Paper Filters & Airbox Lid Mod

[Greg Field]

That's the nice thing about K&N's - you never need to vacuum the crap out of them.

 

Rj

 

 

Yes. Especially if you run them dry like those on most V11s I see.

[guzzijack]

 

Does this mean with the airbox in place, with the holes drilled in it and the intake snorkels opened up, but with the bellmouths on the throttle bodies opened up to 50mm?

 

GF

 

Greg,

 

I'll take the opportunity to reply on Phil's behalf as we're in time zones on opposite sides of the planet and he's probably asleep at the moment.

 

When he/I mentioned opening up the 'bellmouths' to 50mm it refers to the ports on the intake side of the airbox. I.E. the inlets under the tank that are left after you have taken off the rightangled 'schnorkels' which are held in place with the large hose clips. Nothing further into the inlet tract than the airbox lid is touched or modified.

 

To answer Nogbads question as to why all this time and effort (Phil's not mine!) has been devoted to gaining such a small (?) increase in bhp and torque. Well with the V10 engine and also the 1100 Sport Injection there were/are problems with the standard ECU/FI anyway. So in resolving these issues Cliff Jefferies has developed the My16M ECU and Phil has done an enormous amount of development work with fuel maps for the My16M, (possibly also My15M as well as he has told me he has a map suitable for the ECU box Cliff has supplied me for the V11 Sport engine I am going to run on carbs), and airbox modification as you can gather.

 

BTW in answer to someone who said that all this work on the V10 airbox was not really relevant to the 2 valve engines - the Sport 1100 Injection (direct predecessor of the V11 Sport maybe?) is a 2 valve engine so there are maybe valid comparisons in the airbox modification department.

 

Graham

[Guest Nogbad]

That's the nice thing about K&N's - you never need to vacuum the crap out of them.

 

Rj

 

......Because the engine does it for you!

[guzzijack]

This is all VERY interesting! Were any of these tests then followed up by any track testing with a stock baseline to campare the midifications to? sometimes things do not show up on a dyno, but smooth out and/or alter the power curve and thus you can go faster where it counts. Am I right that what might acually work the best then would be K&N pods? Would that aproximate removing the airbox yet retaining the rubber bellmouths on the injectors? And then increasing the bellmouth to 50mm and drilling the three holes at the rear to balance the box out seems to be annother viable alternative.It seems then that there is a little ram air effect with the stock air box but not much. When you look at the amount of hp that the Jap bikes create with their state of the art boxes, it seems that there is a bunch of hp waiting there

The minor problem is digging it out

 

No, not K&N pods - from Phil's testing the cumulative best result was to remove the rubber dodads and open up the intakes on the airbox to 50mm, drill the 3 holes towards the back of the lid, use a standard filter element (or K&n replacement) and remap the My16M.

 

Seems to be a bit of confusion about the term 'bellmouth' here and above. When Phil has referred to the 'bellmouth' being taken out to 50mm it's the intake 'bellmouth' on the airbox once the rubber 'schnorkels' have been removed. You use a heat gun and a suitably shaped bottle neck to flare them out to a 50mm bellmouth in easy stages. I'll take a pic tonight and post it here.

 

Graham

[ArtD]

I know this may sound a stupid question, but if power pops your "pod" (no pun intended) why are you struggling with an old 2 valve ditchpump.

 

Why not buy a state of the art Japanese crotch rocket?

 

1.7hp? 5hp? These gains will be unnoticeable beside the effects of a heavy lunch or not taking a dump before your ride. Let alone air temperature and humidity.

 

Forgive my impertinence, but these airbox and filter issues seem to me to be just so much bunkum.

 

When it comes to making ANYTHING go faster, there are very, very few "free lunches". Airflow is one of these few 'free lunches". If you would read the excellent articles on Ram Air posted early on in this thread you will see that there are very real and substantial HP and Torque gains thru intake air flow. And, unlike just about EVERYTHING else that has to do with modifying for performance, these gains do NOT come at the expense of fuel mileage, rideability, engine life etc. From all of the excellent information thru-out this thread, its pretty obvious that there is a fair amount of FREE power with these bikes in reguards to intake airflow Of course, that does not mean that the EFFORT to get the abovementioned power OUT of the "air" is free The other "downside" is, that the finished product definantly will not look as neat as a pair of K&N pods Personally, I'm still "up in the air" (I couldn't help it) I'm sure I'll do somthing even if its wrong

[Guest Nogbad]

When it comes to making ANYTHING go faster, there are very, very few "free lunches". Airflow is one of these few 'free lunches". If you would read the excellent articles on Ram Air posted early on in this thread you will see that there are very real and substantial HP and Torque gains thru intake air flow. And, unlike just about EVERYTHING else that has to do with modifying for performance, these gains do NOT come at the expense of fuel mileage, rideability, engine life etc. From all of the excellent information thru-out this thread, its pretty obvious that there is a fair amount of FREE power with these bikes in reguards to intake airflow Of course, that does not mean that the EFFORT to get the abovementioned power OUT of the "air" is free The other "downside" is, that the finished product definantly will not look as neat as a pair of K&N pods Personally, I'm still "up in the air" (I couldn't help it) I'm sure I'll do somthing even if its wrong

 

Want to ride faster than the next man?:

 

Go to the gym

Eat less

Buy advanced training

 

Much more cost effective than any amount of airboxes, K&Ns, dyno runs and power confusers.

