• If you log in, the ads disappear in the forum and gallery. If you need help logging in or getting registered, send request to: webmaster@southernairboat.com

Fuel economy

Southern Airboat Gallery Archives

Ron
Southern Airboat First Aid
IMG_09991
0520 Continental with Gitsu Cylinders
IMG_15701
boat_pics_080
F

FloridaQuaker1027

Well-known member
alright.....I have just been wondering how each motor is when it comes to the amount of gas they burn

I have hear mixed reviews......Some say 4 cyl. are pretty good and others say they burn more gas with them than a 6 cyl. Can anyone give me some insite
 
It has largely to do with the amount the motor is loaded. A small motor on big boat gets lousy mileage, small motor on a small boat does good. Bigger motor on a small boat may do well too. Big motor on big boat means big gas.

Every boat will be different and operators have a HUGE influence as well. In "GENERAL" a 4 cylinger say 160-180 on a small possibly narrow hull will do great. Even a 90 HP 4 cylinder on a llittle narrow short hull will just sip gas but there are limitations with carrying capacity.

Gass makes HP so the more HP you extract from an engine the more gas it will need to manufacture that HP.

Scotty
 
Quaker, it's like Scotty said ..... it's the old VW versus Chevy Tahoe thing. Small, light, efficient boats require less fuel to perform.

BF
 
well me, waterthunder,moodfood and swampjet rode from lonecabage to laughman and back mood food has a dd 350 put fuel in at laughman swampjet said that he burned 24 gallons 6cyl aircraft and I burned 18.5 gallons with a 350 and a 2 to1 gear box and water thunder who has a bad ass boat burned 14.5 gallons and he has a 268 gear box .

so with that said look who has the best fuel milage and the BIGGEST GEAR BOX and the BADEST ENGINE and got the best economy.

thats my 2 cents
 
Those HP numbers are bogus on the topic though. Your NOT extracting that much HP as your running.

Like I said every situation is different.

Id still say a light 4 cylinder will sip less gas then the big V8s each in an appropriately sized and weighted hull.

THers actually a formula that considers weight, induced drag, speed, and hull drag per unit of HP per unit of thrust generated, to calculate overall HP extracted to move or make any particular speed. Takes a LOT of instrumentaion to work it though.

The question asked was a general question and a general answer was in order. My opinion only of course.

Scotty :)
 
CC, I once had a little Chevy S-10 pickup with a tuned port 350 engine in it that I took out of a wrecked (roll over) IROC Camero. The little truck would give you 28mpg on the road anytime you wanted to check it, and it was all because the truck was so light that the engine never had to work.

Thunder's boat is the same situation .... a huge motor in a light little deck-over hull. The engine never has to work hard to run with you guys.

BF
 
here's my two cents: my 200 lycoming will burn 8 gallons of avgas on the trip to and from my duckblind (estimated 20 miles roundtrip) or whatever it is while my 260 lycoming (with a much heavier hull) will burn about 12 gallons of super. and thats carrying 2 passengers and a dog. however, when i'm frogging, i burn WAY less in the 200 just idling around for hours, probably 10 gallons less over a 3 hour period
 
I love them O-320 and 360s ! They are the mainstay of light weight airboating ! I know there are the minis too but they are just that....Mini.

Cowboy sez he did a run with a 220 GPU, I think, and they burned the same amount of gas on that particular run. Maybe he will chime in about the conditions and the boat differences that allowed that. I point to Cowboy cause I love that boat ! It's just the wrong boat for me in South Brevard.

Scotty
 
Yeah,
Those fuel burn number were 14 gals for my IO-360 thats on a 12' beach deckover. It's swings a 68x40 sensenich stick.

RDM0470 burned the same with his Modified Glades Style Deckover of his own design. He's got a low compression 540 parallel valve engine on there, swinging a composite wide blade.

We burned that much fuel cruising in skinny water marsh for sixty some miles. Getting on the gas very seldom.

I was surprised when he finally re-fueled his rig, and told me 14 gals. I attribute that fuel efficiency to his modern propeller. It allowed him to feed two additional cylinders, and burn the same fuel. The performance is very similar between the two hulls, and the operation profile that day was very similar. Just easy riding.

If we had been riding deep water trails at lake Okeechobee, Those number would have not have been as good. At least thats what I would expect.

