Hood Vent
Jul 9, 2013, 05:45 PM
#1
Hood Vent
In the quest for frigidity, the next step after the oil cooler is venting the hood. I picked up a donor hood (thank you evom member!). Wanting to put some science into this, I made a project out of it for a bunch of grade 12 tech kids.
We made a 1/2 scale model of the front of an RA. I got a dozen pieces of sheet metal so we could try lots of different combinations of scoops and holes and locations. Some furnace filter material acted as a radiator. We placed wool tufts all over each hood to be able to visualize the airflow as we pushed air at it with two powerful jet fans I borrowed from a restoration company.
Here is one hood configuration:
The kids painted the windshield, and added a bride and groom in the window. They drew the groom smoking a, umm, "cigarette". A really uptight teacher saw it and went nuts, so I painted over it. Hypocrite.
Well, what we observed pretty much followed theory. Remember, we want hot air to get sucked out of the engine bay:
Summary: I chose an Evo 8/9 style vent with no lips in front of it, located about an inch after the radiator (or about 13" back from the front tip of the hood). Yeah, Mitsu designed the evo vents right, of course.
Put painters tape on, use a cardboard template, and mark out the shape.
Ready to cut. Cover the rest of the hood with something.
The 5" angle grinder with 0.090" thick metal cutting wheel did the heavy lifting and the small cutting wheel on the die grinder made some finicky little corner cuts. If you only have one tool, make it the angle grinder.
First cut, I am nervous but the angle grinder goes very straight, it is fast, and not once did it do that dreaded "catch" and wrench itself into the virgin hood material nearby. Awesome. Stop before you get near the corners and use the smaller wheel there.
Complete cutting the hood skin. Don't worry about the big support members underneath, get'em later. Use a 32 tooth per inch hacksaw blade to make the finishing corner cuts.
The hood skin is stuck to the support members with blobs of stiff foam. Gently hit with a wood chisel to unstick them.
The hood is weak mild steel, so use the chisel to break any metal bits that the saws didn't cut through.
I'm going to cut away the outside support members and leave the center one, but trim it's sides down a bit.
That's it for now. Total work about 2.5 hours, being careful. Tomorrow I will deburr. More to come. Sailor Jerry is waiting for me, I'm bringing the cola.
We made a 1/2 scale model of the front of an RA. I got a dozen pieces of sheet metal so we could try lots of different combinations of scoops and holes and locations. Some furnace filter material acted as a radiator. We placed wool tufts all over each hood to be able to visualize the airflow as we pushed air at it with two powerful jet fans I borrowed from a restoration company.
Here is one hood configuration:
The kids painted the windshield, and added a bride and groom in the window. They drew the groom smoking a, umm, "cigarette". A really uptight teacher saw it and went nuts, so I painted over it. Hypocrite.
Well, what we observed pretty much followed theory. Remember, we want hot air to get sucked out of the engine bay:
- A plain hood with no vents actually lifted off its supports due to underhood pressure. This illustrated why the front end gets lighter at speed.
- Vents near the front really drew air out of the engine bay.
- Vents on the sides of the hood sucked air out too, though not as vigourously.
- Vents near the windshield sucked some air into the engine bay.
- Hood scoops in the middle were mostly useless (see the wool tufts getting sucked in).
- A hood scoop facing backward near the windshield drew air into the engine bay.
- Evo 8/9 type raised surfaces (made with clay) located in front of the vent hole introduced a lot of dirty swirly air to the windshield.
- Little vortex generators like an airplane wing has, placed in front of a vent, did smooth the air flow somewhat going to the windshield.
Summary: I chose an Evo 8/9 style vent with no lips in front of it, located about an inch after the radiator (or about 13" back from the front tip of the hood). Yeah, Mitsu designed the evo vents right, of course.
Put painters tape on, use a cardboard template, and mark out the shape.
Ready to cut. Cover the rest of the hood with something.
The 5" angle grinder with 0.090" thick metal cutting wheel did the heavy lifting and the small cutting wheel on the die grinder made some finicky little corner cuts. If you only have one tool, make it the angle grinder.
