Hey guys, not a big poster on lstech, but I thought you car guys might like to take a look at my new LS motor I had built for my airboat.
4340 forged 4'' crank, ACL/Kings main bearings ARP PRO main studs


6.2 block, 4340 4'' stroke crank, 4340 H beam 6.125 full floating bushed rod's, custom forged pistons, total seal file fit rings, ARP pro Main Studs, ACL bearings





LS3 block with a 4340 forged 4'' stroke crank, with 4340 full floating bushed H beam rod's with ARP rod bolts, Forged flat top pistons with Total Seal file fit rings, ARP Pro Main Studs this combo come to 418 cubic inches. Demon 850 cfm carb with annular boosters sitting pretty on top of a spider intake. We're making over 600hp with this combo! It spins a 4 blade R series carbon fiber prop(13''x82'') up to 5600rpms with 12 degrees of pitch in it. All that goes through a 2.68 to 1 gearbox

 

oh yeah, I almost forgot. We built this to be a pump gas motor and so far it is just that! Ran great on the thrust tester with 93 octane.

 

what are you running for ignition?

 

That is a sick *** motor man, i am going to move this to the new carbed section, this is(was) the old SBC section.

 

That's awesome. You air boat guys are crazier than car guys. LOL.

 

stand alone programmable ignition controller, gm coils.

 

Way to fast on water for me.
What brand pistons and are they 4.080.

 

 

How fast does something like this go?

 

That thing is pretty.

Hard to believe you will keep it right side up with all that motor.

 

crazy

 

A few questions. What heads are you using and what are the cam specs? How much timing do you run for pump 93 octane? What comp is it. My power requirements are simular to yours but it is a jet boat.

 

The motor was built in florida by a company called Waterthunder proformance, they specalize in LS motors for airboat use. Though they have built engines for drag cars, jet, boats, drag airboats, and airboats. I'm currently in Iraq and I've yet to lay my eyes on the motor and I wasn't involed to much in the build up of it. Dave has done tones of R&D on his custom cam grinds from carbed and EFI engine and I don't think he'll be giving out the specs. The heads are L92.

You can check out his website www.waterthunder.com or even give him a call, but he's an engine builder and all the R&D he has done puts food on his table, I doubt he'll give any info up at all unless your considering buying a motor from him.

you can also see more pictures of the engine/boat build on my site, www.bullshithill.org

 

My boat is pretty big(8'x16') and it really isn't built for speed. If I took this motor and put it on a small hull I could make it scream. I haven't got it on the water yet but it will be around 40-50mph. The boat will also pretty much go anywhere on dry land and up hills.

The drag racing airboats run a 400' track and top out around 98 mph in the unlimited class in 400'. They'll goes faster, but the get pretty squirrly and it takes some ***** to stay in the gas to get up to higher speeds.

 

Hot Damn that's sexy!

 

I just noticed that they was core plugs in the heads so they may be catherderal ports. Not bad or good just an observation. Awsome looking engine.

I assume that you are over ther in the service so even though I am from Canada I would like to say thanks for your service!!

 

He says in post 13, that they are L92 heads

 

If he's in the service hes been saving his money since he got there that thing looks expensive. I would guess contractor. Blackwater or similar?

 

Here you go guys, I've got her all finished up and put about 30 hours on her while I was home. She runs like a bat outta hell.

 

NICE! Could you get us a sound clip or a video?