BTW,
A Palm Beach style deckover could be the perfect boat for you in Melborne. Besides the way they look, they are the best Light hull design going, so far as allround perfomance. Their the best light aluminum airboat design going. IMO. I say aluminum, cause I believe that some glass hulls offer similar performance, but perhaps a little heavier. I'm not sure about that. Just saying a glass hul can do darn well. Aint nothing wrong with them.

Also,
I think RDM0470's got the Palm Beach fever!
It's a shame.
I don't think science has found a cure for that affliction. (other than owning one) He's just gonna have to suffer till he gets one. He won't have to endure much pain, cause he's got one killer running boat now.

Stop looking at those Palm Beach hull photo's now, while you still can Whitebear. Stop scrolling now Whitebear!

Who's the Southern Airboat Surgeon General?
Perhaps they can put a consumer warning on those photo's. Hee-Heee

95DSCN0037.JPG
 
PERFECT EXAMPLE Cowboy.

Similar hulls in similar conditions extracted about the same HP out of the engines to do an equivalent amount of work. Hence, the same fuel burn.

In different conditions like deeper water then the application is different and each hulls profile will be somewhat different resulting in a different amount of HP required to do the same ride, hence a different fuel burn.

I do find it interesting how much difference his advanced engine detail made in his fuel burn. i.e., the composite prop etc. Of course if you had the same setup it might not be as equal as it seems on the surface.

STILL: In general its fair to answer the question that a 4 cylinder will GENERALLY get better fuel mileage than a 6 or 8 or 9 or 12 will.

Scotty

P.S. We need to talk about them PB hulls again :) Does Tylenol help at all ????????
 
If i remember we ran about 60 miles round trip and alot of it was deep water and then we did run about a 1/4 mile dry and mine and thunders boat was WIDER than the trail so we had to try to keep the boat moving
4 boats same trails and the 2 boats with gear boxes got the best fuel

also we are running less rpm on a plane than the other boats
 
I've been behind SwampJet, I know why he burned so much...he doesn't know how to keep his RPM's below 2400 or so!!! When SwampJet asks you to go on a ride he wants to go on a ride!!!! :p

I don't know how far that Shady Oaks ride was but Nicole and I went farther than everyone else because of our detours. My angle valve 470 on a Cottonmouth 13'6 burned between 30-35 gallons (I check with a stick so I can't say how much exactly). I tend to always get better mileage than the three 540's that I ride with the most. But I was cruising at around 1700 RPM's most of the day.

Adam
 
There can not be a formula to calculate fuel consumption by only reading horsepower that applies to both motors. The only accurate way to do this is by reading BSFC on a dyno. Air-cooled motors waste fuel to cool the cylinders water cooled engines don’t so one formula can not work for both style engines because it takes an aircraft motor more fuel to create the same horsepower as a car motor. Whitebear I hope you were not implying my horsepower numbers were bogus because I have proven time and time again they are not. On at least 4 occasions somebody has removed a 502HP 502 G.M. crate motor installed one of my 500HP LS’s and swung the same pitch more RPM’s so either G.M. is lying about their 502 or my motor makes more power then I claim. I know exactly what my 500HP LS1 makes at 5,600RPM. As for economy it depends on your complete combination from, Hull, prop, rigging, bottom of boat and tune. I can set my boat up where I burn 10 gallons and every boat around me burns 20. When I go on long rides I change my set up. I have rode with several 180’s and burned less gas then them so to talk economy solely on a motor is fine if you only sit on your motor with no boat. That’s an argument that makes nothing but a mute point. I will however make the comment the basic aircraft engine that was designed in the 40s and is not very efficient, neither is the small block Chevy that was designed in 1953-54 the difference between a conventional SB Chevy and an LS1 are astounding. G.M. put their heart and soul into designing the most efficient powerful modern pushrod motor ever built and they succeeded. I think engines have improved drastically oh say in the last 75 years. One difference I feel is even though I get great fuel economy I can load 4 people on my boat and run dry it’s also fairly quick. As always I say with every technical post “what do you want your boat to do best�. Well I was aiming for the best all around boat I could build I was surprised when I finished how great it is on fuel especially running the hill. If I was only concerned about fuel economy I would run a DFI and drastically improve my economy so right off the bat the best fuel economy motor would have a DFI system on it no matter what type of motor it is. HMMMM maybe that’s my next project build an extremely fuel efficient boat. Just for shit’s and giggles I’m ridding tonight were running south and North river 3 boats have the same exact hull all boats are .100 deck overs one has a carbed O540 one has a fuel injected 520 the third has a carbed 180 so we will see who get’s the best fuel economy. Were running mostly water accept some black mud behind bulldozer which I doubt the 180 will make it thru but we will run the gammon of surfaces and I will tell you how we did on fuel Friday. Out of the other boats the injected 520 always impresses me it's a great all around boat too so is Swamp Jet's. You guys don’t know how many times I wanted to build another aircraft and run a DFI and play with it but I LOVE my boat and don’t want anything else. Plus the fact my wife said it’s the couch if I get rid of it.
 
