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Discussion Starter #1
I bought a 16' Mantra Tunnel hull a few months ago with a blown engine and haven't got it in the water yet. The motor has been pulled and fixed and just needs dropped back in. This is my first jet boat, and the guy I bought it from was not very helpful with info or anything for that matter. Does anybody here have experience with these boats? Just wondering what to expect from it.
 

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I think that Tom E has a boat like what you are talking about. Search the forum for posts under Impatient1, if nothing else, I am sure that he will be chiming in as soon as he sees the topic. He has searched all kinds of info on these hulls. Post up some pics. I have only see two of them, including Toms. Congrats on the new ride by the way.
 

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I have several pics but I get on here on my iPhone.... I'm not sure how to post them from here?
 

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mo balls than $cents$
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hey ive got 1 too, worked on it alllll weekend trying to hurry up and set my engine in:)devil
 

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mo balls than $cents$
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here's mine, looks nothing like this anymore tho, i brought back the gel and she shines awesome now! doin and interior revamp as we speak and then dropping in my engine so i can finally hear the phucking thing:)devil:)grn built a nice tight pump with a htp detailed b-cut, 800hp/ftlbs+ pumpgas ls sbc turbo engine and have started on a bigger cubed shortblock that'll make 1100hp pretty easy with my same turb kit and carb.






 

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Discussion Starter #7
Looks like an LS engine? That's actually my plan for next year is to lighten it up a bit with an LS3. I came from drag racing an 02 Ws6 to boats... So I'm a little out of my element with this carb'd BBC. I'll try and get some pics up but my base color is red with black and white stripes. Have you ever had yours in the water to know how it handles?
 

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mo balls than $cents$
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Is that a built race gas motor? How are you going to make 800+ with no IC?
:D good eye bro, 3 nozzle ais water/meth injection;) the turbo is a custom built from jose at forced inductions, worth 125+lbs 80mm. it'll be ran on nothing but -20* washer fluid(spiked with more methanol, bout 60% meth) and 91 pumpgas



 

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mo balls than $cents$
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Looks like an LS engine? That's actually my plan for next year is to lighten it up a bit with an LS3. I came from drag racing an 02 Ws6 to boats... So I'm a little out of my element with this carb'd BBC. I'll try and get some pics up but my base color is red with black and white stripes. Have you ever had yours in the water to know how it handles?
nope, never seen this hull before till i saw it sittin by someone's barn and had to have it:D the previous owner had a bbf in it with 700hp and ran 110 on a sdba 1000ft track. figure it'll do better than that with 200lbs less weight and 200ftlbs/100hp more. when i get the 1100hp iron blocked ls1 shortblock done i'll swap it into the boat and and hopefully itll be so quik from the holeshot itll be uncatchable. from what im told they're super quik hulls, damn sure unique which is why i bought it, i'm alil different:p
i've gotta all alum 6.2liter i may end up using at some point, but the 1100hp ls1 otta do the job and be more power than i need anyways
 

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Yeah I hear ya.... I hate having the same thing as somebody else. I found mine on Craigslist in Meridian MS. It had been sitting in a barn 15 years so of course it spun a few rod bearings when the guy fired it up in his driveway gonna warm it up when I was on the way to get it. I've converted my trailer to single axle now and it pulls SO much better IMO. I've got a buddy that runs a vinyl shop close to me, so it's fixing to get wrapped in vinyl something really wild looking. Did you build all of your piping for your turbo setup or is that bought from somewhere?
 

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mo balls than $cents$
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Yeah I hear ya.... I hate having the same thing as somebody else. I found mine on Craigslist in Meridian MS. It had been sitting in a barn 15 years so of course it spun a few rod bearings when the guy fired it up in his driveway gonna warm it up when I was on the way to get it. I've converted my trailer to single axle now and it pulls SO much better IMO. I've got a buddy that runs a vinyl shop close to me, so it's fixing to get wrapped in vinyl something really wild looking. Did you build all of your piping for your turbo setup or is that bought from somewhere?
i used gm performance parts 1/2in thick header flanges and bought the rest of the thick walled mild steel header piping off the net, cant remember where exactly:)sphss built it myself and had embee performance coat all of it including the turbo exhaust turbine housing, its copper coated inside. should be at 5lbs by 3500rpms, 10lbs by 5k, 18lbs by 5500 range, my cam peaks at 6500 so that's where ill be runnin the motor at 18lbs at. im boring a 5.3 to ls1 bore, using the stock 5.3 crank and goin with diamond ls1 dished pistons/scat 6.125 rods and ill run that motor at 25lbs:)grn im a gm tech, so ive got plenty of ls's:p
the turbo is real big on the compressor side and by the map i was told to go by, i'll be in the 80%+ efficiency island so my intake air temps with the 3 nozzle injection should be in the 70-80* range at full boost, which is bout as good as it gets.
 

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Discussion Starter #13
Is a 5.3 not wet sleeved like the 5.7?

What is a detailed impeller?

If mine breaks 100mph I'll be tickled pink for this coming season atleast. This is my lake boat lol.

Does your hull bow in like cardboard when you put much more than a finger on it? Mine does... And makes crackling noises sometimes.

Gonna be a learning experience for sure!
 

