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V8 seadoo motor swap
- Thread starter V8seadoo
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This is going to be much more of a challenge (and an expense) than you'd anticipate. Honestly if you are asking questions then you probably cannot single-handedly do a swap such as this.
Weight distribution will certainly be an issue with an engine that heavy, as will overall size (mostly length).
Go into this assuming you are the first and do some research. Feel free to share what you come up with on here and you'll certainly get some realistic feedback.
Btw, don't anticipate doing this for less than several thousand dollars after you have both the engine and the hull.
Weight distribution will certainly be an issue with an engine that heavy, as will overall size (mostly length).
Go into this assuming you are the first and do some research. Feel free to share what you come up with on here and you'll certainly get some realistic feedback.
Btw, don't anticipate doing this for less than several thousand dollars after you have both the engine and the hull.
I already have hull and drive.
I`ve measured everything and i`ll need to remove fuel/oil tank and poss. hinge the rear bench or just center seat. I need 50" from transome/jaczzi flange to front of 455 crank. there is enuf room between jets to mount jacuzzi.
Plan B: From the rear of the 455, drive both jets w/ a 2:1 cogged or v-belt drive. That measures up as well (455is34"longx28"pan to carb top. Due to jet shaft side load, i would need a dbl. pillow block bearing. I`ll need 7000 rpm at shaft w/3500rpm. This allows me to keep the fuel tank.
I`ve measured everything and i`ll need to remove fuel/oil tank and poss. hinge the rear bench or just center seat. I need 50" from transome/jaczzi flange to front of 455 crank. there is enuf room between jets to mount jacuzzi.
Plan B: From the rear of the 455, drive both jets w/ a 2:1 cogged or v-belt drive. That measures up as well (455is34"longx28"pan to carb top. Due to jet shaft side load, i would need a dbl. pillow block bearing. I`ll need 7000 rpm at shaft w/3500rpm. This allows me to keep the fuel tank.
When you compare the 60lb Rotax to the other engine I wonder where will you have the helium holding tanks to keep this project from being an anchor, I experimented with hydrogen in my 95 gtx and it goes on plane in a breath but I do not think there is enough room to support any iron driveline stuff. Measure the gravitational pull, torque and horsepower are unable to correct the math you use for this equation.
This will make great tavern closing discussions.
I had thought of weight as well
So i`m figuring both rotax engines fully dressed (exhaust as well)should be 150-200 lbs. The 455 is in the 500# range. So i eliminate the ability to ride 3rear passengers. Thats 600#.
both motors are still in there, so I`m going to set her in the water today with 8-50# sand bags in the eng. bay to simulate the added 400#. I`ll get back to you with the results and i`ll take a few pics as well.
You mentioned both helium then hydrogen. I get the helium joke. I`ve built a few hydrogen generators. Sure gave my truck a noticeable boost in off-the-line performance. Comparable to adding an msd box and k&n filter. I wasn`t measuring fuel gains however.
So i`m figuring both rotax engines fully dressed (exhaust as well)should be 150-200 lbs. The 455 is in the 500# range. So i eliminate the ability to ride 3rear passengers. Thats 600#.
both motors are still in there, so I`m going to set her in the water today with 8-50# sand bags in the eng. bay to simulate the added 400#. I`ll get back to you with the results and i`ll take a few pics as well.
You mentioned both helium then hydrogen. I get the helium joke. I`ve built a few hydrogen generators. Sure gave my truck a noticeable boost in off-the-line performance. Comparable to adding an msd box and k&n filter. I wasn`t measuring fuel gains however.
How did your weight test go? Glad you've put some thought into the drive. Sounds like a lot of fabrication to drive both pumps, but with appropriate funds seems feasible. I wouldn't trust a belt drive with the loads involved.
I'm curious, how much power do you plan on making from this 455? Is the reason you plan on using the 455 solely because you have one sitting around?
You will have to consider prepping the engine for marine use, as well as figuring out how to properly cool the engine.
I'm curious, how much power do you plan on making from this 455? Is the reason you plan on using the 455 solely because you have one sitting around?
You will have to consider prepping the engine for marine use, as well as figuring out how to properly cool the engine.
