Ok, a quick down-n-dirty mini silicone elbow workshop...
03-16-2007, 03:00 PM
#1
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Ok, a quick down-n-dirty mini silicone elbow workshop...
<center><img src="http://pictureposter.audiworld.com/711/silelbow1.jpg"></center><p>
I'm getting too many emails to answer so I'm gonna post this here. The pic above is of the 3" silicone elbow used in the S3 hose kits of yore. It has been cut down to clear the A4/B5 and C4 cars between throttle body and firewall. This is the max that can be cut from the sleeve and still manage to get them clamped on to the throttle body flange securely. If you have 3.10" between the outer rim of your throttle body and firewall this will work for you.
The straight section of tubing coming off the elbow that clamps to the recovery sleeve outlet is left about .180" longer than the straight that clamps to the throttle body straight section. This is done because the sleeve walls flow better than the silicone walls in the elbows (more on that in a subsequent post.
This also shows why I don't like the short silicone elbows with the "bumps" near their inside radius. If that bump is there when you cut your elbows down you cannot get the clamps to tighten on the bumps without them "squishing" the elbow out & away from the throttle body flange seat, pushing it away from the flange seat and nearer (or into) the firewall.
TB= Throttle Body
TBF= Throttle Body Flange width
RS= Recovery sleeve
Pardon the text in this pic as it was all done in " MS paint" (ick!).
I'm getting too many emails to answer so I'm gonna post this here. The pic above is of the 3" silicone elbow used in the S3 hose kits of yore. It has been cut down to clear the A4/B5 and C4 cars between throttle body and firewall. This is the max that can be cut from the sleeve and still manage to get them clamped on to the throttle body flange securely. If you have 3.10" between the outer rim of your throttle body and firewall this will work for you.
The straight section of tubing coming off the elbow that clamps to the recovery sleeve outlet is left about .180" longer than the straight that clamps to the throttle body straight section. This is done because the sleeve walls flow better than the silicone walls in the elbows (more on that in a subsequent post.
This also shows why I don't like the short silicone elbows with the "bumps" near their inside radius. If that bump is there when you cut your elbows down you cannot get the clamps to tighten on the bumps without them "squishing" the elbow out & away from the throttle body flange seat, pushing it away from the flange seat and nearer (or into) the firewall.
TB= Throttle Body
TBF= Throttle Body Flange width
RS= Recovery sleeve
Pardon the text in this pic as it was all done in " MS paint" (ick!).
03-16-2007, 03:12 PM
#2
AudiWorld Super User
Thread Starter
#2: Spend MORE time making your elbow flow than on the entire installation...
<center><img src="http://pictureposter.audiworld.com/711/silelbow3.jpg"></center><p>
of all the other parts of your hose it. It's altogether common for me to spend 3 hours just making an elbow flow.
Short, tight-radius elbows are almost impossible to wrap smoothly for much the same reasons you cant get 2" wide tape to conform and lay flat on a baseball. It's called "compound curvature" and it's a necessary evil when dealing with tight radii.
A peek inside the short elbows will reveal something that looks like the pic below. That just cannot be allowed to remain and live there if "flow" is on the menu.
There's only one way to do this and thats by sanding with a drum (dremel) or flap wheels (die grinder or Foredom type) as you cannot cut this stuff easily with an X-acto knife or razor blade. And yes, it matters! That single ridge in this pic was costing me just under 42CFM of air (between both elbows). It's a dramatic flow impediment! And remember you have TWO silicone elbows to do this on!
of all the other parts of your hose it. It's altogether common for me to spend 3 hours just making an elbow flow.
Short, tight-radius elbows are almost impossible to wrap smoothly for much the same reasons you cant get 2" wide tape to conform and lay flat on a baseball. It's called "compound curvature" and it's a necessary evil when dealing with tight radii.
A peek inside the short elbows will reveal something that looks like the pic below. That just cannot be allowed to remain and live there if "flow" is on the menu.
There's only one way to do this and thats by sanding with a drum (dremel) or flap wheels (die grinder or Foredom type) as you cannot cut this stuff easily with an X-acto knife or razor blade. And yes, it matters! That single ridge in this pic was costing me just under 42CFM of air (between both elbows). It's a dramatic flow impediment! And remember you have TWO silicone elbows to do this on!
03-17-2007, 06:10 AM
#4
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wicked man, the 1st pic is a real handy dandy one, question for ya...
the B5 has more room between the T.B. and firewall right? so you could cut the leg going on to the T.B. a but longer?, right?
03-17-2007, 06:11 AM
#5
AudiWorld Super User
Thread Starter
B5 has "less" room than B4 (if thats what you're referring to) due to dual firewalls
and while most any section of hose "could" be longer you'll never find even one instance when it comes to intake tracts where "longer is better" even if you're only talking 1/4". If you find a spot where you can safely trim 1/32" off a 12V (or any other N/A car) intake tract length, take it!
Secondly, as I mentioned in this post the silicone cannot flow as well as a properly finished and correctly honed internal aluminum sleeve. By leaving the silicone slightly longer you have decreased flow/increased turbulence into the throttle body/plenum. Not a lot but a "measureable" amount. Thirdly, "if you're gonna be a dog, why intentionally choose Chihuahua!?!" ;-)
The "shortest distance" between air-filter and throttle body is to always be preferred.
Secondly, as I mentioned in this post the silicone cannot flow as well as a properly finished and correctly honed internal aluminum sleeve. By leaving the silicone slightly longer you have decreased flow/increased turbulence into the throttle body/plenum. Not a lot but a "measureable" amount. Thirdly, "if you're gonna be a dog, why intentionally choose Chihuahua!?!" ;-)
The "shortest distance" between air-filter and throttle body is to always be preferred.
03-17-2007, 09:13 AM
#7
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Re: Ok, a quick down-n-dirty mini silicone elbow workshop...
<center><img src="http://www.meckisforum.de/phpBB2/album_pic.php?pic_id=11571"></center><p>C4, ABC 2,6l 195HP
intake flows 600cfm @ 24"
(including filter, pipes and short elbow)
intake flows 600cfm @ 24"
(including filter, pipes and short elbow)
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03-18-2007, 03:00 AM
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Pic worked for a couple hours => mysterious, mysterios ???
<center><img src="http://freenet-homepage.de/flowbench/HPIM6167.jpg"></center><p>C4, ABC 2,6l 195HP
intake flows 600cfm @ 24"
(including filter, pipes and short elbow)
intake flows 600cfm @ 24"
(including filter, pipes and short elbow)
