1997 challenger, Can you swap a 787cc with a 951cc

[TerrenceBennett]

Can a 1997 challenger with a single 787cc have a 1999 951cc installed without much to do?
If I do, will I get much performance improvement?

 

[Guest_User]

Can a 1997 challenger with a single 787cc have a 1999 951cc installed without much to do?
If I do, will I get much performance improvement?

I don`t see why not if your willing to do some extensive work...

just swapping the engine, NO

you`ll need the electronics and everything from a donor boat or ski to make her run... IMHO I`d go with a carb`d model and not the DI.

and then there would be an issue with the neutral safety switch etc etc...

 

[Slasher]

Tweak the carbs and try to find a Factory Pipe spec 2 pipe with ECU rpm increase ... Cheaper and better power

 

[TerrenceBennett]

I'm interested in this "Tweak the carbs and try to find a Factory Pipe spec 2 pipe with ECU rpm increase ... Cheaper and better power " tell me more!

 

[chucked]

I think he meant its cheaper then installing a 951

 

[LouDoo]

My best advice is if you want a faster boat, sell your boat and buy a faster boat, almost any thing you do to increase performance is going to affect reliability. BRP does a good job of getting max. performance out of these engines at the factory, 110hp from a 787cc, 2 cylinder engine is pretty good. It will be much cheaper in the long run just to buy a faster boat.

Lou

 

[richardpr]

Less of a headache too

 

[Dr Honda]

My best advice is if you want a faster boat, sell your boat and buy a faster boat, almost any thing you do to increase performance is going to affect reliability. BRP does a good job of getting max. performance out of these engines at the factory, 110hp from a 787cc, 2 cylinder engine is pretty good. It will be much cheaper in the long run just to buy a faster boat.

Lou

I agree 100% with Lou on this one.


The issue is... because boats are heavy, and displace a lot of water.... they don't respond to mods as well as a Ski. You will spend $800 on a pipe, and in the end... you may pick up a couple MPH. AND... if you have an older engine, that's tired... a new pipe could be the "Nail in the coffin" for your engine.


Also... because of the weight of the boat, and since you have a single (small) pump... more HP may just cause cavitation.


As Lou was saying... sell that boat, and buy a twin engine.



Now... as to you original Question..........

Anything is possible, but it's not a bolt-in project. AND, it will cost you more than just buying the faster boat.

 

[TerrenceBennett]

if I and my friends do the work or send it to a shop?

 

[TerrenceBennett]

Com' on guys I can get a 454ci jet boat, even blown one or 351 day cruiser BUT where is the fun with that! Someone else building it! This is the right hull for me it turns on a dime and pulls out with min. speed loss. Hell I can even submarine it and keep going. The only thing that gives me more excitement is blasting down the track at 200+ mph and beating someone with a bigger, prettier car, because I hooked it up right. Something I picked up in high school. I’m very use to putting big things in small places (350 280Z, 350 V-Dub, 454 Vega, 351 Pinto Ect…. O There are some Autorama type show cars that I’ve helped on to!). Again from what I have gleamed from all you folks so far is 2 Pumps, 2 Engines is twice the headache in get them to pull their own weight and not get in the way of the one that’s running ok. So I’ll stay with my 97 single Pump and go larger or more efficient (it may not be BHP) until like that guy in Florida, I can pull up to my friends with there bad ass boats and PWC (60+ MPH) and blow them away, if not in speed, then with what I can do and they can’t, both work for me. I’m not a fool I just know what I like and with all of your valuable help and information I will get what I want out of this boat and pass it along. O.. I see myself having a drag boat in the future as well but not now.

Everyone has to have a hobby and I got so much to learn about boats. Thanks Terry

 

[racerxxx]

Com' on guys I can get a 454ci jet boat, even blown one or 351 day cruiser BUT where is the fun with that! Someone else building it! This is the right hull for me it turns on a dime and pulls out with min. speed loss. Hell I can even submarine it and keep going. The only thing that gives me more excitement is blasting down the track at 200+ mph and beating someone with a bigger, prettier car, because I hooked it up right. Something I picked up in high school. I’m very use to putting big things in small places (350 280Z, 350 V-Dub, 454 Vega, 351 Pinto Ect…. O There are some Autorama type show cars that I’ve helped on to!). Again from what I have gleamed from all you folks so far is 2 Pumps, 2 Engines is twice the headache in get them to pull their own weight and not get in the way of the one that’s running ok. So I’ll stay with my 97 single Pump and go larger or more efficient (it may not be BHP) until like that guy in Florida, I can pull up to my friends with there bad ass boats and PWC (60+ MPH) and blow them away, if not in speed, then with what I can do and they can’t, both work for me. I’m not a fool I just know what I like and with all of your valuable help and information I will get what I want out of this boat and pass it along. O.. I see myself having a drag boat in the future as well but not now.

