undertray for our cars?

[black 10th vert]

Undertray for our cars will do nothing for cooling and even with vents there is not enough airflow. To install an undetray you will need to remove the bumper lip and also remove the air dam under the radiator support, right there you just removed two items that promote air flow under the car and one that promotes cooling.

Cooling mods vs aero mods
1.Boxing in the radiator better for cooling but not any good for high speed runs.
2.Undertray with or without vents will be slower for high speed runs and cooling will be compromised, too much air trapped under the hood.
3. Splitter will increase downforce, helps cooling by directing more air into the bumper openings but slows high speed runs because of increased drag.
4. My hood, reduces the drag which in turn increases the top end, added cooling and increased downforce.

For speed runs i only have 3 sides of my radiator boxed in and a mach 1 front lip.
For open track i have 4 sides of the radiator boxed in and a splitter with an underetray only going back to the radiator support.

Wow, some excellent info here based on real world testing! Thanks for posting this comparison.:beer:

 

[svtjoe123]

Undertray for our cars will do nothing for cooling and even with vents there is not enough airflow. To install an undetray you will need to remove the bumper lip and also remove the air dam under the radiator support, right there you just removed two items that promote air flow under the car and one that promotes cooling.

Cooling mods vs aero mods
1.Boxing in the radiator better for cooling but not any good for high speed runs.
2.Undertray with or without vents will be slower for high speed runs and cooling will be compromised, too much air trapped under the hood.
3. Splitter will increase downforce, helps cooling by directing more air into the bumper openings but slows high speed runs because of increased drag.
4. My hood, reduces the drag which in turn increases the top end, added cooling and increased downforce.

For speed runs i only have 3 sides of my radiator boxed in and a mach 1 front lip.
For open track i have 4 sides of the radiator boxed in and a splitter with an underetray only going back to the radiator support.

Do you have any testing done proving that an undertray won't help us out in cooling?
To install an undertray you don't "have to remove the chin spoiler."

Although it would be a fantastic idea to remove the air damn under the radiator support because having stuff like that hanging down just generates lift and therefor induced drag. That radiator support air damn is just a band-aid on a problem ford has had of maintaning the high pressure area in front of the radiator and a more effective solution would be a properly fitted forward undertray that is sealed against the radiator support.

1 and 2. Boxing in the radiator is indeed better for cooling but should only increase ram drag if you don't have a low pressure area under the car to suck the air out of engine compartment from below. Or you could find a way to make a shroud behind the radiator fan that seals against the hood vents and forces the air to exit outside of the vents instead of increasing pressure in the engine compartment and thereby reducing flow through the radiator.

3. You are correct on the point about the splitter. It also increases the frontal surface area if you put it any lower than anything that is hanging down below your car. I once read a study that was done on the affects of a chin spoiler based on how low it sat to the ground. It was found that there were diminishing returns in the amount of lift they were able to reduce from undercar drag, when they sat lower than anything hanging underneath the car. They did this because they increased the frontal surface area too much and also become a problem with bumps.

4. It is possible for your hood to do that but the only way to prove that is with an underhood temperature drop or by using a Dwyer Magnehelic gauge to measure the pressure drops before and after the hood install.

With all of that said I respect you as a person on this forum and you always have a wealth of knowledge that is very beneficial to our community. I am also aware that you may have SOME real world experience with this, although you have shown no factual data supporting almost anything you have had to say about the subject.

With that said the main reason I would like to give an undertray a try is because i am interested in seeing how much we can increase our ground effect, reduce lift generated by the undercar obstructions, and if we can reduce wake with a properly designed diffuser that maintains airflow attachment. Which could greatly reduce the dirt that flies up onto our rear bumper due to turbulence in our wake. Also if we can reduce wake and increase ground effect we will generate downforce at speed without increasing drag and making our cars more aero.

A link to some of the samples in reading I've done over the past 2 years

http://www.svtperformance.com/forums/terminator-talk-229/683135-anyone-running-custom-undertray.html

 

[greengt88]

I'm intrigued......when r racebronco hods going to be available?

 

[moonltgold]

I think the SN95 CD measures in at .36 (the S197 is .37). That is not very good......./QUOTE]


That is on stock height car. I saw a study on lowering the car about a year ago. It drops .01 CD for about every 1/2" the front end gets lowered (I can't remember the exact measurement taken). Anyhow, with a 1.5" drop in the front of the 03-04 Cobra, the car gets a .33 or .34 CD. Still not great, but definitely better, and actually better than most other SN-95 type faces.

 

[svtjoe123]

Apparently I've already helped my aero a bit then hahah

 

[svtjoe123]

Any of the other Y2K-R guys play with this idea?

 

[SVTDice]

S Type Jags have it, I have not heard any problems from it.

[nomedia="http://www.youtube.com/watch?v=NXLzU03z6Do"]YouTube - ‪Oil change on Jaguar S type R Part 1‬‏[/nomedia]

 

[svtjoe123]

Most newer cars have one. Even if it is just a crude piece of plastic that goes from the bottom part of the front bumper to the radiator core support.

I started work on mine today, got it shaped using my plastic knife and a 36"x72" piece of acrylic. I have it shaped to where it slides in from behind the bumper by the front tires and locks in above the screws for the chin spoiler. Started making it conform to all of the heat exchanger bends and the radiator core support using a heat gun. Started running out of day light so I pulled it back off and will start work again on it tomorrow maybe.

 

[03 DSG Snake]

Most newer cars have one. Even if it is just a crude piece of plastic that goes from the bottom part of the front bumper to the radiator core support.

I started work on mine today, got it shaped using my plastic knife and a 36"x72" piece of acrylic. I have it shaped to where it slides in from behind the bumper by the front tires and locks in above the screws for the chin spoiler. Started making it conform to all of the heat exchanger bends and the radiator core support using a heat gun. Started running out of day light so I pulled it back off and will start work again on it tomorrow maybe.

How thick is the arcylic? Sounds like it might get a little heavy depending on the size.

 

[svtjoe123]

1/8 of an inch weighs less than 2 lbs.

 

[03 DSG Snake]

1/8 of an inch weighs less than 2 lbs.

Pics needed good sir. :beer:

 

[svtjoe123]

I'll try and get some pictures tomorrow, if I work on it after work. Although it's really hard to take pictures of the acrylic since it's clear lol.

 

[svtjoe123]

Put the finishing touches on my undertray yesterday. Pics will come as soon as I get batteries for my camera and may take pressure readings within the next few weeks to get some factual numbers.

Refer to post 42 on page 2 by me if you're jumping in on this thread and are confused as to why I have done this.

 

[Jefe]

Looking forward to pics

 

[termin80r]

I wanna see pics of this, this is something ive been searching for. Ive seen them for the newer stangs, but not for our model. I dont want one for aerodynamics or anything, I just want some sort of protection against small critters on the highway.

 

[03 DSG Snake]

Put the finishing touches on my undertray yesterday. Pics will come as soon as I get batteries for my camera and may take pressure readings within the next few weeks to get some factual numbers.

Refer to post 42 on page 2 by me if you're jumping in on this thread and are confused as to why I have done this.

:rockon:

 

[cobrakidz]

The new Boss LS splitter goes pretty far back under the car.....it must help.

 

[svtjoe123]

Still haven't gone out to get batteries and a pressure gauge sorry guys :/

 

[svtjoe123]

Made a seperate thread with some good info I discussed earlier in this thread along with some pictures, the dimensions, and a video of it under the car.

Here's a link
http://www.svtperformance.com/forum...ndertray-our-cars-part-done.html#post11044060

 

[N/Angel]

subbing and replied to the new thread, great topic!