LS Swap Seafari 25

[Xcomunic8d]

Purchased a Bravo 3 with counter rotating props yesterday from a guy on another island. Had a friend go look at it and pick it up. Seems to be in good shape. I’ll be tearing it down when it comes but $800 was a steal.



Engine is all the way down. All apart, cranks out, pistons, all of it. The oil galleys have been tapped for the vvt/Afm delete. The holes are 5/16” so a 3/8-16 tap with 3/8 set screws with thread sealant is perfect. Make sure to use thread cutting oil the block is hard.

Tap these pedestal looking things:



But you’ll have to clean this out of everywhere. The valley plate has sensors on it that deactivate these weird looking lifters.







Engine will be going to machine shop for the works:
Cleaning
Block decked
Main bearing alignment and honing
Camshaft bearings aligned and replaced
Pistons cleaned, ringed, and checked hopefully not replaced but who knows.
Block honed and overbored if necessary
Heads to be cleaned, valve job, and shaved .030 to bump up compression on 243’s
Gotta find somebody who balances cranks for bob weight etc.

Will post pics when I can.

[Xcomunic8d]

Took a little while for the first batch of parts to come in.

Engine has gone to machine shop for the works. Will be a couple weeks before it’s done.

Once completed more parts to follow.

Decided on this cam: https://www.michiganmotorsports.com/...nd-gasket-set/

It’s a 223/226 cam. 226 seems to be max you can run on a budget. Problem is you have to worry about reversion unless you have a fully sleeved header and I’m not spending that kind of money. (4-6k). The problem happens when both valves are open and you have a piston drop. It creates a vacuum and can suck the exhaust water into the engine causing lots of issues.

[flyingfrizzle]

Originally Posted by Xcomunic8d

Yeah that terminator x looks to be best way to go. I haven’t figured out the gauges yet. I wanted twin lowrance screens tied together on the outboard. But I’m leaning towards just analogs now. I just want this done.

Sounds like you have a great project too. Don’t forget about that throttle body... I’m going cable drive. And a 102mm vs 92mm adds no hp on dyno according to Richard holdener.

I’d get one of those Fast Lsxr intakes if I could afford one. Sharps custom intakes look great too. But I have the TBSS which is identical power to a LS3 intake and the best OEM you can get. I just can’t justify $1k for 30hp.

PS check out that F35 cam from Texas speed for your swap. It won’t work for me but oh I wish it would.

Yea, the terminator x is really economical compared to the dominator or HP. The digital dash is really over priced especially the 12.3" that I got (got mine 20% off on Holley deal days over the holidays). The little 7" display is not to bad cost wise and you can catch it on sale too somtimes but I don't know how well it would hold up to the salt or marine environment.
Far as my build, I would like to do a billet intake but may just end up with a holley high ram for now. For the throttle body I will probably go the 102 or 123mm due to we are trying to support 2000+ hp. I have TKM right now building the rotating assemble (stage 3 LSR) solid aluminum block, Callies magnum crank, GRP aluminum rods, custom full skirted turbo pistons and it will have to top fuel hoops (solid ss fire rings with copper head gaskets). Similar sister stage three engines they have done made over 2300 with a single 98 mm turbo which had a little smaller back side than mine which is a Forced inductions 98mmx116mm built by Jose. Cam is a custom grind spec from Kevin Mullins at TKM for the application running Methanol on billet atomizer 700s. It is going to be a full tilt race motor so not the common LS stuff. Love to do a mild LS in a seacraft though, I think that would be a really good fit for a 25 seafari. Looks like yours will be plenty strong for the 25 with the 243 heads. Should make a nice piece.

Picture and link to an article below of the sister engine. Mine will be based off of it with a few variations...hope to have mine ready this fall.


https://www.dragzine.com/news/john-d...m-dyno-record/

[Xcomunic8d]

Wow! Bravo 3 could not handle that! I couldn’t agree more on your thoughts on a mildly built LS.

Good ideas on tb. I’m going cable drive. 103 would need an adapter I think.

Agreed on gauges. I’m either going analog or doing a nmea2k gateway into a 2nd display like another lowrance hds7 gen 3. I really like simrad and furuno but use what you got. Analog is in the lead at moment for wallet reasons.

Imagine this for an intake: https://www.ebay.com/itm/SUPERCHARGE...EAAOSwLsRgcOA1

Macdaddyparts makes an adapter for it.

My goal is 500ish. Sharps custom has a nice intake, as does Holley. I have the tbss. I’m considering the fast Lsxrt but that supercharger would be spicy. I’m going to set it up as is and see how I like it and upgrade intake if I want more.

The seafari 25 originally maxed out with twin 351 Windsor’s to make 500. Making it with a single Ls should be awesome. Doubt I’ll get to 500 but 450+ would be nice.

[Locke N Load]

I just want to hear a 500 hp straight-piped (assuming no mufflers) LS in a boat. I bet it will make the hairs on the back of the neck tingle.

[Xcomunic8d]

I expect so. I’ll probably soundproof and heat shield the cover I’ll make for it. And maybe put some inline mufflers to it. But I expect it will sound incredible.

