Airbox design references

[paulbutcher]

Can anyone here point me in the direction of books or articles on airbox design?

Thanks in advance for your help!

[flynfrog]

a book - tune to win by carrol shelby

[paulbutcher]

a book - tune to win by carrol shelby

Thanks (although I assume you mean Carroll Smith )

Anyone know anything about "The Scientific Design of Exhaust and Intake Systems" by Smith and Morrison? It certainly *sounds* like it should contain the sort of information that I'm after.

Thanks again,

[flynfrog]

im sorry carrol smith is what i meant i guess i should ahve asked how in depth on your air box you needed to go before recomnding a book

[paulbutcher]

i guess i should ahve asked how in depth on your air box you needed to go before recomnding a book

I'm trying to get as much background information as I can before designing an airbox for a motorcycle-engined single-seater. The sort of thing that I'm trying to work out are what volume it should be and how to decide where the airfilter should be (closer to, or further away from the trumpets?).

Theoretical info would be useful, but I'm more interested in practical advice.

Cheers!

[Scuderia_Russ]

Worth registering here just to look at the pics. All very helpful in the art of car building, and not just Lotus 7 replicas.

http://www.locostbuilders.co.uk

[knighty]

look at this thread -

http://p081.ezboard.com/fdsrforumfrm12. ... =723.topic

and the forum in general - lots of bike engined car people from the US, heres the home page

http://p081.ezboard.com/bdsrforum

from my experience of bike engined cars, see my old car below - use the standard bike airbox and just ensure ist got a nice feed of cool air.......heres pics of my car with a blackbird engine.......I converted it to Ram-air by using the pipework from a CBR600F3.......pulled like a train........the trick is to equalize the airbox pressure with the float bowl and CV slide-vent pressure

[IMG:816:612]http://img.photobucket.com/albums/v627/ ... inebay.jpg[/img]

[IMG:816:612]http://img.photobucket.com/albums/v627/ ... /Front.jpg[/img]

[knighty]

also check out this link.......this is the best method I have seen for sizing the air-box opening........and it obviously works!

http://www.ten-tenths.com/forum/showthread.php?t=76195

[paulbutcher]

Thanks - good stuff!

from my experience of bike engined cars, see my old car below - use the standard bike airbox and just ensure ist got a nice feed of cool air

Yeah. Unfortunately there are reasons why I don't want to do that. My car is a Jedi:

http://www.formulajedi.com/

There's a chassis brace which runs from the rear of the engine bay to the rollover hoop - right between the carburettor trumpets. Some competitors get around this by cutting holes in the bike airbox, throwing the filter away, running the chassis brace through the middle and then sealing things back up "as best they can". I want to see if I can come up with a better solution!

Thanks!

[knighty]

regarding your volume - the likes of Honda, Yamaha and Kawasaki spend a lot of time and money developing their airboxes in order to achieve the correct intake harmonics - if you do a back-to-back dyno run with and without the airbox you will often find the airbox is worth 2-3hp......the reason being - airbox harmonics - the volume is precisley developed for more power.

The threory goes something like this - when you hum into an empty glass, at certain humming frequencies the humming effect will tickle your lips........this is the sound waves bouncing back and forward........the same effect happens to the trumpet openings

I know what you mean about the jedi air-box bodge - nasty!

so in short - block off all the standard plenum openings, fill it with water, and hey presto - there is your volume figure for your new plenum........as a guide I think it will be around 10 Litres

[RH1300S]

That sounds like very solid advice knighty - a quick question........

Bike air-boxes tend to have the filter within the volume of the air-box - is the volume counted as both sides of the filter or just engine side?

Paul - if your engine has been jetted to run without an air-box you can expect to need dyno time to get it running as well as it can with the airbox on.

My understanding was that the airbox size had little effect on top-end power - but well tuned can provide a useful gain throughout the mid-range (always worth having )

Final thought on the bike air-boxes; yes they do spend loads of time designing these things - some of that time is devoted to keeping induction noise down.........

What about find out what bike racers are doing to their engines?

[knighty]

I dare say if you was to ask an F1 engine designer - the answer to the air filter positioning question qould be "yes - its absolutley critical".......but for the purposes of what matey is trying to achieve with his Jedi - I would just try and replicate the standard bike TOTAL airbox volume and place the filter in a similar position......so you will need to pour water in each half of the airbox and work out the locating point of the filter in the new design.

when designing the new airbox I would go for something that has the trumpets entering the air box at 90 degrees, so the inside of the airbox is looking at the side of the trumpets......on this box would be a good place to mount your filter.......then go for a design that takes it from a - say 4" by 12" rectangle (containing all 4 trumpets) into the intake opening of about 3" - above the drivers head......this will give you a nice diffuser effect that is critical when your trying to efficiently convert flow into pressure in order to achieve the ram-air effect.

someone mentioned above that some people run them without filters.......if you do this the bores and rings will not last very long - deffo not a good idea!

[Scuderia_Russ]

Someone also might be able to help here too.

http://www.eng-tips.com/threadarea.cfm