My TTD build thread

[lizardman743]

Any particular reason you're losing the air dam? Seems like it would be pretty critical on a FWD car especially

Huge splitter and canards? (Crosses fingers) (evil)

 

[sm76]

Any particular reason you're losing the air dam? Seems like it would be pretty critical on a FWD car especially

Partly because of points. I am changing my classing this year to run 150 lbs lighter so I won't have the points left to run the air dam / splitter combo I ran last year.
And partly because with the 15s the car will be 2 inches lower than it is now which doesn't really leave enough ground clearance for any kind of air dam (or the brake cooling ducts since I should have less than three inches of ground clearance). I will be putting the stock 03.5 fascia back on so there is a little bit of a splitter on the car. Then I will be putting a flat bottom tray back to the axles and sealing that with an "air dam" piece straight down from the radiator core support. That will block all air flow from the grill from going under the car and will build up high pressure on top of the splitter and the tray. Also, the accelerating flow under the splitter and tray will produce a low perssure area. Combining that with evacuating the air out of the engine bay through the hood should give me higher pressure above the car then under and should give me the downforce I need. Any high speed grip I am losing will be more than made up for by the lower weight and lower center of gravity. I'd like to extend a splitter a couple more inches in front of the stock splitter at the bottom of the bumper, but don't have the points for it.

 

[sm76]

Huge splitter and canards? (Crosses fingers) (evil)

I had a huge splitter last year, but won't be able to use it this year.

 

[aMaff]

yep, makes sense

 

[lizardman743]

I had a huge splitter last year, but won't be able to use it this year.

Sure did!

 

[sm76]

Finished up my semester last night so its time to start working on the car. Today I started modifying my hood for heat and pressure extraction (and a little downforce but don't tell anyone). Of course I still need to rivet the aluminum in place. Not sure if I want to add wire mesh or not Any thoughts on the mesh?.

Here are the holes:

And this is what the air sees:

 

[fishdonotbounce]

Just my .02 but you are going to trip the flow very early on and it will stay detached for a long way toward the back of the car. I would consider chamfering those to make a smooth line from the front of the hood to the back. I could show it better than I could explain it but I hope you got what I'm trying to get at. Maybe you could use some bondo or something. It would be easy and cheap.

 

[aMaff]

Yeah, without any sort of end plates on those, it looks like you'd just be adding turbulence and disrupting any aero advantage.

I have a good buddy who's way better at aero than I am (he's an aerospace engineer that just graduated from Georgia Tech this weekend..... seriously knows his s***). He's at the SCCA Atlanta National Tour this weekend, but next week I'm sure he'd be glad to have a look. I'd be more than happy to put you in touch. And he'd be more than happy to help. He absolutely loves off the wall / sneaky aero tweaks

 

[fishdonotbounce]

That's cool. A fellow aerospace grad should be able to help you out just as much if not more than I can. If you wanna talk some aero, feel free to PM me. I just got done with a capstone course where we designed an aerodynamic car and tested it in a wind tunnel. I'll be graduating in June. Where the hell did the last 4 years go?

 

[jri4]

Subbing. Don't know why I wasn't before... Hurry up and get this thing back out on track so I can take pictures of it!

Edit: I don't know s*** about aero and downforce, but I would add mesh to keep it looking clean... just thought I would try and add some bit of helpful information instead of straight spamming your thread!

 

[sm76]

Thanks for the concern guys. I actually spent the last few years working in fluid dynamics where one of my projects was actually to determine the effect of small disruptions near the leading edge of objects in the development of laminar flow. By the time the disrupted fluid from the middle of the hood surface re-enters the flow at the roofline, the diruption will be minimal. The cooling effect and release of pressure in the engine bay however should be very helpful, which is why I need to have the low pressure above the holes.
Also, using the straight plate instead of a smooth design that would suck the air out like a venturi is mainly to get the high pressure in front of that plate. It will develop a recirculation pressurized area, so the majority of the flow going over that section won't be effected by the plate other than a little bit of loss from the recirculation area interacting with the flow going over it.

 

[fishdonotbounce]

Ahh I see. Lol should have realized your primary goal was to draw the air out of the engine bay. I get carried away sometimes and focus solely on aero lol

 

[Lewis7789]

I just read that mesh can constrict airflow (a Miata building book of Phens) as much as 40%. No mesh for race cars. That's my contribution. heh-heh

 

[sm76]

Riveted in place:

And the support structure on the inside:

 

[AngryScottish]

looking good, love the fab work!

 

[sm76]

Thanks AngryScottish.

I got my rear shocks installed today and lowered the suspension 1" front and rear. I now have about 5 1/2 inches of ground clearance at the frame rails. Might lower another half an inch. Oh, and I can't even move the rear suspension by pushing down on the bumper with the 850 lb/in springs.

 

[lizardman743]

That's one mean looking MSP.

 

[sm76]

Made up some mounting tabs for the front mount intercooler and welded them up to the bumper.

Test fit of the intercooler and bumper:

 

[sm76]

Intercooler bolted up:

Cold pipe connection and entrance location to engine bay:

 

[sm76]

I put in a net style window net instead of the ribbon style. HUGE improvement.

Also added padding to the door bars to protect my legs and arms.