2002 Celica Modification (Grill Block)

[aardvarcus]

Edit- Do not install a belly pan like this covering the exhaust. It is a bad idea.
I did the under engine section of my belly pan over the weekend, just temporarily did sheet metal screws to hold it in. I may do dzus fasteners in the future to make it easier to remove. I now have the front 50% of the pan done. I took a few pictures of the pan.

I also got some better pictures of the car, including some close up shots of my grill block showing the lexan behind the aluminum. (You can only see it at the edges if you look really close.) I had to remove the lexan behind the upper grill and lower grill due to temps, but if it stays cooler this week, I may put the upper lexan back in.

Anyone have any tips or suggestions? I am still looking for input on using a "velocity stack" intake (designed for a turbo or carb) in the center of the lower grill to provide more air, and then being able to block off more of the little openings in the grill.

Oh and lastly I fit the "new" template to my car instead of a random celica off the internet. My oversized tires "adjust" the height as opposed to stock celicas.

[Sporty Modder]

Looking really good. Love that bodystyle.
It looks to me that you could really benifit from removing the rear wing(parachute)
On my Celica when I removed the ac condenser I was able to run a full upper block and still run nice and cool. I didn't notice if you are running ac or not.
I don't think a velocity stack would be very effective with a ac condenser in the way of the radiator.

[aardvarcus]

Yes, the rear parachute is slated for removal as part of the long term strategy. If I take it off now, I will have holes, pins, and different colored paint showing from under the wing. I am planning on having the car painted in the not too distant future, so the wing removal will probably coincide with that activity.

I am maintaining the AC, resale value and WAF dictate that. Also I know from driving my 88 Celica without AC that if I sweat in my clothes in my car we end up doing more loads of laundry, so it’s either use gasoline or water and electricity. (I know excuses excuses.) I do try to minimize the use of the AC and have found the AC makes a great “engine brake” for slowing down in gear instead of hitting the normal brakes. The grill block would get the car too warm even with the AC off. My thought on the velocity stack was that air would be traveling faster through it than through the punched aluminum, and installing it would let me 100% block a larger section of the aluminum mesh and maintain the same temperatures.

While we are on the AC topic, has anyone got their windows tinted with a UV reflective film to minimize the amount of heat entering the car? I notice that on a cloudy day when the sun suddenly pops out it quickly gets a lot hotter in the car, even if the outside temperature hasn’t changed. I feel like I am in a big greenhouse with all the low sloped glass.

[aardvarcus]

I thought it was about time to update this thread with some recent progress. I have quite a few things, so I will break them up into sections.

1. I had a very dangerous experience with my belly pan yesterday. I started a new thread in the EcoModding Central to discuss this, because this issue was too dangerous and important not to get a new thread started. If you have a belly pan please go look at this thread if you have not already, but I don’t want to clutter the forum repeating the story here. Spoiler alert: It involved a belly pan, exhaust heat and a fuel tank.

2. After finishing the back 40% of my belly pan, I had to remove this section (see above). I was able to reinstall the last 15% or so, so the car is about 75% panned as it sits. I would like to install another 15% or so of pan under the fuel tank before it gets to the muffler, leaving the section under the muffler out. However there is an exhaust pipe running beside the fuel tank at this part. I am looking for suggestions on this part, has anyone simply cut holes in the belly pan to allow heat to escape, or should I only install the pan under the fuel tank and leave the section under the exhaust completely out?

3. Since I was already working on (and mad at) my car, I removed my “Drag Parachute” of a wing yesterday as well. The bolts came off easily enough, but the tricky part was getting the mountain of adhesive off. This has changed the look of the car, and I think I like the fact that it has “toned down” the aggressive appearance of the car. There are open bolt holes there, so I have temporarily used masking tape to keep the water out. Getting the holes filled and painted is on the to do list now.

4. Since I was in a removing mood, I completed the real clean up by removing the rear window windshield wiper from the car. I will probably miss this functionality in the rain, so my thoughts at the present are to either deal with it, make a lower profile wiper handle and blade to reinstall, or make a quick attach/release mechanism to be able to reattach the wiper as needed.

5. Something or someone assisted me with an antenna delete a few weeks back. I think it was some limbs by my driveway hit it too many times and snapped it. I will need to remove the remaining assembly and fill this hole in as well.

6. In other belly pan news, when I had to remove the engine pan to change the oil, I replaced the screws with Dzus fasteners, which are spring loaded half turn quick releases, but they won’t shake open and let the pan loose.

7. I was going to get the windows tinted, but the only day I could get away to do it, I called and they were out of the tint I wanted. Next time I can get free time to be able to drive the car there I will probably try to get that done again.

I am posting this to get all of your thoughts and opinions, so let me know what you think.

