Maxton Design Diffuser: Kpeng Improved

[Perscitus]

Nope no cutting at all, that is the winglet you see there that comes as part of the diffuser and it does not protrude out or cover the painted bumper skin... it instead perfectly traces the OE splash shield plastic on the outside of the OE fins. If you look down and see what the OE setup is like right behind your rear wheels, you will see what I mean. Tha grey plastic that you will find gets covered, nothing less, nothing more.
Push clips added for good measure. The screw further back is stock.

Maxton has an addon winglet that hugs the diffuser and protrudes. Its a separate part number and we all hate it lol

 

[Skione65]

Nope no cutting at all, that is the winglet. Maxton has an addon winglet that protrudes that is a separate part number and order and we all hate it.

Copy that! You just answered my question in the other thread. Didn’t realize that winglet was an “add on”! So no trimming. Awesome. I can see what you’re referring to now in that dark area now that I increased the brightness.

Ski

 

[tlr1000]

Thanks Perscitus! Really appreciate the detailed photos and write-up. Looking at the part by itself in the website pictures I could not tell if that little winglet part stuck out and that was the main reason I was ready to cut it. Since it doesn't stick out, I'm no longer going to do any surgery. Better cancel my VHB order and glad I have loads of pushpins on hand.

By the way, it's a bit hard to tell but did you also put a pushpin on the winglet part?

btw, PMSS FTW!

 

[tlr1000]

Copy that! You just answered my question in the other thread. Didn’t realize that winglet was an “add on”! So no trimming. Awesome. I can see what you’re referring to now in that dark area now that I increased the brightness.

Ski

time to order up

 

[Perscitus]

Yes, a pushpin on either side of the furthest out fin (to secure the winglet).

The diffuser isnt going anywhere with all these pushpins, makes no funny wind or other noises after extensive closed course professional driver testing (do not attempt) today. Triple *caugh* digits and all.

 

[tlr1000]

Yes, a pushpin on either side of the furthest out fin (to secure the winglet).

The diffuser isnt going anywhere with all these pushpins, makes no funny wind or other noises after extensive closed course professional driver testing (do not attempt) today. Triple *caugh* digits and all.

Excellent. Thanks!

btw, did you where a helmet in the closed course testing?

 

[Perscitus]

Why certainly. Plus a facemask, gloves and more traditional 'protection'.

Some moarh photos, this time from the camera (credit for pics goes to my brother)

 

[euG3fo]

Looks like it would cause drag and ruin aero.

 

[tlr1000]

Looks like it would cause drag and ruin aero.

You could be right and pretty much guaranteed these were not developed in a windtunnel. But essentially rear diffusers work if there are 3 elements present being vertical fins, smooth underbody, and expansion chamber. Definitely the fins are vertical, the Tesla Model 3 has a flatter, smoother bottom than most cars, and the upward slope of this diffuser gives the expansion chamber effect. Check, check, and check. Not saying it has an overall beneficial effect but it is possible and if it's an overall negative effect it would likely be immaterial. This, or any other, diffuser is not for everyone but some (myself included) at least like the aesthetics of it.

 

[euG3fo]

You could be right and pretty much guaranteed these were not developed in a windtunnel. But essentially rear diffusers work if there are 3 elements present being vertical fins, smooth underbody, and expansion chamber. Definitely the fins are vertical, the Tesla Model 3 has a flatter, smoother bottom than most cars, and the upward slope of this diffuser gives the expansion chamber effect. Check, check, and check. Not saying it has an overall beneficial effect but it is possible and if it's an overall negative effect it would likely be immaterial. This, or any other, diffuser is not for everyone but some (myself included) at least like the aesthetics of it.

I would love a functional rear diffuser that could replace the stock panel.

 

[Perscitus]

No need for a functiinal one on a production car. This isnt ALMS or DTM.

200 miles later, no change in Wh/mile.

