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STROKER ENGINE

swampdonkey

Well-known member
Need some advice. I purchased a 18x8 panther with 2:1 gear box. I need to put a engine in her. Thunder talked about a 496 in a earlier thread and that engine struck my fancy. A 496 is a stroked 454, Now I'm thinking would it make sense to stroke a 455 olds just for the weight factor. If so would it be as good? Next is a big block the best motor to put in a boat this size. Would a 383 stroker be sufficiant? Once I decide on which block I'm going to use then I will be asking for your help as far as what cam, intake and heads I should use. I sure wish I wasn't so far North then I would definately be talking to THUNDER AND FELBER and get me an awesome motor. My engine knowledge for airboat application is zero. This is my second airboat that I purchased my first boat is a 18x8 and I put a 455 olds Direct Drive. She runs fairly well but this one will be much better will the gear box. I have so many more questions but I will save them for other post.
Thanks in Advance
Swampdonkey
 
SD you can always get them to build you a motor and come to florida to pick it up while on an airboating vacation. Don't forget to check on jegs or summits web site for complete engines in the box ready to run and classic has crate motors for sale also ready to go on an airboat, just a few options. I would lean towards a big block on an 18' boat myself, probably a 572 cu. in. 620hp version. but thats just me. I was thinking of putting one of those on my new boat and it is only 15'. Don't worry pm thunder or felbe rif they don't respond here in public, they have been catchin heck lately for the opinions expressed, LOL
 
I used these folks for my crate motor, had excellent service and the thig runs like a top.

http://www.paceperformance.com/index.as ... tegory=130

I hope it wasn't me who was givin Thunder heck. I do find it interesting that for long term airboaters we have had experiences that on the surface "appear" to be exact opposites. Not sure they are they just seam that way. Since we don't know eachother yet, it may be that My comments come off other than genuine to some.

Scotty
 
I would recomend big block. IT all depends what you want to do with it. Running something that big dry will take a lot and even a built small block will have to work it's a$$ off. With a hull that big I don't think the weight diference between big and small block is a big issue.
I hve always believed in MORE POWER is better. You can always back off the loud petal when you dont need it, but if you don't have it when you need it , well you know what happens then. Muddy shoes.
Tim
 
There are guys out here in Nebraska running 455 olds engines wiht 2 to 1 belt boxes on 16 x 8 fiberglass boats with poly that run dry pretty good. As far as I know the engines are stock and turning 3 blade powershift props. There is probably about 100# difference in weight between a 454 and a 455 olds (olds is lighter). They seem to do ok with reduction. I'm not sure if stroking an olds will gain you too much. To me reliability is more important so I prefer to stay as stock as possible.

Just my opinions and experiences.
 
as long as you were spending the money you should up grade your gearbox.it takes lower rpm monster torque to use a 2-1 gearbox to make it run really well.
 
A million times! It's like everything else it's all a combo and no crate motor is optimum and peak dyno numbers mean nothing and the badest combo on a dyno or desk top dyno will kill it's self from detonation in 1 trip oh yea MARK V VI BBC are not good for airboats if you run hard. I'm sure all the crate engine peddlers will argue with me but you will not find a serious off shore boat racer or a serious drag motor who runs one and nobody dares to run the new gen VI on N20. The best 496 to build is a mark IV 454 with a 1/4 more stroke you can't hurt em.
 
I like the Mk 1V,
Tons of choices for new and used performance parts at affordable prices! Plentyful combinations for a 496 at reasonable prices. Or go as wild as you want! :twisted:

Waterthunder! you mentioned you might post some LS1 torque/hp curves. It would be interesting to see them and compare to some different engines, different crate stuff and perhaps some of Felbergs stuff! 8)
 
MarshGator":mm7y9qk4 said:
Has anyone used a desktop dyno program on big block engine combos for airboats?