455 V8 olds engine in my 1800 challenger
I failed to tell you all that i have a fully operational 1976 Waikiki 20` jet boat w/ a 455 olds/400 hp./ jacuzzi jet. The floor is soft, interior is shot and the paint is an ugly burnt orange. Hardly worth the investment. I rebuilt the engine last fall. A lumpy cam, stock comp., dual plane intake & a 650 edelbrock carb. I have over-the-transom Bassett headers & a set of water cooled logs as well. I have a set of 3" thru hull exhaust tips as well.
This is a budget build otherwise a short stroke small chevy w/ alum heads would be much smaller and lighter. But i`m not spending that much.
I`ve advertised the boat on CL and can`t seem to get a decent offer. I`ve even offered to part out the boat as well to no avail.
The challenger has 1 burnt piston and both engines have freeze damage. i can`t seem to get a decent offer on this boat either.
So this is what spawned the idea.
I think it will be easier to cut a 14" square between the jets and use the jacuzzi jet. I would have to cut off the bottom of the center fiberglass swim platform brace. I will glass over the void and have to sandwich 3/4 starboard for the jet flange. I have not laid out the jacuzzi intake hole but there`s room. Not a structural safety element far as i can see.
Going this route, i can`t think of anything major to purchase. Can you?
I have aluminum side fuel tanks from the donor boat.
Block off plates for the intakes of the twin jets.
Hmm...I could drive all 3. LOL.
I would prefer to drive the stock jets. I was thinkink of a 3 or 4 wide V-belt or cogged belt arrangement. 2:1 Hypoid gears in a wet box would work best. 3500 rpm= 7000 rpm @ the jets. That motor should scream at 3500.
Far as i can see. I will need to cut out the fiberglass seadoo engine mount tunnel to clear the 455 oil pan. The 455 has a saddle which the rubber moust are attached. A steel bellhousing at the rear has 2 large bolts. Another cinch.
The stealthier the better i say. Can you imagine the look on the faces when they hear this sleeper fire up. Or, i could cut up the rear deck with the headers sticking out.l Hoo-wee!
Does anyone out there have any advice on this subject?
Thanks
I failed to tell you all that i have a fully operational 1976 Waikiki 20` jet boat w/ a 455 olds/400 hp./ jacuzzi jet. The floor is soft, interior is shot and the paint is an ugly burnt orange. Hardly worth the investment. I rebuilt the engine last fall. A lumpy cam, stock comp., dual plane intake & a 650 edelbrock carb. I have over-the-transom Bassett headers & a set of water cooled logs as well. I have a set of 3" thru hull exhaust tips as well.
This is a budget build otherwise a short stroke small chevy w/ alum heads would be much smaller and lighter. But i`m not spending that much.
I`ve advertised the boat on CL and can`t seem to get a decent offer. I`ve even offered to part out the boat as well to no avail.
The challenger has 1 burnt piston and both engines have freeze damage. i can`t seem to get a decent offer on this boat either.
So this is what spawned the idea.
I think it will be easier to cut a 14" square between the jets and use the jacuzzi jet. I would have to cut off the bottom of the center fiberglass swim platform brace. I will glass over the void and have to sandwich 3/4 starboard for the jet flange. I have not laid out the jacuzzi intake hole but there`s room. Not a structural safety element far as i can see.
Going this route, i can`t think of anything major to purchase. Can you?
I have aluminum side fuel tanks from the donor boat.
Block off plates for the intakes of the twin jets.
Hmm...I could drive all 3. LOL.
I would prefer to drive the stock jets. I was thinkink of a 3 or 4 wide V-belt or cogged belt arrangement. 2:1 Hypoid gears in a wet box would work best. 3500 rpm= 7000 rpm @ the jets. That motor should scream at 3500.
Far as i can see. I will need to cut out the fiberglass seadoo engine mount tunnel to clear the 455 oil pan. The 455 has a saddle which the rubber moust are attached. A steel bellhousing at the rear has 2 large bolts. Another cinch.
The stealthier the better i say. Can you imagine the look on the faces when they hear this sleeper fire up. Or, i could cut up the rear deck with the headers sticking out.l Hoo-wee!
Does anyone out there have any advice on this subject?
