Go Back   Club Lexus Forums > Lexus Model Forums > SC Models > SC 400/300 > Performance & Maintenance
Sign in using an external account
Register Forgot Password?

BFI thoughts

Reply
 
 
 
 
Thread Tools Search this Thread Display Modes
Old 06-10-14, 11:37 PM   #16
oldManTan
Lexus Test Driver
Trader Score: (0)
 
Join Date: Jan 2014
Location: illinois
Posts: 1,031
Default

the BFI usual method works, so i'm just sitting here thinking why all this lol???
This ad is not displayed to registered members.
Register your free account today and become a member on Club Lexus!
__________________
'92 SC400 Tan on Tan, BFI, Tanabe Medallion exhaust,
Megan Racing EZ Street Coilovers, TechnaFit SS lines, Blue TT Calipers,
A/T Solenoid Bypass, TT Auto Diff, MKIV LCAs,
4300k HIDs, IS300 Steering wheel,
Cobra R Reps 17x9 DZ102 225,45,
hopefully a 5 speed swap in the near future Build Here
Custom Headlights Build
oldManTan is online now   Reply With Quote
Old 06-10-14, 11:49 PM   #17
t2d2
Lexus Test Driver
Trader Score: (4)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 1,209
Default

Quote:
Originally Posted by oldManTan View Post
the BFI usual method works, so i'm just sitting here thinking why all this lol???
The automatic transmission works, but has that stopped you from wanting to improve on it with a manual?
__________________
'94 SC400: Goodkat ... "It's not something people hear about. Falls on deaf ears mostly. This particular one has been over twenty years in the making."
t2d2 is online now   Reply With Quote
Old 06-10-14, 11:59 PM   #18
oldManTan
Lexus Test Driver
Trader Score: (0)
 
Join Date: Jan 2014
Location: illinois
Posts: 1,031
Default

Quote:
Originally Posted by t2d2 View Post
The automatic transmission works, but has that stopped you from wanting to improve on it with a manual?
i doubt any sort of snorkel will ever improve flow because it's exactly that, a snorkel. it's a confined small space and it will be very hard to get it to suck air better than an open chamber of high pressure air. good luck though. i'm interested to see something.
__________________
'92 SC400 Tan on Tan, BFI, Tanabe Medallion exhaust,
Megan Racing EZ Street Coilovers, TechnaFit SS lines, Blue TT Calipers,
A/T Solenoid Bypass, TT Auto Diff, MKIV LCAs,
4300k HIDs, IS300 Steering wheel,
Cobra R Reps 17x9 DZ102 225,45,
hopefully a 5 speed swap in the near future Build Here
Custom Headlights Build
oldManTan is online now   Reply With Quote
Old 06-11-14, 07:53 AM   #19
t2d2
Lexus Test Driver
Trader Score: (4)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 1,209
Default

Quote:
Originally Posted by oldManTan View Post
i doubt any sort of snorkel will ever improve flow because it's exactly that, a snorkel. it's a confined small space and it will be very hard to get it to suck air better than an open chamber of high pressure air. good luck though. i'm interested to see something.
Have you read the whole thread? It's quite clear to me that very little measurement went into designing the typical BFI for ideal airflow. As I said above, it works by blind luck, not by science. That tells me it can be improved upon.

Right from the start, the "B" in BFI tells me it's an erroneous approach. Big has nothing to do with why it's an improvement. The stock snorkel is sufficiently big to provide as much air as the intake tube behind the filter can accept. It's actually 50% bigger, so you could get by with a smaller than stock snorkel and have the same performance as the BFI. It just needs air from a pressurized source. That's probably why Lexus put in an oversized snorkel, since that's low pressure air behind the headlight. That also keeps the filter clean and dry.

Opening up the airbox for a large volume is not the answer. At least, not in anything but a sledgehammer approach. If the BFI were better thought out, it would just be a tweak to the stock snorkel, routing its open front end over to the radiator cowl flap. Admittedly, that's a very tight space to work with and options are limited. Which is exactly why I started this thread to discuss better ways of doing things.