Dave (Waterthunder) and myself have been over this years and years and beers and beers, with plenty of real life testing to back it up.....I figured out Desktop dyno's program a long time ago...ALL it's variable measure is calculated cylinder pressure. If you do ANYTHING to increase compression or widen the lobe seperation of the camshaft it WILL show an increase in power. But in the real world EFFICIENT, DETONATION-FREE COMBUSTION is what converts heat into motion...NOT spikes in cylinder pressure. It's a great toy, and if you know how to use it compared to proven combinations you've tested on the dyno, and cylinder heads you've flowed on a bench it does a decent job...But if you dyno test and have a flowbench....DDD isn't something you spend much time with. LOL

But in all honesty...It does work OK if you don't walk outside these things I mentioned. If you can put in flow numbers for the heads, and use actual cam profiles in production it will give you some good direction...Just remember that giant low RPM torque in an airboat has to be followed by real-world knowledge of the internal combustion engine before you start orderin up parts for that magic combination that kicks ass on the hill for 2 minutes before covering all the passengers with motor oil.
 
nebraskaairboater":rbvy7f7o said:
There are guys out here in Nebraska running 455 olds engines wiht 2 to 1 belt boxes on 16 x 8 fiberglass boats with poly that run dry pretty good. As far as I know the engines are stock and turning 3 blade powershift props. There is probably about 100# difference in weight between a 454 and a 455 olds (olds is lighter). They seem to do ok with reduction. I'm not sure if stroking an olds will gain you too much. To me reliability is more important so I prefer to stay as stock as possible.

Just my opinions and experiences.

There is between a 50-60# weight advantage to the Olds in stock form with all iron components. The mass of the weight on a big block Chevy is the cylinder heads (Their main claim to fame for HP production BTW much like the Chrysler Hemi) weighing ~80#ea. When you outfit both engines with aluminum heads the weight becomes within 25-30#s with a major HP advantage to the Chebbie. In DD form, I tip my hat to the Olds...But reducted...There's no discussion as far as I'm concerned. And remember that the phsical size of the Olds is actually larger and the weight savings comes from thin-wall castings and a very weak bottom-end in comparison to the BBC. AKA You can build an Olds to be semi-competitive with the Chevy HP wise with 4X the $, but once you use the parts to make it as reliable it will be heavier all the while still not as strong. Stroking the Olds will help DD, but remember that if it builds too much cylinder pressure it will tear itself apart. Oftentimes increased RPM is much easier on parts than lugging at low RPM. If we were talkin diesels it would be a different story but...JMO
 
swampdonkey":2zvzwtm6 said:
Need some advice. I purchased a 18x8 panther with 2:1 gear box. I need to put a engine in her. Thunder talked about a 496 in a earlier thread and that engine struck my fancy. A 496 is a stroked 454, Now I'm thinking would it make sense to stroke a 455 olds just for the weight factor. If so would it be as good? Next is a big block the best motor to put in a boat this size. Would a 383 stroker be sufficiant? Once I decide on which block I'm going to use then I will be asking for your help as far as what cam, intake and heads I should use. I sure wish I wasn't so far North then I would definately be talking to THUNDER AND FELBER and get me an awesome motor. My engine knowledge for airboat application is zero. This is my second airboat that I purchased my first boat is a 18x8 and I put a 455 olds Direct Drive. She runs fairly well but this one will be much better will the gear box. I have so many more questions but I will save them for other post.
Thanks in Advance
Swampdonkey

Sorry for my last two rants, and I will get to your original question, and hopefully answer things the best I can from my side of the street without mudding it up anymore. I think I can can skip some topics since many have been covered already by others and myself.

You are pushing a decent sized boat with a conservative gearbox. I'm not sure what performance expectaions you're looking for, but bare-minimum you will need a pretty stout powerplant/TQ curve if you want it to do much more than cruise down the river. You will need an engine that makes great lowend TQ with a broad curve (Avg HP). But in an airboat the more power it makes and the heavier the load, the more heat/stress it goes through. Now this is where I stress a BBC over an Olds...An Olds cannot take the abuse that a BBC can in my honest opinion, and that's pretty tongue in cheek. Ask an offshore boat racer to run an Olds, and you get my point. An Olds in stock-slightly modified form is a beast...NO question...But under long-term stress and heat........

Now as for the 496 BBC...Actually, it's an engine I HATE in car...It doesn't rev quick enough, and makes less HP per CID than a 454 or 427. BUT in an airboat with a gearbox...It's just what the doctor ordered. It has a good bore/stroke ratio to avoid detonation and has a cylinder head that will allow you to make whatever power you want. And the platform of the MK IV block is second to none in terms of integrity. Combine that with relatively low expence, and insane parts availability...It's a no-brainer to me.
 
