2002 Celica Modification (Grill Block)
 

---Intro---

Hello all,

Some of you may remember a few months back I posted a pickup truck project. I have worked on it some in my limited spare time, but I ran into a few issues with some of my ideas. While I am still committed to working on that project when I have the time, my daily driver (2001 Celica GT Auto) has been replaced with a new daily driver (2002 Celica GTS Manual). Since I am planning on keeping this car for a while and since I drive it a lot more than my truck I am putting a priority on getting some mods done to this car, and will deal with the truck when I am happy with the car.

First off, I am doing general maintenance and upkeep to the car, and am establishing a MPG baseline. My next step is to get some instrumentation and do some partial grill blocks. Further out would be a belly pan and other aero mods and distant future would potentially be a gear swap.

---Body---
Attached is a photo of the car. This car has the “Action Package” front end on it, which has a LOT more openings in it than the normal front end (shown in the small side picture) that was on my old car. In my opinion, there is way too much air getting into the engine bay, the car takes forever to get warm, and never really gets to the “normal” temperature on the digital display. So obviously I am looking at doing some grill blocks. There are seven openings on the front of the car in five general groups. There is the Hood Scoop, Upper Grill, Lower Grill, Fog Lights, and Fake Ducts.

Lower Grill- This opening feeds the radiator. My plan is to do a full size plug that fits against the wire screen that protects the radiator. I would incorporate one main opening in the center of the plug to let air to the radiator. I figured I would ghetto in a temporary, and then fix it up real nice when I know the size opening I want. I am guessing about a 75% block would do nicely. I am also considering making a few additional smaller plugs towards the sides that could be added or removed for summer/winter adjustment in the final version.

Upper Grill- This cools the upper part of the engine bay, and hits the exhaust header. I am planning on blocking most but not all of this opening, probably 90% or so. Based on how the engine compartment is laid out, I don’t think the air through the radiator gets to this part of the bay that well. I will investigate this some more.

Hood Scoop- Ok, I don’t have a clue what benefit the air coming in here has, it looks to be mainly hitting the firewall. I think a 100% block would be fine here.

Fog Lights- This area is pointless, and I would do a 100% block, but I worry a little about my fog lights overheating. I was thinking of a block that included a Lexan cover with a small opening to let a little air hit the light.

Fake Ducts- I don’t even know the intended point of these, except possibly for track cars to remove the covers and duct them to the front brakes. The covers jut out, and I am planning to replace them with something flush.

For material, I am planning on using Extruded Polystyrene Foam board cut to fit and painted. After I tweak the design and get them good, I may redo them and cover with fiberglass. I have looked at a lot of the projects on here and have grazed a lot of ideas.

So, does anyone have any thoughts or ideas on my endeavor?

Sounds pretty good. I know grill blocking REALLY helps out the Prius and even when I had my Matrix I ran a full grill block in winter. It helped warm up times quite a bit.

recommendations:
Get a scangauge or other mpg guage! Its invaluable.

Thanks for your reply.

I actually ordered a gauge today (other brand), unfortunately the one I ordered is on backorder and I might not get it for a bit. I have wanted one forever and I don’t know why I just now ordered it. To anyone reading this and still on the fence about gauges: one added benefit of some gauges is the ability to read and clear codes. That will save me gas from driving to the auto parts store to get the code read.

Just from looking at your pic, I would say block everything but about half the lower grill.:) Btw I am jealous of that motor you have.

Gear swap? You already have the best gears...:P We 1ZZ folk (and most of the Honda crowd) are stuck with the ultra short 5th gear that is complete garbage on the highway. What are you planning to change out? Final drive is VERY hard to replace in these Toyota transmissions. If you want to swap trannies the only thing that would make sense would be a used Euro 6 speed with the 3.9 final drive, a MWR built 4.3 final drive wouldn't really make sense. Luckily for you, C60s go for a good amount of money.

I see your 36mpg average on the old Celica, this new one should do even better.

How long have you had the 2002? Do you have any fuel data? I look forward to seeing your progress.

Thank you all for your replies.

Yes, the 2zz motor is quite nice. :) Yeah, the front end is really really (really) open.

