PZtuning and William Au-Yeung’s Record-Crushing RSX
rear diffuser mounted under rear bumper
PZtuning has additionally created a rear diffuser to help guide airflow under the vehicle, which also improves overall grip, downforce, and stability.

This “basic” (their words) diffuser has been around on the car since 2013, but I am told that the much more elaborate Civic’s rear diffuser will influence a future unit on the RSX.


rear-vented front fender and side skirt
The front fenders on the RSX come from Anointed Aero, and they are tied into the custom side skirts.


close up of fender and side skirt corner showing honeycomb
Another view of the fender and side skirt shows the prefab carbon honeycomb sheets that are used.

All the carbon work is done in-house by William and the gang. They do all the rest of the fabrication, too.


bumper sitting on ground without splitter
The RSX’s front bumper has been mostly closed to help direct airflow either around the vehicle, to be used for downforce, or to ensure it goes through the opening for cooling the intake charge and engine (coolant).


crew working under and on top of front of car changing transmission
Prior planning prevents poor performance, but even PZtuning is not immune to gremlins.

In this case, the gremlin was a popped second gear on the first day of competition. But, William and crew were prepared, and they were able to swap to a back-up transmission that they had for just such a circumstance.


    1. Lol, that’s where those spacers are … now I remember, needed them for the ZE40’s (they’re actually 24 offset, and minus 3mm for the spacers, so 21 offset). We usually run 57FXX’s that are 22 offset (and no spacer)

  1. You guys did an excellent video + article on fixing the EP3’s steering issues. Did they do any similar work on this car? I imagine they had to.

    1. All we have in our steering rack is a custom rack slider (which we had made), otherwise its all oem steering gear in it.
      That being said I’m sure there’s room for improvement there in this car – we actually retired the RSX in 2014 and have been slowly bringing it back up to competitive form, so we’ll keep developing it as we can!

  2. Well, you’ve got a lot of development to do. Here’s some freebees.

    Honestly, I don’t know why I bother, but whatever…when I get back on track, it will make the competition interesting.

    First of all..

    Why do you have the stock radiator mounting core? this is a freebee. but if you have hood locks, you don’t need all that shit, cut it out…save some weight, i did it on my car.

    bumper support? worthless…drop 20 lbs, right there. another freebee.

    Not the greatest cage…but, maybe your spring rates are not high enough?

    Factory crash bars? worthless 10 lbs.

    You got your spring rates all wrong, on on FWD, you run soft fronts, and stiff rears. Don’t need sway bars, for the rear, either. Run some neg camber, and some positive caster, and you’re golden on a Mac-Strut. Saves weight, too.

    If you had a ‘proper’ splitter you would be able to use those soft front spring rates to your advantage, because under brake dive you would get more grip. But, you need to have a front diffuser/splitter to do that. Which, obviously, you do not have, otherwise you would not have such a huge front splitter because you don’t need it because a front diffuser makes much more downforce, and far more efficiently. Look it up, on LMP1 cars.

    Wank, rear wing should be mounted to the rear frame rails. Period.

    Rear diffuser is beyond basic. For one, double decker. Secondly, lateral diffuser. Third, blown diffuser. If you know racing, you shouldn’t even have to look those terms up.

    Wank, lame side skirts. How about sliding skirts, FTW…maybe you can catch up to 1980’s F1 technology. Or are you that slow?

    Horrible front bumper design, you should have radiused inlets, obviously.

    1. You don’t need a double deck diffuser if you have enough room to make a large one. Also the golden rule of all things aero: you design to the rule set. Just because something is “the best” in one series of racing does not necessarily make it correct for another series.

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