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HaxbySpeed 12-01-2011 07:20 PM


Originally Posted by freshwaterfiend (Post 3561849)
Pretty sure the LSX376 has the same internals of the LS3, just with the stronger block.

No

glassdave 12-01-2011 07:52 PM


Originally Posted by HaxbySpeed (Post 3560494)
CMI makes a nice unit but a little pricey. There are lots of cast manifolds available too. We've been using LS engines for years in aluminum jet boats up here. If you want to make your own the cheapest route is GM performance parts. They've really done a good job of keeping parts prices down to help promote the platform. The LS3 is a great starting point if you want an all aluminum engine and will make 500hp with just a cam swap. Personally I like the LSX 376 forced induction package. It's got a tougher rotating assembly and 9:1 compression. With a cam swap it'll make just a bit under 500hp but live on cheap gas. The LSX 454 was tested for 50hrs straight WOT between peak torque and peak hp without issues. If you're going to run a blower on any of the production engines with cast pistons be careful with the tune up... :eek:

Here's some out of the crate LS7's with only a cam swap. As usual I think Weismann was ahead of the curve running LS's years ago. I'd like to hear an update on his experience with them. Sounds awesome! http://www.youtube.com/watch?v=EFZP9...eature=related

cool, that lsx376 is a nice piece, pricing seems go to. what whould one do for induction? My first thought was to just pick up a pair of LS3 Vette or GTO takes outs. I dont plan on anything over 500HP and would like to retain the port FI. Sounds like that shoudnt be to much a streach

HaxbySpeed 12-05-2011 12:59 PM

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Originally Posted by glassdave (Post 3561996)
cool, that lsx376 is a nice piece, pricing seems go to. what whould one do for induction? My first thought was to just pick up a pair of LS3 Vette or GTO takes outs. I dont plan on anything over 500HP and would like to retain the port FI. Sounds like that shoudnt be to much a streach

For the lsx the ls3 intake is a great value at about $750-800 complete with injectors. The injectors are 42lbs @ 58psi which is enough for what you're doing. For that power level you won't need a FAST intake or anything exotic like this one.. :drink: The only downside to the LS3 take out is the compression. When subjected to the continuous load of a boat 93 octane is necessary, or very conservative timing which is pretty hard on the exhaust valves over time.

glassdave 12-05-2011 01:33 PM

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mostly i am looking for reliability over HP. Years ago i did a long runner TPI for a Camaro i had. Used all off the shelf stuff with the exception of a no vats chip. My thought was i was going to drive he heck out of it and wanted the ability to replace any sensor or ??? at a place like AutoZone on the weekend if need be, although i used all GM components i was looking to keep going in a pinch if i had to. Wanted to use as few mail order only type parts as possible. I even went to the length to make a custom collector to house a non heated O2 sensor so as not to need a heated one. The entire system worked like a charm and gave me thousands of trouble free miles from day one. I would like to do something similar for the LS motors. Use as many readily available Merc or GM parts as possible if i can. Would also like the ability to replace most anything using off the shelf stuff. I have no prob giving up hp for reliability in this project. In this boat 900hp is plenty for me. Is it feasible to build a system using this concept? I know the computer will need a custom burn but what FI computer would work best for what I'm trying to do? Thanks for your input.

Incidentally when i did the old school long runner TPI for my Camaro it really sold me from never building a carb system again. Really simple and easy to work on, i did mine in the mid 90's while that was still the trick set up lol. I still have an old 305 TPI engine out of a 80's Iroc i am sticking in an S-10 Blazer for fun. Easy ,cheap system to install. Funny story, i was working for a Chevy dealer when the 85 Vette came out with that system. I remember when we got the first one in i popped the hood looked at the near Area51 alien like system and said "oh my god . . . this is the end of street roding . . . how are we ever gonna work on this stuff" lol no schit :D

Steve 1 12-05-2011 01:49 PM

Very Cool stuff Guys,Thanks.

