like the tittle says... i am pulling my 383 sbc/th350/205 in favor of swapping a ls/4l80e/205 into my 1974 gmc 3/4 ton truck it has 4.56 gears and 35'' tires and is mostly street driven with light offroad use. weighs in at 6200lbs

i have been googling and searching the forums quite a bit today

i have been researching the 408 stroker vs a 421 stroker using a 4.125 stroke crank. from what i read most prefer the 4.0 stroke crank due to oil consumption, as i understand it the piston rocks at the bottom of the sleeve and allows oil to pass by, is this correct? i also read Wiseco makes a piston designed to help with that? does it work? anyone have any experience with it?

i am looking to get the most amount of use able torque and hp as i can, but my goal is 600hp, i think this is a realistic goal? i am also looking to keep the fuel injection, i was figuring the longer stroke would help me out in the torque dept, but may not be woth the extra 13 cui vs longevity, and Wiseco's catalog gives a specific deck height for the
4.125 stroke piston

as for cam, alot of people refer to a guy named Pat for a custom cam recommendation, which for my application a custom cam is probably a good idea

looking at these cylinder heads https://www.summitracing.com/parts/n...make/chevrolet

they look like a good option to me for cost vs performance will probably match it up with a FAST lsxrt manifold with a 92 or 102mm tb

thats about as far as i have gotten so far with ideas, id like to get it build on paper before i start throwing money on parts and end up with mis matched stuff,

and very ope to suggestions and tips for these motors, i would like to build a beast to put in my truck, my 383 on the guestimation dyno is running between 450-500hp? and just want more

oh and what im looking at right now is a 2003 gmc 2500hd donor truck, it says the motor is bad and has a knock, but i figure if the crank and rods are hammered it doesnt matter so long as the block as good, lots of wiring and accessory drive pieces parts and they want 1000$ for it which imo isnt bad

 

If you pick up the LS3 heads, just use a stock LS3 intake. A FAST 92 isn't worth the money for the extra 8-10 HP over a stock LS3 manifold.

Anything greater than a 4" stroke doesn't play well with the stock block because of deck height.

I'm a big advocate for a turbo setup. I could NEVER justify buying a stroker setup when I've built a full turbo setup for the same price multiple times.

 

4.125" stroke is fine in a stock block, especially in an iron 6.0L. It has almost nothing to do with deck height, and almost everything to do with cylinder length. You are right, when poorly done, the piston can rock at BDC which causes oil contamination in the combustion chamber and excessive wear on the skirts. Right now, I think Wiseco has the best piston for these types of builds. Deburr the bottom of the cylinders really well and you should be perfectly fine with the 4.125" stroke.

The LS3 heads you're looking at are rectangle port heads. The LSXrT manifold is for cathedral port heads, so that won't work together. Unless you want to port the manifold, a stock LS3 manifold is probably adequate. You shouldn't have any trouble making 600hp to the flywheel with this combo, but 600hp to the tires needs a completly different game plan.

 

I am not opposed to other options, i have seen alot of people using turbo'd 5.3 set ups, im just not familiar with forced induction set ups, and would itake the torque where i need it, im not dead set on a 408, just seemed like the best route for my heavy truck. But even with a turbo'd 6.0 id need a fully forged motor?

 

My junkyard 5.3 (95% stock long block) made 650 ft-lbs on a Mustang dyno at 3500 RPM on my pump gas street tune. That's ~760 ft-lbs to the wheels on a Dynojet through a heavy 4L80e auto. That was 6 PSI and a TBSS intake ago, I've probably gained 100 ft-lbs since then. With a mild cam, it has tons of low-end torque. I have probably $1800 in the whole turbo setup not counting fuel, and I could have done it for $1200 if I had to do it again.

Weigh your options. If you're not comfortable with a turbo setup, then staying N/A is probably best. In reality, you'll end up spending twice as much money to make less power. With a turbo setup, there is no need to change heads, intake manifold, throttle body, exhaust manifolds, or even cam/valvetrain if you don't feel like it. Everything simply becomes an option.

 

Thanks for the input, are the cathedral pirts better than the square? Or does it only matter ehat they flow, not so much shape?.

What would it take to hsve 600 at the tires? I dont really have any game plan and nothing is really out of the question, i have alot of room under the hood and the truck is a 1-2 year project at this point

I read through your 440 build, i see youre a machinist lol

 

As far as cathedral vs rectangle, I think it all depends on application. The rectangle ports are big and have big valves, so I think they work great to feed bigger engines. The cathedral ports are smaller and have smaller valves, so they are more appropriately sized for smaller engines.

In your application, there will be a lot of power lost through the drivetrain so you need a big engine and big cylinder heads, and it probably won't get it done through a FAST or other plastic manifold. I'd say boost is the best way to go to make 600whp through a 4l80, 4WD, and 35" tires.

There are lots of options for boost. As Joe said, turbos are one way to go. You could also look for a used LSA blower that came off of a Cadillac CTSV or Camaro ZL1. With the right modifications, 600whp would be pretty easy.

