I looked at buying a bigmouth spoiler until I saw the price. last night I made the same thing in about an hour and it works great. I used a peice of aluminum and bent it with my bench vise and a hammer. I have not had a chance to paint it yet or polish it. I am thinking about polishing it like chrome. anyway here it is! I used one self taping screw with rubber washer on each side so if it hits anything it will pivot up. Hey I know it is a pretty weak DIY but I tried.

 

How so? That product has looked like a gimmick to me. There was one test that showed no real difference in temps. Good DIY work though!

 

My factory plastic spoiler was getting pretty bad I needed to replace it, so instead of buying a new one I just made the big mouth. Does it work better then a new plastic spoiler, I dont really know. From what I saw the plastic spoiler just points strait down, this thing is like a big scoop. I attached it to the two skid pads on the front of the car. It goes from the front edge of the skid pads to the bottom leading edge of the evap coil. I do not want to mislead anyone by saying it made my car faster or better MPH.

 

That is how it works...at speed: it creates a low pressure area just behind it which draws the hot air from the radiator down and away.

Maybe the "big mouth" idea works (I bet best at lower speeds) I have no idea but seems like it would "catch" too much air at high speed(s) and create additonal drag.

Maybe do some runs with/without it mounted and see what the affects are on the ET.

 

I never knew it was designed for the air to be drawn away from the front of the radiator. I thought the stock rubber spoiler was to prevent too much air getting under the car and causing lift at high speeds?

The fans in back of the radiator are designed to help pull the air through the radiator, and also provide a breeze of air through the engine compartment.

The aluminum "big mouth" should direct more air directly at the radiator, which I would think would help the cooling?

The part about too much air under the car, if that is a consideration, then it wouldn't help too much there, except for the air it was scooping up and forcing towards the radiator?

Steve Nix

 

every day at lunch I get stuck in the same traffic for at least 3 miles and my temp gauge goes to 3/4 and then I get clear and drive about 2 miles to the office and the temp goes 1/2 way. Today it is 81* I have the top off and I sat in the same traffic with the AC on and the temp went 3/4 of the way as normal but when I got clear my temp dropped real quick, by the time I got to work my temp was 1/4 the way. When I am driving my temp stays about 1/4 of the guage.

 

Cool to see some tests there. That's what I've read in the past, that it does help it cool down quicker. I'm not sure how that helps anything though. Traffic hot, cool down, then traffic again and hot. Any difference in overall cruise temp without getting into traffic? I saw this posted awhile back:

Before Big Mouth

----------- Temperatures
Distance, Outside temp, Oil, Coolant

Start 92 195 185
13 miles 93 203 188
19 miles 91 204 188
32 miles 93 208 189
37 miles 91 206 186
42 miles 92 201 182
52.5 miles 91 204 188

After Big Mouth

----------- Temperatures
Distance, Outside temp, Oil, Coolant

Start 94 204 188
13 miles 96 204 185
19 miles 95 204 185
32 miles 95 204 182
37 miles 94 204 184
42 miles 94 201 180
52.5 miles 93 204 182

 

those numbers are of little use...only show the thermostat is working.

mid-80's full-size sedan needed 12 HP to cruise 55 mph over nominally flat pavement...under similar conditions a c4 would likely need less HP...summation: cooling system load is minimal at 'cruise'..extraction: put engine under heavy load of acceleration/towing/etc to determine performance of BM.

if commonly accepted laws of thermodynamics are truly valid, with all other factors held constant more airflow will increase heat transfer.

 

Good lord how are things going at NASA?

 

I dont need to read any reports, noticed a worthwhile difference in mine both in cooling down AND cruising temps. Put it on, it worked and ran cooler end of story. No scoop in the world will make it idle cooler

 

It works..
the tiny air dam from the factory lets too much air slip past. This is a compromise to allow for ground clearance.

I have had several types of fiber glass spoilers, (all created more heat and slower to cool, purely aesthetic) and even made a lower hanging stock type. That was an improvement but not great and ground clearance suffered terribly.

The big mouth is angled forward, longer and has the sides to contain the air thats been "scooped" and channel it into the air-box. I lost my last one to a dead truck tire on the freeway and realized that everything that I needed to build one was already in place...

So I chose ABS plastic...I took the radiator bottom shround and laid 2 rows of aluminum C channel across left to right. This was to reinforce the bottom and give me a place to mount a trans cooler directly in the airstream.
I added a sheet of ABS to the bottom, then extended that forward and sloped it to meet at a point that was determined by the skid rails that were used as side mounts. I made the 2 side pieces, and used them to attach the edges of the bottom plate with small angle brackets.
Now I collect more air at 20 mph than I used to at 60...cooling takes place faster, and the trans cooler, a/c condensor and radiator all have sufficient fresh air to have way above avg heat exchange. The scoop grounds sometimes, but because its made of ABS it just makes noise...no real damage so far, and these useless Houston streets are as ragged as the mountain roads of Afganistan.

Over all, a dramatic improvement and simple to modify or remove for straight line high speed.
I have also been looking at using a servo to raise or lower the leading edge as needed for low or high speed. Easy enough to engineer now that my bottom shroud is reinforced. A hinge, lever and motor and I have a remote activated air-dam. I'll work on that after I save up enough to buy gas so I can drive the damn thing...

 

BTW... Good Job !

 

Odd that no one has yet popped up with the time-honored "they are supposed to run hot" comment. Must be a shortage of Corvette Kool-Aid somewhere.

But for my part I can't really see how the big mouth approach can do much for a properly-functioning cooling system. Air movement is adequate to keep things in the thermostat-regulated temp range (180-190) while moving, and a larger intake won't make any difference at all when the car is sitting in traffic -- which is when the overheating problem crops up.

I'm very happy with the manual fan switch solution -- cheap, easy to do, and effective.

 

true for many...culprit there is water pump output at idle is minimal...bringing engine speed (rpms) up a bit above idle (if auto trans must be shifted to neutral) will often reduce water temp (some ecm's may turn on MIL if engine speed is above idle for extended period with no signal from VSS of vehicle motion)...simply shifting an auto trans to neutral when stuck in traffic may be effective (engine load is small but ecm adds throttle (IAC) to maintain programmed revs)

'normal abnormality' of water temp is often reported by drag racers at the 'big numbers' end of the strip, with temp returning to 'typical' during the return road 'cruise'.

 

The real test of your DIY big mouth comes at 100+ mph ..... if it stays on ... if it doesn't ...............

 

I have run well over 100mph and I have sprayed nitrous on the engine with it.