scootz
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| posted on 2/9/15 at 05:48 PM |
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Air Intake Velocity
Evening!
I'm trying to make a (very) locost set of throttle bodies.
The first pic shows the donors plastic inlet flange which I plan to take a drawing from. I'll get an ally flange cut from the drawing
It also shows one of the TB boots.
Plan is to get holes drilled and tapped in the flange to take these boots.
As you can see in the bottom picture, the boot port is fractionally smaller than the engine inlet port. The pic makes it look worse than it is...
I'd say it's out by 1mm on the top and bottom vertical plane (each side) and 0.5mm's at either side of the horizontal plane (each
side).
Sooooooooooo...
Is it likely that the small 'step' will disturb the air flow to a noticeable level?
Is it worth me porting-out the boot a little to match the flange port?
Cheers
It's Evolution Baby!
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coyoteboy
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| posted on 2/9/15 at 06:02 PM |
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Genuinely don't think you'll notice it without hours on a dyno and back to back variation.
Some designers use step-up's like this to reduce flow reversion. I think the key questions is "is the boot big enough for the flow you
expect"? If yes, the step out will be fine.
http://www.austincc.edu/wkibbe/headdesign.htm
[Edited on 2/9/15 by coyoteboy]
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scootz
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| posted on 2/9/15 at 06:06 PM |
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Cheers... off to put the kettle on, then will have a read.
It's Evolution Baby!
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bi22le
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| posted on 2/9/15 at 06:36 PM |
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I made my own set of trumpets for my 4 age.
I did a fair bit of reading and one of the things i read was that little steps are often used to make the air tumble. This actually helps fuel mix and
is designed in.
If its forced induction all of this makes little difference
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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coyoteboy
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| posted on 3/9/15 at 09:16 AM |
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You really don't want tumble before the valve as you choke flow through it. You want tumble initiated at the valve so you get full flow through
and better dispersion afterwards. The steps are used as antireversion though. That step is too small to affect anything in reality.
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chillis
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| posted on 3/9/15 at 11:18 AM |
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Which way is the air flowing? if it flows against the step there will be airflow disruption, the other way will be fine.
Never under estimate the ingenuity of an idiot!
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scootz
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| posted on 3/9/15 at 12:27 PM |
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The air is flowing 'down' the step.
It's Evolution Baby!
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Ugg10
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| posted on 3/9/15 at 12:47 PM |
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What size and spacing are the ports ?
If they are anything close to 43x33mm then have a look at the Triumph 955 RS Sprint Triple throttle bodies as these can be fitted with a simple flat
plate as I have done on my 1.7 Zetec SE, these are 42mm inlet for info and approx. 88mm pitch. They are very similar to the Zetec SE Jenvey direct to
head TBs as they have a round inlet and an oval outlet so looks like they may match your set up well. IIRC I paid £35 for the TBs and about £25 for a
10mm ally plate laser cut adaptor (lasermaster).
Example here - http://www.ebay.co.uk/itm/Triumph-Daytona-955-i-1999-955i-Throttle-Body-/181808754925?hash=item2a54a570ed
Dimensions of these on here with pics of my adaptor plate (I have CAD of the TB mounting surface if required) -
http://anglia1968.weebly.com/engine--gearbox.html
If this is too big the 595's may be a bit smaller but don't quote me on that -
http://www.ebay.co.uk/itm/Triumph-Daytona-T-595-i-1998-T595i-T595-Throttle-Body-/161718103749?hash=item25a7266ec5
[Edited on 3/9/15 by Ugg10]
[Edited on 3/9/15 by Ugg10]
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1968 Ford Anglia 105e, 1.7 Zetec SE, Mk2 Escort Workd Cup front end, 5 link rear
Build Blog - http://Anglia1968.weebly.com
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scootz
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| posted on 3/9/15 at 01:47 PM |
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Cheers Ugg.
I had a look at them, but they're a tad too big.
This is my inlet port diameters...
I eventually went for the Triumph Speed Four TB's which are also seperable. A bit too small (obviously), but they're going onto a 3
cylinder 1.0 engine, so will still be capable of flowing far more air than the engine will ever need (within my budget!).
The other benefit of the Speed Four TB's is that they don't have injector apertures, so I can use the existing injector apertures in the
cylinder head.
Oh, and I get to keep one TB as a spare! 
It's Evolution Baby!
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