Flat Deck vs Drop deck

[ZERO25]

I have always wondered if some well placed naca ducts would be an advantage.

Im sure technology has changed but a good friend of mine was a crew chief on a team that had an engineer as a consultant. This was back in the late 80's, but his cars always had rolled lips on the roof and a and b posts. He said the engineer had Cup connections and had found this made more rear downforce in the wind tunnel.

[Ltemodel]

I think if the oil cooler were close enough to the drop in the deck after the firewall, it would pull air out from under the deck. The further back the oil cooler is, the more likely the oil cooler would push air under the car.

I never understood why people put scoops on the back of the oil cooler to force air under the deck.

If someone were to put a bump shroud covering the first small portion of the cooler then leave the back open, the air racing over the front would vacuum air through the oil cooler and onto the top of the deck.

[Punisher88]

I have and always will face the scoop backwards. No idea why you'd force air under the car on purpose.

[Ghopper]

Remember the ground is "moving" at nearly the same speed under the car as the air moving above (hence rolling floor wind tunnels are much more accurate that static floor designs).

A cross section of the pressure distribution is visualized in a link above. This car was an XR1 with the oil cooler covered.

The easiest way to know where air is moving is to tape on a group of strings and watch where they go. Deck mount oil coolers suck the string from the deck through the oil cooler. ....Suck, as in high pressure above deck moving to low pressure below.

[Ghopper]

<- there is a constant Keyser ad for wireless data acquisition using a string potentiometer for length measurement. These are great for slow speed test-rigs (like pulldown types). They are not as accurate for high speed suspension movement as they rely on spring tension within the sensor; which can give misleading results. Get regular linear potentiometers for suspension position and velocity measurement.

[Burke1118]

Keyser made some overpriced gimmick that doesn't actually work as intended!? Say it aint so........"DATA ENGINEERING TECHNOLOGY ACQUISITION STRING BOX WILL INCREASE TRACTION AND WHEEL LOADS USING ENGINEERING AND DATA TECHNOLOGY"

[MasterSbilt_Racer]

Keyser made some overpriced gimmick that doesn't actually work as intended!? Say it aint so........"DATA ENGINEERING TECHNOLOGY ACQUISITION STRING BOX WILL INCREASE TRACTION AND WHEEL LOADS USING ENGINEERING AND DATA TECHNOLOGY"

It works. It just has frequency limitations as Ghopper mentioned. I haven't looked at price for those specially, but that technology is much cheaper than an lvdt.

In general, data measurements practice is very crude and not well done in our sport, where it is done at all.

[MasterSbilt_Racer]

Those expensive smashers that auto run are great to compare with a guy that has the exact same equipment as you, but are terrible for actually knowing what you have.

[Jking24]

Those expensive smashers that auto run are great to compare with a guy that has the exact same equipment as you, but are terrible for actually knowing what you have.

I love when a guy just has to spend that 7k and then he says all my numbers are totally different with this machine or what's even better is the guys that aren't even smart enough to catch it they just assume it's the same and "right" because it was expensive and the big guys use them.

[MasterSbilt_Racer]

I love when a guy just has to spend that 7k and then he says all my numbers are totally different with this machine or what's even better is the guys that aren't even smart enough to catch it they just assume it's the same and "right" because it was expensive and the big guys use them.

"Can't even race a LM without one" I was told.

[MachineMasters]

Good discussion in this thread.

Thx for the info.

[ZERO25]

Remember the ground is "moving" at nearly the same speed under the car as the air moving above (hence rolling floor wind tunnels are much more accurate that static floor designs).

A cross section of the pressure distribution is visualized in a link above. This car was an XR1 with the oil cooler covered.

The easiest way to know where air is moving is to tape on a group of strings and watch where they go. Deck mount oil coolers suck the string from the deck through the oil cooler. ....Suck, as in high pressure above deck moving to low pressure below.

So theres no device that could be made/mounted onto the deck, that would create a venturi effect?

[Ghopper]

So theres no device that could be made/mounted onto the deck, that would create a venturi effect?

It can be argued that is the intent of cars with the oil cooler scoop facing the rear spoiler. I did not test to see if that works, or just creates low flow across the heat exchanger.

I put my cooler under the deck with a fan for the last ~13 races I have done since 2018 (smh). This years car is standard Mars supplied Keyser cooling package. I will test relative to my Fluidyne system.

[Ltemodel]

"Can't even race a LM without one" I was told.

Funny, I was told the same thing by a very prominent shock guy. It strange when people believe in all this voodo magic.

[ZERO25]

It can be argued that is the intent of cars with the oil cooler scoop facing the rear spoiler. I did not test to see if that works, or just creates low flow across the heat exchanger.

I put my cooler under the deck with a fan for the last ~13 races I have done since 2018 (smh). This years car is standard Mars supplied Keyser cooling package. I will test relative to my Fluidyne system.

What about rear facing louvers in certain areas of the deck?