Well i have been doing some reading the last few weeks on car aero and more in particular hoods
What i found was the goal of any aero was
decrease drag
decrease lift
increase down force
decrease engine bay temps?
Correct?
Anyways i figured my car body wise is a piece of junk and its perfect for experimenting.
My s13 is a pignose and with a front mount i can’t see much air circulation making it into the engine and significant pressure build up resulting in air eventually rising in temps and being passed under the car creating lift.
Ok here is the point were u can tell me if im just being a ricer or if im actually trying to apply factual theories
Cars have numerous high pressure and low pressure zones, and the goal would be to dissipate high pressure zones into low pressure zones correct?
Anyways i figure lets apply some new found knowledge to my hood.
At the front right side (right=hotside) of the hood i figure if i cut a vent it will allow high pressure ambient air into the engine bay. Downside would be pressure build up. Next Step
At the middle portion of the hood as it levels off i would cut slits that would be bent outwards. This would then cause outside air passing over the hood to create a low pressure zone behind the bent slits allowing the pressure within the engine bay to pass upwards and out. Reducing lift from engine bay pressure and potentially reducing temps. Not this slits are similar to what see on the tops of wheel wells on LeMans vehicles, vipers, and others.
i don’t drive my car in the rain… well can’t… no wipers
You are right about the water issue, but i think it mite make things complicated so i won’t touch on it. PLus i think this is more for a strictly race app.
Actually i did think about it and it would the high pressure vent that would be the issue cause my intake is right there. So potentially some sort of fine mesh (basically acts like filter, won’t be a good one however). Relocate my intake.
What kind of vents are you doing to your hood? Stealing my design?
i like it… i wouldnt be concerned about water to much, if it really does get hot then it should evaporate. just locate a scoop right above the turbo so all the air is forced on it cooling it and not into your intake.
and for the slitsl, put them about 5inches from your windsheild and you should be gravy
i power wash my motor no prob with water, i have also thought this threw a few times and have a few ideas. i seen a nice scoop on another car im thinkin of using. ill let you know if i actually decide on cutting my silvia hood LOL!
so far ive done this scoop on my silvia to keep it cool at the track , originally planned for my top mount setup i reverted back to a low mount but i am soon to do too more little duckts , probably flat triangle designs with mesh , up front over the headlights to help the cold air intake on the passanger side , and bov on the driver side.
p.s. this car rarely ever is in rain.
180’s 200’s didnt come with a hood scoop.
The only reason why the subarus / mazdas etc had hood scoops were to get air directly to their the top mount intercooler.
a hood scoop is probaly the last thing on the list of mods on my car im gonna get nailed for, some factory cars come with em LOL not in anyway illegal ? curious to know the logic behind that call?
i agree the hood scopp is probably the last thing i get pulled over for, especially considering its not like those big massive ones u see on ricers.
the two on nico i believe are not effective, the center hood possibly yes, but it depends on the air flow directly behind the rad. But i don’t believe that one is the best. The spacers lifting the back of the hood up is not good except at very low speeds. Thats actually a high pressure air zone so in driving conditions that will actually allow air pressure in. Stop and go traffic sure it will work, but on a track i don’t think it will be effective
yea mohawk… im an idiot and i always forget his name. I think hes a v-dub guy can’t remember.
your theory is all dependent on the what the pressures are IN the engine bay at speed. it may be that your bay will have a higher pressure then the area where your 'intake ’ is…
The only way to make this system work 100% of the time is to make it a close system, so that the air coming into the air filer is ONLY coming from that duct… and you don’t need a scoop or any of that rice/grade 5 cool beans trash… a NACA duct or constant volume duct will work 100%++ better and NOT be a heat magnet in the process.
Just to clear some things up so IF your talking to someone educated in physics and/or rng. … aero does not reduce lift. and there is no such thing as down force… it’s called negative lift ( this relates back to the first correction )
With reference to this post, the two best ways to reduce drag on your car; make the front bumper as seamless as possible and don’t cut holes in your hood…
im not really trying to provide the intake with a “cold air intake” it just so happens to be on the hot side. Now the only place for air to travel into the bay currently is through the fmic, then the rad, increasing in temps, then circulate through the engine bay building up pressure and more temps from passing through the bay and finally exiting through the bottom of the bay creating lift.
I don’t think its possible for the pressure inside the bay to exceed the front air pressure of the vehicle.
However i still don’t know what would be the best way to alter the current flow of air in the bay.
it actualy increases drag on the car by cooling the top of the engine bay…
when the engine bay is not hot the cold air running under the car runs up into it as well as down into it from the hood…
then the engine bay is sealed and hot, cold air naturaly is always lower than hot air. so the air going under your car goes stright back and not up. there for giving you better areo because theres no hood vents. know what im saying?
ok i understand it will cause drag. And i think i understand what u r saying and that does seem right. I also think that sacrificing drag on the top would decrease overall drag in my theory. I do agree that the vents will cause more drag then a stock hood.
Now in question to what u said. If the cold air passing under the car flows faster and faster does it not create a vacuum like effect sucking air from above and out below the car. Plus any pressure in the bay it would help exit out below. Now this would be good for cooling but horrible because it would cause lift especially at high speeds.
Now the slits on the top of the hood that i added would be bent upwards causing drag however creating a vacuum sucking air upwards just as air is sucked under.
Also note that doesn’t drag in specific places also causes negative lift. example “spoilers, lips, splitters, valances” (correct me if i’m wrong)
