ditchlewis
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| posted on 21/11/07 at 10:26 AM |
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Making an air box
The problem I have is that I have a pinto (don’t laugh it’s a boat anchor I know) and it is fitted with a 2.1 pinto and twin 45’s. The engine was
built by Vulcan engineering and was supplied with K & N pan filters 75mm deep and the carbs have been jetted to suite.
When I dropped the engine into the car I found that the carbs sat level with the top chassis rail and so the pan filters would not fit, I removed the
filters and fitted carb socks.
The socks don’t flow air as well as the filters and so I will never be able to tune the carbs to the best without re jetting.
I was thinking (very dangerous thing thinking) is it possible to make an air box and use a ducting and cone air filter to draw in cold air?
I want to make a back plate out of aluminium sheet and then rivet and mastic up a box that bolts to the back plate. I would use a compressible rubber
strip to seal the two together.
The box would be deeper at one end than the other, would this cause a problem?
Would this set up flow more air than the socks?
can anybody see any major problems?
Ditch
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twybrow
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| posted on 21/11/07 at 10:40 AM |
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Shouldn't be any problem. The volume can be quite critical, as can the shape. But when you say on ened is deeper than the other, that is
actually desirable! Quite often, the airbox tapers from the inlet, towards the furtherst away cylinder, to improve even air distribution. Pick up a
copy of G. Bell's book lots of airbox design info in there. Good luck.
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ditchlewis
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| posted on 21/11/07 at 11:33 AM |
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this sounds complicated.
the box would be tapered as i have 60mm clearance between carb face and the chassis rail while the other end there is about 100mm clearance.
good to know that the inlet side should be the shallowest end as i would have put the intake at the other end as it would have allowed a bigger
intake so clanger avoided
what is the title of G. Bells Book?
ditch
oops just re read your reply, i now read it as the narrowest point chould be at the furthest point from the intake. is this correct?
[Edited on 21/11/07 by ditchlewis]
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will121
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| posted on 21/11/07 at 12:30 PM |
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shouldnt be a problem, i made a air box as i didnt want any more holes it the bonnet mine tapers to, with a panel filter in the top which draws cold
air through the old hole in the top of the bonnet where the old down draft filter was. got some pictures somewhere!
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twybrow
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| posted on 21/11/07 at 01:10 PM |
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http://www.amazon.co.uk/Four-stroke-Performance-Tuning-Practical-Guide/dp/1844253147/ref=sr_1_1?ie=UTF8&s=books&qid=1195650257&sr=1-1
This is the book I have, and it is wonderful. Very detailed - sometimes far too much, but with basic engineering principles, you can get your head
around most of the issues. A really good read (although the Mrs will call you a geek!).
Can you see the taper on the airbox in this pic? The further from the inlet, the lower the roof of the airbox. Apparently (if i remmebr correctly from
the book), this has benefits in terms of balancing the volume of air able to enter in a stroke. That is what I am getting at...
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2b_pablo
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| posted on 21/11/07 at 01:16 PM |
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pipercross make one for webers but its pricey. 200 coupons ish
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ditchlewis
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| posted on 21/11/07 at 01:45 PM |
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many thanks.
the pipercross box is 78mm at its narrowest point so it will foul the chassis rail. also the £199 + price tag.
the book and a couple of sheet of aluminium it is.
ditch
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2b_pablo
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| posted on 21/11/07 at 01:52 PM |
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good man, look forward to seeing (stealing) what you come up with 
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Paul TigerB6
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| posted on 21/11/07 at 04:26 PM |
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Is a different manifold not an option to raise the carbs above the chassis rail??
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2b_pablo
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| posted on 21/11/07 at 05:24 PM |
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Ive been after one for ages mate impossible to find
old cortina 6.5" long one is what u want lifts the carbs up
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badding
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| posted on 21/11/07 at 09:43 PM |
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I also made a ustom airbox...some alu, glasfiber and a little patience, cost me about 40 euro...
 
Rescued attachment CIMG1931.jpg
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vinnievector
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| posted on 22/11/07 at 04:18 PM |
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your pinto airbox
The advise for the tapered air box is correct ,as the air at the shallow end will be slightly compressed.
But however i do have another solution to your problem ,i have a manifold 20mm in thickness this should allow you to fit any air box you desire .
will sort out a pick if your int.
20 coupons to you
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Schrodinger
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| posted on 22/11/07 at 06:44 PM |
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I had the same problem with my Tiger Cat and and got a blank back plate and cut the carb mounting holes as far down as possible this cleared the
chassis rail.
Keith
Aviemore
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jacko
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| posted on 22/11/07 at 07:23 PM |
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Air box
Have a look in my photos under zx9r carbs it may help you
Jacko
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will121
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| posted on 22/11/07 at 11:01 PM |
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pic of my air box
 
Rescued attachment air box email.jpg
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Jos Fury
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| posted on 23/11/07 at 07:14 AM |
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I made my airbox from stainless ( thin sheet) and some polycarbonate. just take some cardboard to make a moud. after that you will see it is not so
hard just take your time.
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