Made the caliper bracket out of pvc to test-fit. I was satisfied with the fit with a few improvements. Then, I started making the caliper bracket out of 4340... this proved to be a pain to cut into , specially when all i got is an angle grinder and Harbor Freight mini milling machine.
I broke the gear on the milling machine so i'm waiting for parts haha

16 mm drill bit for caliper holes

 

For all the CFD lovers.... it's CFD Tuesday lol

Anywho... I played with different things to see their effect on drag and lift of the car. First I added the wheels I actually have (TE37's and mounted tires). I then added a tire deflector, you know, these plastic things you see hanging in front of the tires of most cars nowadays. I also added a flat floor all the way to a conservative diffuser in the rear. Overall drag coefficient decreased to .28 (baseline/stock was .31). Lift decreased to approximately 0 ( baseline was around 100 pounds).


The front tires are still kicking the flow out. The rear wheel definitely does sticking out that much lol







Viewing from beneath, the diffuser ain't much. basic curve-up with two walls on the side. Turbulence is definitely leaking from the rear-wheel area. Maybe strakes can help with that.







Wake from behind the car...

 

the actual leaks were in the turbo housing? where, i have the same one and seems like it wont boost on my rb25

 

My leaks were from T Clamps that were not tight enough, one port on the throttle body that wasn't plugged, and a leak from the intake manifold itself. However, you might have leaks elsewhere. I just rebuilt my turbo and the compressor cover was nice and tight. Yours may be leaking.
Hook up the leak tester and let pressure through from your compressor. The hissing sound will lead you to where the leaks are. it goes without saying, but I'll say it anyway: This is performed while the engine is off.
If you don't have a compressor, you'll just have to listen while the engine is on for vacuum leaks, make sure all your clamps are tight, all the couplers are intact and check your compressor cover for any signs of leaks. You can always buy the leak tester (it's 40-50 bucks) and go somewhere that has shop air and ask them to let you borrow an air hose for a few minutes. If you have air it's so much easier. Good Luck.

 

Dude, love the CFD results! What a cool thing to get to play with. Also cool to see a car with such an incredibly low drag coefficient for a production car see a reduction in drag from some small modifications (granted, a flat bottom isn't necessarily an easy task).

 

Yeah CFD is awesome. My favorite tool to use and it has come a long way the last 10 years for sure. Right now I'm just sorta messing around with the aero mods. Just want to know what to plan for once I get to a point where I can build the parts. Mechanical modifications are priority now.

Eventually, I'll have to actually refine the CAD model a little bit. Make sure it's accurate based on actual dimensions from the car. The model I'm using now, I constructed based on web pictures and published dimensions haha. Once the final model is complete, I reckon the numbers will change a bit. But, qualitatively speaking, the trends I see now should hold.

A flat floor may seem complicated , and maybe it is lol I built one 10 years ago out of 6061 Al and mounted it to the bottom of the car using angle brackets. I then put expandable foam in key areas to stiffen the floor. It worked well and held together @ 160 mph in Fontana Autoclub Speedway (AAA). It was, however, a pain to remove (especially with no lift). I'll have to think of a quick way to install and uninstall this time. It will also be out of carbon fiber.

 

I'm very much enjoying your process and thoughts on this! I know how tedious some of these things can be so I appreciate someone that takes the time and effort to do research like this. Eyes are open for updates!

 

Thanks for the kind words.
It's definitely a lot of work. Grateful to my wife making it possible for me to be able to wrench on my car. I can't wait till everything comes together, but I'm patient when it comes to cars haha.

 

Have you ran any computations on wheel well venting on this car? I am just curious if venting the pressure behind the front wheel yields anything significant. Also, any work on hood vents?

In our race series we can't do a splitter or air dam or wing or diffuser without taking points, so those are out for us but modifying existing body panels is fair game so trying to find any help we can find with aero that doesn't cost points.

 

