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Thinking of using a mopar big block.

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CHRIS PULLING A SUNK AIRBOAT
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18 x 8 1/2 GTO that is headed to Louisiana
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Sitting at Bears Bluff
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Insta-gator82

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Hey ya'll. I am inthe process of aquiring all of the parts to build my boat, but I was looking for some suggestions. I know alot of guys that run Chevy motors, and a few Ford guys. But no Mopar guys. I know the motrs are heavy as hell, but I am thinking of putting my 472 Mopar big block on a 12'6 alum hull. The motor puts out around 625 hp. Any hints as to whether it'd be a good idea or not. I know it'll be tricky to get the weight balance right, but I want to be different. Marshmaster or WaterThunder, any advice?

Greg
 
Greg - No clue about them. There was an earlier post about other motors besides chevy. Something about some of the other brands not able to take pushing on the crank as well as chevy.

That would be something Waterthunder or someone else would have to comment on.
 
Thanks Marshmaster, I was wondering about the strength of the crank. I think it would work....... but I want to be sure before I put the motor on the boat and it falls apart the first time i throttle it up. Anybody out there have any expeirience with these motors?
 
That's probably a little bit small of a hull for that heavy of an engine

Most of the big block boats you see are 14' or more
 
Hello, Were you going to use a gear box? If not i would NOT use a motor like that. You say you are making 625 horses. WHERE? At 5000 or 6000 rpm plus? To make that kind of power you need a cam that would not even START making power until 2500rpm MINIMUM. Look at dyno sheets of motors that make that kind of power and you will see that until 3000 they are making 200 to 300hp maybe. Once the motor starts spinning the power levels come up. By putting a motor like this in a direct drive application I feel you would be building a Insta-Pig!!!!! Put a box on this animal and then you would have something!!!!!!!! Also there would be no question about crank problems with a box. If you use this motor in a direct drive boat you could put a smaller cam in it and target your power for lower RPM's. You have the cubic inches to build a D.D. boat ,just fit the motor for the application so you are happy :D . I love to see ads for boats for sale or B.S. circles and guys saying they have a 400+H.P. engine on a D.D. boat. Thier engines might make that much power but NOT at 3000. Everybody likes to see different engines used just make your choice proud!!!!! :mrgreen:
 
Under pressure has made some good points. I have destroyed a lot of boats that have a dyno sheet showing they made 650HP. And they did but the motor I killed them with in some cases made as little as 475 and others made up to 600HP. I don’t care one bit about peak Horse power. I’m building a motor now to out run a motor that dyno’ed over 900 peak HP and I bet we will out run him making 800HP. I have seen several motors that the owners claim make 600, 700, 800. There are limitations in certain components and just by looking at their motor. I know their full of BS even if they twisted their motor 9,000 it couldn’t make 650HP. Anyway the Big Block Chrysler isn’t a good choice no offense but their very heavy. However they are a good broad motor but they also have their thrust bearing located in the middle main instead of the rear. Plus I have never seen a gear box for one. My opion (only) but I would never run a direct drive car motor boat unless some one held a gun to my head. But hey if you have one and it’s your only choice what the hell but if you have options I would look into them. Oh yea I am a closet Mopar guy my first hot rod was a 340 Demon and at 18 years old I had running 11’s on motor and drove it to the track so I’m not anti Mopar. I would only consider running the BB Mopar if it had aluminum heads on it. Most Mopar engine builders are very conservative on cylinder head ports and camshafts so you may have a decent combination. If you care to, give me some specs and I can tell you how it will function in an airboat.
 
Thanks for the advice, Thunder. I've been debating about it, and I think I'm going to keep looking around for ideas. I didn't really want to go the car motor route, but I thought the chrysler would be cool. I see that the weight would pose an issue, as I want to build a light weight boat, to run dry. I think I might just leave the Mopars on the road. Oh yeah, back in high school, I built a 525 hp 440 Magnum, that was grafted into an 85 Ram. It was on old schoolboard work truck. Never ran it on the track, but probably high 11's, low 12's.
 
There is a neat Mopar all aluminum big inch 565 or bigger twin turbo Hemi on an airboat running around. I saw him at lake Kiss years ago and spoke with the owner and found out the motor was built by Dick Landy. It was an awesome boat the most decked out boat I ever saw it had a night vision monitor and every form of GPS and communication made it was built with a budget like the pentagon’s. The motor obviously made well over 1,100HP but it was one of those typical millionaire airboats where somebody has a ton of money and they must have the baddest airboat. I see a lot of them big inch 572 plus motor on hull’s that are more of a pontoon boat or river barge. It’s funny when they’re done their no longer an airboat and a good strong 180 Lycoming or a crate motor vortec boat will run them ragged on the hill. Anyway it was a very unique airboat I will never forget it.
 
heard that boat was a real showpiece, but did not perform as well as it looked. I ran with the owner about a year ago and he had alot of motor problems with this particular boat and was running a new boat with a bb chevy and counter rotator box, that boat was real impressive.
 