 

You know it's true!

[ArtD]

Want to ride faster than the next man?:

 

Go to the gym

Eat less

Buy advanced training

 

Much more cost effective than any amount of airboxes, K&Ns, dyno runs and power confusers.

 

You know it's true!

 

I'm almost there

 

 

[guzzijack]

Here are the airbox modifications mentioned earlier:

 

]Bellmouth[/url]

 

Rubber intake elbows removed and 50mm I/D bellmouth created using heat gun and bottle neck.

 

]Airbox lid[/url]

 

3 x 25mm holes at rear of lid and side view of the bellmouths on the intakes

 

Hope that clarifies things

 

Works for me

 

Graham

[ArtD]

No, not K&N pods - from Phil's testing the cumulative best result was to remove the rubber dodads and open up the intakes on the airbox to 50mm, drill the 3 holes towards the back of the lid, use a standard filter element (or K&n replacement) and remap the My16M.

 

Seems to be a bit of confusion about the term 'bellmouth' here and above. When Phil has referred to the 'bellmouth' being taken out to 50mm it's the intake 'bellmouth' on the airbox once the rubber 'schnorkels' have been removed. You use a heat gun and a suitably shaped bottle neck to flare them out to a 50mm bellmouth in easy stages. I'll take a pic tonight and post it here.

 

Graham

 

Thanks Graham, would love to see the pic, I think I've got it. I'm going to give this a shot, and I have a very good stretch of road that I know my speeds at quite well I'm pretty sure that I can get a very good "real world" test of it, I think. I figure that the worse that can happen is that I screw up a couple of airbox parts which are easy enough to come by. I guess what threw me a bit was the following from Phil's earlier post here:

 

"Once you totally remove the air box but retain the std bell mouths on the injector bodies the gains above 6300 do not taper off as above with the gain being approx 5hp at 8000 or so."

 

I sort of shot from the hip and mentally substituted K&N's for what I'm assuming would be the rubber bellmouth runners...but then runners can be a good thing....... you can drive urself nuts

[badmotogoozer]

I am not currently using K&N's on any of my vehicles but in some of my previous ones they made a HUGE difference. eg. My 57 Chev pickup with the stock 6 cyl was a massive improvement with the K&N. I no longer had to drop down a gear to get up the Royal Oak hill (steep!). Night and day.

 

You won't see that kind of improvement in a modern vehicle. You DO get more flow which does get you a bit more power and better acceleration. The tradeoff is you do allow more dirt in the engine.

 

If you are using K&N's there are a few things to keep in mind.

 

1. Always keep them oiled.

2. Clean them regularly!!!

3. Avoid dusty environments.

4. Change your oil more often. (negates the whole "not spending money on air filters" argument...)

 

If you live in a dusty area or frequently drive dirt roads, K&N's are NOT for you.

 

You WILL get more dirt in your engine and you Will be doing more damage to the engine. How much more? Depends on how well you follow the rules.

 

As a side note, my 74 Duc has had open bell mouths for at least 15 years. Long before I owned it. I had the heads off last winter and didn't see much in the way of cylinder wall damage - certainly no more than I would expect in such an engine.

 

Your bike, you choose according to your desires...

 

cheers,

 

Rj

[Phil A]

Thanks Graham, that pretty much sums it up.

Its good to see your photos, I still havnt taken any of mine so I wiil just take this oportunity to add some comments for the benifit of those like Greg.

 

The front hole in the lid needs to be about an inch further forward to get the best effect.

 

What seems to happen is that as the air starts to dip towards the centre hole it starts to pull the layers of air outside the diameter of the inside hole, towards the low pressure area created by this air dissappearing down the inside hole.

In other words the air gets pushed inwards and then down towards the rear two holes. (some would say sucked.)

 

If you dont have the front hole far enough forward then the rear air for the rear holes is not pushed in at the maximum effort. ie a lot of it over shoots the rear holes which are then in a partial vacuum (relatively speaking, and you run the risk of decreasing the flow into the rear holes.)

 

Sounds a bit complicated doesnt it but if you spend enough time working with smoke then it all becomes easy, ha ha.

 

Graham, Your bell mouths are not big enough yet. I wondered why yours didnt hit on the tank!

 

You need the id at about 50mm the od should hit on the tank so that you just need to file a 20mm flat on the lip of the bellmouth where it touches the tank. You get better flow by turning the bellmouth further outward and fileing the small flat than leaving the bellmouth smaller. Dont ask me how I know this!

 

Greg,

my experience with lid vs no lid vs big sqare holes etc is that once you get up to a reasonable flow then you just seem to get dirtier elements quicker with out a large increase in hp. Guess its the law of diminishing returns set up.