First cut, I am nervous but the angle grinder goes very straight, it is fast, and not once did it do that dreaded "catch" and wrench itself into the virgin hood material nearby. Awesome. Stop before you get near the corners and use the smaller wheel there.
Complete cutting the hood skin. Don't worry about the big support members underneath, get'em later. Use a 32 tooth per inch hacksaw blade to make the finishing corner cuts.
The hood skin is stuck to the support members with blobs of stiff foam. Gently hit with a wood chisel to unstick them.
The hood is weak mild steel, so use the chisel to break any metal bits that the saws didn't cut through.
I'm going to cut away the outside support members and leave the center one, but trim it's sides down a bit.
That's it for now. Total work about 2.5 hours, being careful. Tomorrow I will deburr. More to come. Sailor Jerry is waiting for me, I'm bringing the cola.
Last edited by RalliartN; Jul 9, 2013 at 05:59 PM.
Jul 9, 2013, 09:42 PM
#3
Epic! 
I can't wait to see more.
I saw a rally lancer where a fabrication company did this to an OZ's hood and they had an insert for the hole. Id like to know where they got that insert from. I seem to remember a GT-A evo 7 getting a similar insert too...
EDIT:: here it is. Second to the last post on that page. https://www.evolutionm.net/forums/sh...=612025&page=2
I can't wait to see more.I saw a rally lancer where a fabrication company did this to an OZ's hood and they had an insert for the hole. Id like to know where they got that insert from. I seem to remember a GT-A evo 7 getting a similar insert too...
EDIT:: here it is. Second to the last post on that page. https://www.evolutionm.net/forums/sh...=612025&page=2
Last edited by bakuro117; Jul 9, 2013 at 09:46 PM.
Jul 10, 2013, 05:01 AM
#5
na zdrowie 
Yes there are inserts available; besides evo styles there is the mustang item that functions similarly: http://www.stage3motorsports.com/100...le-Insert.html
Plastic version: http://www.championmustang.com/moder...c-109_185.html
btw, slats were used instead of mesh in a couple of our hood models and they work well; those mustang slat style vents that go more on the side of the hood would be a decent option.
I decided against an insert because:
Want a flat smooth hood surface around the vent
Want a choice of mesh styles
Want to learn how to properly secure the mesh so we don't have to pull out half a bird
I wanted to keep the center support member for some stiffness and strength (who knows, its probably fine if you cut it away)
That said, a proper insert is a cool useful option if you like it.
Yes there are inserts available; besides evo styles there is the mustang item that functions similarly: http://www.stage3motorsports.com/100...le-Insert.html
Plastic version: http://www.championmustang.com/moder...c-109_185.html
btw, slats were used instead of mesh in a couple of our hood models and they work well; those mustang slat style vents that go more on the side of the hood would be a decent option.
I decided against an insert because:
Want a flat smooth hood surface around the vent
Want a choice of mesh styles
Want to learn how to properly secure the mesh so we don't have to pull out half a bird
I wanted to keep the center support member for some stiffness and strength (who knows, its probably fine if you cut it away)
That said, a proper insert is a cool useful option if you like it.
Last edited by RalliartN; Jul 10, 2013 at 05:09 AM.
Jul 11, 2013, 08:20 AM
#7
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I'm liking this project a lot. I swear, I want to do all the mods that Nick is putting on his Ralliart. I can't wait to get started on mine!
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Jul 11, 2013, 01:27 PM
#8
Update
Today I deburred the structural members without going too crazy on it, and sanded the edges of the vent hole. I painted on some grey primer so rust wouldn't start on these surfaces, since I'm storing it outside now. The vent hole edges are actually really straight, if they don't look like that it's because of the primer that wasn't applied evenly.
I'm trying to find some local grille mesh. I bought some samples from this company in the USA: http://customcargrills.com/
I think their "stacking oval XXL" mesh is stock evo 8/9? The "diamond XXL" is identical in style to our RA front grille. I'm worried about shipping damage en route to Canada. What to do, what to do... anybody in southern Ontario got something nice I can buy?