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nope, never seen this hull before till i saw it sittin by someone's barn and had to have it:D the previous owner had a bbf in it with 700hp and ran 110 on a sdba 1000ft track. figure it'll do better than that with 200lbs less weight and 200ftlbs/100hp more. when i get the 1100hp iron blocked ls1 shortblock done i'll swap it into the boat and and hopefully itll be so quik from the holeshot itll be uncatchable. from what im told they're super quik hulls, damn sure unique which is why i bought it, i'm alil different:p
i've gotta all alum 6.2liter i may end up using at some point, but the 1100hp ls1 otta do the job and be more power than i need anyways
Tom.... the engine looks great. Can't wait to see the full combo run. I know your a little different and that is what makes it all fun:) Should be interesting. I like your new school approach to the old jetboats. I'm fairly new school in the race car, but a bit of old school approach on the boats. What I am trying to learn is better ways to optimize my old school boat approach.

Gear
 

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mo balls than $cents$
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Is a 5.3 not wet sleeved like the 5.7?

What is a detailed impeller?

If mine breaks 100mph I'll be tickled pink for this coming season atleast. This is my lake boat lol.

Does your hull bow in like cardboard when you put much more than a finger on it? Mine does... And makes crackling noises sometimes.

Gonna be a learning experience for sure!
a 5.3 is a 3.780 bore, 5.7 is 3.905 cleaned up. gna take a .125 over bore to get to where a ls1 piston fits, and big hp lsx guys are telling me that the 5.3 block will go that easily and still be capable of big boost without a half filled block, so that's what im doin. diamond pistons can be bought offa ebay for 600 delivered, rods 350bucks, and if you're using a 5.3 crank, it'll have to have material removed from it to be balanced to the ls1 forged pistons and hbeam scat rods. the ls1 pistons are lighter than stock 5.3 cast pistons and the 5.3 crank is the same as a ls1, but the ls1 crank is crossdrilled and lightened stock, so bobweight is lighter too. so that basically allows ya to bore a 5.3 to a ls1 bore, use ls1 forged pistons/hbeam rods and you'll still be lighter on the rod/piston combo than the stock 5.3 stuff, which makes it easy and cheap to have balanced:)devil nooooo mallory!:)devil

yes sir, my hull weighed 340lbs with the pump intake in it, and the sides are veryyyy thin, im painting them black so while on the lake, i dont see thru the hull and make myself nervous:)st:D i love the look of the hull, and from the pics ive seen of them runnin, they jus look killer:)grn as lite as they are, its a no brainer to use a smallblock, a bigblock is gna make them react odd and might get me pitched out, so ive stuck to keeping it as lite as possible and have been building the inside of the hull to offset my own weight with the fuel cell, battery, turbo , everything i could is hung to the passenger side to offset my 165lbs

if that blown engine you've got is making over 700hp, i bet it'll do 100+ easily
 

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Discussion Starter #17
Blown as in came apart blown lol.... I wish this one was boosted!

This motor is a 454 block de-stroked with a 396 crank and it's bored .060 over coming out to about 440ci. 12 to 1 TRW pistons. Good rods. GM's closed chambered squared port heads that have been ported. My machine shop said the cam is .640" lift. Tunnel intake with twin holley 660's.

I'm lost on knowing what makes what hp on a BBC so I have no clue how it's going to run. The previous owner said he's never gps'd it but it turned a B impeller 67-6800 on the big end
 

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mo balls than $cents$
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Tom.... the engine looks great. Can't wait to see the full combo run. I know your a little different and that is what makes it all fun:) Should be interesting. I like your new school approach to the old jetboats. I'm fairly new school in the race car, but a bit of old school approach on the boats. What I am trying to learn is better ways to optimize my old school boat approach.

Gear
hey steven! im doin all i can to hear it fire off before xmas, gta get it done or ill lose interest in it:)st ive got everything i need to make it run, jus havent gotten the hull interior done yet and have to have the bilge area , then i can put rails back in and build my frt engine mounts, the rear is the same as sbc/bbc.already have the engine plates built for the frt, jus gta put legs on them over to the pillow blocks. gta move soon, so it HAS to get done now:p

we're building billy's 17ft earl with a ls smallblock nitrous motor with lil zoomies on it, should be pretty quik but gta feeling it may leg out to fast and be done by 600ft, but he jus wants something lite and fun to play with from now on, dont care bout being the quikest anymore. have his twin turbo tx20 sold :)devil

i think everyone does what they're comfortable with, i do nothing but modern engine work all week therefore its what im comfortable with and know best. i jus see all these racers goin alum blocked bbc's and making 1200hp on engine, but still weighing 600lbs plus in the engine dept, makes no sense to me when they can do the same with a ls sbc and be a ton lighter. tired of playin the bbc cubic inch and nitrous game, there's always someone with more nitrous or cubes, so im taking a different approach at it all, big boosted sbc's weighin 200lbs lighter, more engine controlability and functions.if ya cant beat, out smart em :) lol
 

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mo balls than $cents$
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Theyre quick boats. Just becareful, they are dangerous. They guy that ran one out at Blarney Island with me wound up getting pitched and trashed the boat.
oh no! is he ok?

if the interior of that boat was saved, i might be able to use it, colors were close.
 
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