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Old 06-09-14, 04:54 PM   #1
t2d2
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Default BFI thoughts

I started in on this in one of the BFI (air intake) threads and it didn't gain any traction... It seems to me that the airflow of the BFI designs is misleading and that opening up the whole front of the box isn't adding much more air than just the stock snorkel, due to the limitations of the space being modified behind the headlight.

Additionally, the snorkel is as big as the tube leaving the filter, so the idea that adding more air is the key doesn't make a whole lot of sense.

Looking at things closer, I think the real issue is the snorkel pulls air in from a low pressure area. Diverting flow from the radiator doesn't add air volume so much as it adds much higher pressure air. Which leads me to think the cleanest solution is to route the stock snorkel over to the radiator cowl and cut a hole in that to drop an extended hose down into the grill opening. The challenge is getting something over there through the tight space between the headlight and radiator support. I'm still working on that...

I suppose that's not a whole lot different than lowering the radiator cowl's flap like described here:

http://planetsoarer.com/BFIHardware/BFIHardware.html

It just seems cleaner than bending an aero piece into a shape it wasn't designed for.

To skip over the brainstorming and go straight to the eventual mod, jump ahead to post #27.
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Old 06-09-14, 04:59 PM   #2
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These are the ideas I mentioned in another thread for where to route a secondary source of air to tap into the front of the air box, above the stock snorkel. That opening is just below and in front of the sway bar, seen from the bumper opening below the headlight. I imagine it would be sufficiently high pressure if whatever hose was inserted there could be affixed to face forward.

Possibilities for what type of hose include 2.5" shopvac hose, chopped up garden hose, etc., attached to an ABS plate that could be clamped down in that opening that I assume is the RHD symmetrical equivalent of the oil cooler. If going with one bigger hose, the best I've come up with is cutting out the forward most support leg of the power steering reservoir, as shown in the second picture. I don't think that would have any structural impact, but it's a rather permanent experiment.
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Old 06-09-14, 05:11 PM   #3
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I have the eBay BFI (same one as you linked to above) and it seems to work perfectly fine on my '99. To be honest I'm kinda having a hard time seeing how you're ideas would be a real improvement over what is essentially a big hole in the air box.
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Old 06-09-14, 05:24 PM   #4
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That's the same guy as the eBay kit?

I'm not really saying my ideas above are an improvement (other than I'm not crazy about bending back the radiator cowl like that, even if it supposedly holds up just fine), just that the rationale behind why the BFI works seems erroneous. In which case, why not look for alternative ways to accomplish the same thing, i.e., higher air pressure than stock routing?
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Old 06-09-14, 07:19 PM   #5
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I dont know if its the same guy or not, but its the same product.
And I really dont see anything wrong with the way it is routed, the air is forced through the front corner of your bumper and routed up underneath the headlight, and straight into a compartment made to surround the stock air intake. Its the most direct route available unless you get rid of the headlight.
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Old 06-09-14, 07:23 PM   #6
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It seems like a lot of work for little gain. I've cut a big hole in the airbox but I never tested it back to back. I haven't searched but I would assume 1-5rwhp increase, which I wouldn't be able to tell the difference anyways.

Here's an idea, get a Soarer or MKIV Supra SMIC ducting and place it in the stock location under the headlight. Drill a 3" hole where the stock air filter is and run a pipe down. Cut your stock air box and seal it to the ducting. Be prepared to clean your filter weekly, lol.
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Old 06-09-14, 08:03 PM   #7
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Quote:
Originally Posted by scENFORCER View Post
And I really dont see anything wrong with the way it is routed, the air is forced through the front corner of your bumper and routed up underneath the headlight, and straight into a compartment made to surround the stock air intake. Its the most direct route available unless you get rid of the headlight.
My issue is with the bending back of that flap in the bumper, not with the routing after that. All that the stock intake snorkel needs, IMO, is more air pressure. (Today was the first time I felt around in there to figure out where it feeds from, and was surprised that it's just an open end behind the headlight.) The various BFI designs that funnel a large volume in with sealed side and top pieces aren't really accomplishing anything that a single tube the same size of the snorkel would accomplish if routed directly to that radiator/bumper area.

Consider the planetsoarer.com page's part about opening up the flap further having no additional benefit. That's because the intake can't flow any more air! It's already maxed out by the size of the main tube and snorkel, as long as enough air enters the box in the first place.

To clarify, I'm not questioning the effectiveness of the BFI. I just think the benefits of the design are more luck than science. I'm merely wondering if there's a better way to get to the same point.

