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LS Boat Motor help!!

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Old 04-29-2015, 10:36 AM
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Default LS Boat Motor help!!

Ok so here's the deal, I've got a 5.3 laying around the house that my buddy wants to do some trading for... I'm not gonna use it so I figured why not...

He's currently running a 460 BBF in his Jet boat and he's been hearing all the hype lately about all the LS Engines and how they come alive with FI. I don't know enough to tell him everything he needs to know so I'm looking for some help. He runs the 460 at 5800 from the time he takes off to the time he shuts her down and it's lived through 2 hard summers and takin quite a beating... he's skeptical that the 5.3 wont hold up...
He wants to run a Turbo but not be out a whole bunch of money (within reason)... he's got an hx35 turbo from a Cummins diesel and wanted to know how well it would work... Like I said, I don't know enough to give a straight enough answer so we need some advice...

and GO!!

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Old 04-29-2015, 11:55 AM
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Originally Posted by InsaneDomestics
Ok so here's the deal, I've got a 5.3 laying around the house that my buddy wants to do some trading for... I'm not gonna use it so I figured why not...

He's currently running a 460 BBF in his Jet boat and he's been hearing all the hype lately about all the LS Engines and how they come alive with FI. I don't know enough to tell him everything he needs to know so I'm looking for some help. He runs the 460 at 5800 from the time he takes off to the time he shuts her down and it's lived through 2 hard summers and takin quite a beating... he's skeptical that the 5.3 wont hold up...
He wants to run a Turbo but not be out a whole bunch of money (within reason)... he's got an hx35 turbo from a Cummins diesel and wanted to know how well it would work... Like I said, I don't know enough to give a straight enough answer so we need some advice...

and GO!!
tell you what, I've got the hook up for him. a forged 4.8 iron block with lunati forged crank, lunati h beam rods, and wiseco pistons

block is bored .040 over so it's a 3.82 bore size

this engine will live at "900 at the prop" (gee that sounds wierd) all day long if you keep the revs reasonable at about 6500

after that I'd think about better heads

so here's what I have for him

4.8 engine with corvette 799 stock heads
truck intake (better for boat low end torq)
two T04 T60 turbos (flow well for sustained high rpms that boats typically pull)

an air water intercooler (enough for 1k)

I will make him a KILLER deal on all of the above

engine is apart right now to have the rotating assembly balanced, but I can have it together

in lieu of that, if he only wants puny BB ford power (sorry just had to go there) I can sell him a rebuilt stock 4.8 long block It will live all day at 600 at the prop, and more if pushed or run on good fuel

willing to sell complete or whatever parts he needs.

he will forget all about that ford torq once he

boostamuv! PM me if interested.
Old 04-29-2015, 02:42 PM
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Whew!! Did I mention were tryin to do this cheap?! Haha, I know the words Forged and Lunati means $$$ Starting point is a junkyard 5.3 that we'll most likely freshen up with new bearings and rings and add some ARP fasteners...

Just trying to get opinions on where to go from there... he told me he's wanting to make around 800-850hp..
Old 04-29-2015, 04:47 PM
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He won't be able to make that reliably on a stock bottom end. You stay around 600, he can probably make it last.

Keeping it at 600hp, cheap ebay head studs and maybe a cam if he wants to have it sound decent, not necessary at all though. Gt45 turbo off ebay and all the cheap parts that go with it. They have been proven to make those numbers and work.
Old 04-29-2015, 05:53 PM
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He wants to find out what the limits are on stock internals, trying to stay away from a forged bottom end. It's going in a 300lb jet boat, the 460 is makin around 600hp as it sits right now, he's wanting the 5.3 (aluminum) because it'll be about 300 lbs lighter than the 460. He read the GM article bout the little 4.8 makin 1300+ with over 60 dyno pulls and I think that may have sold him on the idea.
Old 04-29-2015, 06:50 PM
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It's truly all in the tune. If he can tune, he will be fine at modest HP levels. Nobody can tell you what the limits are. As far as the article your buddy read, that seems far-fetched. He shouldn't be getting excited predicting he will make those numbers, he should honestly be happy if it makes half thst and stays together.

Tell him to READ till he is cross eyed and then do it some more the next day. It's a huge change from NA and is not as simple as some people make it seem. I just finished mine and thought it would take a couple months. Seven months later and about 2k over budget, it barely idles..
Old 05-01-2015, 08:37 AM
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Any idea how the hx35/hx40 from a cummins would work as a pair? He already has those laying around... My personal opinion think they're too small but I don't really know. They push 30 some psi on the diesels I think
Old 05-01-2015, 10:35 AM
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hx35/40 would work fine in a pair should make more power than his 460 as it was most likely crank hp where most of us make over 600hp threw unlocked automatics how long it will last hang out ***** to the wall at 5800rpm is the question cooling and oil will probably play a big part of that



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