getting quieter

Airboat propeller discussion.
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RickMc
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getting quieter

Post by RickMc »

hello, I have a boat , 12 x 7 fiber glass hull ,o290 its pretty light with light rigging . The prop is a 4 blade warp drive 55" one way, 63" the other . The pairs are matched sets pitched 15 at the 55 in. mark. It turns around 2600 rpm on the trailer , a little more on the water and cruses around 2000 to 2200. I am pretty happy with performance but its loud at full song . I have a plan for the exhaust but what about the prop. The cage will clear a 70 " after ex mod. Will other blades fit my hub ? Any suggestions . Thanks Rick
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Dirtman
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Re: getting quieter

Post by Dirtman »

Whirlwind Razor blades and Sensenich Sabre blades are both supposed to fit your Warp Drive hub. Don't have any real experience with either but the Whirlwind blades seem to be real popular with the race boats :stirpot:
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mojoe
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Re: getting quieter

Post by mojoe »

Warps are loud. They have their advantages, just loud. The razors sound a little better. But by the time you replace the blades, you could just about buy a whisper tip narrow. It comes in a 70". Worlds apart for noise signature. Keep the warp as a spare.

Not apples to apples, but I replaced a 70" 5 blade warp for a 72" whisper tip standard on a 0-540 sv. I never put the warp back on!! Not because of huge performance improvements. Better, yes, but not major. The enjoyment of the sound reduction and the noise signature is worlds apart. With ear plugs in at cruise, it is VERY relaxing. Getting on it just sounds right, a combination of power an push. No thin 4 blade compares in sound.
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Deano
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Re: getting quieter

Post by Deano »

If you want quiet, a 66" Water Walker Cypress is about as good as it gets (if it's stock).
If it has angle valve cylinders on it or other upgrade(s), then a 68" would work.

Your cage is no constraint whatsoever with your 290. No need in swinging 70" with that engine.
IMO, going beyond 68" will only promote excessive drag without providing additional thrust.
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Olf Art
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Re: getting quieter

Post by Olf Art »

Plenty of good advice already. Another thing you can do (after you've changed-out your prop) is to
get rid of your flex pipe and get a muffler shop to bend a couple of solid exhaust pipes for you between your headers and your mufflers. Flex pipe is very noisy.
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RickMc
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Re: getting quieter

Post by RickMc »

My plan with the ex is header flexible joint muffler custom bent pipe through hull and down turns. Should be much better than flex pipe mufflers witch were way better than the open cut down 6 cylinder pipes that came on the boat. Rick
The glass is always half full....til I get a hold of it

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ptr34
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Re: getting quieter

Post by ptr34 »

A 66" NGQ would be quiet on it. i have one we can try on it
if u don't run dry .then should have gotten a bassboat
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RickMc
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Re: getting quieter

Post by RickMc »

I'm going to try my exhaust mods first . I'll try to post pics before and after. This winter i intend to vacation in Fla and bring the boat . I've had a few offers to try some props and would love to try a few . I 'm from north east Pa. . Currently there are no rules or restrictions on air boats here and I dont want to be the guy with a law named after me. Thanks Rick
The glass is always half full....til I get a hold of it

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Deano
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Re: getting quieter

Post by Deano »

That makes sense except for one thing . . . you'll need to loose that warp drive before you can

assess and/or appreciate having a quiet exhaust, no matter what you do to arrive at that end. :dontknow:
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
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Olf Art
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Re: getting quieter

Post by Olf Art »

RickMc wrote:My plan with the ex is header flexible joint muffler custom bent pipe through hull and down turns. Should be much better than flex pipe mufflers witch were way better than the open cut down 6 cylinder pipes that came on the boat. Rick
Rick, that sounds good to me. With aircraft engines you definitely want the mesh flex couplers
because an A/C engine tends to torque (move) more than a car motor, and there's no reason to
crack the headers. Keep us up to date on your progress!
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Prototype
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Re: getting quieter

Post by Prototype »

Deano wrote:That makes sense except for one thing . . . you'll need to loose that warp drive before you can

assess and/or appreciate having a quiet exhaust, no matter what you do to arrive at that end. :dontknow:
I was thinking the same thing and as far flex pipe, I haven't seen one rig yet that can get around it thats quiet. Old steel limp flex is totally different than new ss flex. I kind of go by if it can move it's going to make noise. Lots of old steel flex pipe moves like crazy after a year or two of burn. Also a few guys now days also avoid the flex and just weld muffs to headers. I probably couldn't even consider a sound idea until the warp blades was way gone and my ears and seat was receptive to a better prop. I ran warp blades for about 3 weeks which was probably 20 days longer than I needed too. I'm not bashing warp blades but warp a quiet really don't belong in the same sentence.

Olf Art
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Re: getting quieter

Post by Olf Art »

You can kind of get away with welding muffs directly to headers, but the problem
I have with it is that if you use mufflers large enough to be effective then they're
probably going to eventually crack the headers or break the mounting studs.

I know what I'm about to say is gonna sound crazy, but big mufflers make a lot
more torque and horsepower than little ones do .... they have enough internal
volume to absorb the flow of what is actually a very high efficiency hot air
compressor and at the same time curb the explosions of each power stroke with-
out trying to contain it to the point of adding back pressure. Make sense?

Exhaust tuning is a science all it's own. It has it's own rules, and it can make or
break an installation if you're looking for maximum power and engine life.
Flip any NASCAR car or truck over and you'll see a X-over exhaust system ....
not just because it's easier or cheaper, but because it makes horsepower and
protects the engine in those cars by adding just enough anti-reversion so that
their exhaust valves don't sit in a furnace when they're running at 9,000 rpm.
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