Airboats are intented to run aircraft engine.You guys with car motors will never learn. :twisted:
 
If you get down to it aircraft motors are made to run on planes at 15,000 feet
 
you car motor guys must have more money than brains.Because the car motors around here seem to only last around 100 hours or less.And you have to spend 3 times as much money to get the torgue as an aircraft with 3 times the weight. :twisted:
 
3 times the weight?? Ever weighed a gear nose supercharged aircarft engine?? I would like to see the numbers on a scale of a supercharged 0540 and one of WaterThunders LS1 motors. I gurantee it would not be 3 times the weight difference. The can of worms is officialy open. I own an aircraft engine airboat. I am going to a car motor, but if its in an airboat its an airboat motor, not a car motor.........
 
You guy's Kill me!!!! I have at least five friends who average three or so aircraft rebuilds to a friend of mines car motor boat and he goes places they cant even dream of going when they try they overheat and he has never had a problem with his motor what so ever he also has $3,500 in it. Oh ya aircraft motors are not intended to run at sea level either so what's everybody's point.
 
Well,

Rick solved part of this problem by making it necessary to be a member to post here. This is a move that I totally agree with.

Read the above paragraph between the lines.

As for the engines, I like both and both have their place. We learn by experementing.

A normally aspirated aircraft engine is designed to produce rated horsepower at take off. As the airplane climbs the engine loses power, even at full throttle unless it is turboed or supercharged. By 7,500 feet it will only produce 75% power at full throttle (even when leaned for best power) due to the reduction of air density at that altitude. That is high cruise power. By 10,000 feet the climb performance is considerably reduced and some of the naturally aspirated engine aircarft are unable to reach 15,000 ft, if they do, the climb at that point is very slow. Most light aircraft are unpressurized and do not carry oxygen so are normally not operated above 10,000 feet due to lack of oxygen for the pilot. The maximum speed for a normally aspirated airplane at full throttle will occur at the lowest possible altitude because that is where the maximum manifold pressure is available to the engine, and that is where it produces the most power. It is designed that way. The reduced drag of the airplane at high altitude is more than compensated for by the lack of effeciency of the engine up there.

Some models of the Mooney airplane have a bypass for the air inlet filter that can be opened at the higher altitudes (where the air is clean) to provide a ram effect. This is a fuel injected engine so it can respond to the ram effect and it produces a slight power increase.

Jet engines and supercharged engines are a different story.

Jim
 
Oh don't get me wrong I was being sarcastic! This discussion is like watching two people who have never built a motor or car arguing about a Winston cup car. You know The Ford VS Chevy thing I thinks comical that people don't realize motor has it's place and no motor ever designed is the best for every application. That's why I said aircraft motors are not designed to fly at sea level. I built a LS1 motor for an experimental aircraft and they pilot stated the fact his plane is faster has far more horsepower and get's better fuel economy so what's the point. I just like stirring the pot when people say stuff like My Ford rules and your Chevy sucks or vise versa and when I ask them why the are absent of all relevant facts. In other words they are just stating an opinion. I’m a fan of all motors that burn gasoline well almost all motors.
 
Thanks for clearing that up Jim.


Thunder, I keep hearing you say that and 0540 can only dream of following a carboat. Maybe that’s the case where you are from but around here its not. I run side by side with zz4s, zz5s, and 454bb and I stay right there with them. Of course the bb will out run us all but that’s expected. Now you say you are pushing 450 and 500HP from an engine that is the same weight and maybe slightly less than the 0540, if that’s the case then it better run like a bat out of hell. It would be in your best interest to contact the two builders here in south Louisiana and send them one to test, if it’s half as good as you say they would sell like hot cakes.

As far as overheating, I run a cooling shroud from Marks. We bust shooting lanes in the marsh right before hunting season with our boats when the marsh is still green and hardly ever have trouble with running hot (oil temp and CHT). That’s running 80% to WOT 6 to 8 hours at a time with small breaks in-between to refuel. If it’s set up right they will run within specs.


Where your at Passtime, jump in here.

Kevin
 
I have seen some bad ass O540’s too. It all depends on the combination and I have noticed that just about all car motor boats unless their in mid or south Florida are way too big, heavy and don’t run good and have a 250Lb belt drive that’s only 2 to 1 on them. Most car motor boats in my area the ones that I’m referring too are 12 feet with a gear box from 2.38 to 2.68 and the will run 99% of the 540 ragged on the hill till the 540’s are glowing red and pinging to death. Me and a friend of mine both have deck over boats with 2.68 boxes and yet have to find an aircraft that would run the woods with us. However if we had the usual 14 to 16 foot boat with a 2 to 1 gear box or even worse a belt drive I’m sure the O540’s around here would eat us up. Also most car motor boat are turned into 15 ft barges. They eat up motors because it’s so hard to push a barge that’s why they don’t last long. I have buddies with 6 to 7 years on a car motor and they run their stuff hard and stupid and average 200 plus hours a year. They haven’t even had to take off a valve covers yet. I guarantee you no 0540 could push a tour boat dry with 5 people on it. See it all depends on the combination.
 
I am proud to admit,I AM aMOPAR FREEK! My first boat was to be a mopar powered ride but everybody talked me out of it(went with gpu- empathis on pu!) Pumped up the gpu and its constantly burnin pistons even with100% av-gas. But i do have a size 12eee foot!
 
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