Undercover replacement...
- Thread starter sathu
- Start date
albertmdh said:
and WD-40, tightin dem bitches up. thow sum zipt ies on th'a damn cuva and ya gotcha self a new cuva
hell yea
yee haw.
WTF.
:3d_frown:
Adjuster
Supramania Contributor
At minimum, you need to close off the area from the grille opening to the lower core support tie bar. Best is like the stocker that goes back to the crossmember and around the oil pan slightly.
This keeps air from dumping down under the car, especially at speed. In traffic, it also keeps your fan from pushing too much air back through the radiator/condensor and other coolers. Stand infront of your car on a hot day with the AC on, and all the fans running. If you have this cover off, there is quite a bit of air being blown forward. This is not a good idea, as those fans are supposed to pull or push air towards the rear of the car. Any air you feel being blown forward is lost energy and cooling that might cause a problem.
Last but not least, is the downforce effect you lose without the cover on there.
Air reacts much like any other fluid/gas. It takes the path of least resistance. If you place a cooler into the air flow, the path of least resistance is not to go through the cooler, but around it.
On this same note, the air that does make it through the grille opening, now has the opportunity to either go through your FMIC/oil cooler/Condensor/radiator, or just dump down under the car... Which way do you think it's going to go?
That same air is now adding lift to the nose of the car. It can build up pressure there, and since the air going smoothly over the curved hood (like the curve of an airplane wing...) creates a low pressure area, your car's front end starts to lift a high speeds.
The stock undertray smooths out the air that does get under the car, and limits the air that dumps down from the grille inlet, and forces more of it to go through the coolers where it's usefull.
This also creates a low pressure area at the rear of the oil pan, and that helps to draw the hot air out of the engine bay, and away from the car. This is a good detail too for downforce.
Low pressure always wants to be filled by higher pressure air. Always.
This is why simple vents in the front of the hood will draw air out of the engine bay. And why your car has airflow from the HVAC vents at highway speeds even when your fan is off. (The screen vents at the base of the windshield is a high pressure area, and that forces air into the car via the HVAC system since the car also has vents to pull air out of the car at the C posts. (Just behind your glass in that low pressure area.)
Many cars with frameless glass will suck the windows out at high speeds due to this low pressure area over the side glass. Our cars generally control this very well, but the low pressure area still exists.
Best option would be a undertray/splitter design. It would enhance the downforce, and keep more air going into the grille, and less under the car. Best option is to make the splitter at minimum the distance of the front bumper, and even sticking out further is better, but becomes non-streetable at the extreme.
Good thing is the MK3 is a nice areodynamic design from the start, so you really have to screw with it to make it perform poorly. (I've owned older muscle cars that at 115mph were taking off on the front end. The Supra with or without the tray is still rock solid at that speed. It is better with the tray on there however. Experiment with it if you don't belive me.) Also, due to the downforce created by the tray, you need to make sure it's attached well, or it will rip off at speed.
Good luck.
This keeps air from dumping down under the car, especially at speed. In traffic, it also keeps your fan from pushing too much air back through the radiator/condensor and other coolers. Stand infront of your car on a hot day with the AC on, and all the fans running. If you have this cover off, there is quite a bit of air being blown forward. This is not a good idea, as those fans are supposed to pull or push air towards the rear of the car. Any air you feel being blown forward is lost energy and cooling that might cause a problem.
Last but not least, is the downforce effect you lose without the cover on there.
Air reacts much like any other fluid/gas. It takes the path of least resistance. If you place a cooler into the air flow, the path of least resistance is not to go through the cooler, but around it.
On this same note, the air that does make it through the grille opening, now has the opportunity to either go through your FMIC/oil cooler/Condensor/radiator, or just dump down under the car... Which way do you think it's going to go?
That same air is now adding lift to the nose of the car. It can build up pressure there, and since the air going smoothly over the curved hood (like the curve of an airplane wing...) creates a low pressure area, your car's front end starts to lift a high speeds.
The stock undertray smooths out the air that does get under the car, and limits the air that dumps down from the grille inlet, and forces more of it to go through the coolers where it's usefull.
This also creates a low pressure area at the rear of the oil pan, and that helps to draw the hot air out of the engine bay, and away from the car. This is a good detail too for downforce.
Low pressure always wants to be filled by higher pressure air. Always.
This is why simple vents in the front of the hood will draw air out of the engine bay. And why your car has airflow from the HVAC vents at highway speeds even when your fan is off. (The screen vents at the base of the windshield is a high pressure area, and that forces air into the car via the HVAC system since the car also has vents to pull air out of the car at the C posts. (Just behind your glass in that low pressure area.)
Many cars with frameless glass will suck the windows out at high speeds due to this low pressure area over the side glass. Our cars generally control this very well, but the low pressure area still exists.
Best option would be a undertray/splitter design. It would enhance the downforce, and keep more air going into the grille, and less under the car. Best option is to make the splitter at minimum the distance of the front bumper, and even sticking out further is better, but becomes non-streetable at the extreme.