FELBER632":2k5ti7nx said:
swampdonkey":2k5ti7nx said:
Need some advice. I purchased a 18x8 panther with 2:1 gear box. I need to put a engine in her. Thunder talked about a 496 in a earlier thread and that engine struck my fancy. A 496 is a stroked 454, Now I'm thinking would it make sense to stroke a 455 olds just for the weight factor. If so would it be as good? Next is a big block the best motor to put in a boat this size. Would a 383 stroker be sufficiant? Once I decide on which block I'm going to use then I will be asking for your help as far as what cam, intake and heads I should use. I sure wish I wasn't so far North then I would definately be talking to THUNDER AND FELBER and get me an awesome motor. My engine knowledge for airboat application is zero. This is my second airboat that I purchased my first boat is a 18x8 and I put a 455 olds Direct Drive. She runs fairly well but this one will be much better will the gear box. I have so many more questions but I will save them for other post.
Thanks in Advance
Swampdonkey

Sorry for my last two rants, and I will get to your original question, and hopefully answer things the best I can from my side of the street without mudding it up anymore. I think I can can skip some topics since many have been covered already by others and myself.

You are pushing a decent sized boat with a conservative gearbox. I'm not sure what performance expectaions you're looking for, but bare-minimum you will need a pretty stout powerplant/TQ curve if you want it to do much more than cruise down the river. You will need an engine that makes great lowend TQ with a broad curve (Avg HP). But in an airboat the more power it makes and the heavier the load, the more heat/stress it goes through. Now this is where I stress a BBC over an Olds...An Olds cannot take the abuse that a BBC can in my honest opinion, and that's pretty tongue in cheek. Ask an offshore boat racer to run an Olds, and you get my point. An Olds in stock-slightly modified form is a beast...NO question...But under long-term stress and heat........

Now as for the 496 BBC...Actually, it's an engine I HATE in car...It doesn't rev quick enough, and makes less HP per CID than a 454 or 427. BUT in an airboat with a gearbox...It's just what the doctor ordered. It has a good bore/stroke ratio to avoid detonation and has a cylinder head that will allow you to make whatever power you want. And the platform of the MK IV block is second to none in terms of integrity. Combine that with relatively low expence, and insane parts availability...It's a no-brainer to me.

Felber
I sure wish I could be a fly on the wall when you and Thunder exchange thoughts over beers. Really enjoy reading all posts. I think I will keep my eyes open for a MK IV engine. What year and what type of vehicle are the MK IV most commonly found in. I will keep my eyes on local auto insurance auctions in hope to luck out on a 496. And especially if you say that they are not a good car engine. I hope that I can pick one of these TORQUE MONSTERS up for a reasonable price.
Thanks for all the respondes. Any info on what vehicles and years I should be looking for to find a 496 MK IV I will be for ever greatful.
THANKS GUYS
 
Any of ya'll looking for a GM crate or Performance Parts motor, send me a PM and let me see what I can do on price.
 
The 496 MKIV is definitely a custom stroker engine. If you buy a crate/generic 496 it will be basically nothing more than a more reliable 502 with a similar power curve. The truth of the matter is it's the combination of parts and finesse of the engine that makes it pay off.

Quench, domeshape, rod length, combustion chamber modifications, port flow, shape and velocity, camshaft lift velocity, intake manifold and carburetion are all custom in a "real" 496. Anyone who knows me here knows that I never pimp my stuff or try to sell anything. But honestly you can build a tricked out AIRBOAT DESIGNED 496 for quite a bit less than a 572 and only a little more than a 502/502.

Bear in mind that the crate engines do great at their power levels (detuned/mild) with the relatively weak parts in them. If you try to step them up much, you wind up throwing away most of the parts in them.

So if crate engine power is all you need, you will be happy. But if you realize you need much better performance, do yourself a favor and start from a clean sheet of paper. JMO
 
IS A 502 A STROKED ENGINE. We don't need high performance. I'm just look for an engine with alot of grunt so we don't have to push it to hard. When you have to push an engine to hard your fuel economy goes out the window. I know some might say that with a boat that big you won't get any fuel economy. I'm more concerned about over working the engine which will afect its longevity. If a 502 is more reliable then a 496 stroker that might be all we need. What do you guys think? I really appreciate all the info.
THANKS AGAIN
SWAMPDONKEY
 
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