So, I came here over a year ago asking some questions, got some great answers. After learning my uncle was a gear head, we slapped an LSA blower, ported 317 heads on it, and a cam. We turned up the boost, he tuned it, and away I went into the wild blue yonder.

Apparently daily driving an lq4 with 12-14 lbs of boost, pulling trailers quite often and having a maniac behind the throttle will destroy it and its 4l80e in just over 60,000 miles. Who woulda thunk it?

So I'm rebuilding my engine/trans. I'm kinda unsure what to do at this point. I'm trading my lq4 with cracked pistons and tons of knock to my uncle for one of his lq4 short blocks with a factory crank, forged rods, and forged pistons that are the same dish as the factory.

I was heavily considering just keeping it N/A putting some 243/799 heads on it, maybe a 216/224 ish cam, and just keeping it mellow.

But at the same time I don't really want to take a step back in power, and with forged bits in the block, I probably won't break it... maybe? I'm not gentle to the thing, but we've got meth injecton on it now...

Meanwhile my uncle is in the background going, "Do the same thing, only lets add NITROUS to it this time!" He isn't a source of many of my responsible decisions.

I just don't know. Looking for ideas. I've got a daily work truck now, so it won't see as many brutal miles. But its not going to see what one would call an "Easy" life.

For the record, the truck in question is a 2001 2500HD (ECLB) with 3" of lift, 4.56 gears and 35" tires.

 

Ok. Take a 6.0 block, add 4" stroke crank for a 402-408 displacement. Use LS3 heads and aim compression for right around 9.5 to 10.0 to 1. Run a mild cam like 218/230-112. Use a 4L80 transmission. Stall speed around 2200. Use LS3 intake manifold, 1-7/8 long tube headers.

That'll be beefy and torquey.

 

Got a 6.0 block. Its already a 6.0. From what I've been told the 4" stroke does not have the life span of a 6.0. I would like to get a bit more life out of this engine than I did the last one.

I was running 9.5 to 1 compression pushing boost through the engine, I'm gonna go higher if I'm gonna go N/A.

Already have a slightly broken 4l80e in the truck. I'll get it rebuilt when I decide my course of action on the engine. No need to build it to hold 700 hp if I'm only gonna have 400. I'll stay with my 4l80e.

And why would I run a 2200 stall when it comes with a 2600 stall from the factory?

And before you suggest that I want to beef up my rear end, I've already got a 14 bolt back there that was rebuilt about 30,000 miles ago. Because it came from the factory with a 10.5 inch 14 bolt.

I don't want to be a dick, cause this is a forum full of lots of knowledge, and I don't come here often enough to be a dick... But did you read my post? There is alot more to my build than me putting a new engine in my 4.8l 1500 silverado that pulls a lawn mower trailer on the weekends. I've got what I consider a fair bit of technical knowledge, but I'm just looking for general advice as to whether go big, or not. Maybe something I haven't thought of.

 

I don't think you need to worry too much about reliability from a 4" stroke. The LS7 was factory 4" stroke. There's enough 408's out there to back that up. The stroke should help make up for the grunt you'll lose from going back to NA.

I tend to see high compression and towing and hauling not always go so well together. For a truck that's. Gonna be working, I'd honestly keep compression closer to 10 vs the 11.5's you see on cammed street car motors.

Rear axle, I figured you had a lifted truck with high gears, tall tires, behind a boosted motor and it survived. And you're not racing a 2500HD anyway. So I wasn't worried about that part.

I figure a 80E will be fine behind a NA 408. Stall speed - my bad

So yeah, I read the post. Best of luck with your build.

 

2 trans shops and several forums I've checked. I wanted to go higher stall on it, wanted about a 2600 or 2800. 3000 or 3200 was going to be too high with how I pulled, even with my bigger trans cooler I've already got. Then I found out that I already had a 2600, and decided to regear instead of new torque converter.

Am I wrong? Does the 2500 HD have a lower stall? I know its a higher stall than one in a '05 1500 with a 5.3 and a 4l60.

 

No, I though it was lower, but from Darth's comment above I realized I was wrong. 2600 might be right.

