Functional Aero...who's done it? - I now have!

[AndyW]

UPDATE: Got the S2000 diffuser and fitted it to a 135i. See post below.

OK, so the Berk 135 got me thinking of starting down the aero path and I am now considering adding some sort of front aftermarket dam to the front bumper (think slek, but that thing is wayyy too pricey for something that will scrape on the ground from time to time) and a diffuser(but no one seems to make a truly functional one for the 1er from what I have found).
At the same time, I don't want to stray too far from a factory look as this is dual use car.

Ultimately I will probably add an APR splitter also, at some point, but from talking to the APR folks I need to "even up" the front with a dam first to mount their splitter for it to be fully effective. There are a number of fairly inexpensive ones on ebay (as well as expensive CF ones). I am leaning toward the copies of the BMW Perf kit piece like this:



I'd also love to know what Berk used for their diffuser on their 135. Article indicates it's an APR, but I can't find one for the 135 at the APR website. Looks like a modified S2000 or Mustang one, but I am not willing to risk $450 to test my theory...



Anyway, if you use aero on your track 135i, what are you using and what do you recommend? TIA!

[bbnks2]

Most of the functional aero pieces are all designed for the 1M bumper. You don't have many options for the 135i. You showed a picture of one of the few decent air dams, but that piece is not nearly as aggressive as the 1M stuff.

[AndyW]

Originally Posted by bbnks2

Most of the functional aero pieces are all designed for the 1M bumper. You don't have many options for the 135i. You showed a picture of one of the few decent air dams, but that piece is not nearly as aggressive as the 1M stuff.

Yeah. I have noticed that. I actually prefer the look of the 135 M sport over the 1M front bumper...

[Ginger_Extract]

Berk used a modified S2000 diffuser. I actually bought their splitter when they stopped campaigning the car. Currently sitting in my garage, as I still have a few no-aero lap time goals.

[AndyW]

Originally Posted by Ginger_Extract

Berk used a modified S2000 diffuser. I actually bought their splitter when they stopped campaigning the car. Currently sitting in my garage, as I still have a few no-aero lap time goals.

Jealous...you may be about to be my new best internet forum friend...

Thx for confirming the diffuser (can't believe I called it...I am normally not very good at where's waldo...). Do you know how much they had to do to it to get it to fit? Or their opinions on effectiveness? If they had any data on how they mounted it I would love to know. No reason to reinvent the wheel! TBH, another reason I liked it was because it is also visually stealthy and understated to me.

I just looked at the pics from their "last 135 event"...man that car turned out pretty in it's final form. What ended up happening to it?

[lowside67]

I am not sure that the type of aero you are looking at will actually have a measurable impact on lap times. The factory bodywork is reasonably good with a decent flat underbody so you will need to go up in size a fair bit to improve this.

An "air dam" (of which the pictured is really not, it's just a small stick on lip) is not going to do much, you are going to need a real splitter that is low and long, it won't be pretty and it won't be street friendly. Ditto the rear diffuser - the underbody is not set up to feed it efficiently, so you are really just sticking on cosmetic parts.

For clarity, functional aero is of a significant benefit, I just don't think any thing you have pictured is actually functional. I would spend my money on better dampers and tires if it was me and I think you might actually see more lap time improvement there.

-Mark

[AndyW]

Originally Posted by lowside67

...good stuff...
-Mark

Thx, Mark. I am actually not looking to improve lap times with areo...yet. just add stability margin on the high speed straights. Plus it helps me learn about this stuff in the process, for later.

Agree on the lip alone...it is just the base for adding the splitter later. I am basically looking to mimic what Berk did with their time attack 135. This will be a process...

[AndyW]

Check out this aluminum underbody for an S2000... probably wouldn't be hard to modify to fit 135.

[AndyW]

So I went for it and purchased the Alloy craft S2000 diffuser discussed here:

https://www.s2ki.com/forums/sponsor-...ffuser-903746/

I modified the diffuser shape a little ( 3 small sections need to be cutout to fit under a 135 to clear the exhaust pipe and lower control arms) and made my own adapters to bolt it up. Pics below. Was actually easier than I thought and the parts probably only cost me $40 or so. I also used or re-purposed as many of the parts, bolts, and holes that came with the original parts in the kit. The biggest challenge was offsetting the rear part down and inch or so to clear the factory muffler. With a Berk or something similar, I could have omitted that step and it would be flush. I also used the two screw hole locations on the factory lower bumper insert, so only had to create one extra on the left.