Good thing is the MK3 is a nice areodynamic design from the start, so you really have to screw with it to make it perform poorly. (I've owned older muscle cars that at 115mph were taking off on the front end. The Supra with or without the tray is still rock solid at that speed. It is better with the tray on there however. Experiment with it if you don't belive me.) Also, due to the downforce created by the tray, you need to make sure it's attached well, or it will rip off at speed.
Good luck.
CTsupra
Supramania Contributor
Damn good post Adjuster!
What do you think of the do-luck front splitter? Or, anybody for that matter. Does anybody have it, or have experimented with it?
I wonder if it will provide the cooling effects just like the stocker, and if actually does what it is designed for with helping under car aerodynamics.
I'am all about front and rear diffusers for our cars. If somebody could ome up with funtional ones, that would be kick ass.
What do you think of the do-luck front splitter? Or, anybody for that matter. Does anybody have it, or have experimented with it?
I wonder if it will provide the cooling effects just like the stocker, and if actually does what it is designed for with helping under car aerodynamics.
I'am all about front and rear diffusers for our cars. If somebody could ome up with funtional ones, that would be kick ass.
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The minimum piece would be the one between the very front of bumper, and back to the metal framework under the radiator. This will force the air coming in the front grill area to go into, and thru, the radiator. Mine ran noticeably cooler when I made one out of galvanized sheet metal. (approx $ 5).
I believe the factory undercover had louvers in them to let the air out of the engine compartment. And it stopped about 1/2 way back. Does anyone have a photo???
You MUST let the air out, so it will flow thru the radiator. Otherwise you build up a 'back-pressure' in the engine compartment, which will lead to over-heating.
I believe the factory undercover had louvers in them to let the air out of the engine compartment. And it stopped about 1/2 way back. Does anyone have a photo???
You MUST let the air out, so it will flow thru the radiator. Otherwise you build up a 'back-pressure' in the engine compartment, which will lead to over-heating.
Well, after 3 days of searching I finally found a good and cheap replacement for the plastic undercover. You can get this at HomeDepot in the window flashing section. A 36x48 piece of galvernize sheet metal for 13$ with tax, that is much cheaper than any other stuff out there.
There was a problem in getting this because most store were sold out so I had to get it from a store that has the least customer
. So I got one yesterday, take out the plastic and draw the outline on it to make a template. I also leave room on the side and front for better mounting hole and to be able to bend the side up to attach it to the stock hole.
The fine tunning of the side took me an hour as I just lay down there with my sheet metal scissor to cut it and bend it and my metal drill bit to drill the hole and put it on. If you have old mounting hole, they might bend and don't line up right so more time is needed to get the bolt in.
For the front, there were 3 bolt but I didn't use those. I bolt them between the metal piece and the bumper with the 3 bolts. You can bolt them to 5 if you want, just make sure not to cut the front too small like I did.
Finish it and took it out for a ride to see if it flex and bend and make those thunder noise. No noise as far as I can hear it doing 40 and on freeway at 70. Temp still remain the same after driving, metal feel warm to the touch after, same thing with the plastic anyway.
It not really hot out today so I can't really take it out for a ride to see how it react on hot weather yet. It suppose to be sunny and warm tomorrow, so I'll be doing the run on the freeway tomorrow and see how it do.
Edit: The original plastic has hole and cut in it but I didn't do any of that for the sheet metal. I was gona do it but right now it's just up there for test. If it does overheat and what not, some mod will probably be req to control the air flow out of the engine bay.
There was a problem in getting this because most store were sold out so I had to get it from a store that has the least customer
. So I got one yesterday, take out the plastic and draw the outline on it to make a template. I also leave room on the side and front for better mounting hole and to be able to bend the side up to attach it to the stock hole.The fine tunning of the side took me an hour as I just lay down there with my sheet metal scissor to cut it and bend it and my metal drill bit to drill the hole and put it on. If you have old mounting hole, they might bend and don't line up right so more time is needed to get the bolt in.
For the front, there were 3 bolt but I didn't use those. I bolt them between the metal piece and the bumper with the 3 bolts. You can bolt them to 5 if you want, just make sure not to cut the front too small like I did.
Finish it and took it out for a ride to see if it flex and bend and make those thunder noise
. No noise as far as I can hear it doing 40 and on freeway at 70. Temp still remain the same after driving, metal feel warm to the touch after, same thing with the plastic anyway.It not really hot out today so I can't really take it out for a ride to see how it react on hot weather yet. It suppose to be sunny and warm tomorrow, so I'll be doing the run on the freeway tomorrow and see how it do.
Edit: The original plastic has hole and cut in it but I didn't do any of that for the sheet metal. I was gona do it but right now it's just up there for test
. If it does overheat and what not, some mod will probably be req to control the air flow out of the engine bay.
CTsupra
Supramania Contributor
Here are the pics, the edge of the sheet metal is still rough from my cutout yester. It working fine right now so I am not gona take it down and smooth it out. If I do some work that require to remove it I'll smooth it out then .
The left and right side doesn't required all that metal for the bolt to be mounted, but when I did the template I left that much space to do adjustment, make thing easier incase you accidentally undercut and scrap the metal and buy a new one.
