Well I've been toying with the idea of going to a bigger engine. Why you ask....Let me explain.

To get the power i'm wanting, i'm have to run at least 20lbs of boost. Pump gas and that much boost probably are a time bomb. I'll admit. Its going fine on 18lbs and a little bit of meth as it is. But thats just it, its going fine...till it doesnt.
I dont like having to run that much boost, brings iats up too, i'm getting nervous about my intake manifold failing, head gaskets failing and i've popped the elbow off at the throttle body too. The engine temps start climbing if I make a couple rips back to back. We all know as you go up in boost, things get riskier.

So...my thought process is I could either
A) Build the ls6 block I have with a stroker crank and maybe better heads, bigger cam and get about 383 cu.in. out of it and be able to lower the boost and it'll make just as much power on less boost and be safer doing it or
B) sell the ls6 short block, add in money and get an ls3.....however, for the same money, I wont have forged pistons, rods and crank....So I'll have to spend even more money...unless I can find a bare block and buy a rotating assembly. That little 500hp destroked 5.3 I read about in another thread sounds tempting...I like rpms.


So I'm not about to start this right away, but I would like some opinions on it. Surely i can pick up a block sooner or later if I decide to go ls3. Remember, I could take the crank out my ls6 bottom end and buy rods and pistons as $$$ permits. Or I could pick up another stock crank cheap and just sell the whole 5.7 shortblock. AND I'd be ahead power wise if I can use ls3 heads. Just dreaming right now...but it may become a reality before too long.

 

I sold my good running stock short block and went with a forged LS3 short block no regrets.

 

How much power are you wanting to make? If it's 750 at the crank (and I set) and under you can do NA or forced injection. Neither are cheap if building everything with new parts. One allows more ease in power changes (boost) and the other offers advantages of no extra plumbing (NA).

No wrong way to do it just various ways and neither are cheap.

 

i was trying to understand your post....I'm already turboed. I just dont like the amount of boost I'm having to run as it is. How much does it make? I dunno, whatever a cam and ported head 5.3 will make on 18-20lbs of boost.

I was just talking to my buddy and he said if I'm hell bent on another motor i need to do the ls2 or ls3 block and leave the ls6 block along because its too thin and the bigger bores are a bigger advantage than the stroke. I already knew that but i guess hearing it from someone else makes it come more into perspective I guess. He says Really i should upgrade The turbo or exhaust housing and the exhaust because at that boost level its being choked up. And i know hes right on that also.

When I say this, you guys are probably gonna wanna give me a slap to the back of my head.....I'm running a single 3" exhaust all the way out the back with a borla muffler and a vibrant resonator with no cutout. I'm sure i'm choking it up right now.

 

Both of my rigs are 402’s with T6 turbos and they’re awesome. But I will say I hate even thinking about killing a crank, or a piston for that matter. With a rods/piston setup you can at least slam stock stuff back in it, assuming stock bore. if everything goes sideways on you. I’d go with your LS3 option. Actually I’d go LY6, but I get the whole weight thing as well....

 

370 ci Iron 6.0

done.

 

No iron block. I'll never go iron unless I'm desperate, need a motor and its free. Otherwise i will always stick with aluminum. I think the 6.0 aluminum block is harder to come by than the 6.2 aluminum block, isnt it?

I thought about finding a 6.2 block, pulling my crank and rods out my 5.3, put that and some forged pistons in a 6.2 block, milling some weight off the weight pads in the pistons to lower the weight and get it closer to the 5.3 piston weight. Reciprocating weight balance doesnt make as much difference than rotating weight difference anyways. then I could sell the aluminum 5.3 block and pistons. You literally could get a gen 4 crank and rods and put these pistons on it with no balancing. It was so close, I didnt even need to balance what I have.

 

LS3 gets my vote.

 

As an engineer with a strong thermodynamics background, I laugh when I hear people discuss the effort they go through to make the same power on less boost because "its safer".

Want to elaborate how you came to that conclusion?

 

I sure would.
1) less boost is less stress on the head gaskets. No?
2) less boost and couplers and joints won’t pop off as easy. I’ve had the boost on the throttle body pop off three times at 20psi. I’ve tried different clamps. Tightening the **** out of it. My throttle body doesn’t have much of a lip. I’m gonna have to machine a bigger lip.
3) less boost will be more friendly on pump 93. am I wrong?
4) if I make more power on the motor before boost, i won’t need as much boost to make the same power.

Or maybe I’m some kind of idiot living in a fairy tale? Because you know...engineer makes you know everything. Lmao. Not. I laugh when someone says they are an “engineer” and think that automatically gives them the credibility to act like they know everything. I deal with engineers on a daily basis that get put in their place by normal civilian non engineer dumbasses like me.

 

Im in this same boat. I have a good running LS1, been gathering parts now for a while. Torn between exactly what you're going through because I want to stick with aluminum. Looking at a good crank/rods etc for the LS1 total cost VS. picking up an aluminum 6/6.2 and then forging that. Then of course factor in any odds/ends stuff required for the conversion. In for results...