Regardless, I'm going to install this thing and go to a lapping evening on Monday. I don't care for grille installation or looks right now, just wanna see how it affects engine oil and underhood temperatures.
More later.
I'm trying to find some local grille mesh. I bought some samples from this company in the USA: http://customcargrills.com/
I think their "stacking oval XXL" mesh is stock evo 8/9? The "diamond XXL" is identical in style to our RA front grille. I'm worried about shipping damage en route to Canada. What to do, what to do... anybody in southern Ontario got something nice I can buy?
Regardless, I'm going to install this thing and go to a lapping evening on Monday. I don't care for grille installation or looks right now, just wanna see how it affects engine oil and underhood temperatures.
More later.
Jul 16, 2013, 04:14 AM
#12
Installation and Results
I used this auto body caulking to add some rigidity by squeezing it between the support beams and the hood skin, around the vent hole.
For ten bucks, Red Line Tuning sells a little hood strut kit. I can rivet these ***** onto the new hood and use the struts I already installed before.
Removing the original hood and installing/aligning this one was easier and faster than I thought, about 15 minutes from start to finish.
I drove to the track yesterday afternoon. Driving on the highway for 40 minutes at 120 km/h (about 75 mph), outside air temperature 80F, the oil temperature was spot on 200 degrees. You cannot see the vent at all when sitting inside the car. There is no extra weird noise or fluttering or anything at highway speeds.
After several laps on the 4 km track, the maximum oil temperature was 225F. Wow, I can't believe it's that low on such a hot muggy day. Parking in the pits after, the engine bay cooled down without me having to open the hood.
Considering how well this works, I cannot understand why all "sporty" cars don't have a working hood vent system, with a blocking plate for winter.
Well, all thats left is the aesthetics. Make the exposed support beam look pretty or not? Just leave the hole, or glue in some mesh, or make a nicely framed drop-in? Leave it silver or paint it yellow? I'll finish this post later with those pics.
Who'd have thought there would be so much to say about two simple dumb holes.
For ten bucks, Red Line Tuning sells a little hood strut kit. I can rivet these ***** onto the new hood and use the struts I already installed before.
Removing the original hood and installing/aligning this one was easier and faster than I thought, about 15 minutes from start to finish.
I drove to the track yesterday afternoon. Driving on the highway for 40 minutes at 120 km/h (about 75 mph), outside air temperature 80F, the oil temperature was spot on 200 degrees. You cannot see the vent at all when sitting inside the car. There is no extra weird noise or fluttering or anything at highway speeds.
After several laps on the 4 km track, the maximum oil temperature was 225F. Wow, I can't believe it's that low on such a hot muggy day. Parking in the pits after, the engine bay cooled down without me having to open the hood.
Considering how well this works, I cannot understand why all "sporty" cars don't have a working hood vent system, with a blocking plate for winter.
Well, all thats left is the aesthetics. Make the exposed support beam look pretty or not? Just leave the hole, or glue in some mesh, or make a nicely framed drop-in? Leave it silver or paint it yellow? I'll finish this post later with those pics.
Who'd have thought there would be so much to say about two simple dumb holes.
Jul 17, 2013, 01:57 PM
#13
personally i think it'd look slightly better if you would've made drilled holes at the coners of the so it's rounded on the corners, instead of pointy...but i think it looks BA anyway
but it's your hood...if you like it that's what matters(and if it works too...haha)
it defnetly needs some kind of mesh in it...
tho also i think painting it yellow to math the car would also look better than silver on the yellow car...lol...(or maybe paint it black..?...maybe plastidip so it's cheap/easy/reversibly black?)
ps: i've always wanted to do hoodstrut support for my RA...i did piece together a pair of good used hoodstruts and 3 ball mounts(still needed a 4th tho...all from scrap pieces from used cars from work..."mr mechanic, i need 1 hood strut...mr customer, wanna buy both?, your still good one will likely go weak soon too."...."ok then..SOLD! said mr customer" ) but i never got around to finding where/how to install them so it'd work....
