boat repower Q? SBC to LSx & OMC to Bravo 3
03-27-2017, 05:04 PM
#1
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Thread Starter
boat repower Q? SBC to LSx & OMC to Bravo 3
I'm heavily reconsidering repowering my boat. its an 1989 sea swirl spyder sport 176. has a chevy 350 mated up to OMC.
I found a 6.0L LS2, wiring harness, computer & transmission for $800 and a guy who is willing to sell me a Bravo 3, gimbal, & rams for 2k obo.
I was after a 5.3L LSx truck motor.
i want to stick with the EFI so I know I will need a tune to tune out some of the emissions stuff. I think the next big issues is the cam, is there a good marine cam for these motors? i know a street cam wont work. truck cam?
the exhaust for the LS motors looks to be a little harder/more expensive to find. however it looks like I could get away with getting a set of Ford marine headers, cut off/machine off the flange and weld on a flange meant for a LS motor. Has anyone else tried this?
keeping the o2 dry would be the next issue.
on my OMC there is a shift interrupt to get in and out of gear is this something that will have to be transferred over to the B3? I'm unfamiliar with the bravo units.
I'm guessing I will also need a different bell house than the one I have on my current 350, and a different coupler as the cranks are different, a different starter and alternator.
going from a single throttle/gear to a dual boox and a linkage for the TPS/DBW
engine mounts are different, i know there is an adapter plate.
an high pressure EFI fuel pump is also needed. do you guys pull straight from the tank or do you run it to a smaller sump tank then the motor to prevent fuel starvation.
overall goals are lower GPH, better dock behavior (EFI), less weight, stronger drive line. more speed is nice but not the main goal as the boat will already do ~50-60mph depending on the prop I have on. shallow V bottom at speed can be a bit sketchy with some chop.
I found a 6.0L LS2, wiring harness, computer & transmission for $800 and a guy who is willing to sell me a Bravo 3, gimbal, & rams for 2k obo.
I was after a 5.3L LSx truck motor.
i want to stick with the EFI so I know I will need a tune to tune out some of the emissions stuff. I think the next big issues is the cam, is there a good marine cam for these motors? i know a street cam wont work. truck cam?
the exhaust for the LS motors looks to be a little harder/more expensive to find. however it looks like I could get away with getting a set of Ford marine headers, cut off/machine off the flange and weld on a flange meant for a LS motor. Has anyone else tried this?
keeping the o2 dry would be the next issue.
on my OMC there is a shift interrupt to get in and out of gear is this something that will have to be transferred over to the B3? I'm unfamiliar with the bravo units.
I'm guessing I will also need a different bell house than the one I have on my current 350, and a different coupler as the cranks are different, a different starter and alternator.
going from a single throttle/gear to a dual boox and a linkage for the TPS/DBW
engine mounts are different, i know there is an adapter plate.
an high pressure EFI fuel pump is also needed. do you guys pull straight from the tank or do you run it to a smaller sump tank then the motor to prevent fuel starvation.
overall goals are lower GPH, better dock behavior (EFI), less weight, stronger drive line. more speed is nice but not the main goal as the boat will already do ~50-60mph depending on the prop I have on. shallow V bottom at speed can be a bit sketchy with some chop.
03-27-2017, 05:40 PM
#2
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If your going that far throw a carbed BBC in it and be done with it. Sorry I'm sure it's not what you wanted to hear or the kind of advice you were looking for but that's a relatively easy conversion.
03-27-2017, 07:56 PM
#3
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Thread Starter
the BBC is a less efficient, heavier motor than is LS EFI counterpart. I also have a Z height restriction, currently about 1/2" gap between the bottom of the sun deck and top spark arrestor. so I cant put a taller motor in there and I don't want to cut a hole in the deck either.
03-28-2017, 06:26 AM
#5
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Join Date: Oct 2011
Location: Dayton, OH/Burnside KY
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I think that is one of the biggest dickhead comments I have read on here. What, because his boat is only 17ft long he can't do something cool and different with it? Your boats are old as ****, why do you do anything with them? I'm guessing its because you love them, just like this guy loves his boat. Pisses me off to no end when somebody with a bigger boat thinks they're better than somebody with a small boat.....
Anyways, to the original poster, the LS swap is a lot easier than you are making it out to be. I ditched the old heavy 454 in my boat for a 408ci LS2. Here are a few things to know.