 

after you posting, it kinda made me want to create a new thread. I thought about creating a thread outlined what I’ve gone through, how ive progressed and learned. I’m still learning. I’m learning that I’m ending up doing things more than once, costing me more money, and with those lessons learned I could pass that on to others, potentially saving them time, headache and money. Of course I don’t know everything as I still rely on others from time to time asking their opinions and sometimes their input helps me progress past an issue, goal or problem.

if you want my opinion, I wish I would have gone ls3 from the onset. However, life got in the way, I scored a aluminum 5.3 for really cheap. Sat on it for a while. Then ended up getting a deal on parts from summit. Then I pulled my 5.7 out thinking the block was damaged and it wasn’t. So I wish I had at least built that.

so my advice is go with the ls3 if you have the money. If not, build the 5.7, but you’ll be down longer. I know it’s easy for me to say what to do because I’m not in your shoes, don’t know your situation or budget....


what do you guys think about a thread about what I’ve learned? I mean I’ve changed turbos, intercooler a, exhaust, injectors, wastegates, engines, Oil pumps, cams, transmissions, stalls etc. I kinda feel like I could save people time and money. Geez, after realizing all of that...I’m kinda depressed. Lol

 

I don’t know if you saw my build thread, it’s in my signature. I built a boost ready 5.3. It runs good, currently running 18lbs on it. This is a full street trim, pump 93 car, no weight taken out, and stock drivetrain except the built trans. The single 3” exhaust is holding it back greatly right now. The 5.3 has plenty of potential if you want to run race gas or e85 and alot of boost. I don’t think I’ll be able to go past 20 on pump gas, probably asking for trouble at that point. My buddy did go in the 8’s with a 5.3 in a 3500lb f body. So it’s got potential, with the right fuel.

 

Honestly I'm always going to recommend more cubic inches if the budget allows it. With that said in your case I'd just keep what you have, boost it to the moon even a high boost race gas tune for race day since you don't have E85, and have a bigger cubic inch build in mind if it lets go on you.

I don't know if it's a coincidence or other issues, but most of the cooling issues I've seen in the GTO community were with iron blocks. Also the GTO is already disadvantaged with suspension and front heavy compared to an fbody for example. I've had an iron block 408 in a GTO and it isn't really noticeable, but add an iron block and a turbo kit? It starts to get pretty front heavy and more power only does so much when you can't transfer weight to 60' worth a damn. I don't have any data or experience to back it up, but I wouldn't be surprised if pushing water doesn't start to happen with either an ls3 block or an iron 6.0 block at about the same power level before any other issues with the block itself arise.

 

1. No. It has absolutely nothing at all to do with it.
2. Popping couplers = poor execution. OEM 4 cylinders can go 150k miles at 20 PSI and not pop off a coupler.
3. Its not that simple at all. Pressure itself has almost zero effect on detonation. Gasoline won't automatically light at 200 degrees and 2 million PSI.
4. Again, WHY? Other than couplers popping off, you haven't give me a solid answer as to why its so much better. Why not just ditch the turbo competely and try to make the same power without it. Its obviously better, right?

 

Boost is just a measure of restriction. A larger bigger bore engine will make more power on less psi because there is less restriction. That equals less heat, lower cylinder temps, and better efficiency. Many builders will say to make the engine as efficient as possible on motor then add the least amount of boost required to hit your power goal. Obviously budget plays a big factor and why the 5.3 has been such a popular option over the years. It's cheap power, but now days you need to push 25+ psi from a 5.3 to make enough power to be relevant compared to what the some of the newer stuff runs. And those boost levels introduce some issues that you have found. A H/C LS3 will make over 900 on 14-15psi and live a long time doing it. Some don't like replacing engines faster then tires and others don't seem to mind. lol

 

1) nothing to do with it at all? So when the boost is being turned up and up, water starts being pushed into the cylinders or a head gasket failure occurs, the higher boost didn’t cause that? Have you been drinking? I don’t have a 5 bolt block. My block is aluminum, which I plan on staying with and I have bolts instead of studs. All of those factors fall into place that will limit the reliable boost level. Not sure how you could disagree with this, but whatever.

2) poor execution? Really? How would you like me to execute a simple 4” 90 degree silicon boot into a throttle body with a t bolt clamp? Not like I’m using a worm drive clamp on it. I’ve tried a $30 mishimoto clamp. It’s not rocket science. It doesn’t take an engineering degree to put a damn boot on a throttle body. I didn’t machine the throttle body. If I had, there would be a bigger lip like all of the other connections that I made. None of which have popped off. I can fix it, I just haven’t. I’ll chuck it up in my lathe and make a better lip and put grooves in the surface behind the lip.

3) that was a half ***, smart *** answer. I’m limited at the amount of boost I can run safely on pump 93. Is that not a fact? How many people run 20+ psi on pump gas only? So you disagree that it’s not safer to run 14-15psi with a bigger engine than it is to run 20-22 on this smaller engine. Please explain how it would not be better to lower the boost. I’m interested in that.

4) once again, take a 5.3 making 400hp. Add 15psi to it. IF everything was optimal, it SHOULD make 800ish hp. Take a ls3 that’s 500-550hp. If everything is optimal it should make 1000-1100hp. How is 200hp at the same boost not better?

and building an na setup? Where did that nonsense come from? I’d have to have a louder, way more radical combo and it wouldn’t be as fast as it is now. My setup is quiet, idles at 650rpm, gets decent fuel mileage and drives perfect. Why would I want to take two steps back? You make no sense. You just feel like arguing or something? I mean if that’s what you wanna do, it’s cool with me. I haven’t had a good argument in a while.

 

I agree. And I’m not going to iron no matter what.

 

LS3 for sure

 

this post is spot on. Thx.