Not cheap, but 500 pages packed full of info and lots of pictures. Highly recommended if you are looking to reduce drag and lift on your car.

Thoughts and feedback appreciated.

Here it is: As an example, imagine a 6" deep splitter mounted fairly high off the ground, maybe 4" or 5" high, with an air dam skirt on the leading edge that hangs down basically on the ground. I was looking at Competition Car Aerodynamics and it's clear that with both an air dam and a splitter you have a low pressure on the underside/backside. In theory the splitter have less pitch sensitivity and still have a nice pressure differential between the top and bottom of the splitter. As a side bonus it would be a lot easier to load a car on a trailer with 4" of ground clearance in front.

I know the pressure differential doesn't look as high for the air dam in CCA's diagram on p 65 so the splitter may be less effective, but I still think this might work reasonably well and solve the pitch sensitivity issue and might be an improvement over a traditional splitter on a relatively low speed car that is relatively softly sprung. I see guys putting splitters on cars with relatively soft suspensions, and I can't help but thinking that the splitter is probably doing as much harm as good as it bounces up and down at the front of the car.

I am putting together an E- engine 4.5VKDD engine to attempt breaking the E/GT record currently held by a Vette. Horsepower should not be a problem.....Dave and Brian at Rebello are busy doing the homework to make ???hp. We will publish the HP numbers after we dyno it.

My issue is wanting to know the real numbers with and without the G-nose vs the attitude (rake) in the car plus what angle and position to place the parachute(s) at so they don't fall on the ground when deployed. I have a very capable guy who is willing to do the CFD analysis to give a 95% certain answer to all of my questions above. 

Anyone that can help I will gladly share our results with.

I have seen several posts where people have some models started but really need one complete with as much undercarriage as possible. 

Of course apple juice at the diner at the entrance to the Bonneville speedway will also be included.......

Thanks

Burton Brown

www.victorymotorsports.org

Just look at the front end. Don't mind the huge BRE at the back.

So say we close up the front end even more than it is there. Maybe half that size.

Would completely blocking off the engine bay and diverting air over the hood be a good idea?

What about useing the same hood vents but extend the front end out like the janspeed Z's hood with the Gnose buckets.

The question is, should the back of the tray stay flat or should say 75mm/3" of it be bent up or down?  Going on what a lot of modern cars have I've bent the back down to about a 45 degree angle, assuming this will help extract air from the engine bay and not have any negative aero effect although the result is an upside down hatch spoiler shape there which may by itself generate lift. But of course there is air flow on both sides of the 'spoiler' which I assume changes things.

In all my aero research I've never seen this point discussed so does anyone have some good info that they could share?

I mean, this car is going a good 30 (to 50!!!) mph faster at Bonneville than our slicked-up 2+2 with a G-Nose and the light covers, blocked radiator inlet, and full belly pan.

They are running this year in F/BFMS, which is 3 liter (F/), Blown (, Fuel (F), Modified Sports (MS)...which MS is the class you run in with a 240-280 that has non-stock body mods, after that all the other stuff should be self explanatory in the class.

So take a look at what they are running and comment as you will.

Any one got a copy I can buy? or direct me to? 

Thanks

After going back and forth, and not wanting to weld up new end tanks/intercooler piping I was left with the challenge of working around my intercooler. I had a few requirements of ensuring I fully blocked off air from escaping and going directly under the car, and ensuring all the intercooler saw air. I also wanted a small portion of the air to bypass the intercooler, to go straight into the radiator. I came up with the below...

I started with a large 24x24 sheet from home depot, and really only ended up using 2/3rds of it. From the pictures below, you can see my main goal was to keep as much of the metal as I could, and fill in the rest with fiberglass. So what I really made was a skeleton shell out of the metal sheet. I followed the contour of the core support diagonals, and used cardboard to make the angles.

Yes, I know there are drips, and such, but my intercooler almost rests on those areas so I let them be. All the areas which are visible, saw a small coat of bondo. This also ensured that this mated perfectly with my air dam. I let the pictures speak for themselves, and please feel free to reach out with questions.