Everyone has to have a hobby and I got so much to learn about boats. Thanks Terry

LOL, don't lump me in that equation. If it's a Seadoo boat it better have twins, if I wanted a single I'd get a canoe and a trolling motor.

I think what guys are saying is the work involved to get the extra 20hp isn't worth it. Honestly what your looking to do is build a 2000+ Sportster LE that came with the 951 from the factory. Later ones came in Yellow and white.

 

[Coastiejoe]

In a nutshell, yes, it can be done.

In the end, if is not really worth it.

If you were making this decision on paper the answer would be no.

You would not increase the value of the boat any measureable difference but you would have put in thousands to do so.

Buyers in many cases do not want a mod-ed ski/boat as they assume they are ridden MUCH harder and obtaining parts will be expensive and difficult.

So, unless you want to do this for your self and be happy with it for that reason only, it really isn't worth it.

 

[Dr Honda]

I love projects.... but unlike a car engine.... your engine displaces less than one liter... is the size of a microwave oven, and makes 110 HP !!!! It's already at it's potential.


Think of it this way........


Your 800 seado is producing 140 Hp/L. Today's Hyper-Cars cant even thouch that, without superchargers, or Turbo !!!! A typical 350CI engine is only making 45 hp/L So, with that example, can you see what we are talking about?????


Then, the next thing is your pump. It would be like taking your 350 V-Dub, and trying to put the power to the ground using the original skinny tires. (just can't move the enough water) Also... you are dealing with a single speed. (opposed to a shifting transmission) SO.... you can make 10,000 HP... but if it's only spinning 7000 RPM...... GUESS WHAT... you won't go any faster. You need a bigger pump, and more pitch to take advantage of the higher HP and torque.



Finally... lets say you do your project, and you build a kick-@$$ single. In the end, you may not be able to sell it for what a "Stock" boat was worth, because most people can't do their own service, and with a mix of parts... people will shy away.



As I said... I love a project, but it doesn't make financial sense.


I guess if I was going to tackle a project like this... I would hold out, until I could find a newer 255/260hp ski, with a damaged hull. Then... I would transplant the entire drive. But, in the end... you would sill just have a 260 Sportster. But, since they made those... you can sell yours for $2k to $4k (depending on condition) and find one made in 2007 to 2012, and probably still have less into it.

 

[IDoSeaDoo]

the problem with the newer 15' boats is they're heavier, and not as attractive as this 97 challenger. I particularly like mine in the fact that it has a seat in the front and a rounded rear vs the step in the front a mid-90's star-trek spaceship rear (I really have some bones to pick with the SeaDoo designers as of late). I also am looking into getting a busted hull ski and going mad-scientist on it. To me, I don't care about resell value or any of that, I just want the RIGHT boat. I look at it as "I"m goign to spend, say, $7k on a boat. What can I get for that price? I strongly believe that the 97 Challenger with a 130 or 150hp 4-tec motor is the way to go.

So having said this, I have two questions:
1: will the new 3cyl 4-tec even fit in place of the 787?
2: will the 155mm pump be able to get the necessary amount water from the 140mm channel, or would that intake portion of the hull have to be widened?

PS I've asked this on this forum before and got the exact same response: it's not worth it. Well, I'm glad someone out there shares FINALLY my enthusiasm in this venture. I hope to get some of these questions answered finally.

 

[IDoSeaDoo]

And honestly, I don't think the 951 is much of a step up from the 787. It's still a gas-guzzling 2-stroke noise generator and WILL break down just like the 787. I'm tired of the constant RAVE and carb problems, not to mention the priceless 2-stroke oil. I'm so ready to move to a 4-tec!!

 

[TerrenceBennett]

LOL, don't lump me in that equation. If it's a Seadoo boat it better have twins, if I wanted a single I'd get a canoe and a trolling motor.

LOL

I'm not stuck on 951 (just what's in Florida boat) I really want a large 4-tec. Well from what I know its not all in the HP its in breathing, RPMs and pump pressure. Just smoothing out the water flow (like polishing ports) got me a couple more mph maybe! did a lot before I tested it. I'm thinking of moving the gas tank to ski locker with baffles and deaf-initely sound proof the engine compartment. O if that 20hp get me into a bigger pump and faster speeds or better hole shot then YES its worth it to me.

