Boat Build

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
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xCHUMPxCHANGEx
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Boat Build

Post by xCHUMPxCHANGEx »

So after 15 years of riding on other people's boats it's time to build my own starting in march I will be compiling parts putting my boat together.

So here's what I want.

Set up
16x8 ¾ deck deep side (atleast 24") aluminum hull
4 split seats with removable single front seat
top seat captain


Power
6.2L L92 from 07 Escalade 400hp 415tq
Oxbox haven't decided on ratio yet
Still researching props

So I guess my only question is will I be able to run dry ground with that motor and the right box or do I need more power for the size hull I'm wanting

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Andy
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Re: Boat Build

Post by Andy »

No replacement for displacement

xCHUMPxCHANGEx
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Re: Boat Build

Post by xCHUMPxCHANGEx »

As a former mud truck racer I completely understand that but I'm also not trying to race I just want a boat I can cruise around on and run dry when I need too also not trying to have 20k in motor and reduction

SWAMPHUNTER45
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Re: Boat Build

Post by SWAMPHUNTER45 »

The answer is yes with the right ratio and prop it will allow you to run some dry. Not mile long stretches of green sticky dry but a stretch here and there and a mild grade.

The problem you may incur will be a poor tune or defective sensor that will allow detonation. That will be a fast catastrophic fail.

The LS Wizard had in the past suggested boats 16ft and loaded heavy are better served to run a big block. LadyBlackwater a tour guide had found a 540 inch on a 2.55 was a great combo for the heavy 16ft and up barges.

That 400hp would work real well on a 14ft boat

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OneBFC
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Re: Boat Build

Post by OneBFC »

The formula never changes.

6lbs of loaded boat weight per available hp and it will run dry acceptably.

The less weight per hp the better.

Imo, 400hp on a 16x8 is going to under perform because you will exceed 2400lbs easily.

Big boat, Big power. No way around it.

Good luck!
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy

xCHUMPxCHANGEx
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Re: Boat Build

Post by xCHUMPxCHANGEx »

So essentially I need to be shooting for 500-550hp on 16ft boat

xCHUMPxCHANGEx
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Re: Boat Build

Post by xCHUMPxCHANGEx »

So after going back threw my notes and pictures of how I want to build it wasn't a 16x8 hull it's a 15x8 and 90% of the time will only have two adult passengers when running dry down in kissimmee the times I have 4 or 5 passengers will be ran on nothing but water out of steinhatchee

SWAMPHUNTER45
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Re: Boat Build

Post by SWAMPHUNTER45 »

The 15ft boat was some what of a maximum standard. Every boat is different but weight is a constant. To counter weight you need power and power is not cheap and power if not purpose built will not have a long life.

So for a general purpose ride the 6.2 LS take out platform works, a lot of people use them. Just ensure you get a tune from someone who knows airboats and pray you don't have sensor fails. Builders like WaterThunder use forged internals in their purpose built LS airboat engines. You will have stock hypereutectic (brittle) pistons and powered metal rods that do not handle detonation well at all. That said there are guys on here running take outs and they have had a lot of fun with their boats.

TUNE....TUNE....TUNE do your homework and don't just use the stock program or drop in something by a tuner inexperienced with airboat needs.

xCHUMPxCHANGEx
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Re: Boat Build

Post by xCHUMPxCHANGEx »

Wasn't thinking about all the sensors when I decided on that for my powerplant I know blueprint makes a 400sbc I can get from summit for around 5k it makes just over 500hp and 475 ft lbs should be able to add fuel injection to it and still come in under budget from finding a take out and having my motor guy go through it not to mention then I dont have to worry about cutting down the harness or ordering a stand alone

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SWAMPHUNTER45
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Re: Boat Build

Post by SWAMPHUNTER45 »

PURPOSE BUILT this is something that is key with airboat engines in my opinion. Plenty of guys use LS take outs with mild mods or a turbo and get good power for the dime just not the masses.

Crate can work but for a little more money you may get an experienced builder who will get you a few more years of use.

Don't let me scare you but if you research 6.2 fails they had mostly been (lean) bad tunes or issue related to knock sensors.

I have a buddy who runs a 427sbc built by MAS it does well but they cost.

There are some folks in Tampa who have quite a bit of airboat engine build experience and have been airboaters for many years, I suggest you speak with them for advice also.

United Speed World Tampa - Phil http://unitedspeedworld.com/

Lady friend of mine runs one of their sbc stroker engines on a 14ft it is a well respected boat!

CarMotorBarge
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Re: Boat Build

Post by CarMotorBarge »

xCHUMPxCHANGEx wrote:
Sun Dec 08, 2019 3:35 pm
So after 15 years of riding on other people's boats it's time to build my own starting in march I will be compiling parts putting my boat together.

So here's what I want.

Set up
16x8 ¾ deck deep side (atleast 24") aluminum hull
4 split seats with removable single front seat
top seat captain


Power
6.2L L92 from 07 Escalade 400hp 415tq
Oxbox haven't decided on ratio yet
Still researching props

So I guess my only question is will I be able to run dry ground with that motor and the right box or do I need more power for the size hull I'm wanting
How much are you paying for the L92 and how many miles? You could do a valve train upgrade on the L92. Also could use a carb and MSD box if you are worried about the factory EFI and knock sensors.

