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-   -   Better Aerodynamics for the Corolla (

ps2fixer 02-26-2012 01:54 PM

Better Aerodynamics for the Corolla
Here is my build thread of my 1997 Corolla DX with a 1.8L I4 with auto trans 4 speed with lockup.

Quick story about the car, my normal car was a 1992 Toyota Camry with 303k miles and the brake line went out for the rear tires (and tank rusty, other brake lines, fuel lines, fill tube). Everything but the tank is original! I have wanted a corolla since I first bought the Camry about 2 years ago, and I spotted a overly cheap corolla on craigslist. To make the long story short, I got it for $700, and needed brakes redone all around, struts all around, front end alignment was WAY off, been in several small wrecks (city beater), and a few other minor things (light bulbs etc). I have around $700 in parts and around 4-5 hours of work into it. Same car in fair shape sells for around $2500-3000 all the time locally.

Now for the mods...

First things first... the upper grill block!

A quick background story on this, my mom use to make home made soap, and used clear plastic to wrap them and a hair dryer to slightly melt and shrink it to seal it up. I ended up taking a trash bag and putting my OEM grill in it and wrapped it like a present. Using my solder rework station, I melted the overlap first and continued to "shrink" it till it was tight. Only thing I don't like with this mod is that I used a thin trash bag, so I had 2 layers instead of 1 which makes it look a bit odd when you get close. From a distance You can barely notice it.

I do not have ABA testing, since I knew the Corolla has oversized engine cooling abilities.

The last one is kind of hard to see, the back side is solid like the front, but looks bad due to the overlap etc. Cardboard is there since I don't have a lower grill block in yet.

Next mod is my hood seal since the OEM ones were shot. The last owner forgot to put the oil cap on the engine, and it spit oil all over under the hood... not good for that rubber! I removed the rubber strips and ran Camper Mounting Tape using as many layers as needed to see the foam hitting the hood when closing/opening the hood to check.

Lately I just noticed the back side of the hood isn't sealing (vibrates at idle), so I need to upgrade that one as well.

ps2fixer 02-26-2012 02:23 PM

Planned mods:

Lower grill block (adjustable at some point in time)
Rear wheel skirts
Full belly pan (need to find a better supply of chloroplast)
Replace most lights with LEDs
Over sized tires for the front (guessing about 10% oversized would be good)
seal headlights, grill, etc. Silicone/Hot glue?
Warm air intake (since my current intake appears a bit restricted and away from the engine.

LeanBurn 02-26-2012 05:49 PM

A small caution about LED replacement lamps that there are a great deal (almost all) that are dimmer than their incandescent siblings. Compounding this is that most LEDs are directional, that means off axis they are much dimmer. This could be escalated by inclement weather. For things like licence plate lights is not much concern, but brake and signal lamps are a consideration for safety. If the LED replacement you are considering are double what a regular bulb would be you are losing out on all fronts of safety and cost savings.

If your radiator is in good shape and you have a scangauge, you can block up to 2/3 of the lower grill as well especially in the winter. I would use caution in the summer with a lower block. Up to ~86F you can keep the upper on as well, but a scangauge should be used to be certain.

Looks like an eligible car for pizza pan hubcaps as well.

Sven7 02-26-2012 08:52 PM

Great start! Out of curiosity, where in Michigan are you?

ps2fixer 02-26-2012 10:41 PM


I understand the differences with LEDs, how my tail lights are setup, the bulb shines straight back into the colored lens. I ordered these LEDS (around 210 degree output) eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices. The main reasion for these LEDs is because Corollas and Camrys (my family has a lot of them) always have 194 bulbs blown out in different areas of the car, heater controls, trunk light, gauges, etc, so worst case, I will just use them for that. Some of my marker lights are 194s so I plan to do some "ABA" testing to see if they are fair. I can wire up my own LEDs if needed, I have some 165 degree CREE style 3 watt LEDs which I could run really underpowered to give a good brightness but not blinding. For blinkers, I will have to change my turn signal flasher due to the lower load (~20ma per led)

Mid Michigan, north of you (Detroit) 2 hours or so according to google maps.

I'm wanting to do the lower grill block next, but I'm not sure how I want to go about it. I would like to make it flush with the front of the bumper and still have abilities to adjust a flap some time down the road (no pun intended). I'm thinking of using some small chunks of 2 inch high density styrofoam where the zip ties would mount it, and leave the area I plan to have the hole at empty behind it. Only thing that kind of stinks is my chloroplast is white and only 3'x2.5' (10 sheets).

