Help details of my underbody/front

[NismoMax80]

I plan to finally add my custom underbody tray, seal my radiator, and maybe block my lower grille. looking for anything i missed, or better suggestions.

http://ecomodder.com/forum/showthrea...xima-3467.html
I have 4 holes from the oem one that i can easily attach the center of my tray. i guess i will drill 6 holes into the bottom of my bumper cover to add more push clips.

i had this concern:
http://ecomodder.com/forum/showthrea...sure-3511.html

ideally we want to seal the grille opening to the radiator, then seal/duct work the air to exit into a wheel well. I realized though that my tray will only reach 7" further back. so air should be able to escape.

OEM for me was having airflow sealed into the rad. losing my oem undertray, i plan to install coroplast horizontally from just below the lower grille to the bottom of the radiator. this should help keep pressure off the tray as well.


So then I will have 2 large grilles flowing into my radiator. I originally wanted to block behind just the lower grille.
BUT -
1 i think my sensor located there needs to detect airflow
2 i will still have a pocket trapping some air

i will not seal in front. will i notice a difference blocking compared to the air flowing into the rad? if blocked, air will enter from up top and flow down anyway.

the stock tray and my wheel wells had air dams, but my new bumper is lower than they were anyway. so i think more air dams will be too close to the ground.


Anything i missed? or other tips?
thanks to everyone here already. i learned A LOT more reading.

[NismoMax80]

anyone have an idea which setup would be best for reducing drag?



both options seal the openings to only enter the radiator.
#1 is with both grilles unblocked.
#2 is the bottom grille blocked. BUT will having air collect in the large pocket be any different than it flowing into the radiator? i assume more air will be diverted around the car, but won't that air just go beneath and into the top grille anyway???

[NismoMax80]

Any opinion if i should block the top grille or bottom? using lexan or coroplast?

or block neither?

i am really stuck on this.



i'm thinking that if i block the bottom, more air will get caught in it's pocket, then flow up a bit and right into the top grille with more air getting under the car.

BUT if i block the top one, more air will flow over the car, and less under since it will enter the lower grille and scoop up into the radiator.

does this sound right?

[gascort]

I'm working on the same issue; from my reading, I believe blocking the top is best.

[garys_1k]

Originally Posted by Ville80

Any opinion if i should block the top grille or bottom? using lexan or coroplast?

I like your left diagram with the upper grille block. Sending that air up over the hood is better.

As for lexan or coroplast, your choice -- the air won't care. I find coroplast so simple to work with, and stealthy if you do want to install it on the back of the grille's surface. I've never worked with lexan, though.

[NismoMax80]

good to see others agree with my inclination. top grille it is then.

as for lexan vs coroplast, i will have a piece big enough that is left over from my undertray. so the decision will be purely cosmetic. well it would be lighter too.

black mesh over clear plastic that will reflect light. or black mesh over black. i'm thinking the coroplast will be easier to attach. guess i'm leaning towards spray painted black coroplast behind the top grille. if i don't like it, i'll still have the lexan and can worry about fitting it later if i need to.

local sign shop does not have black. dark blue is my best option i think. that painted black will still be dark when it chips where white will show with wear.


well i can get some coroplast Monday to do the 1st sketch. hopefully soon i will cut and attach the lexan to the underbody! 2 years later. man how much gas $$ could i have saved?

[NismoMax80]

I bought a 4'x8' black sheet. it is now 3x8 so it could fit in my car but has some creases.

i really only need the 1x8 section i cut off anyway. so plenty left for future projects.
I assume everyone installs it horizontally. i think it would be more rigid with the lines vertical, but i'll see. i plan to use black gorilla glue tape. just need to get my lazy butt up early enough since stuff comes up during the day.

[NismoMax80]

well i finished the front today. i'm really surprised how it turned out. i just wish i had the mesh for the bottom 3 holes. that was my 2nd top piece. i almost made a 3rd one, but it's close enough. that was a pain to fit. it's sealed all around with gorilla tape. the bottom center is only taped on the cop center tab. it is wedged in. the sides are taped all around.

now just to measure, cut, and attach my under body polycarbonate piece!

[NismoMax80]

btw, you only see the bottom of my radiator. it is completely exposed to the air flowing up from the bottom. it is sealed off on the sides from the factory. the top has a small opening though for the hood latch. i could reattach a plastic piece that will make that hole smaller. you can kind of see my side holes are closed off now. i know they are small pockets to collect air, but I think that is better than flowing through.

if i was a super fabricator i would use my polycarbonate to cover the fogs over to the center opening. but there's no way i'll try that. heating, shaping, and molding, then attaching are way beyond my capabilities.

[NismoMax80]

can you believe my intake only collects air in between the hood and above the grille? you can see the slot above the grille in the very 1st pic of this thread. it's amazing that enough air flows through that tiny crack. though the intake sucks it in, i'm gonna double check nothing is supposed to enter the now sealed off grille