.The left and right side doesn't required all that metal for the bolt to be mounted, but when I did the template I left that much space to do adjustment, make thing easier incase you accidentally undercut and scrap the metal and buy a new one.
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CTsupra
Supramania Contributor
Cool! Looks good! Different.
Thanks for the pics
Let us know if the car overheats or not without cutting holes, or making louvers in the aluminum for air flow.
edit: i'd much rather take that thing off then the stupid giant ass plastic piece and two smaller ones everytime you need to work under the car.
Thanks for the pics
Let us know if the car overheats or not without cutting holes, or making louvers in the aluminum for air flow.
edit: i'd much rather take that thing off then the stupid giant ass plastic piece and two smaller ones everytime you need to work under the car.
I guess you can take them off during summer and fall when there is no rain. Unless you live in a place with minimal rainfall. I am not sure if the two on the side suppose to help cool the brake or not. Having the undercover on would be safe for those who drinve on muddy and rocky road. It help keep the rock out of the belts and prevent some unfortunate accident if the belts brake. You never know what kind of junk is on the freeway when drive over them.
sathu!
quite impressive! i've been thinking of this for quite some time now, and i believe now, i have the energy to do so. that is very nice work there. perhaps a few louvers under there where the stock one has them? not sure. i had entertained the idea of creating a complete underbody sheetmetal liner of sorts. air would fly through it...
of course, it may never happen. i would do as adjuster suggests and add a splitter up there. it wouldnt be a waste of time, as it would be functional... just a thought. good work though. i'm glad someone took the initiative to try something new out.
quite impressive! i've been thinking of this for quite some time now, and i believe now, i have the energy to do so. that is very nice work there. perhaps a few louvers under there where the stock one has them? not sure. i had entertained the idea of creating a complete underbody sheetmetal liner of sorts. air would fly through it...
of course, it may never happen. i would do as adjuster suggests and add a splitter up there. it wouldnt be a waste of time, as it would be functional... just a thought. good work though. i'm glad someone took the initiative to try something new out.
I took mine off couple of weeks after I first got the car. No differance. I should put it back on but will have to mod it as my FMIC hangs a little lower then the stock one ever did. Awsome work though
I was going 130mph... and mine ripped off, bent the brackets under my front lip.. and drug it under my car for 4-5 miles before i noticed that the WOOSSSHHHHHH noise wasnt the wind in my windows
I think my car runs cooler without it though.. I often feel like my car is running too cool, or just lying to me. AL would be awesome looking.. probably be pretty loud on loose gravel roads..
I think my car runs cooler without it though.. I often feel like my car is running too cool, or just lying to me. AL would be awesome looking.. probably be pretty loud on loose gravel roads..
Looks good Sathu.
Curious though, did you block off the gap under the radiator somehow? That cross beam is a lot higher than your sheetmetal, and leaving it open would defeat any improvements with the undercover.
Air is like water, if it can leak out of somewhere, it will. You have to force it with brutal authority through where you want it to go.
The large oval holes in the stock piece are probably just to get rid of large amounts of water quickly. Otherwise it will rip off the undercover due to the large area, and rather weak mounting. Should be okay with the steel there. The less holes the better.
By the way, the thermostat controls your cooling unless it is fully open. You cannot judge the engine cooling by looking at your coolant gauge, since the thermostat will override any improvements. But rest assured, if you force the air through the heat exchangers (radiator, intercooler, oil cooler, A/C condenser) they will all work much better. Plus you reduce overall drag on the vehicle, and get some downforce in the bargain. Static pressure acts in all directions equally (like inside a balloon). If you give it a surface to push against, it will. Since the undercover is on the bottom, the pressure is pushing down, hence extra downforce. Basically all there is to it. If you don't have the undercover, it will just push up against the underside of the hood. Hence lift. The two will cancel each other with an undercover, but less lift is the same as more downforce.
Curious though, did you block off the gap under the radiator somehow? That cross beam is a lot higher than your sheetmetal, and leaving it open would defeat any improvements with the undercover.
Air is like water, if it can leak out of somewhere, it will. You have to force it with brutal authority through where you want it to go.
The large oval holes in the stock piece are probably just to get rid of large amounts of water quickly. Otherwise it will rip off the undercover due to the large area, and rather weak mounting. Should be okay with the steel there. The less holes the better.
By the way, the thermostat controls your cooling unless it is fully open. You cannot judge the engine cooling by looking at your coolant gauge, since the thermostat will override any improvements. But rest assured, if you force the air through the heat exchangers (radiator, intercooler, oil cooler, A/C condenser) they will all work much better. Plus you reduce overall drag on the vehicle, and get some downforce in the bargain. Static pressure acts in all directions equally (like inside a balloon). If you give it a surface to push against, it will. Since the undercover is on the bottom, the pressure is pushing down, hence extra downforce. Basically all there is to it. If you don't have the undercover, it will just push up against the underside of the hood. Hence lift. The two will cancel each other with an undercover, but less lift is the same as more downforce.
The new undercover is a one large piece. I didn't connect the piece to the 3 mounting hole behind the radiator. On the side the metal is bend upward with a curb instead of an actualy straigh cut. I am not sure if u can see it in the side picture or not.