1. You do not need a new bellhousing. The bell from your 350 will bolt right on to your LS (5 out of 6 bolts line up which is more than enough)
2. Your coupler will also work, You will just need to run a flywheel from a LS powered vehicle with a manual transmission. Mine is from a 6.0 powered GTO (Less than $100 at Advance Auto). You will just need to press out the clutch alignment pins
3. Exhaust: Here is a very good and inexpensive set of manifolds and risers for LS motors
http://marineenginedepot.com/MP/Mari....2L-(LS3-LSA)/
I am actually going to be running a set of these manifolds for a twin turbo set up on my LS in the very near future.
4. Cam, actually, the stock cam in that motor is very good for marine use. I'm not sure how much power you are looking to make but that motor stock is 400hp. If you are wanting to go bigger, just be careful because these motors move a lot of air so they like to revert. I found this out the hard way. I ended up having to make my exhaust completely dry because of it. I bought my cam through Bob Madera at Marine Kinetics and he was a huge help and the motor runs great with it.
5. Starter. They say that the stock starter is sealed and marine safe, but it isn't marine approved. CP Performance has a really nice marine rated starter for LS's for like $269.00, that's what I use. I bolts into the stock location on the block and lines right up with the opening in the stock merc bellhousing. And since you are using a stock LS flywheel, it lines up with that perfectly.
6. Accessories. This is where it will get expensive for ya. Since you are running an aluminum block, YOU WILL NEED TO RUN CLOSED COOLING!! I can't stress this enough, again, a lesson I learned the hard way. I ran mine for just a few hours on raw water cooling in nothing but fresh water (Lake Cumberland, KY) and it corroded BAD!! We ended up pulling the motor to inspect it and when we pulled the heads, the block was full of corrosion. Now, Hardin Marine makes a complete accessory package that is extremely pretty and works great, but it's pricey, like $3600. I actually just bought this set up for mine simply because I liked how it looked and boating season is right around the corner for me and I didn't want to take the time to build my own set up, however, building your own set up wouldn't be that difficult if you found a nice heat exchanger.
I'm sure there is stuff I'm forgetting, so I'll shoot ya a PM with my number. If you have any questions, just ask!!
Anyways, to the original poster, the LS swap is a lot easier than you are making it out to be. I ditched the old heavy 454 in my boat for a 408ci LS2. Here are a few things to know.
1. You do not need a new bellhousing. The bell from your 350 will bolt right on to your LS (5 out of 6 bolts line up which is more than enough)
2. Your coupler will also work, You will just need to run a flywheel from a LS powered vehicle with a manual transmission. Mine is from a 6.0 powered GTO (Less than $100 at Advance Auto). You will just need to press out the clutch alignment pins
3. Exhaust: Here is a very good and inexpensive set of manifolds and risers for LS motors
http://marineenginedepot.com/MP/Mari....2L-(LS3-LSA)/
I am actually going to be running a set of these manifolds for a twin turbo set up on my LS in the very near future.
4. Cam, actually, the stock cam in that motor is very good for marine use. I'm not sure how much power you are looking to make but that motor stock is 400hp. If you are wanting to go bigger, just be careful because these motors move a lot of air so they like to revert. I found this out the hard way. I ended up having to make my exhaust completely dry because of it. I bought my cam through Bob Madera at Marine Kinetics and he was a huge help and the motor runs great with it.
5. Starter. They say that the stock starter is sealed and marine safe, but it isn't marine approved. CP Performance has a really nice marine rated starter for LS's for like $269.00, that's what I use. I bolts into the stock location on the block and lines right up with the opening in the stock merc bellhousing. And since you are using a stock LS flywheel, it lines up with that perfectly.
6. Accessories. This is where it will get expensive for ya. Since you are running an aluminum block, YOU WILL NEED TO RUN CLOSED COOLING!! I can't stress this enough, again, a lesson I learned the hard way. I ran mine for just a few hours on raw water cooling in nothing but fresh water (Lake Cumberland, KY) and it corroded BAD!! We ended up pulling the motor to inspect it and when we pulled the heads, the block was full of corrosion. Now, Hardin Marine makes a complete accessory package that is extremely pretty and works great, but it's pricey, like $3600. I actually just bought this set up for mine simply because I liked how it looked and boating season is right around the corner for me and I didn't want to take the time to build my own set up, however, building your own set up wouldn't be that difficult if you found a nice heat exchanger.
I'm sure there is stuff I'm forgetting, so I'll shoot ya a PM with my number. If you have any questions, just ask!!
03-28-2017, 07:25 AM
#6
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In Merc drives, Alphas require the shift interrupt but not the Bravo drives..