if i woulda've ever gone to a junkyard and LOOKED for parts i'd have done it years ago, for dirt cheap...lol(not that it REALLY serves a purpose...just looks much better than a hood prop)
looked around for kits...but all i found was evo kits that have billet aluminum brackets and sell for ~$250+ or so...i was like..."yeah...NO"
but it's your hood...if you like it that's what matters(and if it works too...haha)
it defnetly needs some kind of mesh in it...
tho also i think painting it yellow to math the car would also look better than silver on the yellow car...lol...(or maybe paint it black..?...maybe plastidip so it's cheap/easy/reversibly black?)
ps: i've always wanted to do hoodstrut support for my RA...i did piece together a pair of good used hoodstruts and 3 ball mounts(still needed a 4th tho...all from scrap pieces from used cars from work..."mr mechanic, i need 1 hood strut...mr customer, wanna buy both?, your still good one will likely go weak soon too."...."ok then..SOLD! said mr customer" ) but i never got around to finding where/how to install them so it'd work....
if i woulda've ever gone to a junkyard and LOOKED for parts i'd have done it years ago, for dirt cheap...lol(not that it REALLY serves a purpose...just looks much better than a hood prop)
looked around for kits...but all i found was evo kits that have billet aluminum brackets and sell for ~$250+ or so...i was like..."yeah...NO"
Last edited by nekkidlad; Jul 17, 2013 at 02:07 PM.
Jul 17, 2013, 07:13 PM
#14
Thanks, Nekkid. I agree with you now that I've looked at the vents for awhile - slightly rounded corners would look better, and the hole does need something, mesh or slats I don't know yet. I'm considering making a thin flat frame, gluing mesh or slats to it, and dropping this home-made insert into the hole to see what that looks like. If its awesome I will post a how-to, and get extra frames made for anyone who wants one.
Yellow paint it is.
btw, go to Red Line Tuning website and look up hood struts for our car (Lancer '02-'06). Then you will see installation instructions in a .pdf file. Those instructions show measurements and locations where to install strut hardware on the hood and on the fender.
Yellow paint it is.
btw, go to Red Line Tuning website and look up hood struts for our car (Lancer '02-'06). Then you will see installation instructions in a .pdf file. Those instructions show measurements and locations where to install strut hardware on the hood and on the fender.
Jul 18, 2013, 06:53 AM
#15
Thanks, Nekkid. I agree with you now that I've looked at the vents for awhile - slightly rounded corners would look better, and the hole does need something, mesh or slats I don't know yet. I'm considering making a thin flat frame, gluing mesh or slats to it, and dropping this home-made insert into the hole to see what that looks like. If its awesome I will post a how-to, and get extra frames made for anyone who wants one.
Yellow paint it is.
btw, go to Red Line Tuning website and look up hood struts for our car (Lancer '02-'06). Then you will see installation instructions in a .pdf file. Those instructions show measurements and locations where to install strut hardware on the hood and on the fender.
Yellow paint it is.
btw, go to Red Line Tuning website and look up hood struts for our car (Lancer '02-'06). Then you will see installation instructions in a .pdf file. Those instructions show measurements and locations where to install strut hardware on the hood and on the fender.
thanks for the info on the hoodstruts...
tho kinda late now...i already traded the car in
...and the vw im in now has them OEbut @ least the info is linked here now if anybody else needs/wants it...
anyway it's not too late to enlarge the hole slightly to get the rounded corners...
if you enlarge the hole by ~1/4in, i'm sure you can get the rounded corners look...and since you haven't made any insert or grille section or it..it won't affect that...
personally i think some kind of drop-in design for the grill would look best...altho maybe when you do make the drop-in thing it's "frame" can have a rounded edge to it and give you that look too(and then you don't have to mess with enlarging or re-shaping the hole)...
maybe paint the frame/grille gloss black and get some contrast going...
gloss black on the yellow would look awesome IMHO...
matte black may look a bit cheap IMO
