- Location
- Cruising Around
LMAO, that's the answer.
Engine Air Supply
- Thread starter DAG
- Start date
speedysprocket
Alex
- Location
- Chesapeake, VA
Polaris 950 with 48 Novis and B-pipe in a little Foot Rocket hull. RRP pole with the slightly smaller breather tubes.
I think the vacuum may seem more than it is because the hood is such a large surface area- a minute pressure change can appear to be a lot when it's acting over a large area, say 700 square inches... 1 inHg is about .5 psi. times 700 square inches is 350 pounds. Then again, I couldn't see my gage move at all, and you are still able to open your hood, though it may be "hard" or "heavy", but it's no wheres near 350 pounds of force...
I think the vacuum may seem more than it is because the hood is such a large surface area- a minute pressure change can appear to be a lot when it's acting over a large area, say 700 square inches... 1 inHg is about .5 psi. times 700 square inches is 350 pounds. Then again, I couldn't see my gage move at all, and you are still able to open your hood, though it may be "hard" or "heavy", but it's no wheres near 350 pounds of force...
waxhead
wannabe backflipper
- Location
- gold coast
Totally agree on that. There is a large surface area on the hood
- Location
- sask, canada
I'm definitely starving for air with my 1200 and only pole breathers. Any time I nose in a flip or anything for that matter, and the water comes up over the pole my motor bogs right down and sometimes dies.
- Location
- Valley Springs, CA
You only breath through the handlepole for that big ol 1200?
- Location
- sask, canada
Ya, unfortunately. I'm going to contact Krash about buying another hood I can modify to run breathers.
Generally a vacuum doesn't develop in an unsealed area.........but a low pressure area can
Atmospheric pressure above and below the hood are equal when the engine is off.
Large rapid throttle changes or during high engine demand with an inefficient and insufficient intake air tract can allow an
atmospheric pressure
differential to develop above and below the hood.
During these conditions the atmospheric pressure above the hood is greater, this greater pressure is pushing the hood down from the outside toward the lower atmospheric pressure below the hood, More air is also flowing thru the intake air tract while the pressure tries to equalize below the hood.
Atmospheric pressure above and below the hood are equal when the engine is off.
Large rapid throttle changes or during high engine demand with an inefficient and insufficient intake air tract can allow an
atmospheric pressure
differential to develop above and below the hood.
During these conditions the atmospheric pressure above the hood is greater, this greater pressure is pushing the hood down from the outside toward the lower atmospheric pressure below the hood, More air is also flowing thru the intake air tract while the pressure tries to equalize below the hood.
- Location
- Braapp Factory
Just to put this into the correct thread as well as the tpe thread. Here's what we are running now with success in our obsession hulls.
Sent from my GT-I9505 using Tapatalk
Sent from my GT-I9505 using Tapatalk
DAG
Yes, my balls tickled from that landing
- Location
- Charlotte, NC
Could you tell a big difference in performance?
- Location
- Braapp Factory
it's not the sort of difference you get from going stock to b pipe, but there is definetely an improvement, cleaner hitting for sure 
I did a quick test on mine yesterday. I completely sealed up my squarenose hood with gorilla tape so the air was only coming through the pole bracket. After a couple minutes I could hear the air being sucked in through the pole bracket hole. Lol and the engine felt like a 300cc kawi.
Will need a bracket with more air supply for the hurricane hull.
735 maniac engine, lightened flywheel, vforce 2 reeds, b pipe, msd ignition, dual 38s with stock f/a
Will need a bracket with more air supply for the hurricane hull.
735 maniac engine, lightened flywheel, vforce 2 reeds, b pipe, msd ignition, dual 38s with stock f/a
Just do the test posted by wanderer1, so simple, so pertinent. (rev/pull hood)
DAG
Yes, my balls tickled from that landing
- Location
- Charlotte, NC
Well since this thread was conceived and seeing the issues some of you were having with air flow I decided to play. After a few tweaks to the design this is a teaser pic of what I ended up with. Hot out of the mill room adjustable billet tube pole utilizing 3 inch tubes. Who wants to make me a chin pad?
- Location
- detroit MI
sexy sexy
- Location
- Braapp Factory
Very nice indeedy
- Location
- Cruising Around
Nice piece. What do you end up with after cables and typical bend at pole bracket? Still probably less than a stock WB1?
Ducky
Back in the game!
- Location
- Charlotte, NC
- Location
- sask, canada
Just saw this thread get bumped, I should mention that my previous statements about twin tubes being enough air for a 1200cc motor should be disregarded. In my Footrocket I had some pretty bad bogging issues and my motor would randomly die after tricks if the nose went under the water. Swapped the exact same set up into a Trixstar with twin tubes and hood breathers and I have no more bog issues at all.
DAG
Yes, my balls tickled from that landing
- Location
- Charlotte, NC
In regards to the flex hose at the bottom, that has been a R&D struggle. The samples I got from McMaster and a few other oddball places that popped up in google just did not work with my level of OCD. I must have sampled around 15 different flavors of flex hose before I started looking into a custom hose manufacturer. We ended up with a hose that measures 2.90” OD with a .011” wall thickness. The hose will snuggly go all the way up into the tube itself virtually eliminating water from getting into the hose unless it comes from the steering side of the pole. They were able to make it from a G-14 classified material that is fuel resistant, crush resistant, and my favorite part it’s not that ugly gray color. I’m very happy with what they were able to come up with.