03-28-2017, 07:33 AM
#7
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I don't want to sound like a ass here but I have to side with Mr. Maine. He wasn't trying to be rude but the problem is what's the boat worth? You already said it's pretty fast and tough in some chop. Your going to be into this for a lot of cash with no real return ever. The boat won't go up in value because you put and ls in it. To be honest it will be harder to sell. So they you have to take the motor and drive off. Put the old stuff on or just scrap the boat and move on. I would take the money your gonna spend on this and first replace or fix your carb. If the boat is that difficult around the docks there is and issue. I have had nothing but carberated boats and never had an issue even idling at 500- 600rpm. Then save the rest of the money you would spend and buy a different boat that would really benefit from the ls swap and put it in there. Like Corey did a 253 checkmate would be great with an ls. But a 17ft seaswirl I don't believe would be the way to go. It's just my 2 cents but I believe you will be much happier in the end. Even a 22ft stingray would be a better boat for the ls than the 17ft you have.
03-28-2017, 10:18 AM
#8
I think that is one of the biggest dickhead comments I have read on here. What, because his boat is only 17ft long he can't do something cool and different with it? Your boats are old as ****, why do you do anything with them? I'm guessing its because you love them, just like this guy loves his boat. Pisses me off to no end when somebody with a bigger boat thinks they're better than somebody with a small boat.....
Anyways, to the original poster, the LS swap is a lot easier than you are making it out to be. I ditched the old heavy 454 in my boat for a 408ci LS2. Here are a few things to know.
1. You do not need a new bellhousing. The bell from your 350 will bolt right on to your LS (5 out of 6 bolts line up which is more than enough)
2. Your coupler will also work, You will just need to run a flywheel from a LS powered vehicle with a manual transmission. Mine is from a 6.0 powered GTO (Less than $100 at Advance Auto). You will just need to press out the clutch alignment pins
3. Exhaust: Here is a very good and inexpensive set of manifolds and risers for LS motors
http://marineenginedepot.com/MP/Mari....2L-(LS3-LSA)/
I am actually going to be running a set of these manifolds for a twin turbo set up on my LS in the very near future.
4. Cam, actually, the stock cam in that motor is very good for marine use. I'm not sure how much power you are looking to make but that motor stock is 400hp. If you are wanting to go bigger, just be careful because these motors move a lot of air so they like to revert. I found this out the hard way. I ended up having to make my exhaust completely dry because of it. I bought my cam through Bob Madera at Marine Kinetics and he was a huge help and the motor runs great with it.
5. Starter. They say that the stock starter is sealed and marine safe, but it isn't marine approved. CP Performance has a really nice marine rated starter for LS's for like $269.00, that's what I use. I bolts into the stock location on the block and lines right up with the opening in the stock merc bellhousing. And since you are using a stock LS flywheel, it lines up with that perfectly.
6. Accessories. This is where it will get expensive for ya. Since you are running an aluminum block, YOU WILL NEED TO RUN CLOSED COOLING!! I can't stress this enough, again, a lesson I learned the hard way. I ran mine for just a few hours on raw water cooling in nothing but fresh water (Lake Cumberland, KY) and it corroded BAD!! We ended up pulling the motor to inspect it and when we pulled the heads, the block was full of corrosion. Now, Hardin Marine makes a complete accessory package that is extremely pretty and works great, but it's pricey, like $3600. I actually just bought this set up for mine simply because I liked how it looked and boating season is right around the corner for me and I didn't want to take the time to build my own set up, however, building your own set up wouldn't be that difficult if you found a nice heat exchanger.
I'm sure there is stuff I'm forgetting, so I'll shoot ya a PM with my number. If you have any questions, just ask!!
Anyways, to the original poster, the LS swap is a lot easier than you are making it out to be. I ditched the old heavy 454 in my boat for a 408ci LS2. Here are a few things to know.
1. You do not need a new bellhousing. The bell from your 350 will bolt right on to your LS (5 out of 6 bolts line up which is more than enough)
2. Your coupler will also work, You will just need to run a flywheel from a LS powered vehicle with a manual transmission. Mine is from a 6.0 powered GTO (Less than $100 at Advance Auto). You will just need to press out the clutch alignment pins
3. Exhaust: Here is a very good and inexpensive set of manifolds and risers for LS motors
http://marineenginedepot.com/MP/Mari....2L-(LS3-LSA)/
I am actually going to be running a set of these manifolds for a twin turbo set up on my LS in the very near future.
4. Cam, actually, the stock cam in that motor is very good for marine use. I'm not sure how much power you are looking to make but that motor stock is 400hp. If you are wanting to go bigger, just be careful because these motors move a lot of air so they like to revert. I found this out the hard way. I ended up having to make my exhaust completely dry because of it. I bought my cam through Bob Madera at Marine Kinetics and he was a huge help and the motor runs great with it.