HaxbySpeed 12-05-2011 05:13 PM


Originally Posted by glassdave (Post 3564806)
mostly i am looking for reliability over HP. Years ago i did a long runner TPI for a Camaro i had. Used all off the shelf stuff with the exception of a no vats chip. My thought was i was going to drive he heck out of it and wanted the ability to replace any sensor or ??? at a place like AutoZone on the weekend if need be, although i used all GM components i was looking to keep going in a pinch if i had to. Wanted to use as few mail order only type parts as possible. I even went to the length to make a custom collector to house a non heated O2 sensor so as not to need a heated one. The entire system worked like a charm and gave me thousands of trouble free miles from day one. I would like to do something similar for the LS motors. Use as many readily available Merc or GM parts as possible if i can. Would also like the ability to replace most anything using off the shelf stuff. I have no prob giving up hp for reliability in this project. In this boat 900hp is plenty for me. Is it feasible to build a system using this concept? I know the computer will need a custom burn but what FI computer would work best for what I'm trying to do? Thanks for your input.

Incidentally when i did the old school long runner TPI for my Camaro it really sold me from never building a carb system again. Really simple and easy to work on, i did mine in the mid 90's while that was still the trick set up lol. I still have an old 305 TPI engine out of a 80's Iroc i am sticking in an S-10 Blazer for fun. Easy ,cheap system to install. Funny story, i was working for a Chevy dealer when the 85 Vette came out with that system. I remember when we got the first one in i popped the hood looked at the near Area51 alien like system and said "oh my god . . . this is the end of street roding . . . how are we ever gonna work on this stuff" lol no schit :D

That goal is no problem and you can get the majority of the stuff you need right from GM. At 450hp with proper maintenance they're and easy 1000+ hour engine. If you wanted you could run the factory GM computer and tune it with HP tuner, or efi live; that does have some drawbacks though. Check out my "EFI for everyone" thread in the tech section. The Holley HP is a direct plug and play for any LS and will allow you to run drive by wire or cable throttle, sequential injection, individual cylinder timing and fuel, digital display or gauges, etc. with a potted, water and shock proof, CG approved ecm. If you do find a killer deal on some ls3's you could swap the pistons out for a forged dished unit from Diamond or Mahle to drop the comp and add durability. Give it a quick hone and some rings and you're good to go. About $2500 per engine will get you closed cooling, exh. manifolds, sea water pump, and accessory brackets.

That's a nice clean install on the camaro! Once someone gets over the initial fear of EFI there's no going back.. :coolcowboy:

glassdave 12-05-2011 05:34 PM

Amen on the fear thing, for comparison sake i have no idea how to tune a carb yet i set up the whole long runner TPI myself in a day and pretty much never touched it again, put ten thousand trouble free miles on it before i sold it.

That sounds like a great punch list for what i want to do for LS power. I was hoping i could use the majority of factory components. Man i gotta get out'a the glass section of the tech part of the forum more often lol :D, keep forget'in we have a DIY. Sounds like a good thread for what i am doing

Sonic30ss 12-05-2011 06:01 PM

you do find a killer deal on some ls3's you could swap the pistons out for a forged dished unit from Diamond or Mahle to drop the comp

I've been following this thread since day one and having the same thoughts as Glassdave. Haxby- by dishing the piston would you potentially look at having detonation issues by loosing the quench built into these engines?

HaxbySpeed 12-05-2011 07:38 PM

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Originally Posted by Sonic30ss (Post 3565008)
you do find a killer deal on some ls3's you could swap the pistons out for a forged dished unit from Diamond or Mahle to drop the comp

I've been following this thread since day one and having the same thoughts as Glassdave. Haxby- by dishing the piston would you potentially look at having detonation issues by loosing the quench built into these engines?

You only need to drop about 1 point in compression so you can use a piston with a D-shaped dish with a quench pad. It's not a big deal though even with a full dish. The chambers are very efficient and detonation resistant. The 5.3 LS's come from the factory with dished pistons, as do the 350 Mag's with vortec heads.

Sonic30ss 12-06-2011 04:13 AM


Originally Posted by HaxbySpeed (Post 3565081)
You only need to drop about 1 point in compression so you can use a piston with a D-shaped dish with a quench pad. It's not a big deal though even with a full dish. The chambers are very efficient and detonation resistant. The 5.3 LS's come from the factory with dished pistons, as do the 350 Mag's with vortec heads.

Thanks Haxby!


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