The "gear swap" I referenced would be the final drive ratio gear. One of the reasons I went with the GTS was the lower 6th gear. Yes, the final drive gear would be very difficult to change, definitely not DIY at least for me. MWR actually has a c60 rebuild that had the 3.9 final drive ratio as compared to my 4.5. I will probably be waiting until I have some sort of transmission or clutch service needed before I could seriously consider the swap. My hope is through better aerodynamics the car with a 3.9 could be just as "peppy" as it is with the 4.5 stock.

I haven't had the 2002 for very long, so I don't have a good fuel baseline. I had been diagnosing a few engine issues with the lift mechanism that engages the secondary camshaft, so I had to do a lot of high RPM shifts to test it's functionality, so my fuel data from those tanks isn't the most useful. I am settling back into my daily commute now, so I should have useful data for comparison in a week or two.

Just as a quick update, I have been working on the grill blocks. I installed a piece of clear plastic (Lexan) over the green and orange areas on each side. I tried to make a frame, but gave up and just screwed it directly to the car. I’m not in love with it, but it is working for now. Showing dirt is the biggest “problem.” There has been no big noticeable difference from the small area covered; the front is still so wide open it will need more attention before the numbers start to move.
I have had a few starts on the yellow upper grill. I tried making a flush contoured removable plug from expanding foam covered in fiberglass, but I had no inner reinforcement, so the plug changed shape as it cured. I trimmed and trimmed to get it to fit, but I then had major issues applying the fiberglass to the surface. I have scrapped this idea, and am moving on to other methods. My idea of the moment it to make a textured plug that looks like a grill and paint it black. This is similar to what I have seen done on some newer cars.
In the near future the car is going to receive a belly pan, but I am waiting on a friend to help me get the materials.

Actually some progress!
 

Finally had (made) some time to snap a few pictures of my in progress aeromodding of my Celica. One of the reasons for the delay was several false starts, several failed methods, and my temporary testing pieces just looked horrible (as many people told me). I finally finished my grill blocks and am satisfied with the results. As you can tell, I used punched aluminum to create new aggressive looking grills for all my openings. What (hopefully) isn’t apparent is that behind this aluminum are sheets of lexan acting as the grill block. I tried just the lexan with nothing in front of it, but it was very obvious that there was a sheet of plastic there. With the aluminum in front to distract you, you really don’t notice the lexan. Then you just cut the lexan away from where you want to let intake air in. My lower grill is 40% lexan blocked, plus the aluminum is a 60% block, resulting in a net 75% block. The upper grill is 85% blocked, it needed a little air or my intake temps got too warm for my tastes. The hood scoop and lower side grills are 95+% blocked, aka I tried for 100% but they aren’t perfect. If you look at my earlier pictures you will see that I used the lower side covers to span over two different openings. Most people assume the grill is just for looks, and don’t know it has an aerodynamic benefit, thus I don’t get as many negative comments.

I also discovered from my testing that I needed the front part of my bellypan in place with large amounts of lower grill block, or else the limited air I was letting in was flowing under the car and not though the radiator. Thus you can see the start of my belly pan, which consists of an extruded aluminum frame, 0.060 aluminum sheet, rubber spacers to cut vibration, and stainless steel sheet metal screws. I have enough material to finish the rest of the car in this manner.

You can also see another mod, though non-aero, are my 205/65/16 Michelin Energy Saver tires, which are 26.5” in diameter, as opposed to the stock 205/50/16 which are 24” in diameter. This has lowered my RPMs by 10% and also helped my rolling resistance. I know it has hurt my aero, by raising the car an inch, but when I finish my belly pan and get some tire spats that should greatly reduce the downside. My (very) long term plan is to regear when the transmission needs work, and at that point I will probably revert back to stock sized tires.

All these changes, plus the warmer weather, have taken me from the low 30s (29-32) stock to the high 30s (37-39) modified, with no substantial changes in driving habits between the numbers.

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.

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.

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:p.
I don't think a velocity stack would be very effective with a ac condenser in the way of the radiator.

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.

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.

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.

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.

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.

stack
 

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.

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.