As far as holding this thing in place... You see a stud in the middle of the duct; this pretty much holds it firmly in place. Since I fiberglassed it on the car, it molded/contoured it self in place. I pretty much sat there alone. There were four holes on the core support, which I used plastic push clips to further hold it in place. You see that there are some holes drilled and empty for them.

I am not done with the front end; it will be getting blocked off with a large sheet of ABS. This will further channel the air, but wanted to post small updates as they came. A rear diffusor with pics is also coming as well...

Heres the plan

- Enclose radiator opening, seal the airdam to the bottom of the intercooler, etc

Old setup

Now I have an intercooler so Ill need to redo it.

- Seal the bottom edge of the air dam to the bottom of the core support.

Like this...

I can attach directly to my supports.

Extend it up the sides a bit enough to cover my wheels

-Make some sort of panel to direct air away from the front of the tires. See thread..

http://forums.hybridz.org/index.php/topic/86261-front-of-wheels-aero/

Its not a good picture but imagine something like this (bottom left of screen) but larger and closer to the ground.

Im thinking about using some sort of plastic, imagine something like the garden edging stuff so it could actually scrape the road. It would be flexible enough to not snap off but stiff enough to actually redirect air. It would go all the way across the car in a arc, wheel to wheel with the middle further forward.

- I originally planned on just having a filter direcly on my holset but im thinking of incorporating an intake duct that will scoop up cold air from under the car. If you can imagine the area behind the radiator and in front of the sway bar, thats where the duct would be. Id get alot cooler air and a little bit of a "ram" affect. Should be good for 50hp, assuming the ducting is chrome as well. haha

- Lasty it comes to my primary question, regarding venting the engine bay. I relocated my battery so now both areas under the inspection lids are open. I have a vented hood already and was considering modifying my inspection lids to have a vent. Im not sure how much venting it takes to avoid air going out of the bottom of the engine bay but I suppose too much isnt bad. haha Given that, I was looking into how Id setup fender vents.

There are a few factors that come into play. I dont have fender liners so the battery tray area is directly open to the fender well. If I just install a vent on each side of the engine bay where it just vents to the fender *WELL* would that be effective? With my other modifications wouldnt the fender wells likely be a lower pressure area? Second option is to actually vent from the engine bay through a closed duct and actually out the fender, completely bypass the fender well and vent air to the outside of the car. I was even thinking about the possibility of running two small fans in the ducts to help evacuate air even at low speeds.

See this thread for more pics and discussion.

http://forums.hybridz.org/index.php/topic/61219-fender-vents/page__p__563492__hl__%2Bfender+%2Bvents__fromsearch__1#entry563492

Of course all of this will be paired with equal attention to the back although I havent considered what Ill do as much. For now its just VG, and hopefully a SDI 5.25 inch spoiler.

Any comments and discussion is appreciated. I think this stuff is super cool, hopefully Ill be able to apply some of the what I learn in fluids this semester.

I'll be reaching out to members here, but if you know of a WILD ride that should be in the tunnel, then have them contact me offline.

Mike

I've had a couple ideas rolling around in the back of my brain for a while, things like splitters with airdams on the leading edge, trying to increase airspeed on a flat floor, etc. All have more to do with the underside of the car.

Here are my ideas: 

1. Splitter with airdam on the leading edge. I think this will work better for autox types of situations where the speed differential of the air going under the splitter won't be as significant. Since the windtunnel air speeds are pretty low where you guys are going, I think this would be a good spot to test the theory. I think Cameron actually has this setup so that all he has to do is bolt it on. Not sure if he will be part of this though. This was recently tested in Race Car Engineering on a Porsche, but the airdam they used was still 3-4 inches off the ground and not surprisingly it produced worse results than the splitter alone. I'd like to see it tried with an airdam 1-2 inches off the ground. A variation would be adding dams to the sides of the splitter. This could be fairly easily tested by taping a cardboard strip to the edge of a splitter, with some triangular cardboard braces on the backside to keep it from folding under pressure.