 

if i could make that much torque at 3500, id say thats useable, without od at 55 my truck cruises at about 3000 rpm.

did you use a turbo kit? or fab up all of your piping?

any experience with a turbo'd 6.0? or are the 5.3's just better canidates?

 

All of the iron block motors (4.8-6.0) are great turbo candidates. The difference is price. The 6.0 junkyard pulls command a bit of a premium over the others. Even the higher compression LQ9 6.0 motors respond great to boost, but I would only go that route if you already had the more expensive motor.

 

I'm a NA guy but for your application and goals
A 5.3 Turbo set up suggested by JoeNova is
By Far the least expensive, quickest and simplest
To implement.

 

well looks like im going to force feed the motor then, if i get that truck i will probably pick up a 5.3 as well, and use the 5.3 while i build the 6.0 block, theres a few 5.3's local to me ranging 200-1000$ per motor, quite a few in the 4-500$ range

run the 5.3/4l80 untill i have the larger motor with forged internals and maybe some better heads/intake, just swap motors and have retuned.

so do they make piping kits that are for ls engines? for the exhaust side of it ive seen a few but with out seeing them assembled im not sure where they set the turbo, or am i going to have to make it all myself? any benifits other than looking nicer for dedicated turbo manifolds, vs flipped truck manifolds?

turbo recommendations? i see joenova is running a s474, any companies recommended to look at for misc pieces? waste gates and bovs etc?

what about this kit?

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Most turbo kits are pieced together using various parts from multiple vendors, since Ls motors are being swapped into every kind of vehicle makes it difficult to have a universal kit.

Before buying anything and deciding on a turbo setup, I recommend going into the "forced induction" section and read up on some build threads with photos and see if your up for it.

Some people that have done a few turbo builds make it look very easy lol

Another thing to consider is tuning the vehicle, a turbo car will want an experienced tuner doing the work or else the vehicle won't make it passed the first WOT run.

Read up in the forced induction stickies and take it all in.

 

I have read a few so far, still going through them as a matter a fact, i have seen quite a few builds running singles, with i think it was a 76 mm with a .96 ar housing and one that was a twin setup with 2 66 mm with .68 ar.

The more i look for a kit, the more it looks like im going to buy a good set of turbo manifolds and go from there, or use truck manifolds and just go,


As for tuning, im not.going to try myself, but ill have to do mail tunes most likley, closest tuner is about 400 miles away

 

I would look into a 6.0 as an end goal since the extra displacement will help with part throttle torque.

Start with a junkyard 5.3. If you blow it up from being your first turbo setup, you're out a $400 throw-away. Everything will swap directly over to a 6.0. 99-04 engines are good to ~700 hp at the flywheel on pump gas reliably. Higher than that and you need to know what you're doing. 4.8s can handle a bit more. In 05, all LS engines switched to heavy duty floating pin rods that can handle much more power. I've had my boost gauge pegged at 30+ PSI on a number of occasions, and everything still looks great inside.

For manifolds, look at Trick or KB racing. They make passenger manifolds that the turbo mounts to. You use a stock truck drivers side and then pipe under the converter/clutch area of the trans and into the back of the turbo manifold. Very simple and effective setup.

80 lb Siemens Deka injector are the go-to for anything below 1000 hp. You can't beat them bang-for-the-buck.
Also, if you use a stock truck intake with return style rails, the regulator that is mounted on the rail is good for ~800 hp before it starts becoming a problem, so there is money saved.

 

exactly, i can use the 5.3 for routing all the piping etc, then swap the built 6.0/408 in later if/when the 5.3 gives out and have it re tuned.

ill look into those manifold guys, know anything about cx racing? they make some nice looking manifolds, as well as a set of manifolds for twins.

any drawbacks or benefits to doing a twin vs big? drawbacks other than cost? would 2 smaller ones spool faster than the one larger?

 

I've read that CX manifolds, while well built, have wire routing and plug access issues. I don't personally know how true this is. In theory two small turbos spool faster than 1 larger, but in practice this isn't remotely as big of an issue as getting your intake and exhaust plumbed in the best way possible with the space restrictions that whichever decision leaves you. Also, if mail order tuning is your current best option, you absolutely have to learn to tune for yourself. No mail order tune will even approach reliably doing what you want. Mail order is only good for well known "package" builds, and they are still not ideal. Once you go fully custom, toss that option out the window.

 

Noted on the cx manifolds, i see some companies make remote coil relocation kits, maybe an option if i use those manifolds?

As for room, i think i have enough room for ehatever i need, maybe relocate the battery if needed, have to ser when i get that far.

As far as tuning, yeah im probably going to educate myself a bit, next thursday im going to go get the donor truck, which is 275 miles away, but im getting what i think is a good price for what i need off it. Also going to go by a local shop there to run my Duramax ran on the dyno, i believe they do tuning on ls's as well, but not sure, they do mostly import stuff, audi, subi, etc. But we will see, if i have to ill trailor it down there and have them tune it for a couple days