Martin wrote:......or it could increase the velocity of the air being taken in......

i'm out with the stanley knife as you read this .....

viper_biker wrote:I run the air-box without the snorkel at all and it doesn't seem to make any difference at all. I do have the HRC replica tray to help flow the air into the right direction, so maybe that has replaced the job of the snorkel.

What I'd really like is this. The extra plumbing looks just like the mods I had to do to run the ram-air on the track-bike,

Thats the exact setup im running at the moment viper which although seems rough in the vid i posted recently performs really well on track. Midrange does seems quite weak on my bike tho which does need sorting if im to use it on the road.

That airbox is exactly what i want, i take it you'd need to run a hrc setup with that? Looks proper trick too

Well this is what ive gone for


Mr ABR also had some HRC short stacks im gunna try out


Im going to rig up some sort of fine filter or gauze to stop the bumble bees getting sucked up.
Will have to pull the carbs apart soon and see whats been done so far, the bike came to me already ported and flowed with larger jets(cant remember sizes), 1mm needle washers and i a put in a set of HRC springs just to be sure, other than that im assuming there standard, any sugestions as to what else should be done to the carbs before dyno time would be gratefull?

Cant believe I missed this thread before but its a cracker to read, especially as Iv just sorted a ram air kit and am about it fit it.

some botched physic's aswell which is always fun to read lol


seriously if you guys are into induction systems you should see the formula student car they have at brookes this year, its got an amazing throttle system infront of the airbox and then the box it designed on solid works so that it is the correct size in all dimensions to reflect standing waves of air into the ports and engine at a particular speed and particular timing. this actually means that the engine does no Suck air in but it is forced in as soon as the valve is open. increased power outpu on the cbr600rr engine by about 15% I believe, were not allowed to even take pictures of this throttle system as the tech is being sold to f1 teams when the competition is over.

(Il try and get a some pictures )

FYi The intake snorkel on motorcycle irboxes is there to control intake noise, not much else. The theory re size is fairly simple. a stopped engine will have an internal airpressure of 1bar (or current atmospheric pressure).
As soon as the engine is started it sucks air out of the airbox & thus leaves a depression (vacuum is not the right word !) in the airbox, the external air pressure being higher forces its way into the airbox, in an attempt to equilise the pressure. So as long as the intake port to the airbox is large enough, there will be close to atmospherice pressure in the airbox at idle.

But, if you rev the engine, the demand for air is increased & the air flows into the airbox to restore pressure, so if you only have one carb drawing air at a time (like most 4 cylinder bikes) then the intake needs only be the same size as one carb bore (30mm or whatever for example), but a larger hole will allow pressure to return faster, but there is a limit to how big stops becoming effective & noise becomes a problem.
All normal airboxes operate at less than atmospheric pressure & thus any ram air effect that aids in the refilling of the box will improve power. Whilst JR states that .6psi is all you get, he missed the fact that at high engine speeds your airbox would be at lower than atmosheric pressure by some 1-2psi, so at speed you add more than .6, infact its closer to 2psi or 12% more pressure !

Read this for more details http://www.sportrider.com/tech/146_9912_ram/index.html

Regards

Mohawk

Wont a larger airbox slow down the airspeed within the box resulting in less low down torque?

Wouldn't you have to modify the carb trumpets/inlets (surface area/angle of bore taper) to speed up the venturi effect?

Having more air volume should in turn give more top end power allowing the engine to not run out of breath at high speed/revs.

This set up will also need bigger main jets to cope with the extra fuel needed so as not to starve the engine and run it to lean.I have found the NC30 does like to run alittle lean and will produce more power but you will still need 126 mains or bigger to cope with the extra fueling required, running it that little bit lean we are only talking 1-2hp max extra power.

Having the shorter stacks allows for the air to flow better down the carbs and should also give better torque. The key to this set up is getting the air in and to get cool air in rather that stale warm air from the engine as cooler air also will give better power results.

I like it cos it looks nice lol!

I noticed this thread has become active again. Just thought I should add that since this thread started, as well as the carbon air box, we now make a more race orientated air box in GRP for the NC35. It has a larger intake and internal tray roughly based on the HRC design with some of our features thrown in for good measure. It has the extra volume of our original one (this only takes it to the height to the outside of the ribbed surface on the stock one by the way) and also has better sealing with a proper base unlike most of the others on the market. It won't take a filter. Details here:
http://tyga-performance.com/site/produc ... ts_id=2100

We plan to make the air tray too.

For comparison purposes, here is the original one:
http://tyga-performance.com/site/produc ... ts_id=1116

Paul, how does your hrc replica box compare in size to the proper hrc box?