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?

area
 

Walter Korff of Lockheed Aircraft recommended using the dimensions of the radiator core as the basis for inlet design dimensions.
He advocated an opening which was as wide as the radiator,but only 1/6th as tall,into an airtight diverging duct which was as deep as the full height of the core.(All NASCAR teams use this inlet)
This would handle the full heat flux of the engine under full load.(Racing)
I choose my trashcan lid according to Korff's rule-of-thumb,but at Bonneville realized it was too large since I never actually got to full power,and was so indicated by the temp. gauge.
So I dumpster dived at the Dollar Store in Wendover for cardboard boxes and taped up half of the opening.
I'm at 1/12th radiator area and I'd driven on to Carson City,Nevada,and back home with the cardboard,registering the highest mpg to date.
Once home I duplicated the block with sheet aluminum.
It's on the truck right now and will remain.
I'd let your radiator be your guide.
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There are aluminum and plastic Jello molds that might have some diameters of interest.Architectural supply houses can provide aluminum waste receptacle lids of many sizes.(Love Field in Dallas has amazing jet-turbine inlet trashcan lids in all the restrooms).
Also,some commercial rooftop exhaust fans have an inner fairing concealed within the main housing which has an ideal leading edge inlet.
The aluminum Jello molds you'll most likely find in antique shops.Thrift stores will have the plastic.
Go by the outlet diameter,this is your critical dimension.:thumbup:

Once again, thanks to everyone for all the help and advice.

Ok, all the rest of the aluminum underbelly panels came off yesterday. They would vibrate going down the road, among other issues I was having with them. Version 2.0 will definitely be made of coroplast. I left a few of the aluminum angle pieces mounted to be used as mounting points for 2.0.

In other news the aluminum grill mesh and lexan covers are also slated for removal. I am now thinking of plain black grill blocks on all the openings, and I can incorporate an appropriate cooling air inlet in the one main one. I am out of the “make everything out of aluminum” phase, so some cheap plastic curved items are in my future. Black spray painted plastic is much more economical. I am thinking of starting with a block the radiator width and 1/6 the height and a real duct. I could then start blocking the width of the opening to fine tune the size.

My “radiator duct” was a part of the aluminum pan which is now removed, so the air through the grill is once again going under the car not through the radiator. The airflow entering the grill is much less restricted since it isn’t going through the radiator and the car engine bay was a lot warmer driving to work this morning, so my MPG actually went up from the pan removal. The downside is that it will be hot all the way home, hopefully not to the point of overheating. It was already heating up and kicking the fans on this morning.

My “Aerodynamics of Road Vehicles: From Fluid Mechanics to Vehicle Engineering” got here last week, so I have been reading that with fascination. Thanks to that book, I will try to have better questions to ask.

Alright I dreamed up another crazy idea. I have been studying the radiators section of Hucho’s book and several of the drawings posted on this site. In Hucho’s book, a radiator inlet low on the front of the car and exhaust up on the hood was stated as most efficient, but only practical for race cars. Most of the other opinions I have read are to dump cooling air out in the wheel wells or under the car at the rear of the engine bay.

Well I did some measuring, and this is what I came up with. My radiator is 14” tall and 25” wide mounted at an angle with the base about 10” from where the grill opening is. What if I did a duct at the front bottom that was actually under the current front of the car. It would be at the lowest point on the front bottom, but it would be out of view. A 2” opening 25” wide would get me close to the 1/6 ratio, and my duct would be 10”, or 71% of the 14” height. A picture is worth 1,000 words, to it is attached.

My way of thinking, this idea wouldn’t be that different than doing a 2” air dam and mounting the 2” opening just above the air splitter. The inlet side of the radiator would be sealed, and the outlet side would be semi sealed by belly pan/hood/etcetera and would dump the air out in the back of the engine bay, or maybe by the wheels.

Will this work? Do I need to radius the bottom lip of my inlet opening? Thoughts or ideas are welcome.

How would this benefit more than just having a 2x25" opening in the bottom grill. I would think smoothing out the belly completely and just having a small opening in the front would be more beneficial, but you got the holy aero bible, so you would know better.

Although, you may benefit even more if you do what you say in your diagram, but instead of an opening with an angle (which creates a parachute), you could have a completely flat belly with NACA ducts. That is my plan for my belly pan, whenever I get around to it.

