RSTSpeed

iTrader: (4)

First off, these pictures suck; sorry.
Secondly, this is the same BFI that Peter Scott did on PlanetSoarer.com, it just shortened it.

Tools Needed:
10mm socket
Socket wrench
2 Socket extensions (approx. 9" overall)
10mm wrench
2 1/2" hole saw (2 1/4" may work, but I dunno)
Drill
3 Eggcups
Bench grinder
Bench Clamp (dunno if that is what it's actually called)
Old coth/rag
Pliers
Air Compressor (optional)

siniquezu

Cool write up. I have a spare air box if anyone wants to do it.

jet864

Thanks a lot. You always have the great write ups

Where did you get the egg cups from? I remember them being hard to come by stateside.

James

PERRYinLA

How has this changed how your car runs and sounds?

RSTSpeed

iTrader: (4)

Thanks guys!! I apreciate the kind words!

I got the eggcups from a fellow member who got them from another member in Australia, lol. After I did this little project my step-mom said "Oh, we have 9 or 10 of those." I felt dumb; but if she does, I'll try to put them on the market place for a dollar or two, each. We'll see. If I had cut the holes correctly, I think it would have looked fine w/o anthing in them.

Perry - Most noticably, the car is louder. THe idle sounds a little deeper to me, but even my friends have noticed it sound louder under hard acceleration. I Think it has improved throttle response a tad, too. Engine seems to rev quicker. But sound (esp. that sucking whooshy sound when you rev out of gear) is most noticable.

jcm3

great post! Pics helped alot.

SupraCoup3

Very Nice Writeup -- clean pics, easy to follow... can't wait to do it myself.

Philly#1 Lex

iTrader: (2)

If you got any extra cups PM me.

Cant find them anywhere
Philly

RSTSpeed

iTrader: (4)

Thanks guys, glad I could help some people out a bit.

IF (and that seems to be a big IF) I can get my hands on some of those eggcups, I'll let everyone know and I will TRY to remember to PM you, Philly .

lexsoarer400

what difference do the eggcups do?

Buttercup

OOO's and Ahh's

SupraCoup3

Actually, before you oo and ahh, look it up.

http://www.planetsoarer.com/#BFI
http://www.planetsoarer.com/BFI3/bfi3.htm

"Using a hole saw is easier than cutting the whole front of the airbox out. But after cutting a round hole I wanted a neat edge to it. The autospeed.com article on Ballistic Bellmouths was my inspiration - another great idea by Julian Edgar"
http://www.autospeed.com/A_1266/cms/article.html


The purpose is to improve air flow even more with good aerodynamics.

Buttercup

It won't improve aerodynamics. That's only on a tube. This is a bellmouth on a flat wall (the airbox). Not only that but this is a BFI, which uses a ram air effect. That article you linked is using normal aspiration (suction). Even if the bellmouths help smooth out some airflow at the edges, it doesn't have the same amount of surface area as the whole front of the airbox being cut off. Not only that but if you look at the bellmouth, it does have edges on the other side! So the once "smooth" air will get eddied once it leaves the bellmouth.

A better shape would be a big fat cone that stops right in front of the air filter. Although I've never seen the cone I'm thinking of, it's the cone that appears in movies and wraps around the dog's neck.

Here's a good place to start looking up: http://www.grc.nasa.gov/WWW/K-12/airplane/bga.html

SupraCoup3

I was just re-iterating with all my links why the bell mouths were installed. If you read the way the author worded it, he did it as an experiment – it was guess in check as far as how many mouths were needed to ensure there was no pressure drop according to the manometer.

The only real way to tell if the egg cups improve the airflow is to dyno it and run a ¼ mile as well. You can't argue with a print out or a time slip.

I replied to your “oos and ahhs” comment because even if you disagree with an idea, it's always a halfway decent idea not to ridicule and demean the thought process behind it. If you disagree with an idea, explain why beforehand. Let’s keep the discussion intellectual and not resort to short responses that kill the thread.

Honestly speaking, I agree with you -- anything that gets in the way of the surface area of the filter isn't productive. I liked the earlier BFI design better. But as I said earlier, until we can test this on the dyno and a track we won’t really know. The ram-air functionality is a unaccounted for variable when you’re sitting still, so the ¼ mile time slip could be very useful when comparing the different models.

I looked around to see what exactly the egg cups were trying to accomplish, and I came up with a venturi tube. It seems like this is what the egg cup is doing from an aerodynamic standpoint, but my last link seems to show that it’s pretty much useless. I could be wrong on this, so feel free to respond with a useful comment or link!

John

http://www.mste.uiuc.edu/davea/aviat...Principle.html
http://www.ce.utexas.edu/prof/kinnas...i/venturi.html
http://www.centennialofflight.gov/es...tion/TH8G1.htm

RSTSpeed

iTrader: (4)

Yea, Peter Scott used 3 of them instead of two because 2 still wasn't allowing enough airflow. However, he also altered the whole ram air system, where as I just added three holes. Plus, his car is a V8, not the straight-6. 2 might be enough on the SC3, but I dunno.