TPO Beast vs. Open Air Box w/ K&N

[scott_araujo]

I think the TPO are better than the stock stacks in the box.  Correct me if I'm wrong, but the lip on the stock ones is sharp, the lip on the TPOs is rolled over.  That little roll over at the edge usually makes a big difference in flow rates.

Scott

[He Man]

I think the TPO are better than the stock stacks in the box.  Correct me if I'm wrong, but the lip on the stock ones is sharp, the lip on the TPOs is rolled over.  That little roll over at the edge usually makes a big difference in flow rates.

Scott

nah they are flared too.

Damn

and here I just went through the pain of talking myself out of the TPO kit

youz guyz are killin me

Obama is pro choice
McCain is ProPods

your choice. =p

[scott_araujo]

They are both flared and greatly improve flow.  It's the very edge that's different and that I'm referring to.

Nice and rounded like this:
http://www.vogelmanufacturing.com/images/horn.jpg

generally flows better than a sharper edge like this:
http://performanceparts.com/performance_parts_images/mr_gasket_46.jpg

I think the ones in the stock air box do NOT have rounded edges though I could be wrong, I haven't looked in there since the beginning of the season.

Scott

[Norm]

I'm far from an expert on the subject, but why would the shape of the outer lip matter?

[scott_araujo]

It's all about turbulence and smooth air flow.  That sharper edge creates more turbulence and lower air flow.  Less oxygen for the engine.  It's a really small thing that makes a measurable difference on a dyno.

Scott

[Bill in OKC]

Also, a lot of people who comment on PODS install them directly onto the intakes.

That looks like where I'm heading.  I waited for TPO to make a 4-valve beast, but they didn't make it POD friendly.  I'll lose some power along with the velocity stacks but I'll just have to live with it

[He Man]

It's all about turbulence and smooth air flow.  That sharper edge creates more turbulence and lower air flow.  Less oxygen for the engine.  It's a really small thing that makes a measurable difference on a dyno.

Scott

How much of a measureable difference?

[supertjeduc]

I die dyno my m900sie with airbox/k&n/half open lid
And with the Pods on the stock stacks
Difference was 0,5hp (airbox won)

[Norm]

OK, I get it now. I thought you meant using the velocity stacks with pods clamped over them. I'm trying some ram air experiments with 41FCRs but won't know much 'til spring. BTW, nice machining.

[EEL]

Actually Norm,

TPO velocity stacks ARE slipped inside the pods..

[Norm]

Then, assuming the filter touches the edge of the velocity stack, would the edge shape make a difference?

[EEL]

Couple of comments:

1) Norm: I think you make a very good point.

2) I think this conversation is getting too theoritical. The fact is that most of these comments about about air flow are related to a stable/fixed environment, reality changes these results significantly (i'll explain this in a second). The important goal is to ensure that the stacks themselves are long enough to establish a laminar flow path based on the maximum air intake capacity that the bike is utilizes. We have to realize that TPO pods are in reality cantilevered off the intake ports. So they will vibrate a tad due to many factors such as engine vibration, bumps, etc. This will (and DOES) inherently impact air flow. This effect is more evident when I go over cluster of bumps at high speed.

THAT is the major drawback of pods and the TPO setup. For some reason, no one ever talks about it. Proper bracing could solve this problem but I dont think anyone has attemped to secure them in this fashion.

3) In regards to the HP. I agree that pods are probably a tad less than efficient and most likely down on peak HP. But I own a MONSTER,if i cared about peak horsepower, i would have bought a 4 valve bike. Personal opinion here: But I feel that Pods work much better in the mid and low rpm range. I wouldn't be surprised if the dyno shows this. Whoever mentioned that they have a dyno test, can you post the results for comparison?