What happens if that radiator cowl flap that is being bent out of position to supply high pressure air somehow fails, either from the bolts loosening up or the plastic itself cracking at the washers? It is subject to very high wind forces in a manner it isn't structurally designed for, after all. Suddenly, you're choking the engine of all airflow, since you've sealed off every other entry point. That's why I said I'm not fond of that approach. If I end up pulling air from there, it'll be with an actual hose dropping down into the bumper opening.

I haven't yet come up with a good plan for how to pull air from the right bumper opening (the intercooler area) and up to the stock airbox without a lot of sharp bends back to the front of the box... There's something workable there, I just haven't settled on what yet.

I'm thinking dual 2" pipes straight up from below, lining up with the bottom of the box. That's just enough space internally to clear the filter. What it would do to airflow characteristics in the box, though, is a tough question. Once pressurized, maybe it doesn't need to point straight at the filter? Dual 2's is a bit on the light side, so I would probably supplement it from an additional hose or two over from the radiator cowl. That should exceed the intake hose's volume further down the line.

I'd also need to cut a new panel to glue in for sealing the stock snorkel on the front of the box, otherwise all that pressurized air just hits the back of the headlight.
__________________
'94 SC400: Goodkat ... "It's not something people hear about. Falls on deaf ears mostly. This particular one has been over twenty years in the making."
t2d2 is online now   Reply With Quote
Old 06-11-14, 12:10 PM   #20
t2d2
Lexus Test Driver
Trader Score: (4)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 1,209
Default

Actually, the stock snorkel isn't quite as low pressure as I was thinking. Looking up into the right side bumper opening, I realized daylight is visible up above. Feeling around in there, that's the snorkel dropping down into that area.

It's up high enough that it probably isn't getting any direct airflow, but at least it has access to a great source of pressurized air. Which leads me to think there's a way simpler solution than I've been trying to come up with: just a modification of the snorkel itself to dip down into that opening and scoop the air up. Seems worth taking the headlight out (which would have answered numerous such questions from the start!) and seeing what I can devise for that.

If I can make that work, it'll maintain the airflow characteristics in the box that it was presumably designed for, but with the addition of higher pressure. It might require some custom hosing to fit the snorkel shape, though.
__________________
'94 SC400: Goodkat ... "It's not something people hear about. Falls on deaf ears mostly. This particular one has been over twenty years in the making."
t2d2 is online now   Reply With Quote
Old 06-11-14, 12:17 PM   #21
Sc400NL
Driver
Trader Score: (0)
 
Sc400NL's Avatar
 
Join Date: Dec 2013
Location: The Netherlands
Posts: 136
Default

sounds like you figure it out T2D2 and i would like to see what you come up with since your story is very sensible too me , keep posting
Sc400NL is offline   Reply With Quote
Old 06-11-14, 01:36 PM   #22
t2d2
Lexus Test Driver
Trader Score: (4)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 1,209
Default

Headlight is out and I now have a clear plan of attack. No need to size a hose to fit the front of the snorkel. Just gotta cap that off and open up the whole bottom of it with a scoop that extends down six plus inches to be directly in the path of the incoming air. Now to figure out materials; maybe find a small airbox at the junk yard and cut that up?
Attached Images
  
__________________
'94 SC400: Goodkat ... "It's not something people hear about. Falls on deaf ears mostly. This particular one has been over twenty years in the making."
t2d2 is online now   Reply With Quote
Old 06-11-14, 03:21 PM   #23
t2d2
Lexus Test Driver
Trader Score: (4)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 1,209
Default

Upon further reflection, I think some PVC pipes up into the snorkel will be much easier, and I might be able to blend some 45 degree elbows in to smooth the air flow back toward the box. The pictures don't show it, but the snorkel has a brace down the middle that splits it into two 2.5" wide chambers. I'm not sure if that was to keep it from collapsing on itself and pinching off air, or if it's to control the size of the intake.

