Airbox modding

[8541Hawk]

oh sure, encourage me... lol

the quest for a lid begins........

I've been helping you spend your money for years ...so why stop now....lol

[mik_str]

well, you're consistent, lol

BTW, seems I may have found a lid to play with

[lloydie]

Hawk - Then take a flat plate of Al or even plastic that is slightly larger than the filter itself or possibly a strip slightly wider than the bell-mouths of the stacks.
Find a set of stand offs the size that you raised the filter and mount the plate under the filter. A bit like the mwr -i think thats what its called that tony is testing but with the plate on the bottom .

I think you would need to smooth the inside of the air box for that to work well as it will pull the air from around the stacks and rough places in the box will cause turbulence .
May be a moriwaki air box bottom mated to a standard top so you could still use the standard filter . I might look into this sort of :-)

[VTRDark]

May be a moriwaki air box bottom mated to a standard top so you could still use the standard filter . I might look into this sort of :-)

I was just thinking you might as well use a Mori style airbox. The only thing is that they would be a bit of a pain in the butt when it comes to carb removal as the carbs are inside the airbox so need to be sealed around the base and have the vents feeding outside. I think the mori box gains it volume from the bottom and sides.

(:-})

[lloydie]

Gaffer tape :-) have a look a yetis

[mik_str]

Removing all the unnecessary bits has been well covered and while Micky's latest adventure looks interesting, I'm not sure how much it will help with the sharp corners.

that is precisely my concern as well. I tried to smooth things ou as much as possible but edges remain.... guess we'll have to try it and see.....

[mik_str]

well, I got a good deal on another airbox, so will try to keep it more simple this time, mimicking Lloydie`s...... will try both set-ups......

[mik_str]

started work on the "new" modded box and must say that using a soldering iron is a wonderful thing; much easier and a lot cleaner.... will look almost OEM when I am done.....

am also looking forward to getting the modded airfilter done up too (yes, another "welding" job....)

[lloydie]

I've been messing again today without success :-( I modded a lid to take a k&n in the roof and filled the snorkel hole
But no air could get in to it when fitted so I popped it in the oven so I could heat it up to able me to push the filter down a little to help air flow .
All went well till I left it in to long
doh
It was worth a try.

[mik_str]

overcooked filter...... shame.....

On another note, I wanted to share a question I received on teh Superhawk forum, along with teh reply I gave. This is by no means meant to be the Gospel truth, but merely a point for further discussion that I thought some of you might enjoy... so, without further ado........

Question: “maybe this has no relation at all.. but a lot of people on here keeps saying that K&N are crap and that your bike will run better with stock air filter, yet it's obvious that the K&N would allow the bike to breath better, all you have to do is compare the stock vs K&N. the K&N is almost see through.
So if more air is a bad thing why would you want to modify an airbox to get more air?”

My reply:
I have read in numerous places that an engine`s airbox volume should be at least 10 times its displacement for good breathing and power production (in a performance application anyhow). This is especially true in the case of a big twin since it takes in large gulps at irregular intervals (unlike an I4 which takes small and regular "breaths"; read up on V&H`s numerous challenges when they began work on their V-Rod drag bike for an idea). So, giving a larger reservoir of air to draw from should enhance teh engine`s ability to draw in needed air. Also, as the thing which actually "pushes" air into the engine is the pressure differential between the airbox (essentially atmospheric pressure) and cylinder (partial vacuum), adding volume to the airbox reduces the rate of pressure drop (due to larger volume), so, in theory, keeping the pressure in the airbox slightly higher should help to push more air into the engine at each induction event (=greater cylinder filling = more torque).

Two other points: Roger D has told me on numerous occasions that the VTR engine (a modded one anyhow) is strangled by the stock airbox, particularly at high rpm, so increasing the volume should help alleviate this to some degree (especially seeing as how my snorkel has been opened up already, and I have two 1" holes in the lid, for better air replenishment).

Finally, one should not confuse airbox volume with intake velocity. It seems to me that the problem with the K&N may be that it doesn`t offer sufficient resistance (essentially acting like a hose with an open end, with the water just flowing out as opposed to having your finger on the end in which case it shoots out), leading to stagnant airflow. That is just a theory or thinking out loud, however.....
Comments welcome

[8541Hawk]

The one thing that I see you missed would be turbulence.

CV carbs like smooth calm air, give them a disrupted air flow and you have issues. A flo-commander can help with these issues but the smoother you can get the airflow, the better off you are.

With the K&N filter and no air damn, you get the exact opposite. Sure you get lots of air low but it is far from "smooth & calm"

So IMHO this is where a lager airbox comes into play. It's not that you are trying to ram more air into the box but to give a larger reservoir of smooth - calm air to draw from.

At least that is how I see it.

[mik_str]

good point Mike

[mik_str]

Modded box #2 is now done. All that is left to do is to to sand over the "welds" a bit and she`ll be ready to install.... The new BMC and old OEM air filters shouild be arriving soon too, for the airfilter element (punny, yes?) of the experiement to get underway.... will post pics later

[tony.mon]

What you need, then, is a negative of the K+N. a blank plate over the intakes and filter medium everywhere else....

[mik_str]

I was thinking of running the valve cover vent hoses through the (new) airbox to the Kranvent and then feed the outlet (coming from KV) to a holding tank but, upon reflection, will route them outside the box completely (reasons: no volume loss, no warming of airbox interior, no cluttering to hrm internal airflow). I will run the line from the front cylinder under the airbox (looking for plastic retaining clips to hold it agianst the underside of box) and the rear cylinder I will feed directly to the Tee for the KV. I will run the KV outlet to the OEM holding tank (with a cone filter to let air out but ensure that no dirty air inadventently enters the engine), stashed away somewhere under the gas tank......