5. Starter. They say that the stock starter is sealed and marine safe, but it isn't marine approved. CP Performance has a really nice marine rated starter for LS's for like $269.00, that's what I use. I bolts into the stock location on the block and lines right up with the opening in the stock merc bellhousing. And since you are using a stock LS flywheel, it lines up with that perfectly.
6. Accessories. This is where it will get expensive for ya. Since you are running an aluminum block, YOU WILL NEED TO RUN CLOSED COOLING!! I can't stress this enough, again, a lesson I learned the hard way. I ran mine for just a few hours on raw water cooling in nothing but fresh water (Lake Cumberland, KY) and it corroded BAD!! We ended up pulling the motor to inspect it and when we pulled the heads, the block was full of corrosion. Now, Hardin Marine makes a complete accessory package that is extremely pretty and works great, but it's pricey, like $3600. I actually just bought this set up for mine simply because I liked how it looked and boating season is right around the corner for me and I didn't want to take the time to build my own set up, however, building your own set up wouldn't be that difficult if you found a nice heat exchanger.
I'm sure there is stuff I'm forgetting, so I'll shoot ya a PM with my number. If you have any questions, just ask!!
Anyway, wasnt trying to be rude. Just seemed like a lot of work for a small hull thats already at its limit.
I have a 20 foot formula, and had a 19 foot stingray and a 19 foot mfb and have had a lot of fun on them.
03-29-2017, 04:38 PM
#9
Registered
Thread Starter
I don't want to sound like a ass here but I have to side with Mr. Maine. He wasn't trying to be rude but the problem is what's the boat worth? You already said it's pretty fast and tough in some chop. Your going to be into this for a lot of cash with no real return ever. The boat won't go up in value because you put and ls in it. To be honest it will be harder to sell. So they you have to take the motor and drive off. Put the old stuff on or just scrap the boat and move on. I would take the money your gonna spend on this and first replace or fix your carb. If the boat is that difficult around the docks there is and issue. I have had nothing but carberated boats and never had an issue even idling at 500- 600rpm. Then save the rest of the money you would spend and buy a different boat that would really benefit from the ls swap and put it in there. Like Corey did a 253 checkmate would be great with an ls. But a 17ft seaswirl I don't believe would be the way to go. It's just my 2 cents but I believe you will be much happier in the end. Even a 22ft stingray would be a better boat for the ls than the 17ft you have.
I want to get away form carbs, this one is just a pain in the ass. doesn't like to sit, I can get it to where it idles fine and gets out on plane fine, but then it wants to die as soon as I go form idle to gear. when I adjust it so it doesn't die as soon as you put it in gear then hard to get in and out of gear even with the shift interrupts. EFI solve the issues of poor idle, partial load, full load, fuel trims.
seem silly to spend 600-800 for a marine carb when i can get a whole motor + wiring harness + ECU for the same cost. I could probably even pick up a TBI system for much even less.
I think that is one of the biggest dickhead comments I have read on here. What, because his boat is only 17ft long he can't do something cool and different with it? Your boats are old as ****, why do you do anything with them? I'm guessing its because you love them, just like this guy loves his boat. Pisses me off to no end when somebody with a bigger boat thinks they're better than somebody with a small boat.....
Anyways, to the original poster, the LS swap is a lot easier than you are making it out to be. I ditched the old heavy 454 in my boat for a 408ci LS2. Here are a few things to know.
1. You do not need a new bellhousing. The bell from your 350 will bolt right on to your LS (5 out of 6 bolts line up which is more than enough)
2. Your coupler will also work, You will just need to run a flywheel from a LS powered vehicle with a manual transmission. Mine is from a 6.0 powered GTO (Less than $100 at Advance Auto). You will just need to press out the clutch alignment pins
3. Exhaust: Here is a very good and inexpensive set of manifolds and risers for LS motors
http://marineenginedepot.com/MP/Mari....2L-(LS3-LSA)/
I am actually going to be running a set of these manifolds for a twin turbo set up on my LS in the very near future.
4. Cam, actually, the stock cam in that motor is very good for marine use. I'm not sure how much power you are looking to make but that motor stock is 400hp. If you are wanting to go bigger, just be careful because these motors move a lot of air so they like to revert. I found this out the hard way. I ended up having to make my exhaust completely dry because of it. I bought my cam through Bob Madera at Marine Kinetics and he was a huge help and the motor runs great with it.