I like the pic looks like mine cute

 

[TerrenceBennett]

Doc
your right on as usual, talking my language, except for the resale part, its like your house being worth 500,000, I say ok if I was to sell it.
If I keep the hull in great shape (no water, or soft spots and re gel-coat to keep it clean, my grand kids grand kids could have a boat no one else has and by then can do things with it no one else can.
I do read you, and somewhere there is a line! that's why I pose these questions and relish the responses for information.

O... I posted somewhere maybe not in here, that I have a line on a 2007 Wake ready for a new body, but I measured and the engine is a little long to fit, so I'm looking at moving some peace's around (gas tank) to see if I can get it to fit.

 

[TerrenceBennett]

And honestly, I don't think the 951 is much of a step up from the 787. It's still a gas-guzzling 2-stroke noise generator and WILL break down just like the 787. I'm tired of the constant RAVE and carb problems, not to mention the priceless 2-stroke oil. I'm so ready to move to a 4-tec!!

LOL

Everything need love and breaks but yes if what your saying is, if you cant fix it you shouldn't own it. I agree.
Yes 4-tec is the way to go but for now the cheep way is 2-stroke and all you guys getting rid of them.

 

[TerrenceBennett]

So having said this, I have two questions:
1: will the new 3cyl 4-tec even fit in place of the 787?
2: will the 155mm pump be able to get the necessary amount water from the 140mm channel, or would that intake portion of the hull have to be widened?

A 1. Not with out moving some peace's around and a new shaft (so far)
A 2. Yes the ride plate needs a little more room and shaping but with a race flow grate to increase the water flow the 155mm should work, but not definitive yet. I'm currently looking for the number and calculations needed (manuals shop talk ECT…) to figure this out on paper first. I'm a member of lots of sites for Jet boats and PWC with lots of different thoughts glad to see a like-minded being.

MY real goal is to a JET BOAT Pilot!

 

[TerrenceBennett]

I guess if I was going to tackle a project like this... I would hold out, until I could find a newer 255/260hp ski, with a damaged hull. Then... I would transplant the entire drive. But, in the end... you would sill just have a 260 Sportster. But, since they made those... you can sell yours for $2k to $4k (depending on condition) and find one made in 2007 to 2012, and probably still have less into it.

This is a thought but while I'm waiting

 

[Dr Honda]

I agree with IdoSeadoo: The 951 would be a lot of work and $$$ for 20 hp. Going full circle.... you can get 20 hp with a "Factory Pipe" and a little massaging from your 800. BUT, 20 hp is probably only 4 mph up top.


OK....


If I was going to do this... I would get away from a seadoo engine all together.

I would swap in a Mazda rotary. (12a or 13b) They are light, they make crazy high torque, and you can spin the piss out of them. (and that's where your speed will come from)


You could make a bearing block to hold the drvishaft in-line with the pump. Then, mount the engine, and do a belt drive. you can even alter the drive ratio depending on the top RPM of the engine. (but Wankels can go up to 8k without an issue)

But that's just me.

 

[IDoSeaDoo]

I looked into that possibility, and it truly seemed like the most expensive one. A big restriction here would be building a watercooled exhaust manifold. I sure wouldn't want anything tha thot near a plastic fuel tank. Also, I'm not sure why, but I remember the intake and exhaust ports were unfavorably placed with respect to each other. I also suspect that this engine will be less efficient than the seadoo 4-tec counterparts, which, to me is a drawback as I'd like a little more lake time out there before returning to the pump... There is a site that already specializes in retrofitting these rotaries for marine applications: http://www.freedom-motors.com/

 

[USAF_Pride]

Wait a year or two and put in one of those Spark motors. That is my long term plan and I need someone to figure it out before I do it

 

[TerrenceBennett]

I would swap in a Mazda rotary. (12a or 13b) They are light, they make crazy high torque, and you can spin the piss out of them. (and that's where your speed will come from)

I like where this is going and the leads I'm getting. Thanks all of you guy. "Every 2 cents I get from you, eventually will make a dollar"

I love this, it reminds me of when I worked in the pits (drag racing) and talking to seniors (not elderly) top notch mechanics and drivers about cars, engines, track and the best hookup for them.

Thanks guys

 

[TerrenceBennett]

Wait a year or two and put in one of those Spark motors. That is my long term plan and I need someone to figure it out before I do it

I was thinking the same $$$ or at least looking into it. The guy at the showroom was cool and let me take some measurement right there and I got an offer to come into the shop and see one broke down. So... yeah I got shop space to hold on the this project for awhile.