So the TUNE is important to ALL motors. This includes carbs and EFI. The TUNE consists of delivering the proper A/F ratio with the correct timing at the RPMs you run the engine. There is no magic here. Just need to make sure it is done correctly.

Finally, I would NOT pick a SBC over an LS because you are worried about sensors failing. A properly built and tuned LS will make more dependable HSP than a comparable SBC on an airboat.
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer

xCHUMPxCHANGEx
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Re: Boat Build

Post by xCHUMPxCHANGEx »

Found one locally for 2k obviously it would have to be gone through as it has over 90k miles on it but from everything know I'm assuming a purpose built motor would be any motor that makes most of its power in lower rpms

I know I'm still green with the whole airboat thing I'm learning as I go I know what I want and where I'd like to keep my price range for the whole build.

Maybe I'm trying to do the impossible building a reliable boat the way I want it and keeping my 25k budget



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xCHUMPxCHANGEx
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Re: Boat Build

Post by xCHUMPxCHANGEx »

So blueprint builds marine application motors they have a 496 but with the 6lbs for every 1 hp idk if the 460hp will be enough it does make 515 lbs of torque at 3100rpms

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SWAMPHUNTER45
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Re: Boat Build

Post by SWAMPHUNTER45 »

There are hundreds of stories out there about what different guys and gals have used to power their boats. The current best dollar per hp is probably a junk yard 5.3 LS or 6.0 with a cam change and stand alone efi or carb. What works for one sometimes will and sometimes won't work for the other boat. If your seeking a frugal LS reach out to OneEyeGator (Mike) he has done a couple and raves about his results. Probably 20 guys on here with BPE engines who would say they work. Back 5-7 years ago there were some 383 BPE engines that developed issues on airboats. It made me look into it and the ones that failed were flat tappet motors and the engines were running sustained 3200-3800 on gear drives. The users had done proper oil changes but valve springs or cam profile just didn't work on an airboat at that sustained rpm.

For a $500 upgrade back then the engines with roller cams lived.

A builder who has put out airboat engines and has a track record on prop / gear ratio (proof is in prop) building a airboat engine (purpose built) always offers value. An accomplished builder with a track record gets it by doing things right which limits problems the user has to face. Dyno numbers are paper and can be embellished and even when not the case having a broad power curve better suits our need than a big HP number at a higher rpm.

You get what you pay for is usually the case with most things in life! If you are going to try to run on the cheap with any platform you best have a very experienced mentor to coach you on where to spend on upgrades. Guys like Branch, MAS and WaterThunder have earned their place.

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OneBFC
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Re: Boat Build

Post by OneBFC »

Sensors aren't something to worry about imo. They are very reliable in my experience.

Also, I actually prefer factory, unopened engines vs "built" engines. The factory absolutely knows how to put them together for reliable operation. Custom builds can also be reliable, but my experience is its hit or miss.

Will 100% agree with TUNE is king. You get it wrong and any engine will not last.

My stock 122 cubic inch engine has survived fine over the years putting out 400+hp ONLY because of the tune.

So, I agree with Carmotorbarge.....stick with an LS and dont look back.
-Russ
-----------------------------------
The only thing stopping you is FEAR
400+hp Ecotec, 12x7.6 DBDO, 80" 3B Maximus, 2.3 OX,85+mph, water = purely optional
Life begins at 2 BAR, Just a good ole boy

CarMotorBarge
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Re: Boat Build

Post by CarMotorBarge »

xCHUMPxCHANGEx wrote:
Mon Dec 09, 2019 7:27 am
Found one locally for 2k obviously it would have to be gone through as it has over 90k miles on it but from everything know I'm assuming a purpose built motor would be any motor that makes most of its power in lower rpms

I know I'm still green with the whole airboat thing I'm learning as I go I know what I want and where I'd like to keep my price range for the whole build.

Maybe I'm trying to do the impossible building a reliable boat the way I want it and keeping my 25k budget



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$25K is hard to do unless you leverage a bunch of used parts. Also you don't want a motor that makes most of its power in the lower RPM band. That is what A/C boats do and is why they are always shaking rudders. Depending on the prop and gear ratio, you want the max HSP to come in around 5400 to 6200 RPMs. The 496 you referenced is a boat anchor. The HSP comes in too early.
14x7.5 Al David hull with 14 inch transom
419 CI Horsepower Barn LS3 with 2.88 Ox Box swinging 4 blade 83.5" R
GTO Rigging and B&S Tilt Trailer

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Prototype
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Re: Boat Build

Post by Prototype »

Why do people argue honest reliable help?
Go for it and be the first 15 footer with a jump seat with a 5k motor from jethro's motor works, some china shit internals maybe involved?
Pre notion of what you've heard but never done is stopping a lot that know better to pull those that don't out.
Bragging about a cheap rig that needs a pull or push on every trip is like leaving your garbage in the marsh!
Chump? Change? I wish you luck but hope you have someone to ride with that is not a chump change kind of person! Not that your responsible for passengers and your build?

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