Quote:
Originally Posted by fried_rice View Post
It seems like a lot of work for little gain. I've cut a big hole in the airbox but I never tested it back to back. I haven't searched but I would assume 1-5rwhp increase, which I wouldn't be able to tell the difference anyways.
Leaving just an opening on the front of it above the snorkel to pull in more low pressure air? I wouldn't be surprised if that gets you to a very similar point as the BFI, although it could allow engine heat in.

Quote:
Here's an idea, get a Soarer or MKIV Supra SMIC ducting and place it in the stock location under the headlight. Drill a 3" hole where the stock air filter is and run a pipe down. Cut your stock air box and seal it to the ducting. Be prepared to clean your filter weekly, lol.
Do you happen to know of a picture of what that ducting looks like? Is there any structural purpose to the shelf the air box sits on? Why would that require regular filter cleaning when a BFI from the radiator wouldn't? (I haven't figured out yet what about that design supposedly allows debris to drop out of air flow.)
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Performance: Alternative BFI (BeeFI?), A/T Solenoid Bypass, M2/Manzo axleback exhaust (awaiting mid-pipe resonator delete), 2-Tone Driver's Seat ("performance" as measured by the butt test).
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Old 06-09-14, 09:36 PM   #8
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The stock intercooler has oem mount holes in the SC chasis. Though you would need to make a bracket to hold the airbox in place, but that could easily be done with with a trip to Home Depot or Lowes for some drilled metal straps. This ducting would pressurize the box at high speeds, in theory, if it was completely sealed. Which in my opinion would be more beneficial than any other ideas I've seen. If it's good enough for 450RWHP with the stock intercooler it's good enough for an intake.

Due to the lower placement of the box and openness to the rocks and dust that are on the roads, it would be more likely to suck in debris than in a higher placed location. A mesh screen would keep bigger rocks out, but may hurt flow a bit. That's the best flowing intake I can think of if you're really serious.Toyota designed and wind tunneled this specific location.


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Old 06-10-14, 12:00 AM   #9
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Aha, so the hole I highlighted in the picture in post #2 is for the intercooler's side pipe? You're suggesting to mount the entire airbox down in the intercooler location and then pipe a duct up to the rest of the air intake (at the MAF)? I hadn't thought of doing it that way... I suppose that could solve the problem of how to squeeze a duct from down there up around to the front of the stock airbox. Remove the stock box from the equation and that frees up a bunch of room. It would make filter changes a lot less fun, though.

In your second pic, where does the intercooler's top pipe go? I haven't noticed any openings in that area. Is that the one you were saying would require cutting a new hole?

I definitely like where you're going with it, as that's the space I keep coming back to as ideal for routing air to the intake.
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Old 06-10-14, 01:47 AM   #10
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I have a all of the MKIV TT air box pieces (not on my car) if you need some reference photos. All of those parts bolt right into the SC chassis. I am sure the Soarer TT air box parts differed little if at all. You can't use a TT air box on an NA engined car but if it helps get ideas I don't mind posting.
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Old 06-10-14, 07:21 AM   #11
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That would be great if you could add a few pics, thanks. It might help flesh out mounting and routing options.
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Old 06-10-14, 09:00 AM   #12
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I was suggesting moving the complete stock aribox to the SMIC location, cutting the front portion of the stock airbox to expose the entire filter, and then attaching the ducting to the front of the stock air box. But you could also make a box that fits the SMIC ducting that will ram air into the filter somewhere else inline. The MAF will also be inline somewhere else.

Basically just trying to use the oem wind tunneled space, so the air is rammed into the intake with no other place to go. Aerodynamics from what I've read is very hypothetical without flow meters or wind tunnels. This is a proven location with the proper ducting.

This is what I did on a previous car to route the 3" intercooler pipe to the location I'm talking about. I used a hole saw to drill the hole.
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Old 06-10-14, 10:54 AM   #13
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I like proven locations. So, there's no harm (structural) in cutting a hole in the horizontal shelf the stock airbox sits on? That would make for a pretty direct route up into the airbox, with PVC options of 3", 4", or 6" being easy to rig up.
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Old 06-10-14, 11:25 AM   #14
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No structural problems at all with just a hole. You have the front frame rail right next to it. I road raced this car many track days. I've seen many others do this on either side for piping.

Edit:
If you just want to duct it you can get brake ducts many places and some kind of hose (high temp brake hose in the picture). I'm installing these in this same location. Don't mind the LS1 they're sitting on.


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Old 06-10-14, 11:32 AM   #15
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No structural problems at all with just a hole. You have the front frame rail right next to it. I road raced this car many track days. I've seen many others do this on either side for piping.
Cool, thanks. I don't like cutting away metal without knowing the full purpose of it. Looks like it may be time to get the car up on jacks and take some measurements underneath.
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Old 06-10-14, 11:32 AM
 
 
 
 
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