In your diagram, you have the air escaping out the bottom, but why can't you exhaust out the top, up and over the windsheild like Hucho mentions (other than having to cut the hood open)?

Thanks for your comments.

How would this benefit more than just having a 2x25" opening in the bottom grill.

If I don’t do this, that is exactly what I will do. I don’t know that this would be better, just different. I already have my aluminum grill cover made, so if I put some lexan or black coroplast behind it I can have a decent looking (to me) 100% grill block with little effort. I have not yet thought of a good easy way to incorporate a 2”*25” radiused opening into the lower grill area without completely changing my design and starting over on all my grill blocks. (Yes, I care a little how it looks.) Anything I do under the car can look like whatever it wants, doesn’t have to be pretty if it is hidden.

Also after reading some about the airflow under the car, I thought it wouldn’t be a bad place to “rob” the cooling air from. My way of thinking it should give similar effects to having a small air dam.

I would think smoothing out the belly completely and just having a small opening in the front would be more beneficial, but you got the holy aero bible, so you would know better.

If I thought that I knew better, I wouldn’t be asking questions. :D Most things I have seen put the intakes low on the front nose of the car. My way of thinking about it, this intake would still be on the front of the car, and even on the nose of the car, it is just below where the other styling features of the car stop. It is almost like dropping the nose 2” (like an air dam) and then putting the inlet right on the bottom.

Also after previous experiences I won’t be smoothing the belly completely, just partially. I will leave the exhaust components out in the open.


Although, you may benefit even more if you do what you say in your diagram, but instead of an opening with an angle (which creates a parachute), you could have a completely flat belly with NACA ducts. That is my plan for my belly pan, whenever I get around to it.

I had considered making it NACA like, but you have to have smooth flow on a surface for the NACA to work properly, I don’t know I have smooth flow right there. I am thinking of my design more like a normal grill opening, utilizing the high pressure at the front of the car to ram the air in.

In your diagram, you have the air escaping out the bottom, but why can't you exhaust out the top, up and over the windsheild like Hucho mentions (other than having to cut the hood open)?

Can’t say I didn’t consider it, but I don’t really want to cut my hood open. Hucho also warned about the heated air going into the fresh air intake on the cabin. Others have warned about dirty water getting on the windshield. It would be interesting to test if I happened upon a spare hood.

Just keep it clean with the mods :) Owned lots of Celicas and I can tell you that the percentage of GTS models and with a 6speed on top of that AND action package are not very common these days.

It’s been a little while, so I figured I would give another update on my car. My large 10% oversized tires were wearing down (the front ones especially), so I decided to order another set. It was hard to take off from a stop with these 26.5” diameter 10% oversized tires without chirping them, which I believe is what wore them out so quickly.

These had already saved me more than enough fuel to justify their early replacement though, so I am not too worried about it. I decided to go in a slightly different direction this time, and purchased a set of 15” wheels off of a Prius and got Michelin Energy Savers in 195/65/15, or roughly 25” diameter, so more like 4% oversized. The obvious downside is my RPMs went up about 6% from where they were, but the advantages are that the car is lower to the ground and these wheels and tires are significantly lighter. Tire went from 22.8 to 18.4. Wheel went from around 21ish to around 14.5ish (lost my exact figures). This is pretty significant to lose 40+ lbs. of rotating weight on a 2500lbish car.

I have run three full tanks through it now and am most of the way through the fourth, and I have not noticed a significant change in fuel consumption positive or negative, so I think the rpm change was counteracted by the lowering and weight savings. The other advantage I have not yet attained is the ability to put my stock wheel well liners back on the car, so that should add additional advantages.

I am starting to work on version 3 of my grill blocks and version 2 of my belly pan, my truck transmission swap had been taking up most of my limited free time.

work?/ radius?
 

