AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Airboat propeller discussion.
sarros2004
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AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Postby sarros2004 » Fri Sep 07, 2018 10:45 pm

Hello All!

New to the site , and new to airboat ownership though I have been around them my whole life.

I am working on rebuilding my dad's 14' Airgator that has been passed to me. The old continental 8cyl he was running was done for. I have since removed it, and am awaiting the arrival of an LS2 6.0 aluminum block that is touted to have 400 HP, and 400 lbs of torque. My intention is to run it standalone with fuel injection. I am currently on search of a gear box and prop to begin building the rigging.

I have come across a seller that has a 2.37 rotator box, and Sensenich 80" R SERIES 3 blade. He is asking $4500 for the box and prop.

My questions are:
Will I be underpowered for this set up? Sensenich website doesn't not offer asuggested horsepower for the R SERIES, but it does mention the JR (which are based on the R series)series are designed for 475 hp engines and up with a 2.3-2.5 reduction. This leads me to believe that I may be under powered with that setup. Will this be a hill burner with the proper pitch? Or should I wait for a different deal to come along?

Secondly, it is my understanding the I will need a spacer plate with the Rotator box on an LS engine. Can someone please confirm this?

Also, I am looking for a general opinion on the price of $4500. Sounds a little steep to me for iaed components, but again am new to purchasing these items.

Any advice would be greatly appreciated.

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Slidin Gator
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Re: AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Postby Slidin Gator » Fri Sep 07, 2018 11:24 pm

$4,500 is not a hell of a discount off new, $2,175 for 3 new blades and $3K or so for the gear box. They don't have much info because the R blades are old tech. The guy you are talking to is upgrading and looking to get max for what he has, talk him down or walk away and buy new stuff yourself.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

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kwanjangnihm
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Re: AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Postby kwanjangnihm » Sat Sep 08, 2018 5:07 am

Welcome to SA and the insanity! :salute:

Good luck with your build.
" I don't care who you are back in the world, you give away our position one more time, I'll bleed ya, real quiet. Leave ya here. Got that? "

sarros2004
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Joined: Thu Jun 20, 2013 10:26 pm

Re: AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Postby sarros2004 » Sun Sep 09, 2018 9:23 am

Thanks for the replies. I visited with the guy, and ended up purchasing the box and prop for $3250, which I thought was reasonable. Now just gotta begin putting her together.

Thanks for the help!

Aeon
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Re: AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Postby Aeon » Sun Sep 09, 2018 9:26 pm

Never done a rotator to ls. I have done both a belt and ox box to ls. The ls crank is 3/4" closer to the block so the pilot shaft on the gear box needs to extend that much farther. They make a adapter you can stick in the crank but Iduno if that's a good idea or not. The bell housing bolts will fit fine


If it's a stock ls give thought to changing the valve springs, also the hyper pistons were not intended for marine use, change the thermostat to a 160.and get someone to tune it
17x8 Circle H powered by a TurnKey LS3, 2.55 ox box and 82" 3 blade JX

One Eyed Gator
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Re: AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Postby One Eyed Gator » Mon Sep 10, 2018 7:42 am

I run a 14' alumitec/airgator.

Just put a 6.0 (maybe 400hp) on it and I run a 79" 3 bld R with a 2.68 stinger. Runs good way better than my stock 5.3.It is carburated for now FI after fishing season

Yes you need the adapter or a dished flexplate. JW Wheel and TCI make several differnt options.

sarros2004
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Re: AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Postby sarros2004 » Wed Sep 12, 2018 11:24 pm

Thank you Aeon for sharing about the pilot shaft. One Eyed Gator, nice to hear from someone running a similar set up. I have bought the 2.38 box. Guess I'll see how it stacks up. If my understanding is correct I will not be able to pitch my prop as much as a 2.68, but I should be able to achieve higher prop rpms?

White Hawk
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Re: AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Postby White Hawk » Fri Sep 21, 2018 9:14 am

I am running a 383 Stroker with about 450 HP and 485 Torque. I just switched from a short hub 76" overall to a long hub 80" overall. When I switched from a 76" overall length to a 80" overall length I had to reduce pitch from just past the 3 mark to just past the 2 mark. The end result was an increased cruise speed , faster top end, and improved thrust response.



1. Determine your desired W.O.T based on your engines performance. (for example on the 383 lets say 5200 to 5600 rpm)
2. Match your gear box ratio to comfortably put your prop in its recommended sweet spot (R Series 2200 to 2400 RPM) at WOT(can turn up to 4800 but will loose efficiency)
3.Fine Tune the prop pitch to put your motor right into its sweet spot by adding or removing pitch. (Very small adjustments use a torque wrench and follow the specs, also use anti seize and factory lock washers if you do not have them order them, they can also provide you with factory anti seize)


5600 RPM / 2.0 gear box = 2800 RPM on prop
5600 RPM / 2.38 gear box = 2353 RPM on prop
5600 RPM / 2.68 gear box = 2090 RPM on prop
5600 RPM / 3.0 gear box = 1867 RPM on prop

You don't want to spin your motor at too many RPM it will be like riding around in 3rd gear and wanting to switch to 4th or 5th.
you also do not want to load up the motor with too much prop and have it feel like you are stuck in 4th gear. (Slow to start-Low WOT)

You want to land close to your engines sweet spot with gearing and a prop. You then want to be able to fine tune your pitch right into the sweet spot where you are happy with both bottom and top end speed and RPM.

sarros2004
Southern Airboat Member
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Joined: Thu Jun 20, 2013 10:26 pm

Re: AIRGATOR, LS2 6.0, SENSINICH R SERIES, ROTATOR 2.38, NEED ADVICE

Postby sarros2004 » Fri Sep 21, 2018 11:10 pm

Thank you White Hawk. I believe the LS2 with fuel injection is going is going to put me right whereI need to be with the 2.38 gearbox I now have: leaving only lunch adjustments. I'm working in my polymer now. Then the rigging. My plans are to be on The water by Christmas day, if I don't run out of money.


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