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Hey guys i have just purchased a 1981 wellcraft nova ll 27ft, i plan to swap two 5.3 truck motors in it. Im looking for some advise before i get started has anyone done it on here? My biggest concern is the interupt switches for the alpha drives. Next would be the cooling system. They make a closed loop system you can buy but at 2k a piece thats a very exspensive system looking for something that maybe cheaper. They will be fuel injected, i do not want to convert to carburetion. Any tips would be greatly appreciated. Thanks in advance
Hey guys i have just purchased a 1981 wellcraft nova ll 27ft, i plan to swap two 5.3 truck motors in it. Im looking for some advice
That hull is pretty much same as the 233, no? Have you gotten a good look at the condition of the stringers and transom? There are tons of Formula 233 restoration threads online and it seems most hulls of that vintage have extensive stringer and transom rot by now. Just a thought.
Neat project! There are LS engines in various new boats. Maybe you can find some of the exhaust parts to use from a boat wrecker?
There is a good swap thread ... LS in to an aluminum jet boat on here, too.
I think you'd need to convert to speed density tuning. I am not certain, but assume O2 sensors cannot be used for tuning.
I wonder if one engine has to counter-rotate?
Doug
The stringers and transom are in great shape. I looked it over top to bottom inside and out. Pull the panels down on the floors looked in there had a boating buddy look it over very well also. We actually pulled the out drives off to look at the transom. The manifolds are no big deal there 260 a peice plus risers witch are aroumd 100.
The stringers and transom are in great shape. I looked it over top to bottom inside and out. Pull the panels down on the floors looked in there had a boating buddy look it over very well also. We actually pulled the out drives off to look at the transom. The manifolds are no big deal there 260 a piece plus risers witch are around 100.
Glad to hear it. I'm guessing it's a fresh water boat, since it's sitting on a painted steel trailer? If so, I'm sure it's in much better shape than most of the Formula's that have spent their life in the salt.
Yes its a fresh water boat at least for most of its life. I think the ls swap would be very cool in it but i still haven't found out how to make the interupt switch work with the ls and switching to a bravo style outdrive just isn't in the budget at this current time.
I'm building a LSA supercharged L92 for my 72 camaro right now, but it's making me think I should do another for my boat when the HP500 gets a little more tired. If you find any good resources on what's needed to do boat vs car please post them up in here!
Can you just use the interrupt to drive the coils and / or injector relays? so both die momentarily when shifting?
It seems straightforward to wire it in to the LS harnesses. It can be in series with the ignition switch.
Bear in mind, perhaps I misunderstood the purpose of the switch. Just did a bit of reading.
I will certainly post them up. The interupt switch kills the motor for a split second to engage the lower unit into gear. Does it fast enough the motor will continue to run after it does it with out restarting it. Now my concern is how can i cut power to the ls motor like they did to the distributor to the sbc bbc and other motors. I have read i can not do it to the the coils on the ls. I had thought about maybe just cutting power to the whole motor like a kill switch would do. Thought on that anyone?
Ye A speed density swap would be required due to the wet exhaust. Now i had thought about building my own set of headers and doing a water injection though then. Im not 100 percent sure how that will work though.
What drives are you using? I'd definitely rather save for Bravos and not mess w/ this interupt if possible.
So is your plan to run a freshwater cooling setup like a BBC? What's the drawback on this w/ an LS, I know Merc Racing went closed cooling with some of the EFI stuff. I'd think just making a bracket for the LS to run the standard mechancial seawater pump and dumping through the exhaust manifold would be much cheaper/easier, just not sure what the draw back is?
Well they make a sea water pump thats 950 a peice for them witch i have thought about but i dont see why i couldnt purchase a couple heat exchangers and make some brackets for them. I have a motor im going to drop in it to test fit it and a bare block just to make sure they will fit with the cast manifolds they make for them. As far as saving up for the bravo outdrives they are about 2500 ea plus 1200 ea for the transom and gimble assembly. I will probably use the mega squit ecus on them. Im thinking ill probably use the truck cams as i dont see a problem with water being sucked up into the motor with them.
07-07-2015, 05:15 AM
wellcraft nova ll ls swap 