@RXRodger I haven't done much in CFD yet. However, you have to look at the whole car to come to a sensible conclusion. Here's a logic that can serve well (even without CFD): If air flows in somewhere, it has to flow out. I actually have two coolers (oil and power steering) on both sides behind the fog light (or where they used to be). Air will have to flow in these areas, so I will have to guide it out. So venting is definitely in my plans. Also, sometimes modifications can be redundant. For example, the tires diverters will negate venting since it's preventing some air from going in the wheel arches.
Same goes for radiators. Most people have them in the front. I'm going for a sealed flat floor, so I'll have to vent from the top. You can vent to the sides (behind the wheel) but that's more complicated and less efficient.
In your case, and without knowing much about what you have on the car (ducts, brakes cooling, coolers...etc) I say definitely add correctly designed hood vents. Fully duct your radiator from inlet to outlet. If you can't add tire diverters, then vent your fenders from the top (aggressively), and conservative shallow vents behind the wheels. Some people cut out their fenders behind the wheels, but without shaping the inside of the wheel arches, I reckon this won't help and it will increase your drag considerably. If you can add a flat floor, I would do it, even if you're not allowed to add a diffuser. A correctly designed diffuser may outweigh the points taken away, so you have to consider that (maybe by testing). If you choose not to add a diffuser, I would cut out the bumper and remove any obstructions behind the rear axle.
Every car is different. What you see on another car will not work the same way on your car. Aero mods are definitely different than mechanical mods. If you put the same engine in different cars, chances are it will put out the same power (given that it has the same supporting equipment). Now put the same canard on a different car and it will have a profoundly different effect. You can follow some good "rule of thumb" (like above), but, unfortunately, without visualizing the effects of mods (CFD, proper Wind tunnel testing...etc) you may not get the full effect. And chances are you're far from optimal performance...

Hope that helps.


EDIT: Splitters and diffusers when done right are major performance adders. So depending on penalties they may be worth it. Key phrase here is "when done right"

 

What would you consider as proper hood vents. I have to use the existing hood material so it would have to be cutting and bending to form the vents.


Also, when you say vent the fenders do you mean at the top or behind the wheel?

Radiator ducting has already been done, sealed up the factory gaps.

 

A proper hood vent should actively extract air from the area behind the radiator. Those vents with shallow louvres are not effective and pretty passive. You want aggressive louvres, good stickout above the surface with a sharp angle. This will create a low pressure area behind them, thus extracting air from below. This will take me to my next point. The less efficient your ducting from the radiator, the more aggressive the louvres have to be. When i said "radiator ducting from inlet to outlet", i really meant from the minute air hits your front bumper till it exits out of the hood. If you dont add a duct post radiator, a lot of air will find ways to other areas under the hood and stay trapped. This would add to front lift and heat soaking. So ducting the exit would really help there. With that said, it may be difficult to do this on a stock SC because of space issues. This is why i tilted my radiator forward. Still, i would do my best to guide that air out.
Long time ago, I dissmissed any rule based racing except for open class. To me, it was heavily biased towards refined cars from factory. If you did anything to the car you get penalized. Add track width, tire width, suspension pickup points... blah blah and get penalized. All while the guy who paid more money for his oem refined car, has all that from the factory and doesn't get penalized. So it was biased towards people who paid more at the dealership... not tuners. Any way... end of rant lol but it sounds like you're in a similar situation.
in your case, for limited class hood vents, you can start with 1" rectangular cuts. As wide as the radiator. Bend them out to 60-90 degrees. That should really help, while extremely limited by your class. FYI, the more aggressive louvres do cost you some drag.

fender venting can either be from the top or behind the wheel. I specified which is what in my post (just reread my post and you'll know what I'm talking about).
I hope this helps.
I will eventually experiment with hood vents, so stay tuned. However, I think my time table is different than yours

 

Good info and I appreciate the detailed response. I should have worded my question differently on the fender vents. I did read your initial message on behind vs top. I meant to ask what you meant by vent “aggressively”? I am having a hard time visualizing how to vent the fender of an SC along the top edge. How and where. I can try some things that seem intuitive but that’s probably not the best without a little more study.

 

You're welcome.
You're right, the oem fenders are not wide. I would do similar cuts to the ones you make on the hood. A few inches wide, or as the fenders allow you structurally without falling apart lol Maybe for 10-15 inches across the top above the tire.

 

Finally fixed my mini milling maching. Here's the gear I had to replace... freaking made out of plastic



Will resume making the caliper bracket tomorrow.

I needed to weld a flex section on my down pipe. Since my Lincoln mig welder stolen, I only had the tig welder and the Harbor Freight flux welder. The pipes weren't a great fit so the tig was out of the question so I had to use the flux core. Welds were horrible and I decided to modify the welder. The Harbor Freight welder is an AC welder, which is NOT great for flux core welding (you want DC). So I started converting the welder to a DC welder and making other modifications hahaha.

Here's the piece of junk:






A look inside...



Pretty simple...



The rectifier and heat sink I lined up for my purpose





Here's the rectifier/heat sink/ capacitor installed




Then I installed a removable welding cable (it was hard-wired before).


In the process I changed the ground clamp. It was some wimpy 8 gauge.I installed a 4 gauge. What a difference!


I also upgraded the clamp from the wimpy one to the silver looking one.






Here's the finished clamp





I will try welding with it tomorrow and see the difference.