SCCA CAM-C Thread

[CobaltFilly]

"Rave" Louvers

Sponsored

 

[NightmareMoon]

Rave Louvers have been wind tunnel tested to work better. I prefer the look of the Trackspec a d got a deal on a set that had been purchased and never installed so paid less than what just the center vent from Race Louvers would have cost.

According to Racelouvers ;). I added wickers to my trackspecs and they do vent air, but yeah, at least Racelouvers has some data.

I’m not an aero engineer, yet I have a tough time believing that just the angle and spacing of metal in what is effectively a giant hole in the hood has that significant of an effect (compared to trackspec with a DIY wicker, but we’ll never know, because wind tunnel time is seriously expensive!)

 

[mavisky]

According to Racelouvers ;). I added wickers to my trackspecs and they do vent air, but yeah, at least Racelouvers has some data.

I’m not an aero engineer, yet I have a tough time believing that just the angle and spacing of metal in what is effectively a giant hole in the hood has that significant of an effect (compared to trackspec with a DIY wicker, but we’ll never know, because wind tunnel time is seriously expensive!)

I think AJ tested both in the wind tunnel and that's where Race Louvers got their data. I would need a massive front wicker to account for the fact that the front of my center vent is recessed into the hood. May have to get some scans and 3d model some stuff though.

 

[CobaltFilly]

Good golly so much to think. I like the idea they have the cfd data...but is it worth the extra $90 after taxes after 10% scca RLouver discount?

Then again, will be adding fender vents later...so maybe matching everything from RLouvers is good.

 

[TeeLew]

The gurney at the beginning of the vent is a huge deal because it creates the low pressure area behind it that draws the air from under the hood. When they're recessed into the hood, there isn't enough of a pressure differential to encourage much flow, especially since the base of the windshield is a high pressure area, and that's a bubble that will migrate up the hood. It's also probably why the side vents are good...they don't have to fight this. Having the fins proud of the surface changes everything flow-wise.

 

[CobaltFilly]

The gurney at the beginning of the vent is a huge deal because it creates the low pressure area behind it that draws the air from under the hood. When they're recessed into the hood, there isn't enough of a pressure differential to encourage much flow, especially since the base of the windshield is a high pressure area, and that's a bubble that will migrate up the hood. It's also probably why the side vents are good...they don't have to fight this. Having the fins proud of the surface changes everything flow-wise.

Aha I see. RL it is.

 

[tosha]

I did an unscientific test with taped on gift wrap ribbons on center racelouver on another car - the ribbons stand upright at 140km/h. I was very impressed. I can do same test with mystang louvers, both center and sides sometime this weekend, if there is interest.

 

[NightmareMoon]

Yeah I did this a while back. This is a little slower speed, (maybe 70? don't remember)


I think you really need to direct the airflow behind the radiator with some ducting, but the intake is right there, so it wouldn't be a very fun project.

 

[WItoTX]

Yeah I did this a while back. This is a little slower speed, (maybe 70? don't remember)


I think you really need to direct the airflow behind the radiator with some ducting, but the intake is right there, so it wouldn't be a very fun project.

I remember watching this video. Awesome data point.

BTW, no wind tunnels even close to us in this part of the country. I think UT or A&M has a small one, not big enough for a car though.

 

[TeeLew]

I remember watching this video. Awesome data point.

Really good stuff, huh?

What this shows on the center vent is really interesting. Right behind the leading gurney, there's flow, but by the time you get to the rearward portion, flow is small and the yarn is mostly flat. The gurney is making the low pressure that feeds the front of the vent. As we move back, the the influence of the windshield high pressure bubble comes into play.

The hood side vents look to flow great. I also think doing the fender vents on the side of the fender out of the wheel well would be a good addition.

I bet you would get a similar total flow on the center vent even if it were only about 3-5" front to back. If the rule is by area, then all the way across the hood (or maybe 75% across to be more reasonable) and right behind the rad looks to be the way to go.

 

[CobaltFilly]

Really good stuff, huh?

What this shows on the center vent is really interesting. Right behind the leading gurney, there's flow, but by the time you get to the rearward portion, flow is small and the yarn is mostly flat. The gurney is making the low pressure that feeds the front of the vent. As we move back, the the influence of the windshield high pressure bubble comes into play.

The hood side vents look to flow great. I also think doing the fender vents on the side of the fender out of the wheel well would be a good addition.

I bet you would get a similar total flow on the center vent even if it were only about 3-5" front to back. If the rule is by area, then all the way across the hood (or maybe 75% across to be more reasonable) and right behind the rad looks to be the way to go.

‘Jots notes.’ Great deductions.

 

[shogun32]

I bet you would get a similar total flow on the center vent even if it were only about 3-5" front to back

so why do the vendors make them gigantic (depth)? The GT500 size would also be questionable, no?

it also explains the 'dinky' vents on the Camaro and S650. Though the S650 ones are AHEAD of the radiator stack which is just flippin moronic.

My hood(s) aren't vented yet. And it's interesting that the frontends that are equipped with shutters appear to have the rads boxed, somewhat reasonably.

I plan to put 2" high (or whatever) firm rubber weather-stripping across the entire 'shelf' that is the rad/headlight assembly so the hood squashes it and seals. That way the vents are venting engine bay air, and not free air spilling over from the front facia.

 

[mavisky]

I can tell you that the large vents do well at radiating heat passively while the car is still, but in all honest I'm sure that a vast majority of it is simply imitation from what Ford did with the S550 GT4 cars.

 

[TeeLew]

How much different is the positioning of the Race Louver, Track spec & GT500?

Most OEM aero tweaks are more for show than practicality. They want the look, but anything that increases drag hurts fuel economy, so they mess it up.

I have the older GT350 spoiler on my car and the ends are peeled back specifically to dump downforce/drag, for sure.

I'm not an aero engineer, but I am a mechanical one with an emphasis in fluids (10,000 years ago) and a wee bit of experience on similar stuff. I'll never give you a straight answer on aero stuff, but I can tell you where to look to find the answer (some times).

 

[CobaltFilly]

I can tell you that the large vents do well at radiating heat passively while the car is still, but in all honest I'm sure that a vast majority of it is simply imitation from what Ford did with the S550 GT4 cars.

Are those GT4 cars also using the Verus Engineering wing? And do you all believe it might suit my lower horsepower and lighter weight vs say an AJ Hartman swan neck wing?

Sponsored