2. Splitter with diffuser. The NASCAR COT's used a diffuser after their splitters. This diffuser was about as simple as it gets. It was just a piece of aluminum mounted at an upward angle at the end of their splitter. Their splitters were very short, and the diffusers were too. If there is room, it would be interesting to try a 12 or 18 inch long piece of cardboard at the back of the splitter, just tape to the splitter and then tilt up towards the rear. The COT had a very rough bottom so you wouldn't think that a diffuser would work, but they were talking about 80 lbs of downforce difference based on the angle of the diffuser in a video I watched. Variations on the angle of the diffuser could be checked.

3. Ground effects. It's really tough to do an aero bottom on a Z because of exhaust and drivetrain clearance, but it might be possible for the guys with larger diameter wheels to do it, particularly if you have very stiff springs. I know 74_5.0L_Z is running at about 2.75" from the bottom of the front crossmember to the ground and not bottoming with spring rates in the 400s IIRC, so if you have 5 or 6 inches to the lowest hanging piece, you could drop a floor down a few inches and still not scrape. Flat bottoms are usually mandated by rules, but aren't the best option. Contoured floors are better and obviously more difficult to fabricate.

3a. Contoured floor. Splitter with diffuser into a second venturi into a rear diffuser. Basically we're talking about aping a LeMans car, mulsannescorner.com has plenty on this if someone wants to try it.

3b. Flat floor. Much easier to make is the pro here, and theoretically much better than the rough bottom with the drivetrain and exhaust hanging down. It would be awesome just to test the flat floor/diffuser setup, but I have a couple variations. The idea behind the contoured floor is that you're creating a venturi by getting the floor closer to the ground and narrowing the opening for airflow, causing the air to speed up. If you have a flat floor, what is to prevent someone from using fences on the bottom to narrow the airflow passage on the bottom of the car and get the same effect? Essentially I'm talking about more airdam material, and making a venturi shape on the bottom of the flat floor. This could be tested with aluminum 1/2 x 1/2 x 1/16 thick angle (easy to bend to shape) double sided taped to the floor and then the cardboard fences could be taped to the angle. A further variation would be to add air from in front of the rear tires to the venturi. I think there would be a decent amount of airflow to tap at that spot, particularly if there were dams pushing air out to the side of the car behind the front wheels, as I know Mike Kelly and others either have or were planning to have.

All of the above can be tested pretty cheaply and easily. These drawings are not to any scale or anything, but I think they might help to conceptualize the overall ideas. Red or blue is a fence that could be tested with cardboard and actually be put on the car with airdam material (plastic lawn edging is what I would use).

4. Spoiler/wing combos. It is pretty well known that a spoiler and wing can be more effective than a spoiler or a wing alone, but I don't think there is a hard fast rule about what size spoiler makes the best result, so that could be tried, in particular testing the amount of increase in AoA on the wing before you get separation on the bottom side with and without the spoiler would be helpful. This would probably be useful only on the car that was tested, but if my car were going in there I would definitely want to do this test.

5. Front fender contour. I doubt anyone will do this, but I'd like to see a Z with the front fenders cut and folded in behind the wheel to the wheel well, imitating what you seen in Spec Racer Fords, Can Am cars, etc. It's not a new idea and we know it works, but I'd like to see what the result is. Would require cutting up a set of fenders and making a fender liner so that air didn't get past the opening and trapped in the back of the fender, but fenders could be grossly cut and cardboard used to push in behind the wheel and make a crude fender liner as well.
 

6. Fender top vents over the front wheels. Preferably alligator tooth style.

7. CFD. Anyone ever considered putting this money into a CFD model? Not sure how much that costs to do, but if you had a CFD model, you could test infinite variations without going back to the tunnel.

The hood vents were designed to spill high pressure under the car. Has this been tried on our Zs? To what success?