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Posted:
Mon Sep 08, 2008 10:56 pmby 106-1194218389
I ran into a great article on Pro. Blairs site about the shapes for the bellmouth on the intake side of an engine. I was looking for this to help design the bell mouth on some injector stacks. Very good article as usual by Prof. Blair. Also note what he states about round ports and rectangular ports 
and me with my Small Block Chevy. This is really good help for you motorcycle guys and for the intake side of turbos.
John
Posted:
Sat Sep 13, 2008 9:51 amby larrycavan
Great timing on that link John. 
Posted:
Sat Sep 13, 2008 10:22 amby 106-1194218389
It really was helpful for me. I want to build and old 235 Chevy style motor for the salt flats to run in a vintage class. They have a round intake, albeit siamesed, and want to run injection. I will have to build my own injectors so I want to know how to design the bell on the stacks. That answers a lot of questions. I thought of you motorcycle guys and thought even if it helps a little it would give an advantage.
John
Posted:
Sat Sep 13, 2008 7:04 pmby larrycavan
John
You might want to look into some motorcycle throttle bodies. Is that an old inline six you're talking about. If so, the KZ1300 touring bikes had 2 venturi injectors on 6 cylinder inline motors.
Posted:
Sat Sep 13, 2008 10:41 pmby 106-1194218389
Posted:
Sun Sep 14, 2008 10:41 amby tweaks
John ,
sounds a great project you have there ....takes me back 30 years ...
There are injection throttle bodies available with the base of the bodies in the shape of the Weber DCOE..they are available in sizes from 40mm up to 55mm dia made by Jenvey and others...only trouble is they are $$$$.. If you have a lathe and or milling machine you can make your own easily enough ..I have for special, applications..
I am also sure that there is a triple side draft manifold been cast for Chevvies here or in NZ ...
I can look into that for you if you like...
Cheers
Lynds
Posted:
Sun Sep 14, 2008 1:15 pmby 106-1194218389
Posted:
Sun Sep 14, 2008 1:25 pmby 106-1194218389
btw Lynds,
I had a friend run away from Salt Lake City, Utah here in the USA and went to New Zealand. He absolutely loves it. He met a lady who was a widow and owned a big sheep enterprise over there. One year when he came visiting he brought us all gloves and boots made from the sheep skin with the wool still inside. Great stuff. He also was at a car show displaying a wheel line they were making in NZ. They looked similar to Centerlines but were a street version. He gave me 2 so he would not have to trasport them back. They are 14" by 7" wide and Chevy 4.75X5 bolt pattern. One polished and one brushed finished. That has to be 32 years ago, my word where has the time gone. OMG I just looked in the mirror! I am an old man!!!!
John
Posted:
Mon Sep 29, 2008 8:16 amby stef-1
I have a spreadsheet you can use to design a simple or elliptical bellmouth. If any one's interested I can email it to you.
Posted:
Mon Sep 29, 2008 5:03 pmby slracer
Stef, Could you just attach it here? That makes it easier for everyone. Thanks, Doug
Posted:
Mon Sep 29, 2008 9:17 pmby 106-1194218389
I hope Stef does not mind as I will attach this. It is really a good one and my hat is off to Stef on this one. It really saves a lot of labor with the old mind, and I reiterate the 'old" part for me.
John
Posted:
Mon Sep 29, 2008 9:29 pmby bruce
Ok, next question how does one machine the bell mouth?
Thanks for sharing!!
Posted:
Mon Sep 29, 2008 11:46 pmby 106-1194218389
Posted:
Tue Sep 30, 2008 3:38 amby stef-1
Bruce raises a point - I usually use a CAD program to draw a template to check whilst machining the former. Although if you have CAD and CNC it's really easy to produce a former.
CAD also makes it very easy to draw an ellipse and I totally forgot about drawing it manually. I will look into calculating coordinates to allow manual drawing of a template. Would take a little while as I will have to find my original bellmouth notes!
Posted:
Tue Sep 30, 2008 6:34 amby bruce
Well being I have no CNC in my shop and my lathe is circa 1919, I'll have to find another way. I do have a taper attachment and could rig up some way to make it into a tracing/follower setup. I can handle the CAD part, then just transfer this to an alum blank, make a fixture for the lathe and use the blank as a pattern.
There problem solved . . . ???
On the other hand a radius cutter could be made to match the program radius callout for the bellmouth and used to cut the radius. Then use the taper attachment to cut the angle. This is how I currently do them for my carbs. I also machine my venturi into my velocity stack so that adds another "bonus" into the design, making sure the venturi ends up sitting in the correct place and width.