Adam, Swampjet may be old, but he ain't SLOW ...... :lol: .

The man will take ya' for a ride.

Thunder, I know all about the couch :? .

BF
 
Fuel efficiency will become very important in the next few years. Fuel prices are going up. Folks want to believe they won’t go up but they are. Mr. Waterthunder your eye on fuel efficiency may be very wise. A balance of power and economy could be a good thing. The cost of oil is going up- everybody wants oil.
 
Thanks for all the info

Before I put money down to get my own boat I am trying to find out exactly what hull and what motor would be best for me....Hopefully yall can help me out

I want a boat basically that I can fit 2 - 3 including myself out to camp, be able to do some frogging and riding without having to take out a loan to run 2 - 3 weekends out of the month...Dont plan on running dry at all

I was looking at possibly a 4 cyl but most people have told me you will burn more than a 6 trying to keep up....I know most of it depends on how you run and I personally like to cruise at around 1800 rpm on my buddy's thruman with a 0540 but I also want to have to power behind me incase I do have to run cross country.....I am on a budget of around $6 grand...opinions?????
 
Try a 220gpu. That would work well for what you described. Relatively inexpensive compared to other aircraft motors too.

Adam
 
Quaker:

I'd recommend a high-sided hull (Rivermaster, Laser, etc) with a 220-GPU for the amount of money you're looking to spend. There's a number of them listed right now on airboattrader.com from $6000-$7000. Here's my reasons:

1) In WCA-2A there's enough deep water to justify a high-sided hull. While I recognize that most of your trips will be out to the camps, in the winter/spring when it's dry out there, it's sure nice to take the Hillsboro canal to the end. It's about a 7 mile ride in deep water (anywhere from 4-20-feet deep), and a high-sided hull will give you a lot more peace of mind during the ride.

2) The 220-GPU is an economical engine which should provide sufficient power to go anywhere you need to go in WCA-2A. The engine's easy enough to work on yourself, there are plenty of parts available, and there are some good local mechanics if you need them. And worst case, a new one should cost less than $3000 should you need to replace it.

3) The 220-GPU will run great on 93-octane. I've been burnin' 4 ounces of Marvel per 20-gallon tank, and am really impressed with the performance. I recommend Amoco (BP) Ultra....

4) The 220/Holley 500 combination gives pretty good gas mileage. My boats a 14-foot Rivermaster with two double seats. With three people in the boat (over 600 pounds) plus another 50 pounds or so in cargo, I get about 2.5 miles per gallon (less than 7 gallons to go from the Lox road ramp to Willard via Patrick camp, then to 4 Moons, and back the East/West trail....about a 16 mile ride).

Good luck with whatever you buy. And no matter what you get, I can almost guarantee you'll be working on it a month or so after you buy it. Least that's my experience. And you'll never stop working on it..........

Doc
 
I have to agree about the gpu, its a good combo on the right hull. Another option is a dd 500 cad. If it is set up right you have the possibilty to run 2-3 people and cover some dry if you have to. I ran one for about 5 yrs and it was alot cheaper to operate and maintain than my 6 cyl aircraft. If I drove with efficiency in mind it used around 3-4 gal per hour. I always ran 87 octane with no problems. I had it on a 13' deep sided combee hull with poly and had a 6 blade warp drive. This combo ran dry pretty good for what it was, but when you got stuck it was a bear to get going again. I also frogged out of it with no problems, all in all it was a pretty good all around boat, wish I still had it for a cruising boat.
 
You must log in or register to reply here.
Back
Top