[aardvarcus]

Well, I had hoped with the recent wing removal and tail belly pan to be able to creep up over 40MPG, but with my last tank I actually lunged over my goal at 43.25 MPG. Future tanks will tell if this was just an outlier, but based on my gauge this mileage seems repeatable. I have also been working on fine tuning my driving style, so that may also be assisting the numbers.

One of the reasons I have been able to work on my driving style is that my car glides much better now. Thank you aerodynamics. When I first got the car I tried to pulse and glide, but it didn’t “glide” it was more of pulse and pulse (and pulse). Now that the car glides halfway decent, I have been using terrain assisted pulse, cruise, and glide on the side roads and secondary highways. I pulse up slopes and glide down them. If I get back up to speed before the top of the inclines, I use cruise until I crest the incline. Even very small declines give me that extra oomph I need to be able to glide for a long way while only losing maybe 5-10 MPH.

Note I don’t pulse and glide nearly as much on the interstate as the slope needs to be steeper to maintain minimal deceleration at the increased speed. On the interstate I cruise at a local BSFC low point, and am able to maintain decent MPG while keeping up with traffic.

I have also found that I can keep the AC off when pulsing and only turn it on only when gliding, I only increase my fuel consumption marginally, but the car stays cool and dry enough that it isn’t miserable and I don’t sweat. To run the AC when coasting in neutral increases my instant gallons per hour at idle used from .24ish to .34 ish. Since this is on a 1 hour trip, and I only run the AC less than 30% of the time, that is less than 0.03 gallons used. This is only in the afternoons so only 50% of the miles have this usage.

Based on all my figures, this AC usage is costing me 0.5 MPG average MPG. If you just turn the AC on and leave it on this would probably be more like 2-3 MPG. Window tint would assist the duty cycle even more. The only negative is that I will probably wear out the clutch on the AC compressor faster engaging and disengaging it. I try not to do it excessively, only when I know I can glide for a decent distance.

[Sporty Modder]

Like it...
Belly pan story, scary!
2zz motor right, what are yout shift points?
Oh and my 97 maxima had a good tint on all windows,(reflective metalic) in summer heat the car would be cool after sitting in the sun for an hour and =to air temp after 2.5 hours. Wit the front sun shade installed. So yes it helps.

[aardvarcus]

Thanks for the confirmation on the window tint, I assumed it would help but it is nice to have some reassurance. On the shift points, to make a long story short, I have found the best shift points are as follows: (note I have non-stock tire size, ymmv)

Eco minded shifting- Shift near 3100 rpm, land closer to 2400-2600 rpm, thus staying in this assumed low bsfc region. Also giving the engine around 1/3 throttle (approx. 3 gallons per hour rate typically) seems to be the most efficient as you get up to cruising speed at a reasonable rate.

Quicker but still semi-eco shifting- Shift around 5000 rpm, landing around 4000 staying in the main camshaft peak torque curve region. Give the car half or more throttle. This method typically uses more fuel, but not an extreme amount, as you get up to cruising speed quicker. Best used for merging into traffic on the interstate or getting up to cruising speed while climbing a hill.

Non-eco shifting. Shift as close as you can to 7800 rpm without hitting the 7800 fuel cut of point. Land in the 6000 region trying to keep the secondary camshaft engaged at all times, using 100% throttle. Uses more fuel as compared to the other methods. Best for occasional use only when necessary, such as getting out of someone’s way or passing on back roads with limited space available. (It is hard to get used to taking the car out of sixth and putting it into second to complete a pass, I have never driven a car like this before.)


A little background on the long story I made short. The 2zz is an interesting motor as it was designed to be a high revving engine. The powerband on the car is from approximately 4000-5000 on the main cam profile and then from 6200-7800 on the secondary camshaft profile. The engine doesn’t have much power below 2000 rpm, and it ends up lugging if you try to keep it that low under a load. I don’t have a bsfc map for this engine, but from reading around and doing some testing I have found the engine appears to have two bsfc sweet spots at 2400 and 3100 rpm. These spots correspond to localized dips in either the torque (3100) or HP (2400) curve of the engine. I am guessing these correspond to the third and fourth order of some sort of harmonics in the engine as additional dips can be seen as a set spacing of approximately 780 rpm, but that is purely a guess. I don’t have the bsfc chart, but I am assuming the region around these two points is the lowest area of the bsfc chart.

