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Lt1 383 or 6.0 swap

This is a discussion on Lt1 383 or 6.0 swap within the LSx Retrofit and Swap forums, part of the LSx Technical Help Section category; I am looking for some opinions on a build I am looking to do. Here's a little bit of background ...

  1. #1
    Junior Member
    Join Date
    Mar 2015
    Jamestown, Ohio

    Lt1 383 or 6.0 swap

    I am looking for some opinions on a build I am looking to do. Here's a little bit of background on the potential build:

    I currently have a 89 k2500 truck that I swapped a lt1 into. The engine has ~145,000 miles on it. I've had it for a few years now with the engine essentially bone stock. It has a set of headers, cai, and has the emissions deleted. It is starting to burn a little oil, and fuel mileage isn't the greatest, which I think is mainly do to worn out heads. I found Elliot Sports Works awhile back and talked with him about having the heads ported and a cam. The original plan was to just do the cam and head swap and go for ~400 hp. He seemed to think that could easily be done.
    But now I'm second guessing it....

    I have a k3500 cab and chassis from a 2000 old body style chevy truck that I am thinking about swapping the 89 over too. The 2000 was rolled so the body is shot, so I'd just have the frame to work with. The 89 frame is getting pretty rusted and it's (in my opinion) a bit of a light duty 3/4 ton truck. The 2000 cab and chassis has a solid and heavier duty frame, a heavier duty drivetrain with 4.10s vs 3.73s in my current truck, and a heavy suspension. So now I'm thinking that if I am going to swap the engine to that frame, now would be a good time to just rebuild the engine. So here comes the dilemma...

    If I rebuild the lt1, I will do a 383 build. With the machine work, parts, computer tuning, and Elliot heads and cam, I would guess I'd be getting up around the $4000 mark, maybe more? But, it should also be a pretty healthy running engine. The truck will be used primarily as a work truck, occasionally pulling a trailer, sometimes could be upwards of 10,000lbs, but mostly just hauling equipment and supplies on a flatbed. I have a diesel that will do most of the trailer pulling, but the 89 already sees it's fair share of trailers, so I wouldn't expect that to change.

    My other option is to just do a 6.0 swap. The lt1 is out of a 93 z28, so it's a 2 bolt main and they aren't built nearly as stout as the 6.0s are. I can find 6.0s in the $1500-$2500 range depending on mileage and year, so it starts out cheaper. But it will also be a used engine instead of "new". Plus, I can't just leave it alone.... I would probably do at least a cam and headers. Then there would also be tuning and the additional costs and time of dropping the ls into an old body style truck that aren't there for the lt1 drop in. So on the outside, it appears the 6.0 would be cheaper, but it wouldn't have the power the 383 would have and wouldn't be a fresh engine. But, being as the 6.0 is an engine designed to be worked, would it still be the better option for overall reliability and longevity? The reliability is my number one concern for this truck, power is second to that. So my question is, what is everyone's opinion for the best engine to go with for overall reliability and power? I've been back and forth 100 times but can't quite make up my mind.

    And for what it's worth, I have a 81 z28 that would most likely be getting the lt1 if the truck doesn't get it, or some sort of ls engine if the truck does get the lt1. But that will be several years down the road.

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  2. #2
    Spaz is My Mentor SMWS6TA's Avatar
    Join Date
    Feb 2009
    Ugy Lower Corner of AL

    Navy Blue Metallic
    98 T/A w/a little mods...

    Go with the 6.0L.

    Reasons why -

    Even if you keep it stock for now you have a solid base to start with and then later on do the mods when you have time & $$$. LT1 383's are ok in power build up but they do have a much lower limit in options and power that a LS 6.0L has.

    You can find long blocks for $600-$1500 and short blocks for $400-800, all depends on where you look. Your area might be higher.

    Issues when considering the LQ4/9 - Pre 99 used the LT1 cranks, so you'll need get a transmission that is setup for a LT1, if it's 99-04 yrs, they are set up with the LS1 crank. The difference between the 2 cranks is the length, about an inch if I remember correctly. What it means mostly is on the transmission you may have to change the input shaft and front cover on the T56 transmission, auto's not sure if any changes are needed. Most of my info is for the T56 because that is what I have in my car.

    Options with the 6.0L - you can use LS1/2/6 style (cathedral port) heads or LS3 style heads (rectangular port). Each has it's pros and cons but not much. Too much to list, so I'll answer as you ask questions so I'm not flooding you with everything.

    Heads - this really is based on your end goals. Some stock heads perform better then others when it comes to power or torque.

    You'll also need to decided on what compression ratio you'll want. The LQ4 come with dish pistons and the CR is about 9.5-1 and LQ9's use flat top pistons and are about 10.4-1 CR. Heads also effect the CR. With the 9.5 you can run regular gas and not have knock, with the 10.4 and up you'll want to use premium to reduce knock possibilities.

    There are alot of other reason but this are the highlights.

    I'm very familiar with the 6.0L blocks and have a LQ4 block that I got for $250 because it had a hydralock piston. Had the blocked bored 4.005" (for longevity and if later on I want/need more I can still punch out to 4.030", any higher then I'll need to have some checks done to the block for structure) for a stockish rebuild. That lasted till the first test drive when I had rod bolt failure and it corkscrewed the crank. So then I went stroker. and made it a 403ci. With refreshed 243 heads and a cam that was designed for stock LS2 (not a stroker cam) and currently putting down 450tq and 450hp at the rear wheels thru a T56 and custom 8.8 rear w/4.11 gr.
    Last edited by SMWS6TA; 05-05-2017 at 08:45 AM.

    6.0L Block - Forged 403 built, breaking it in , Polluter Stg3 Cam, FAST 102mm Intake, NW102 TB, MSD wires, NGK TR6 plugs, Truck Coil Packs, LS3 Fuel Injectors, CC Pacesetter LT Headers, TS&P ORY, QTP e-Cutout, Magnaflow Muffler, 104mm Air Lid & Line Lock, Catch Can, Stage 2 T56 w/Viper shaft, PRO 5.0 Shifter, Tick MC, Monster Stg 4 Clutch, QT SFI BH, MWC DSL, UMI: SFC, PHB, LCA's, LCA Relocation Brackets & TA, Hotchkis Springs (1" Drop), YR1 Snowflake Wheels wrapped in NT555 tires & Custom Fab Ford 8.8 rear w/4.10 Yukon Gears, WSQ Hood, 3"CM Strange Eng Drive Shaft.

    Horsepower never lies, but is often lied about!

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