Ask @kpeng how his efficiency is doing since he's had his diffuser on for far longer than me.

Expect a justified reply along the lines of:

Q: But buuut omg efficency hit!
A: No

Q: Can you elaborate, provide testing evidence, a whitepaper and a journal published article that outlines all minute details of before/after results?
A: No

 

[tlr1000]

Here's a theory: we have all probably seen that on many cars the back bumper gets dirty faster than the rest of the car. I'm guessing this is caused by the turbulent vacuum area behind the car pushing the dirt into the back. In theory, if this turbulent vacuum area was made smaller and less turbulent, maybe the back bumper wouldn't get dirty as fast as it does? So the question is whether this diffuser has made any effect on reducing this turbulent vacuum area.

@kpeng and @Perscitus, have either of you noticed any difference in the rate of how quickly your back bumper accumulates dirt after installing the diffuser? My guess is probably no difference and slight possibility it's a tiny bit better but guess it's not worse.

But regardless of all that, it looks good!

 

[Perscitus]

I will keep an eye out, no rain here in weeks. Similarly to kpeng's, my Model 3 is ppf'ed and ceramic coated, but even with both and periodic maintenance of the coating... the rear bumper and trunk hatch have been dust and dirt magnets, even when the rest of the car stayed clean.

 

[tlr1000]

Thanks!

 

[i2fat2kidnap]

Just curious on the texture. Is it smooth to the touch? I plan on wrapping the front splitter and wanted to know if I should have them paint it just so that its easier to wrap.

 

[tlr1000]

Just curious on the texture. Is it smooth to the touch? I plan on wrapping the front splitter and wanted to know if I should have them paint it just so that its easier to wrap.

The gloss black or fake CF are probably more suited to wrapping as both of those should be smooth.

 

[Perscitus]

Wrapping to highlight the fins or the entire piece that is essentially hidden fron view and exposed to undercarriage elements?

If you going to do either, consider liquid wrapping or hydroprint transfer instead of classic wrapping.

The matt textured black is flat enough, but has a grain or maybe more of a scale-like texture to it. Its smooth but definetly not as smooth as gloss black would be since its painted and uv clearcoat protected.

 

[i2fat2kidnap]

Wrapping to highlight the fins or the entire piece that is essentially hidden fron view and exposed to undercarriage elements?

If you going to do either, consider liquid wrapping or hydroprint transfer instead of classic wrapping.

The matt textured black is flat enough, but has a grain or maybe more of a scale-like texture to it. Its smooth but definetly not as smooth as gloss black would be since its painted and uv clearcoat protected.

Sorry, I am not wrapping the diffuser, but likely the front splitter. I'm assuming the texture will be the same, so thought I'd ask here. Thanks for the clarification!

 

[Perscitus]

Ah that makes sense, although note you can order the front splitter/lip with a white or red stripe also.... not just flat, gloss black or fake cf texture.

 

[Perscitus]

@Perscitus, have either of you noticed any difference in the rate of how quickly your back bumper accumulates dirt after installing the diffuser? My guess is probably no difference and slight possibility it's a tiny bit better but guess it's not worse.

Two updates. 1. The diffuser does nothing to keep the back bumper skin and trunk hatch from getting fouled in bad weather, driving on dirt roads, salt flats etc.

2. Efficiency and aero appear unaffected OR actually improved a marginal (almost immaterial, within error) bit. Drove the car as I usually on a 1.5K mile road trip. Mostly highway, some rural roads, lots of mountains (including scaling Mt Washington as the first car of the day) and seeing the same per trip and avg Wh/mile and 100% SoC guesstimated range as before.

Fun fact - Driving up Mt Washington, used up approx 10% SoC on a cool July morning at 8AM. The car was completely unphased by the grade and climb.

Coming back down, with regen on high, gained back 9% SoC and never had to touch the brakes... in fact a few times I had to use the accelerator to keep the car from stopping (lol).