Note that the engine is geared very low factory (4.56 final drive, 0.70 overdrive, 24” stock tires) and that I have already upped tire size by 10% (26.5”) to assist cruising rpms. With this oversized tire, it puts my bsfc spots on the car at 2400=57 mph and 3100=74 mph. On the interstate, I set my cruise at exactly at74 mph, which on my stock speedometer is about 1/32 of an inch below the 70 mark. I have to read this on the stock speedometer as the rpm gauge is too small to discern this accurately. I also have to check my setting against the gauge, and try again if I am even a little off. If I get the engine in this exact spot (+/- 20 rpms) I get really good mileage compared to similar speeds aka 73 or 75 mph. I have to go around 65 mph to get better, 70 is actually worse. Similarly, the 2400 rpm or 57 mph is useful on the side roads, I don’t cruise as I can P&G, but if I have to climb a large hill I shoot for this spot.

[aerohead]

Originally Posted by aardvarcus

Made some more progress on the belly pan over the weekend, got a roughly 4’ by 4’ section in the middle of the car installed. Sorry I need to get some pictures. Next I am going to bridge from the front pan to the middle pan under the engine bay using dzus fasteners for engine access.

Also I am re-evaluating my grill intake air as the temps rise, wanted to get some opinions on using a velocity stack as a grill air intake. It is 8” diameter at the entry point and 5” at the back point. I know one big hole should be better than a bunch of little holes.

The velocity stack will have ideal flow.Any textbook on fluid mechanics will have either photographs or schematic diagrams of these beauties in action.
I have a form of one on my truck,with the addition of a surrounding toroid to streamline any flow away which doesn't enter the 'grille.'
The inner diameter just has to be adequate to ensure enough flow volume.
I'm at about 1/12th radiator area with mine.Good so far.

[aardvarcus]

Thank you for your comments Aerohead; I am sure you have realized that I am getting most of my ideas from you. Currently my fully open grill sizes are 230 in^2 lower and 100 in^2 upper. (Ignoring the side grills and reducing for the aluminum angles the grills mount to. These are “blocked” with 40% open mesh, resulting in net open area of 92 in^2 lower and 40 in^2 upper. Assuming a vena contracta of 0.64 for the sharp orifice, this nets effective grill area of 59 in^2 lower and 24 in^2 upper or roughly a 3/4ths block. In the winter I ran additional partial lexan blocks behind the grill mesh, resulting in net effective of 30 in^2 lower and 4 in^2 upper, or roughly a 7/8ths block.

I would like to use aluminum for anything I add to my grill. I have looked, but been unable to locate a trash can lid of the proper shape and size. I have also searched for pots, pans, vases, bowls, funnels, etcetera but have not located the proper shape and size. What I have found that are aluminum and the correct shape are velocity stacks for cold air intakes and carburetors. The carb ones are approximately 8.5” inlet and 5.13” outlet, and the cold air ones are a 7” bell with a 3” to 4” outlet. If I were to use the carburetor one, what figure would be best used to compare the amount of air it will flow to what I currently have? Calculating the area based on the inlet would produce 57 in^2, but using the outlet would be only 21 in^2.

I am assuming there is a flow advantage to using the streamlined intake shape as compared to the adjusted area of all the little holes I presently have, but I don’t think that fact is enough to make up for the further reduced area I will have unless I use multiple of the smaller intakes. The only other option I can think of is to make one, however I think I would end up with a wider rectangular type of shape with rounded edges, not an ideal 3d spherical form. I had also considered getting one of the smaller ones, cutting it in half, welding a curved top and bottom piece in that matched the profile, and turning it into a rounded rectangle of sorts, but that would be a lot of expense.

Aerohead, another question I have is do you have any sort of ducting directing your intake air to your radiator? If so is it streamlined? I presently don’t have a duct, but I did block off most of the areas I didn’t want the air to go.

Lastly I am presently working on making some tire spats fore and aft of each of the wheels. I am basing my design loosely off of what they did on the ford probe, except making it out of conveyor belt type material, hopefully in a way that will stand up to rough roads.

[aardvarcus]

Edit- Do not install a belly pan like this covering the exhaust. It is a bad idea.Quick update, I cut holes in my belly pan for additional cooling and reinstalled most of it, I posted more details and pictures in my belly pan exhaust heat related thread. The back middle pan may still need more work, should know by tomorrow. I also got some better pictures of the car now that it is wingless.
Well after I get some of my other projects wrapped up, I am considering a small boat tail type extension out the back of the car. I really like what MetroMPG did on his insight, especially leaving the rear tail lights visible. My car follows AST2 pretty closely, and has close to a 36% “Boat Tail” on it already in side view. I don’t want to make the car extremely long, and it looked like it would be a 24” extension to get to 50%, making the whole car 20” or 12% longer counting the bumper already protrudes.

I was considering a “top only” extension which would extend the roofline to follow the template, but would curve down and stop between the tail lights. A 16” top only extension would only protrude 12” and would take me from 35% to 45%. Would this make enough of a difference to even consider?