There's almost 6" to work with in front of the horizontal metal bracing below the back portion of the snorkel, so I may try doing two 2-2.5" pipes up into each chamber, one in front of the other, with one pulling air from the lower bumper opening and the other from the higher one.

I assume PVC glue will bond to ABS plastic? If not, I'll have to figure out some other way to fasten the stuff. Maybe I can find a PVC flange that's short enough to slide into the chamber, drop into a cutout, and glue the PVC pipe into it so there's a captive lip up in the snorkel.
__________________
'94 SC400: Goodkat ... "It's not something people hear about. Falls on deaf ears mostly. This particular one has been over twenty years in the making."
t2d2 is online now   Reply With Quote
Old 06-11-14, 03:57 PM   #24
oldManTan
Lexus Test Driver
Trader Score: (0)
 
Join Date: Jan 2014
Location: illinois
Posts: 1,031
Default

the thing about air intakes is, they're pretty pointless. might be different on other cars, but mighty car mods is legit

__________________
'92 SC400 Tan on Tan, BFI, Tanabe Medallion exhaust,
Megan Racing EZ Street Coilovers, TechnaFit SS lines, Blue TT Calipers,
A/T Solenoid Bypass, TT Auto Diff, MKIV LCAs,
4300k HIDs, IS300 Steering wheel,
Cobra R Reps 17x9 DZ102 225,45,
hopefully a 5 speed swap in the near future Build Here
Custom Headlights Build
oldManTan is online now   Reply With Quote
Old 06-11-14, 04:39 PM   #25
t2d2
Lexus Test Driver
Trader Score: (4)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 1,209
Default

Quote:
Originally Posted by oldManTan View Post
the thing about air intakes is, they're pretty pointless.
Did I offend you by questioning the effectiveness of the BFI? First you said it works just fine with the usual design, now you're saying it does nothing. It sounds like you just want to shoot down this thread.
__________________
'94 SC400: Goodkat ... "It's not something people hear about. Falls on deaf ears mostly. This particular one has been over twenty years in the making."
t2d2 is online now   Reply With Quote
Old 06-11-14, 05:00 PM   #26
fried_rice
Pole Position
Trader Score: (20)
 
Join Date: Oct 2007
Location: Houston, TX
Posts: 230
Default

I never really looked where the snorkel went, mines removed. I have an aftermarket filter and no headlights, for weight, space and ease of removal. Definitely better to mod the snorkel than what I previously suggested about cutting a hole.

If you're doing racing or running the car WOT for extended periods of time. Fresh air coming from outside, will be better than hot air from the engine bay. In the video they showed the temp log which stayed at ambient, with fresh air from the fan when they pulled the headlight and also when they put the filter directly in front of the fan with a hose.

If you're on a road course, drag racing or doing multiple highway pulls this would obviously be beneficial.

It may not gain horsepower, but instead would maintain horsepower and possibly lower IAT's a few degrees.
fried_rice is offline   Reply With Quote
Old 06-12-14, 12:34 AM   #27
t2d2
Lexus Test Driver
Trader Score: (4)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 1,209
Default

You've definitely got a more extreme application with racing!

I've been toying around with PVC ideas and have a few workable things I can try assembling, but I decided this evening that's needlessly overcomplicated and did up this mockup. I think it'll work well with ABS plastic and some reinforcements. I'll drop the mockup in tomorrow and see how much height it needs to hit both bumper openings.

The biggest challenge will be getting the various ABS panels to bond. I may have to get some corner brackets and screw them through the ABS pieces.
Attached Images
 
__________________
'94 SC400: Goodkat ... "It's not something people hear about. Falls on deaf ears mostly. This particular one has been over twenty years in the making."
t2d2 is online now   Reply With Quote
Old 06-12-14, 01:53 AM   #28
fried_rice
Pole Position
Trader Score: (20)
 
Join Date: Oct 2007
Location: Houston, TX
Posts: 230
Default

You could also fiberglass the cardboard. It's pretty easy to work with, I made doors, hood and a trunk after a few youtube videos. You can use aluminum strap for lightweight structural support. Woven mat and fiberglass can be purchased at Home Depot/ Lowes pretty inexpensively.