If my memory worked,I think Korff was recommending 1/6th 'height' at full width for the actual inlet.If so,you'd want to add a smidgeon more opening for the worst-case-scenario day.
As to a radius for the bottom lip,yes,I think it would prevent any vena-contracta funny-business as the air attempts to enter.
You're creating a 'bottom-breather' which GM has used on Corvettes and Trans Am Firebirds and they relied on a lip spoiler below the inlet to create a stagnation zone right there.If you can locate one of these,you'll notice a modest radius atop the chin spoiler/airdam.
Just watch your 16-degree approach clearance so as not to rip that puppy off on a driveway ramp.
The actual drag data for the Trans Am is above at the mods data thread.I think it shaved 0.011 off the Cd.You'd want to verify that number.

Thank you for your advice, unfortunately when I switched to my smaller tires it dropped the car back down 3/4”, and it would be too tight to still fit a 2+” opening and a radiused lip in within the remaining area without impacting my approach angles and ground clearance.

I updated my drawing, with my new plan of having my radiator intake at the very bottom of the grill opening, probably about 2.5-3” tall and 25” wide, so I will be close to the 1/6 “ideal” ratio. I picked up a flexible silicone baking mat, to actually form the seal between the front end “duct” and the radiator. I am still planning on using coroplast to make the duct, but I may reuse my aluminum front belly pan piece for the bottom, since I already have it made. (It is nowhere near exhaust….)

updated
 

Looks like you're good to go.:thumbup:

How are the screens fastened in? I would be inclined to remove those and use them as templates for sheet material of some kind, and then put the solid pieces back in with the the same mounting system used for the screen. I would fill the upper one and the two side ones completely, and then block of the sides of the lower center one.

I use a hand held jig saw to cut panels for my fabrications. If you are using aluminum, then put a hack saw blade in. If using plastic use a very course cut blade.

Good luck on this project. I love that model Celica. It is unabashedly Japanese, and does not try to be German or American. For this reason I think it is a true expression of the designers artistic nature. At least in the East Coast it does not get the attention I think it deserves.

Sam

Thanks Aerohead, all that is left now is to find some spare time to actually build it. (Too many projects....)

Thanks for your ideas, I actually did that. I had clear lexan plastic hidden behind the top and side screens, with only the bottom middle screen actually open. It worked good, but I didn't get enough air flow from the main screen, thus version two.

Ok, it’s been way too long since I updated this thread. I have made some progress on my car, highlights as follows.

Note I already mentioned this in this thread, but the pictures show my 10% oversized tires I removed and the 4% tires I previously installed. This made the lowering and reinstallation of the wheel well liners possible.

Did a legal factory HID swap (housing and all from a wrecked car) on my headlights, building a new relay harness myself, utilizing all factory style connectors.

Removed a malfunctioning aftermarket alarm system and fixed the remainder of the electrical issues I inherited from the previous owner.

Completely rebuilt the suspension, new shocks, struts, sway bars, end links, bushings, etcetera.

Installed new springs, lowering approximately 1” all around.

Removed all suspension parts and sub frames, removed rust, primed, and painted.

Reassembled, replacing all rusty or worn bolts. Had the car aligned after all this work was done.

Built and installed the forced air intake I had previously posted out of coroplast.

Built and installed new coroplast grill blocks to go behind my aluminum grill screens. Painted these flat black. Note- everywhere you see the aluminum grill mesh is a 100% block, car intakes its air from the 2.5” gap at the bottom of the center grill opening.

Replaced my factory plastic wheel well liners.

Reinstalled my front aluminum belly pan covering the area before the radiator.

So after doing all of this work, the car gets better MPG than it has before, considering the temperature outside. I have set some personal bests, including a 43.4 MPG trip home yesterday with the temperature in the 60s.

The fuel log is not quite that good, as most of my trips are far less than ideal, but even so getting 38 MPG consistently lets me know my goal of 40+ consistently isn’t too far off.

http://ecomodder.com/forum/attachmen...4&d=1392897506

http://ecomodder.com/forum/attachmen...5&d=1392897506

http://ecomodder.com/forum/attachmen...6&d=1392897506

http://ecomodder.com/forum/attachmen...7&d=1392897506

http://ecomodder.com/forum/attachmen...8&d=1392897679

http://ecomodder.com/forum/attachmen...9&d=1392897679

The car looks beautiful. Job well done. I know how much work that represents! I have always liked that model.

Sam

Sorry to bump an old thread, but I was wondering if there are any new updates?