5. Starter. They say that the stock starter is sealed and marine safe, but it isn't marine approved. CP Performance has a really nice marine rated starter for LS's for like $269.00, that's what I use. I bolts into the stock location on the block and lines right up with the opening in the stock merc bellhousing. And since you are using a stock LS flywheel, it lines up with that perfectly.
6. Accessories. This is where it will get expensive for ya. Since you are running an aluminum block, YOU WILL NEED TO RUN CLOSED COOLING!! I can't stress this enough, again, a lesson I learned the hard way. I ran mine for just a few hours on raw water cooling in nothing but fresh water (Lake Cumberland, KY) and it corroded BAD!! We ended up pulling the motor to inspect it and when we pulled the heads, the block was full of corrosion. Now, Hardin Marine makes a complete accessory package that is extremely pretty and works great, but it's pricey, like $3600. I actually just bought this set up for mine simply because I liked how it looked and boating season is right around the corner for me and I didn't want to take the time to build my own set up, however, building your own set up wouldn't be that difficult if you found a nice heat exchanger.
I'm sure there is stuff I'm forgetting, so I'll shoot ya a PM with my number. If you have any questions, just ask!!
Anyways, to the original poster, the LS swap is a lot easier than you are making it out to be. I ditched the old heavy 454 in my boat for a 408ci LS2. Here are a few things to know.
1. You do not need a new bellhousing. The bell from your 350 will bolt right on to your LS (5 out of 6 bolts line up which is more than enough)
2. Your coupler will also work, You will just need to run a flywheel from a LS powered vehicle with a manual transmission. Mine is from a 6.0 powered GTO (Less than $100 at Advance Auto). You will just need to press out the clutch alignment pins
3. Exhaust: Here is a very good and inexpensive set of manifolds and risers for LS motors
http://marineenginedepot.com/MP/Mari....2L-(LS3-LSA)/
I am actually going to be running a set of these manifolds for a twin turbo set up on my LS in the very near future.
4. Cam, actually, the stock cam in that motor is very good for marine use. I'm not sure how much power you are looking to make but that motor stock is 400hp. If you are wanting to go bigger, just be careful because these motors move a lot of air so they like to revert. I found this out the hard way. I ended up having to make my exhaust completely dry because of it. I bought my cam through Bob Madera at Marine Kinetics and he was a huge help and the motor runs great with it.
5. Starter. They say that the stock starter is sealed and marine safe, but it isn't marine approved. CP Performance has a really nice marine rated starter for LS's for like $269.00, that's what I use. I bolts into the stock location on the block and lines right up with the opening in the stock merc bellhousing. And since you are using a stock LS flywheel, it lines up with that perfectly.
6. Accessories. This is where it will get expensive for ya. Since you are running an aluminum block, YOU WILL NEED TO RUN CLOSED COOLING!! I can't stress this enough, again, a lesson I learned the hard way. I ran mine for just a few hours on raw water cooling in nothing but fresh water (Lake Cumberland, KY) and it corroded BAD!! We ended up pulling the motor to inspect it and when we pulled the heads, the block was full of corrosion. Now, Hardin Marine makes a complete accessory package that is extremely pretty and works great, but it's pricey, like $3600. I actually just bought this set up for mine simply because I liked how it looked and boating season is right around the corner for me and I didn't want to take the time to build my own set up, however, building your own set up wouldn't be that difficult if you found a nice heat exchanger.
I'm sure there is stuff I'm forgetting, so I'll shoot ya a PM with my number. If you have any questions, just ask!!
So touchy!!! Im glad you dont like my old as s h i t boats haha.
Anyway, wasnt trying to be rude. Just seemed like a lot of work for a small hull thats already at its limit.
I have a 20 foot formula, and had a 19 foot stingray and a 19 foot mfb and have had a lot of fun on them.
Anyway, wasnt trying to be rude. Just seemed like a lot of work for a small hull thats already at its limit.
I have a 20 foot formula, and had a 19 foot stingray and a 19 foot mfb and have had a lot of fun on them.
03-29-2017, 06:45 PM
#10
Registered
iTrader: (1)
From what I've read the exhaust and water pumps seem to be expensive, hard to get, and not really tested. Finding marine safe electrical components seem to be another challenge. So far the few people I've seen doing an LS swap have a long winter and a heated barn with a machine shop. The aftermarket should be catching up by now though.
The Holley Sniper EFI unit isn't much more than a decent carb and may be worthy of a look.
The Holley Sniper EFI unit isn't much more than a decent carb and may be worthy of a look.
