bmc filter

[crowspeed07]

i got a bmc filter and was told its the race version just wondering if there is a way to make sure of this?

[boloson]

i got a bmc filter and was told its the race version just wondering if there is a way to make sure of this?

Race filter should have a green line through it

[crowspeed07]

this one looks ot be solid red. if its non race filter can i just install without the need for a power commander?

[Jim]

you "should" get a power commander for any after market filter. the race ones just filter less

[boloson]

Yup. Since the race flows more air then I would definitely get a pc

[Kurlon]

Some BMCs flow worse than OEM...

[Degsy]

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Some BMCs flow worse than OEM...

I have heard that before but I think it's utter bs. I'm willing to be proven wrong but I have seen demonstrations of airflow between own and Bmc and the difference is staggering (on the demos I have seen).

[butcher bergs]

I have heard that before but I think it's utter bs. I'm willing to be proven wrong but I have seen demonstrations of airflow between own and Bmc and the difference is staggering (on the demos I have seen).

Flow is one thing but resonance can affect flow.

[Dieseldan]

i can tell by judging by the intake noise/throttle response of my 675 that the bmc race deff helped my bike

[Degsy]

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I have heard that before but I think it's utter bs. I'm willing to be proven wrong but I have seen demonstrations of airflow between own and Bmc and the difference is staggering (on the demos I have seen).

Flow is one thing but resonance can affect flow.

Agreed, somewhat. Suffice to say that most of the time more airflow is going to result in faster intake velocity and more air density in the inlet tract. Ram air effect don't work if you put a wall in front of it.
Yeah, you could run into backflow and turbulence issues but we are talking about motorcycles here, not alcohol burning dragsters. We aren't exactly moving great gobs of air comparatively speaking.

[butcher bergs]

Agreed, somewhat. Suffice to say that most of the time more airflow is going to result in faster intake velocity and more air density in the inlet tract. Ram air effect don't work if you put a wall in front of it.
Yeah, you could run into backflow and turbulence issues but we are talking about motorcycles here, not alcohol burning dragsters. We aren't exactly moving great gobs of air comparatively speaking.

Not necessarily because we still have to consider air box design and how the affects of the occuring resonance will change as intake volume and speed increases. Air box and intake design is where I'm going with this.

Also, at 14,000 rpms, the motorcycle engine is still consuming a fair amount of air.....sure, not as much as an 8000 HP racing engine when measuring sheer volume consumed but still, considering the reduced size of everything, alterations to the intake tract would likely yield some kind of noticeable affect be it positive or otherwise.

Dropping in a free-flowing filter doesn't automatically mean there will be more allowable comsumption. Air box and intake design play a major part in this as well because if their design limits the flow then essentially one is pissing in the wind by using a drop-in filter.

[Degsy]

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Agreed, somewhat. Suffice to say that most of the time more airflow is going to result in faster intake velocity and more air density in the inlet tract. Ram air effect don't work if you put a wall in front of it.
Yeah, you could run into backflow and turbulence issues but we are talking about motorcycles here, not alcohol burning dragsters. We aren't exactly moving great gobs of air comparatively speaking.

Not necessarily because we still have to consider air box design and how the affects of the occuring resonance will change as intake volume and speed increases. Air box and intake design is where I'm going with this.

Also, at 14,000 rpms, the motorcycle engine is still consuming a fair amount of air.....sure, not as much as an 8000 HP racing engine when measuring sheer volume consumed but still, considering the reduced size of everything, alterations to the intake tract would likely yield some kind of noticeable affect be it positive or otherwise.

Dropping in a free-flowing filter doesn't automatically mean there will be more allowable comsumption. Air box and intake design play a major part in this as well because if their design limits the flow then essentially one is pissing in the wind by using a drop-in filter.

What are you running in your racebike?

[Degsy]

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Not that I doubt tour argument Bergs. Just interested to know what you are running in the f4i. The main point I'm trying to make is that pretty sure a bmc race MUST be flowing more air than a stock filter.

[DucDave]

i got a bmc filter and was told its the race version just wondering if there is a way to make sure of this?

Are you racing? Or is this for the street?

[Kurlon]

Bergs nailed it, while the BMC filter material does 'pass' more air, in some airboxes the BMC setup results in more turbulent flow over the intakes which results in a drop in power vs the stock setup. Ducati 996s are the application I'm directly familiar with. BMC's 'shower cap' style filter that goes over the intake bellmouths instead of in the runners does poorly compared to OEM filters on the dyno.

I've seen similar power reversions on ST3s, open the airbox intakes too much, and power starts dipping.

[Degsy]

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Ducati velocity stacks end up .5 inches from the underside of the gas tank which is the real problem. The bmc filters cause turbulence in that scenario because they fit over the bellmouth rather than tuck into the corner of the air box like the stockers do. With a race fuel tank and airbox on a duc the bmc would be a far better choice for that bike. That's not a bmc design flaw, it's a ducati one.

[Degsy]

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And any race 996 shouldn't be running an air filter anyway. Filters on ducati's are for pussies.

[Kurlon]

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Ducati velocity stacks end up .5 inches from the underside of the gas tank which is the real problem. The bmc filters cause turbulence in that scenario because they fit over the bellmouth rather than tuck into the corner of the air box like the stockers do. With a race fuel tank and airbox on a duc the bmc would be a far better choice for that bike. That's not a bmc design flaw, it's a ducati one.

Agreed, it all boils down to a filter change shouldn't be done without taking other things into consideration.

[Degsy]

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Ducati velocity stacks end up .5 inches from the underside of the gas tank which is the real problem. The bmc filters cause turbulence in that scenario because they fit over the bellmouth rather than tuck into the corner of the air box like the stockers do. With a race fuel tank and airbox on a duc the bmc would be a far better choice for that bike. That's not a bmc design flaw, it's a ducati one.

Agreed, it all boils down to a filter change shouldn't be done without taking other things into consideration.

Bingo.

[Degsy]

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Ducati velocity stacks end up .5 inches from the underside of the gas tank which is the real problem. The bmc filters cause turbulence in that scenario because they fit over the bellmouth rather than tuck into the corner of the air box like the stockers do. With a race fuel tank and airbox on a duc the bmc would be a far better choice for that bike. That's not a bmc design flaw, it's a ducati one.

Agreed, it all boils down to a filter change shouldn't be done without taking other things into consideration.

It's only a matter of time now before we have complete closed-loop powerplant-driveline management onboard all bikes. This means managing all a/f, cam and ignition timing,intake length and traction direct from the ecu. No need for any aftermarket products like power commander etc. Plug and play exhausts and filters and let the bike take care of it all.


Of course, this will be rest of the world only stuff. By the next few years the US EPA will have all bikes mandated to have tamper proof seals on the exhaust system and airbox.

Of

[Uncle Snake]

Since it hasn't been mentioned yet and it is important. Doc sucks.