 

Now I feel like a dick... I apologize for my dickishness.

The LS7 had accommodation for the 4" stroke as I understand? But from the research I've done it seems for every 4" stroke success story, there is one horror story. All that is beside the point though. The short block is already built. I mean, if I really wanted a 408, I could tear it apart and put a new crank in it. I'm not against the idea, just trying to wrap my mind around something that I was conditioned to not do.

So I'll take this as a vote to go relatively mild?

 

Please don't feel bad. I didn't read anything into it at all. Here's more where I'm coming from. A 6.0 came with the 2500 and did fine, so it's not like it NEEDS to be bigger. I do think whatever you decide you'll need to keep it mild, because you'll spend a lot of time at high load and low RPM which is a recipe for pinging if you're not careful. So if you're wanting a "little" better than stock, a good towing cam and good flowing heads will help. If you're wanting a lot better you might be in bigger engine territory. Only you can decide that. And like you said, youve already got the 6.0 in your possession ready to go and a running truck is far better than a not running truck.

Having said that, a mild 408 will tow way better than a mild 6.0. Especially going uphill.

If you were talking a 4th gen camaro, it'd be 11.5:1 compression, 23x cam, high stall, etc. just a whole different animal with a work truck.

But yeah, short answer, I vote go mild especially if longevity is a concern.

 

To be honest... I don't even know what I want. I've really got 2 voices speaking to me about this. My uncle who says, "Bigger, faster, better" and my dad who thinks I need to put a 100% factory engine back in it. I was hoping to get some input somewhere in the middle. The truck can sit for a little while. Just need it back by summer, so I've got a month or two.

I'm sitting here holding my blower head unit in my lap, drinking beer, trying to decide what to do. I should probably go put the blower back down. Its not helping the whole being responsible thing.

I almost wonder if I could get this engine dialed up to where it was with the stouter low end if it would hold out for 150-200k miles. I mean, it had quite a few miles on it pre-blower and had a month or so with no meth injection and hot Texas summers. I really think that's what did the most damage. Don't get me wrong, I know it was a ticking time bomb, but I tend to think if I would have got the meth sooner and it might of lived longer.

If it got over 103 or 104 outside, it would start pinging. I would have to shut down when it got that hot. Then I swapped from the CTS-V lid to the ZL1 lid, and that helped some. Then I put the meth on it and it went away 100%. If I go back this way, I need to get some gauges so I can actually keep track of IATs and actually how much boost I'm making, ect. I really did it by the seat of my pants.

It would be easier to decide what to do if I could drive a truck that has higher CR and maybe a 408 in it... but I can't. So I'm kinda stabbing in the dark. I really should of done this slow to begin with. But I'm just not that type of person in general.

Edit: I know I don't NEED more than a factory 6.0. But I've become the guy with the diesel eater... so I can't back all the way off.

 

Back the SC down with 6-7 lbs Get your heads off to Texas Speed and get a good cam from them, good headers and exhaust and you got 500+ to the ground. Long life and better mileage. It will Merge well!!

 

Its a thought. The only part is that my heads are already sold. I'm down to a short block that I'm not entirely sure will stay a 6.0.

You think 6-7 lbs will get me to 500+ to the ground? My old rig was never dyno'd but I was told I was probably making 530-550 with hand ported heads, a mild cam and an approximated 12-14 lbs of boost (it was making 15 lbs on my cousin's 6.0 lq9 with similar heads and cam). Was I making more?

My exhaust is fine. Can flow way more power than I'll ever try to make with this truck.

 

My LS3 with long tube headers Corsa exhaust and a Edlebrock Supercharger put 540 to the ground with Mike Norris tuning it on the dyno. FWIW 5-7 lbs of boost only.

 

That's a really good idea. With stock compression, that amount of boost is nothing. I'm sure the bottom end built on this one is tougher. Given where you are right now, that might be the cheapest way to get running and meet your goals.

 

Alright, Thanks guys. I think I've got a path that I'm confident in. Just sent off the transmission. Perusing heads right now. Once I find a deal on some, I'll send em off to get CNC ported.