facing foward or facing backward.....advantages to both, disadvantages to both? if anyone can help me out with that. i figure that facing foward would get more air, but create more drag, but then i don' t see how any air gets in if it's facing backwards...

 

excerpt from a website

 

Good point's DJ you cover most of what I was going to say. A Forward facing scoop will give you the most ram effect. A rearward facing one will keep more dirt and water out of the engine compartment than the foward one. now to truley get a bonus from forcing air in other than just getting cooler air then you really have to be moving. So chances are with a xB you will never see any advantage to a fwd facing scoop. A rear one will give you some cold air though. Another alternitive is one I haven't seen in years. That is loovers. It wont give you the same effect as a scoop but it will help reduce underhood tempetures and provides good cover for the engine. They also can be stamped into the hood in patterns and look really trick. That and an old school paint job like scallops plus some babay moons would be real trick.

 

thanks for the info guys. how big is the negative effect that the scoops carry? is the benefit worth the drag it causes?

 

I don't think it'll have much negative effect. It's already a brick...

 

i think the only REAL negative will be the flack you'll recieve from all the boneheads out there. stuff like....
"that's not a racecar, so why do you got a scoop", "you're a ricer", and other various insults like those.

 

I think when you are asking about a rear-facing scoop, you mean something like I have on my other car. It looks like this:



The above article describes "cowl induction" which is the only way a rear-facing scoop is going to work to bring cool air into the engine compatrment.

What I have, and I think what you are asking about, is not a rear-facing scoop. It is a vent for removing hot air, not for bringing in cool air.

Cool air flows in through the grille and radiator and flows up and out of the vent, pulling hot air out. When the car is stopped, I can see the waves of hot air rising out through the vent.

The lip on the vent provides a small amount of downforce to the front end.

The downside to the open vent (or a traditional scoop) is that water pours right into the engine compartment when it rains, so placement of the vent and evaluation of the under-hood electricals is important.

-Pete

 

Foward facing scoops (think Subaru Impreza WRX/STi) does brings air into the engine bay, but it all doesn't go into your engine, most of the air has to go somewhere? Where? It hits the firewall and goes under your car, causing a lift and possible hydroplaining in the rain.

Rear facing scoops like the one on the S2000 pictures above doesnt pull air into the engine bay, but rather creates a path for the air to leave the engine bay, therefore the air comes in through the grill, and goes out the scoop rather than under the car. You can also get more downforce from this set up.

For the Scion's you might want a reverse scoop like on the S2000 above, you will get more downforce and your engine will stay much cooler. If you get the foward facing scoop youre gonna hydroplane easier.

 

Good info! This one should be made a "sticky post".

 

woohoo, this is what i was hoping for...good info, thanks guys.

 

You're welcome, glad to know I helped!

 

okay, so if hot air is coming out of the hood, does that fog up your windshield at all?

 

Physics lesson time. Bling-bling folks tune out now...

There is a wonderful physics formula that describes the relationship between height, speed, and pressure. I won't bore you with details, but it basically says that when relative air speed is high, air pressure is low, and when relative air speed is low, air pressure is high.

When your car is sailing along through the air, the relative speed of the air on the outside of the car is high, so if you simply put a hole in the hood air will tend to be pushed out of the hole into the airflow by the greater pressure of the stationary air inside the engine bay.

However, if you come up with a way of stopping the airflow over the hood, the air, in stopping will increase in pressure, making it more likely to find its way into the engine bay.

A forward-facing hood scoop does this task in the obvious way. It creates a barrier that stops the air from moving over the hood, resulting in increased pressure.

You can be a bit sneaky about it and do it with a rear-facing scoop, if you put the inlet of the scoop near the bottom of the windshield. The windshield provides the barrier that stops (partially) the airflow near its base. It's no accident that the air intake for the interior is at the base of the windshield!

A rear-facing scoop near the front of the hood won't work for getting air into the engine bay, but sometimes you see them there for the purpose of getting air out of the bay, or, more likely, just for looks.

There is an _excellent_ intake location on the xB that isn't much discussed. The upper "grille" isn't a grill at all, but a solid panel. It also happens that it is a near-vertical surface, so there is a high stagnation pressure at that location. If you put an air intake in the upper "grille" it will work better than any forward or aft facing scoop you can put on the hood.

In any case, don't expect big pressures from air scoops. The much-touted "Ram Air" scoops of the '60s were good for a couple of horsepower on engines that normally made 300 horses. They were mostly for show, not for go.

George

 

Granted you open the "upper grill" then you get air into the engine bay. Where then, does the air go once it has entered your engine bay? Under the car, causing lift.

Thats why I am getting a reverse hood scoop when I get my CF Hood, and I'll then fabricate a "upper grill" to let air in through the grill and out the rear scoop. I've been planning this since I got the car back in January.

BTW It doesnt matter if air is soming in or out of a rear facing scoop. As long as the air is circulating and isn't going under the car, causing the very much unneeded lift.

 

Here's a couple of quad vent hoods for grand prixs. They both have 4 openings. Two in the front for ram air and two in back for heat removal. All the air that gets rammed in goes to the air box. None is diverted to the firewall and under the car like previuosly stated.

 

Yeah, even John Delorean himself said the ram air scoops that he put on the Pontiac GTO's were just for show and that there position on the hood made them virtually useless above a certain speed which was also a pretty low speed because of the airflows angle over the hood was too high to hit the scoops.

I am not so sure a scoop would look right on a scion. But thats just my opinion. I like the idea of using the upper grill. I checked it out, its just a plastic panel, Im sure you could drill some small inconspicuous holes in it at certain intervals to get more air under the hood. I dont know how well it would work, but its just an idea.

 

You weren't serious with this statement, were you? There's no way a 300lbs+ car would be "lifted" by the pressure going into a hood scoop the size of the one on a WRX. MAYBE if the scoop was as big as the entire hood and you were able to go fast enough.

No. This is a false statement. Omit the hood scoop issue and just look at the front grill of most cars & trucks. If this statement was true, all large-grilled vehicles would hydroplane.

Anyway, you can use scoops to feed CAIs. I did this on my '83 RX7. Worked well.

Enjoy!

 

I think this post may be the dumbest thing I have ever heard in my entire life.

I have had 3 Subarus with Forward Facing scoops... you're not going to get force under the car equal to a Harrier Jet, you are not going to get ANY "lift" from a forward facing scoop.

My god that gave me a good laugh

 

I've heard your not supposed to get water in your wrx scoop when you wash it, is that true?

 

Well what happens when it rains? The car doesn't blow up does it?