I've used ABS plastic for my front splitter and it's also easy to work with. Fiberglass gives you the option to make any shape or design and will bond to the stock snorkel.
fried_rice is offline   Reply With Quote
Old 06-12-14, 10:11 PM   #29
t2d2
Lexus Test Driver
Trader Score: (4)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 1,209
Default

I didn't have time to finish it up today, but I did a test fit on the car of yesterday's initial cardboard mockup and the ~8" height was way too much to fit into the opening from above. It could probably be done from below, but I didn't want to move the car down the hill to a flat spot for jacking just to test fit, and I didn't want to have to go through that if it required tinkering in the future... So, I did a second mockup with a reduced height by 3" or so.

Actually, I'm getting ahead of myself a bit. I dreamed of building it with stainless steel and woke up excited to put a 22 ga sheet to use that's been collecting dust, and apparently rust, in the garage for who knows how many years. I guess it wasn't stainless... Anyway, I cut a piece of cardboard to the same 24x6" dimensions and worked up some origami magic to see if I could build the whole thing out of a solid piece, rather than cutting panels and trying to fasten them securely against the wind forces.

I used a 6" width for the "duct" and a 107 degree angle to make the shape line up with the not-quite-squared-up dimensions of the snorkel. I left the center ribbing in place on the snorkel and cut out four square-ish pieces, keeping some cross-bracing in place. There should be more than enough air entering the space regardless.

In the second pic, where my hand is, you can see the triangle tip from the marked out measurements didn't cover up the bolt hole, so I modified that for the final cut (next post, can't post all the pics in this one).

Fiberglass is an interesting idea. I've never worked with that before, but I see the potential there. Maybe worth trying next time if a next time is needed.
Attached Images
   
__________________
'94 SC400: Goodkat ... "It's not something people hear about. Falls on deaf ears mostly. This particular one has been over twenty years in the making."
t2d2 is online now   Reply With Quote
Old 06-12-14, 10:18 PM   #30
t2d2
Lexus Test Driver
Trader Score: (4)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 1,209
Default

The rust cleaned up nicely with the brush wheel on the Dremel. I'll hit it with Rustoleum tomorrow. I originally planned on cutting it with a metal blade on the jigsaw but decided a cutting wheel on the Dremel would be easier, given all the contours and bends, and lack of rigidity.

I'll be adding a hole to the curved metal addition so it mounts to the snorkel's bolt on that side, plus anchoring the little extensions to the sides of the snorkel in a few places. I left the back lip of the steel (seen in the first pic) on and folded it under the snorkel, which should help fight the tendency of the wind to push the front of it down.

I'm also going to try lining up a hole with one of the stock intercooler mounting points, once I have it in its final place. That'll anchor the lower portion of the metal and should make it very solid. If I can't do that easily, I may just loop some hanger strap between the two.
Attached Images
   
__________________
'94 SC400: Goodkat ... "It's not something people hear about. Falls on deaf ears mostly. This particular one has been over twenty years in the making."
t2d2 is online now   Reply With Quote
Old 06-12-14, 10:18 PM
 
 
 
 
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Ram air idea (silly?) Celtica Performance & Maintenance 5 02-01-14 08:42 PM
My own sc4 BFI version, not done though. Maik04 Performance & Maintenance 14 08-16-12 05:05 PM
Pictures of my 98 SC400 custom made BFI snorkel--Hope it works!! 98supra6sp Performance & Maintenance 19 04-03-09 11:32 PM
OEM intake w/o snorkel in dusty conditions ndk83 Performance 5 09-03-08 10:44 PM
Intake noise on the cheap... jezza Performance 13 11-15-06 02:00 PM


Tags
bfi, club, forum, lexus

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

All times are GMT -7. The time now is 02:02 PM.

Join ClubLexus
Advertising


Copyright © 2000-2008 Internet Brands, Inc. All Rights Reserved
Privacy Policy | Disclaimer | Terms of Use | JOBS


Get all contact info