I’d like to have it quiet when I’m out fishing but every once in a while let her rip. Not sure how I’ll do that tho. I can’t find any affordable captains call exhaust setups.

Until then here’s a preview. But mine’s gonna have a lopier idle.

https://www.youtube.com/watch?v=2AVoeVyvws8

[Locke N Load]

Originally Posted by Xcomunic8d

I expect so. I’ll probably soundproof and heat shield the cover I’ll make for it. And maybe put some inline mufflers to it. But I expect it will sound incredible.

I’d like to have it quiet when I’m out fishing but every once in a while let her rip. Not sure how I’ll do that tho. I can’t find any affordable captains call exhaust setups.

Until then here’s a preview. But mine’s gonna have a lopier idle.

https://www.youtube.com/watch?v=2AVoeVyvws8

https://www.amazon.com/Electric-Exha...ts_id=15726591

Just saying...

[flyingfrizzle]

Originally Posted by Xcomunic8d

Wow! Bravo 3 could not handle that! I couldn’t agree more on your thoughts on a mildly built LS.

Good ideas on tb. I’m going cable drive. 103 would need an adapter I think.

Agreed on gauges. I’m either going analog or doing a nmea2k gateway into a 2nd display like another lowrance hds7 gen 3. I really like simrad and furuno but use what you got. Analog is in the lead at moment for wallet reasons.

Imagine this for an intake: https://www.ebay.com/itm/SUPERCHARGE...EAAOSwLsRgcOA1

Macdaddyparts makes an adapter for it.

My goal is 500ish. Sharps custom has a nice intake, as does Holley. I have the tbss. I’m considering the fast Lsxrt but that supercharger would be spicy. I’m going to set it up as is and see how I like it and upgrade intake if I want more.

The seafari 25 originally maxed out with twin 351 Windsor’s to make 500. Making it with a single Ls should be awesome. Doubt I’ll get to 500 but 450+ would be nice.

Sounds like you have a good path or plan. She will be a ripper at even 400hp. 450-500hp even better and easily attainable with the LS platform. I have always been a Gen 1 SBC guy but I do have to say the LS stuff has a much better architecture. The factory heads on them can be just as good as a mile race gen 1 SBC head. The head I am having done will flow 400+cfm but there are several factory LS heads that flow well stock or with a mild port or CNC run can produce some great numbers. If you do a supercharger do the endplate upgrade as the factory in manifold intercooler will blow the ends out or balloon. The fast LSX manifold dose really well and all of the Holly stuff works and preforms really well. A lot of Drag race guys run the Holly High ram but the Fast manifold will fit much better in a boat under the cover. Make sure you post some pictures of yours once you get moving with installing the LS. I have a seafari 25 and against better judgment have twin 200 merc efis on a bracket for mine. A lot of people say not to do a bracket on a 25 and rightfully so but I am going to give it a shot to see if I can make it work. I need to get mine going. She has sat for a few years now.

[Xcomunic8d]

Thank you both! That exhaust is saved for when I put that thing in. Wow what Amazon has...

I hear you flying on the sbc1. I thought really hard on making a 383 stroker. a block was $100? From junkyard. But I got this running 5.3 for free out of a truck I know and have worked on it for years for my friend.

Free.99 is hard to pass up but I’ve wondered about that ever since. But I’m committed now.

I hear you on that outboard thing I was dead set and you get a LOT of deck space
But the price of outboards, shipping, wait time, installation, and balance issues...no thanks.

My boat guy said he wouldn’t do outboards and said he’d do this. That ultimately pushed me over the edge. Except he wanted me to buy a crate mercruiser. When I told him what I’m doing he started laughing and said I can’t wait to try it out.

No supercharger likely, TBSS first, maybe Lsxrt 2nd, supercharger not likely as they seem to be drying up and not sure I have enough parts that could handle boost. Agreed on Holley high ram and sniper intakes.

[Xcomunic8d]

So block came back from machine shop awhile back.

The pistons were badly out of spec. Something like .009-.010

Just placed order for engine parts a little over $2k not including terminator x and exhaust manifolds.

Have the following on order from summit:
KGB-mb5013xp Main bearings
KGB-cr807xpn Connecting rod bearings
Slp-h1132cpa pistons, wrist pins, and snaps
Mah-41859cp piston rings
ARP-234-6301 connecting rod bolts
Clo-9-3658tx3 timing chain
Clo-9-5417 timing damper
Mah-95-3561 gasket kit
ARP-134-1003 cam bolts
ARP-134-1501 timing cover bolts
ARP-234-2503 crank bolt
ARP-434-1202 exhaust header bolts stainless
Sdm-pce229-1006 flywheel
ARP-330-2802 flywheel bolts
Sum-htlskit2 ls7 lifters and trays
Sum-141560 trunnion upgrade

Already have arp head bolts and summit brand main cap bolt kit.

Planning on getting exhaust manifolds, raw water pump at marine engine depot.
Planning on getting terminator x 990-505 through Amazon or Holley directly.
Local Mercury dealer is sourcing a bravo transom assy and timeline. Looks like sept.
Outdrive is scheduled for rebuild/reseal 7/26 in shop.
I have a plan for heat exchangers on the closed cooling system more to come on that.

Will keep parts list updated and pics as is relevant.