 

Eg if you drill 3 holes and get 1hp, the why dont you get 10 hp by drilling 30 holes?

 

The design of the box and lid (and other factors) determine the optimum area. Make sense?

 

There is another reason as well and that ie that you are "letting out" a destructive harmonic that is active within the airbox. This one I will leave alone for fear of starting a riot!

 

Your comments on the respective results for the respective mods ie (thought that would be more and thought that would be less), just tells us that it was the lid that was the main problem. make sense?

 

 

For those that were interested, YES I did all this work on the 2 valve as well and believe me, give or take, at different rev ranges all this info is valid.

 

Do you think the inlet air knows weather it is going into a 4 valve or a 2 valve? yeah.... right....

 

Nogbad, If you cant feel the difference in 9ft/lb of torque, thats a nearly 20% increase at 2800rpm. then mate, i think this game is definetly not for you...

 

I have been studying inlet tract behaviour for over 25 years so I am sure you understand I have to leave something for YOU to work out!

 

My most developed inlet tract is on this 500cc single

 

http://www.dlra.org.au/profiles/140.htm

 

which runs 2 x 44mm Mikunis (you try and even get em to work) and 5lbs of boost Yes, created by the inlet manifold there is no supercharger on this engine.

 

It has run at over 130mph. It will be the first single to run 150 on the salt.

 

Thanks, love the constructive discussion,

 

Phil A.

 

 

 

 

 

 

"all is not always as it seems"

[guzzijack]

Thanks Graham, that pretty much sums it up.

Its good to see your photos, I still havnt taken any of mine so I wiil just take this oportunity to add some comments for the benifit of those like Greg.

 

The front hole in the lid needs to be about an inch further forward to get the best effect.

 

What seems to happen is that as the air starts to dip towards the centre hole it starts to pull the layers of air outside the diameter of the inside hole, towards the low pressure area created by this air dissappearing down the inside hole.

In other words the air gets pushed inwards and then down towards the rear two holes. (some would say sucked.)

 

If you dont have the front hole far enough forward then the rear air for the rear holes is not pushed in at the maximum effort. ie a lot of it over shoots the rear holes which are then in a partial vacuum (relatively speaking, and you run the risk of decreasing the flow into the rear holes.)

 

Sounds a bit complicated doesnt it but if you spend enough time working with smoke then it all becomes easy, ha ha.

 

Graham, Your bell mouths are not big enough yet. I wondered why yours didnt hit on the tank!

 

You need the id at about 50mm the od should hit on the tank so that you just need to file a 20mm flat on the lip of the bellmouth where it touches the tank. You get better flow by turning the bellmouth further outward and fileing the small flat than leaving the bellmouth smaller. Dont ask me how I know this!

 

Greg,

my experience with lid vs no lid vs big sqare holes etc is that once you get up to a reasonable flow then you just seem to get dirtier elements quicker with out a large increase in hp. Guess its the law of diminishing returns set up.

 

Eg if you drill 3 holes and get 1hp, the why dont you get 10 hp by drilling 30 holes?

 

The design of the box and lid (and other factors) determine the optimum area. Make sense?

 

There is another reason as well and that ie that you are "letting out" a destructive harmonic that is active within the airbox. This one I will leave alone for fear of starting a riot!

 

Your comments on the respective results for the respective mods ie (thought that would be more and thought that would be less), just tells us that it was the lid that was the main problem. make sense?

For those that were interested, YES I did all this work on the 2 valve as well and believe me, give or take, at different rev ranges all this info is valid.

 

Do you think the inlet air knows weather it is going into a 4 valve or a 2 valve? yeah.... right....

 

Nogbad, If you cant feel the difference in 9ft/lb of torque, thats a nearly 20% increase at 2800rpm. then mate, i think this game is definetly not for you...

 

I have been studying inlet tract behaviour for over 25 years so I am sure you understand I have to leave something for YOU to work out!

 

My most developed inlet tract is on this 500cc single

 

http://www.dlra.org.au/profiles/140.htm

 

which runs 2 x 44mm Mikunis (you try and even get em to work) and 5lbs of boost Yes, created by the inlet manifold there is no supercharger on this engine.

 

It has run at over 130mph. It will be the first single to run 150 on the salt.

 

Thanks, love the constructive discussion,

 

Phil A.

"all is not always as it seems"

 

OK Phil,

 

Got that - heat gun here we come again

 

Graham

[Greg Field]

Phil:

 

Yes, makes sense. While I was interviewing Dr. John one day, he talked about chasing harmonics in the airbox while they were developing it, but they ran out of time and money to solve the problem.

 

Can you proveide measurements for proper placement of the holes? I've got a few airboxes laying about. I'll give it a try.

 

And good luck on the 150-mph single.

[Zooter]

Bumpage, worth a "how to" spot!

 

Phil A recipe for drilling stock airbox for 19% increase in torque @ 2800rpm"

[Rhino1]

Bumpage, worth a "how to" spot!

 

Phil A recipe for drilling stock airbox for 19% increase in torque @ 2800rpm"

Agreed, Zooter. Good thread!