If You Think Pole Breathers Are Enough.....

[CARBONX2]

That is how I figured out mine was not breathing enough. It had enough vacuum to put red marks on my hand lol.

I did tell you were going to need more pipes, those that don't listen must feel the pain, haha

 

[Mdavies_02]

But could it run better?

I'll do the hood test next time I'm out. It might be able to run better but I am very satisfied with how it is running right now lol.

 

[Harbor]

Nice test data.. pretty cool. So I have rrp poll tubes and 2 hood breathers tubes just as large. Was gonna say I am good but my engine is larger so I guess I'll have to do my own test.. thanks for posting

So measured mine and it came in at .25 inh20

When I did the finger test, hood open enough for finger and 3/4 inch bilge hose venting back thru bilge pump it only lightly squished on my finger.. So it needed more so I added 2 more 2 inch tubes.

Thnx mikesx and Jr. For the gauge posts

 

[Breese08SJ]

Just to throw another wrench in the works.... The breather tubes like RRP pole tubes are corrugated on inside and outside. This alone cuts down on the airflow a given breather can flow. The corrugations on the inside of the breather cause the air to tumble on to itself. Only breather tubes I have seen with smooth interior are the ones from blowsion however they are no where near 2.5" like RRP or the like.

 

[Freakrider]

Got breather tubes ?

 

[newbee]

Those have helped me out a lot vs having open hole into the hull.

 

[headshock]

Those have helped me out a lot vs having open hole into the hull.

- cool figured out what this is now

 

[CARBONX2]

So 10 to 20% extra Vent Tube Area from minimum Air Supply required to account for Water Blockage and,

do simple Man-O-Peter Squash Test on the Trailer, crack Hood open, insert Appendage, then pull Throttle wide open.

If you hit the High Notes, then more vents are needed...

Any pressure on digits = a vacuum = lost hp

 

[Req]

Something to add about the FrogzSkins is that they have some flow resistance compared to an open hole. I added an extra 2.25 hole in the liner to account for flow resistance. I have no idea how much they choke the flow but you can see them suck in a bit if you dont have enough.

 

[Christian_83]

So, i finally got to test this.
Ive been wanting to do it for a few years.
Ski in setup is a NITRO hull, ET1107 Engine, Dual 49 full specs.
RRP pole setup.
So here goes:

First video, NO hood:

Second video, with hood no air vents:

Third video is with hood with 8 x 22mm holes in "hood liner"

last video, is with hood not fully closed:

 

[Storbeck]

This is interesting stuff. Surprising that the holes didn't make more of a difference, it looks like the pressure change with the holes is closer to no holes than hood open.

Looks like it takes quite a lot of area to actually make no pressure change.

 

[Chase Musetti]

Good work Christian- that’s a nice visual representation


Sent from my iPhone using Tapatalk

 

[mikesx]

So, i finally got to test this.
Ive been wanting to do it for a few years.
Ski in setup is a NITRO hull, ET1107 Engine, Dual 49 full specs.
RRP pole setup.
So here goes:

First video, NO hood:

Second video, with hood no air vents:

Third video is with hood with 8 x 22mm holes in "hood liner"

last video, is with hood not fully closed:

View attachment 381924

Are the 8 holes in the “ outside “ of the liner and the 4 holes on the “inside” of the hood liner? Test shows a bit of friction loss I would say.

 

[CARBONX2]

8 x 22mm holes is equal to 1x 63mm hole, so you are short 24 x 22mm holes on hood outer and 28 x 22mm holes in the liner
Join the holes to form slots to gain flow area more effectively in the same space. The other thing is to check clearance between inner lining and outer hood to make sure passage is big enough for air to flow between openings

 

[Never Enuff]

Here is an altimeter data log from my RC data logger on a 1992 box stock 550sx. This is just for reference only, the stock 550 is not moving anywhere near the amount of air that most of these motors are. If you look at the graph, you will see that the altitude goes from about 0 to 36 feet max (I'm using the altimeter as a pressure gauge, just have to due a little math to back calculate feet of altitude to pressure). This equates to 0.023 psi or 0.637 in H2O. In terms of HP loss it would calculate to a 0.12% HP loss. Looks like the 550 hood flows fairly well.

From graph:
Wide open rpm 6200-6400
Max speed 40.6 mph
Max altitude 36 feet
Inlet water temp 73° F
Head outlet water temp 89°-94° F
Exhaust pipe outlet temp 100°-112° F

When I get time I will put the data logger on my FX1 and see how that hood flows.