If you have any questions on this, let me know. I just did my first track day with this installed and it is sturdy and stable at over 120MPH. Not sure just how effective it is, but...it's actually a real diffuser, not a facade like most so I am going to assume it is doing something... $300ish dollars well spent, I say!

The main piece with mods (before I did the exhaust pipe cutout).



Jacknut and associated hardware that made connection to subframe easy.



Muffler cutaway.



Underside view.



Rear shot in garage.



Rear shot at track.

[spxxx]

So sweet, unfortunately most lower level competitive classes don't allow for flat bottoms but that should work well.

[Suprgnat]

Originally Posted by AndyW

Underside view.



Rear shot in garage.

Just a heads up. I noticed the cardboard and would like to share what I'm now using: Harbor Freight Tools Anti Fatigue Mats. Dirt cheap, durable, waterproof, easy to clean, and comfortable on the back and knees. They're frequently on sale for $6.99 a set, or HFT always has 20% off coupons. I've accumulated enough sets to "carpet" the entire floor beneath my car if need be.

https://www.harborfreight.com/anti-f...-pc-61607.html

[AndyW]

Originally Posted by spxxx

So sweet, unfortunately most lower level competitive classes don't allow for flat bottoms but that should work well.

Good to know. I only forsee me doing HPDE's and TNIA-type events for a while so meeting spec is outside of my concern right now. I am not sure if I'll ever do wheel-to-wheel (I want it to be MY fault if I wreck my car!) and autocross doesn't appeal to me like driving on a track. Now, if we had Time Attack competitions on the tracks up here, I might be interested...

[AndyW]

Originally Posted by Suprgnat

Just a heads up. I noticed the cardboard and would like to share what I'm now using: Harbor Freight Tools Anti Fatigue Mats. Dirt cheap, durable, waterproof, easy to clean, and comfortable on the back and knees. They're frequently on sale for $6.99 a set, or HFT always has 20% off coupons. I've accumulated enough sets to "carpet" the entire floor beneath my car if need be.

https://www.harborfreight.com/anti-f...-pc-61607.html

Thx, man. Those do look nice! Unfortunately, I am not sure I can justify it as my Amazon habit keeps me up to my neck in boxes...

[Suprgnat]

Originally Posted by AndyW

Thx, man. Those do look nice! Unfortunately, I am not sure I can justify it as my Amazon habit keeps me up to my neck in boxes...

Your back and knees will love you though.

[Ginger_Extract]

Do you have access to other tracks? Looks like you're Ridge Motorsport Park. Not really a downforce track, IMO.

[AndyW]

Originally Posted by Ginger_Extract

Do you have access to other tracks? Looks like you're Ridge Motorsport Park. Not really a downforce track, IMO.

Two tracks I use are Ridge and Pacific Raceways.

[AndyW]

Originally Posted by Ginger_Extract

Do you have access to other tracks? Looks like you're Ridge Motorsport Park. Not really a downforce track, IMO.

This Miata that passed me apparently had a different opinion on whether the Ridge is a downforce track...

[AndyW]

Here is a shot from my TNIA event in April with the diffuser clearly visible.



I'll be driving a Pacific Raceways tomorrow and checked the tightness of the diffuser tonight and it is still solid after ~1K of city and highway driving. Pretty pleased with this thing.

[spxxx]

Originally Posted by AndyW

Here is a shot from my TNIA event in April with the diffuser clearly visible.



I'll be driving a Pacific Raceways tomorrow and checked the tightness of the diffuser tonight and it is still solid after ~1K of city and highway driving. Pretty pleased with this thing.

Any issues with heat with the tranny/diff not getting airflow?

[AndyW]

Originally Posted by spxxx

Any issues with heat with the tranny/diff not getting airflow?

Nope. It's fairly open so there is airflow there. It also doesn't go far enough to affect the transmission. Only issue I have had is one of the rubber jacknuts tore at Pacific Raceways Yesterday. I didn't know until I got home and inspected. It was still solid with the other 7 connection points. I think the reason was twofold. One, Pacific Raceways has a "double dip" on going into turn 4 that causes a significant G-force up and down motion. Second, that nut looked like it was overtightened and holding more than it's fair share. I lowered that section a couple of turns on the threaded rod and replaced the jacknut. If it happens again, I'll replace the jacknuts with the metal ones vice the rubber ones.