How close is NASCAR EFI to “Real” EFI?

As we turn on the (new) engines to start the season, the twitterverse is getting even more full of people debating the NASCAR EFI system.  Is it like the EFI in production cars?  Is it throttle body?  Is it multiport?  Here are the answers:

And yes, I think NASCAR did a pretty good job implementing this rather major change in a very short time.  As I note in the video, going to an actual production-car-like EFI system would likely have required a wholesale engine design.  NASCAR engine heads and blocks have special pathways running through them for cooling purposes – so it’s not as simple as just putting in eight more holes.


  1. This is a pretty good video, but you should have said that the more recently designed engines are using direct injection into the combustion chambers (kind of like a diesel) and that multi-port fuel injection into the manifold is gradually becoming obsolete (like what happened to throttle body injection).

    • I was going to add that in because you’re exactly right. Direct injection is the way to go – like TDI. But I have been trying to keep these short and this one was already in danger of hitting the four minute mark. The hardest thing about doing short videos and having to leave stuff like that out! Thanks!

  2. This system is so obsolete its no longer used on any publically available vehicles, car or truck.

    Nascar, went this route because it is the only system that lets them “adjust” things to suit their agenda.

    To try and frame it otherwise is just more of regurgitating the “company line”.

    • Anyone who’s watched this blog knows that I’ve gotten quite a bit of hassle for my refusal to parrot the script. When I think they’re wrong, I say so.

      The reality is that some manufacturers would not have been able to adapt their current engine heads and blocks to a configuration similar to a production car. Putting some manufacturers at a disadvantage relative to others is the last thing NASCAR can do because that would show up on track really quickly – and that would hack off the fans big time. You’re right – you couldn’t buy a new or even a late-model car with that type of EFI configuration. I suspect NASCAR will mandate that the next generation of engines must to accommodate a more realistic fuel injector setup.

      Let’s give NASCAR some credit for moving in the right direction, even if it isn’t moving as far as we’d like to see them move. Thanks for the comment!

  3. Interesting piece on NASCAR EFI. But how will NASCAR “police” EFI usage? After all “cubic money” can drive success. And with the increasing number of true racing engineers filling the garages, there is the possibility that these engineers can draw on past experiences in other racing formats to gain an advantage on a predominantly “turn left” series.

    • I’ve got a piece going up next week about engine maps. NASCAR has blindfolded and handcuffed the ECU. They’ve limited what data the ECU is allowed to have, and that limits how much the race engineers can do. The engine guys are really frustrated because they know if they just had a few more sensors, they could make a bigger difference. NASCAR is going to have access to a huge amount of information from the EFI systems – some of which the teams aren’t going to be able to see. I guarantee that the teams that are doing well right out of the block are going to get a lot more scrutiny! I hope to have some more info as the season goes on about how the policing is going. Thanks for writing!

    • Hey Bob! I’m learning new skills and video production turns out to be a lot of fun. I hope it will take less time as I get better at it! I’m going to need to get you as one of my resources. I’ve found a couple folks running Super Late Models up in PA near us and I’m thinking about doing some blogs about those – much for me to learn!!

  4. Dr D, I learn so much from you, thanks. And, you keep telling it like it is, no matter what nascar says. We fans know what’s going on even though they don’t want us to.

  5. Hi Diandra. I’m glad allows articles written with differing opinions to be posted. Most of the articles posted on are written by NASCAR’s mainstream media. NASCAR keeps those writers on a short leash. The threat of pulling media credentials is NASCAR’s leverage. The mainstream media is lazy. The same old stories, are written by the same old writers, from the same old outlets.
    What a shame.

    I’ve been electronically tuning my own engine for 5 years. My handheld programmer is a great tool and it doesn’t take a rocket scientist to custom tune a motor. The more sophisticated method (like NASCAR’s) is done with a laptop and whatever software program they’ve installed. With this technology, why is a restrictor plate necessary in the first place? Why not program the ECU with a specific max speed parameter and forget it?

    It’s not surprising that NASCAR would withhold vital ECU data from the race teams.

    We can’t refer to NASCAR’s invisible rulebook for clarification. I can download the NFL rulebook directly from their site.

    I imagine NASCAR will severely punish the #48 team after the Daytona 500. I’d love to know what the allowable tolerances are for the sheet metal covering the C-posts. If the pieces fit within the template, NASCAR should readjust the template. Once again, NASCAR’s rules seem to be more subjective than objective. Who knows? We can’t argue a point if we don’t know what the point is.

    I have visions of someone at HMS using an old English wheel to bend,shape and pound those pieces of sheet metal into aerodynamic perfection.

    NASCAR doesn’t like science. Science debunks most of NASCAR’s false claims. Common sense takes care of the rest.

    Sorry for getting off topic a bit. I look forward to your next article.

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