Thanks
hitman782
New Member
I wish i could give you some, but i, along with everyone else reading this, have a request. If you proceed with this build, please keep us posted with some pics and descriptions. I cannot wait to see this in action, even if you have to put it on youtube. Other than that, best of luck.
I can't see you driving the stock jets without investing thousands and thousands of dollars to get the power to them. It would require a lot of custom machining, which isn't cheap, as well as expensive drive parts. Plus WHEN something breaks, you'll likely have to make another one off part.
If you are going to actually do this and on a budget, then your idea of swapping the entire engine and pump from your old jetboat may be the most viable option.
Can you post up some pics of both? I'm sure members are anxious to see what you are working with
btw, did you do your weight test?
If you are going to actually do this and on a budget, then your idea of swapping the entire engine and pump from your old jetboat may be the most viable option.
Can you post up some pics of both? I'm sure members are anxious to see what you are working with
btw, did you do your weight test?
dieselnut2
New Member
how bout this
hers the consept let me know if your follen
if you have a 3500 rpm motor take the 2 out drives isolate the shafts wit berings an atatch different pullys eather rib belt or chane to equate the 6000 to 8000 rpm
that close to a 2to1 ratio fairly simple we doit with our pullin tractor y not in reverse wit a jet drive
hers the consept let me know if your follen
if you have a 3500 rpm motor take the 2 out drives isolate the shafts wit berings an atatch different pullys eather rib belt or chane to equate the 6000 to 8000 rpm
that close to a 2to1 ratio fairly simple we doit with our pullin tractor y not in reverse wit a jet drive
springerpete
New Member
The Olds is a torque monster, but it is an anchor when compared weight wise to other engines. The Jacuuzi jet is probably the most inefficient jet out there. I'm not bashing your stuff but for the amount of work your gonna do, I would try to fix what you have or find other parts.
I like what you are trying to do but how about a SBC or an all aluminum supercharged V6 hooked to a Berkeley or a Dominator with a A/B impeller.
I've been around jetboats for most of my life. I own two right now plus a Sea Doo.
Or you could rebuild your jetboat's interior and floor yourself. The floor is fairly easy. There is a few websites that are dedicated to jetboats. www.talorjetboats.com or www.texashotboats.com are just a few that could help you.
I like what you are trying to do but how about a SBC or an all aluminum supercharged V6 hooked to a Berkeley or a Dominator with a A/B impeller.
I've been around jetboats for most of my life. I own two right now plus a Sea Doo.
Or you could rebuild your jetboat's interior and floor yourself. The floor is fairly easy. There is a few websites that are dedicated to jetboats. www.talorjetboats.com or www.texashotboats.com are just a few that could help you.
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having been around cars and smewhat boats my whole life,i will try to give my take. This is in no way, shape or form feasible without investing an asinine amount of money. Even if you did happen to make this happen,you would be the proud owner of an extremely unstable and dangerous boat. i can respect your desire to take the 'road less traveled'. we have a saying in drag racing 'Cheap,fast,reliable, pick two.'
Anything ever come of this?
I'm guessing no or there would be a TON of pictures here...
True, but the thread was closed some time ago figured I'd ask.. lol.
biffdotorg
Active Member
The new version of this thread will be someone with a Merc-powered Seadoo that has swapped the powerhead for a 4-stroke Supercharged Verado powerhead. Obviously it would be a monstrous task, and highly unlikely due to cost. But some people get desperate when they lose their favorite boat.
I would be jazzed to have a 300hp engine and souped up pump in my X-20!!
I may have to keep my eye on the Boat Salvage sites for some bassboat yahoo that has trashed the lower unit on their fairly new Verado. Hmmmm Daydreaming commence.
I would be jazzed to have a 300hp engine and souped up pump in my X-20!!
I may have to keep my eye on the Boat Salvage sites for some bassboat yahoo that has trashed the lower unit on their fairly new Verado. Hmmmm Daydreaming commence.
Dr Honda
Well-Known Member
Actually... when thinking about my options with my blown 240.... I was thinking about making an adapter, and standing a 3cyl, supercharged Rotax on end. I figure I would add a scavenging pump, and turn it into a dry-sump engine. That way, I could have a 4-stroke, and more power.
TerrenceBennett
Active Member
Been busy so I've been gone - MAN I Like your style if you get it done make a book and prints so others can follow good luck and go for it!
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