most of the interested manufacturers have already started feesability studies. So the time needed to make a modded body is greatly reduced.

      • Nate

        March 18, 2016 at 6:52 pm

        You realize I am talking about bodywork not engines, yeah?

    • Bakkster

      March 18, 2016 at 12:47 pm

      They’ve all seen the draft specifications. Just because they aren’t finalized doesn’t mean they haven’t been communicated to teams.

  3. CD

    March 18, 2016 at 11:01 am

    Regardless what NASCAR says, the DPi cars will always be the priority car. P2 cars will never have a chance at having a winning season. The moment they are .2 seconds a lap quicker than the “Corvette” looking DPi at any circuit, they will be slowed to 1-2 seconds a lap slower than the DPi. It will happen.

    At some point they will start to attack GTLM. Why have GTLM when you have Daytona prototypes that look like your street car. When you also have GT Daytona. It will happen.

    Prototypes should not look like street cars!!!!

    • ShiftingLanes

      March 18, 2016 at 11:44 am

      Branded bodywork doesn’t necessarily mean it has to look like the road car. And I sincerely doubt the bodywork is going to be significantly different than the original chassis suppliers. Think headlights and some modded air intakes. More ford dp than Corvette dp.

    • Camyron

      March 18, 2016 at 2:30 pm

      “Prototypes should not look like street cars!!!!”

      So where were you when The Porsche 911 GT1, Mercedes CLK GTR and Lotus Elise GT1 were masquerading as race versions of the road cars?

      • Bakkster

        March 18, 2016 at 4:32 pm

        Or when LMP1 nearly merged with GT1. The Corvette DP is based on a design for the LMP-Evo rules proposed by the ACO (but shot down by Audi).

    • Larry

      March 18, 2016 at 9:07 pm

      DPi is not the same as DP.

      Read the article again.

      I have been skeptical, but this sounds encouraging.

  4. Mark - Toronto

    March 18, 2016 at 11:28 am

    I’m still somewhat mystified at how a Dpi car can be run successfully at Le Mans. Ok, so you run it with your OEM engine from the US, but must run the generic bodywork for the ACO P2 variant. Are the ancillary changes you were permitted in IMSA for exhaust and cooling also allowed to be run at Le Mans? If so, how does the generic body kit affect that? And now in addition to a tire manufacturer change, you may have to change electronics to conform to the ACO spec as well (depending on what IMSA ultimately allows). Am I missing something….or is running an IMSA OEM engine car at Le Mans going to be incredibly challenging?

    • kv

      March 18, 2016 at 2:21 pm

      LOW drag has a lot to do with high terminal speed down the MULSANNE and bodywork that is low on aero drag can put you in the hunt !

    • Helmut

      March 21, 2016 at 11:39 am

      I think the IMSA had hoped that entering DPi at Le Mans/FIA WEC would require no changes at all. The ACO doesn’t want so for obvious reasons = loss of control. I mean, they could still add an extra class DPi for Le Mans for those few cars that might show interest (I doubt there are that many), but they don’t want to because DPi is not their concept.

      Thus it’s just meant as a theoretical option, as it reads better than “DPi are not allowed at all”. Maybe it will be used if US team 1 sells their car to a European team 2 for the next season. But we won’t see any DPi back-converted to LM regs.

      • Helmut

        March 21, 2016 at 11:40 am

        … back-converted to LM regs within a season / just for Le Mans.

  5. Mark - Toronto

    March 18, 2016 at 11:40 am

    Also…maybe John can answer this one. The current P2 cars are ‘grandfathered’ in IMSA for 2017. What are the engine choices? If an OEM wanted to run a new GT3 based engine, but didn’t want to commit to their own unique Dpi bodykit….is running the new engine for a year in the back of a current grandfathered P2 an option?

    • Pat

      March 18, 2016 at 11:45 am

      The currently homologated P2 cars and engines are eligible next year. Chevy couldn’t put a developmental motor into a 2015 Ligier and run it next year.

      • Mark - Toronto

        March 18, 2016 at 1:13 pm

        Ah…ok, thanks. I couldn’t remember hearing if the current chassis was homologated for use ‘only’ with the current engine or not.

  6. JeffB

    March 19, 2016 at 1:42 am

    “DPi is not the same as DP.”

    That’s the problem. “Daytona Prototype” is a name with a ginormous amount of baggage in the racing community. It evokes images of low-tech, unattractive and slow race cars with many of the old ALMS fans, no matter what they have evolved into currently.

    Many of us were looking forward to the day of their demise as the P2 cars became the new top class of car, and what does IMSA go and do? They name their new top class “Daytona Prototype International”.

    Seriously? What the hell.

    The time was right, and never more so, to revive the Grand Touring Prototype name from one of the golden eras of sportscar racing, the mighty Camel GT. How they managed to NOT call them GTP cars will forever baffle me to no end.

    IMSA, did you run this by any focus groups? Ask for any kind of feedback first? Where was the survey I missed when I was at your events last year?

    To finally emerge from the darkness of the Prototurtles and then saddle your new top class with your choice of crap name? You got this one wrong and I’m not pleased. Not one bit.

    • Troll Me

      March 20, 2016 at 1:27 pm

      They did that to piss you off.

      Go fuck yourself elitist.

    • Helmut

      March 21, 2016 at 11:45 am

      It doesn’t really matter how the classes are called, does it. Leaving this aside, Daytona 24 is the most prestigious race of the series, so it’s not that surprising if you call your top class accordingly. After all, the LMP are called Le Mans prototypes as well.

      Leaving the terming issue aside, the idea behind DPi is way better than that behind the future LMP2. I guess in the nearer future there’s going to be a complete split anyway.

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