I currently have my radiator blocked as much as I could get cardboard over it with the upper grill block. Since I installed a 192 degree thermostat my temp went from 166F to 200-204F. It likes to stay around 202F and sometimes goes up/down from stopping and going. I have never heard my fan run yet, so I'm not even sure if the motors are good. I think I will be safe to block off 100% of the grill for winter driving (currently mid 20s to 40s, normally down to -5F this time of year). Summer time I'm thinking about 1/3 opening on the bottom would be about perfect and have ~5 inches of it that can be closed off from inside.

For the adjuster, I'm thinking a cable with quite a bit of pull distance (5 inch?) would be my best bet and make it a slider with a spring return.

FYI- If I pull off crazy mileage (50mpg+?) my dad said he would buy a corolla and do all of my mods and a boat tail. Not sure how truthful that is, but an interesting challenge :). Last trip home I had 44.7mpg out of the blue, hoping I can figure what happened and continue it :).

I'm pretty sure I have seperation at my rear window, so I wonder how much of a benefit I would get with a kammback vs full boat tail.

Here is a side shot of the car (ignore the rusty car lift :O).

LeanBurn 02-26-2012 11:11 PM

I don't know if I would be comfortable blocking off the radiator with pieces of cardboard right up against it like that. If the fan did come on, it wouldn't be able to draw air through, then engine overheating could be an issue. No aero benefit either. You could always use some tape and mock up a 2/3 - 3/4 lower grill block and remove all the cardboard directly in front of the grill, this would allow the air to be drawn up from between the gaps between the bumper and the radiator...resulting in aero and faster warm up, much smaller chance of overheat with the upcoming warmer temps...and you would have a template for when the color of chloroplast comes along that your like :)

It would be good to find out how much block you can do safely, then work up to a movable type if you wanted to.

Wheel spats and mudflap removal is another area that helps.

ps2fixer 02-27-2012 01:41 AM

The only reasion for the cardboard is because my thermostat was stuck open and was running around 160F, with the cardboard it could get to 166-170 and about 174 in town. I forgot to remove it when I installed the new 192F thermostat, but watching my scangauge closely, it has never gone over 204F. I do plan to remove it once i make a grill block though.

I do plan on removing the mud flaps, they actually have a slot at the top of them to allow the air to go though, so I'm not sure how much of a difference it would make.

I was thinking about a mirror delete, but state law prevents me since it requires two OUTSIDE! mirrors.... Might look at folding in the passenger side since I rarely use it/need it and it would still be there... just not adjusted well :).

The steel rims appear fairly smooth, would smooth wheel covers really make much of a difference? I thing lighter is better for wheel covers, so I would be looking to use chloroplast besides the fact I don't want the flashy hubcaps. Should be fairly easy to cut a circle in chloroplast, make holes for the lugnuts (4) and one for the valvestem. I have an extra set of Camry hubcaps that should go on this just fine, but I was thinking the extra weight would offset the small aero benefit. I'm thinking I could fill the indents in the hubcaps to have a good look yet aero. Ones I have are like these:

I'm also thinking a whiper blade aero deflector might be a fair benefit as well.

So many mods, so little time! I work 8 days on, 6 days off, so in a few days I'll have to play around with some mods :).

RobbMeeX 03-03-2012 05:21 PM

We have the same engine/trans and yet I can't get out of the thirties... 31avg.

ps2fixer 03-03-2012 05:37 PM


Originally Posted by RobbMeeX (Post 290930)
We have the same engine/trans and yet I can't get out of the thirties... 31avg.

What speed do you travel at? I'm driving in almost perfect conditions with very few stops, long drives, and at low speeds. On the highway I have gotten 34ish with my dad driving, but I got 38 on the way back and at 55 I get around 37-40 (instant). I think tire pressure really helps these cars. One thing that I can think of that would result in around 31mpg would be having the over drive button off, or your lockup not engaging (45mph under light load up to about 55 on light throttle). If you don't let off the gas, it might not lockup, my old cutlass ciera did that when on the highway.

It could be possible my car has a "problem" that somehow helps my MPG, but I know the MPG figures are close since I fill up about the same number of times to work, but is $22 cheaper than my Camry (9 gal vs 15).

Yesterday I took out the cardboard from my radiator and noticed something very very odd..... my temp ran HOTTER! Instead of around 202F it would be 204-206F. Intake air temp went up by around 10-15F than before too. I have never heard my fans kick on yet, and idling won't get the temp high enough for the fans. Very strange engine/cooling system.

JRMichler 03-03-2012 06:32 PM


Originally Posted by ps2fixer (Post 289442)

Last trip home I had 44.7mpg out of the blue, hoping I can figure what happened and continue it :).

Take a hard look at temperature and wind direction. I get anywhere from 30 to 42 MPG on a particular 60 mile highway route depending only on temperature and wind. That's with identical speeds and driving style.

The 42 MPG was on a 75 degree day (no AC) and a direct tailwind about 15 MPH.

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