Est Hp of 6.0 with 6.3 heads/intake?

[68shortwide]

What would you guys estimate a stock bottom end 6.0 with ls3 heads and a either a stock ls3 or aftermarket ls3 intake make? Thanks. Edit, with a moderate tune.

[BR3W CITY]

I'm assuming the 6.3 in the title was a typo (since you have LS3 everywhere else).
Anyway, if your going to use the LS3 heads thats the L92 stuff, which has pretty excellent flow. You'll have to use the L92 style manifold obviously, just keep in mind that things like throttle body fitment and a few other little things may also need to be changed or swapped out to make it all play nice (if your starting with a complete lq4 or something).

I'd say leave the ls3 manifold on the top and spend the money on a cam instead of the aftermarket manifold. If you put the matching ls3 heads-intake-cam I'd say you could see 385-400wheel hp with a nice tune (possibly being stingy depending on what supporting mods are done and how rad your tuner is). With the flow the heads have, if you do go with a bigger cam you can see 430-470. There is huge variation with that though, some guys have seen like 540 crank hp from a properly supported L92 style head package and a very well spec'd cam and tune.

[68shortwide]

Damnit. Yeah...typo. And it won't lemme edit again. Yes I meant l92 heads. Never thought about the cam. I guess that is a better way to go. Thanks brew.

[Alex41]

I was reading an article where Tony Mamo did an L92 head back-swap on an engine. Meaning, he took an L92 headed engine and swapped them with a set of ported 243 (ls6 style) heads and a matched cam and they picked up nearly 40 hp over the l92 headed cammed set up. The reason being is the flow and quench of the L92 heads are great.... for forced induction applications but for NA the LS6 head prevailed.

[BR3W CITY]

You need to mill any of the 4" bore heads down to get compression on them due to the size of the champer. 90% of the trucks run dished pistons which artificially decreases compression.

Tony was the old guy from AFR correct? I don't doubt his abilities or his findings, but I think that was more of an experiment that a full proof of concept. Mill the l92's to bump the compression and drop the chamber cc, same block, properly matched cam, the L92 will make more under the curve, and pull higher RPM. If you took the 317's off and swapped out to the 243/799 heads, youd gain power on compression alone.

Our guys at Trick Flow have run pretty much every setup at one point or the other, and from looking at most of the new LT designs, they aren't reverting things anytime soon in terms of design.

[68shortwide]

So what's a better option, complete take out lq4 6.0 or a complete 6.0 stock lower end with different heads and intake. This is kind of a budget build but at the same time ill pay for good reliable hp. I can't a afford a blower or it'd be a twin of Hart-Rods motor. so basically what's the best option while keeping it reasonable. I'd like to avoid machine work if possible. Thanks.

[BR3W CITY]

A few ways to achieve the same thing.

I.e. any of them will make good power, but it depends how far you want to go. You can make mid 400's in hp with a stock-head lq4 as long as you have supporting mods. You can mill the stock 317's for a little bump in compression without killing PTV, and with a good cam make a reasonable amount of power.

If you chose to do l92 stuff, that also means that you'll have to use the same ECM and DBW stuff on that manifold. You can't use the GenIII stuff unless you wanted to run a cableX which is expensive. I'm not sure about cable options for those manifolds, as gm stopped doing DBC largely at that point (someone else might know, I'm sure there is an aftermarket TB which will work).

Keep in mind that while block machine work is a little more complicated, something like getting heads milled down is VERY easy. A good performance machine shop/engine shop can easily throw your heads onto the mill and take off the desired amount of material. How much material? That depends on how much compression you want to squeeze out safely.

As an example, my new heads are 317's which have been largely ported and cleaned up, with a few thou taken off the face. This bumps the stock-block Lq4 from about 9.4:1 to around 9.65 (I can verify the amount it was trimmed and the exact compression in a bit if its important to you.) That bump in compression, alone is worth a few, and then it takes even better advantage of the additional flow the port work provides...meaning more power.

Engines are like alchemy. Its all hard science....right up until its not anymore

If you can go into more specific detail about your goals, I can probably recommend a more specific combo.

[68shortwide]

350-400 to the wheels with 4l80 trans, 3.73 gears. If i find a motor for 1400-2000, id like to try and keep it under another 1-2k in mods if i can. It'll be a Daily Driver so its gotta be reliable. Internal motor components and terms are where my knowledge is stretched. i understand the higher the compression, the higher the octane fuel you have to run but when it comes to drivabilty and dependability, whats the max compression i can go to? What determines compression, besides obvious things like bore, stroke and piston style, if anything? Sorry if being a pain. Lol I figure you know exactly what you're talkin about so i may as well ask questions.

[BR3W CITY]

Your goals are simple on these, no voodoo for that.
Honestly, you can do it with a 5.3 too, it'll just be a little easier with the extra cubes. A 6.0 with a cam kit, set of longtubes, and a pro tune should have no problem getting those ponies. If you spend the $ for a good convertor,you'll be able to feel all of them.

A cam (shelf grind of custom doesn't matter) with some hardened pushrods and good springs is $350-450. Grab a good timing kit, and an oil pump if its got higher miles, again usually under $200.

The 3 most expensive things are also the most important IMO; good headers can be up to ~$650 but your leaving 15+hp there at least. You can get by with cast manifolds, but the headers really do make a difference.

The tune can be expensive (a dyno tune w/ road tune), but it alone nets a good chunk of power, and is crucial to having a good driving truck. Its also a valuable relationship to have with your tuner for when your power goals grow and change, in many cases requiring more..and more complicated, tuning. ~$350-500

Lastly, the convertor. While it doesn't make power (and sometimes appears to steal a few ponies on the dyno), its also what changes a civilian truck into a performance vehicle. It will take the increased power level and better and holding under WOT shifts and downshifts. The stall you choose will also be important into pairing the gearing and cam so that your spending time with the engine in the sweet spot and not wasting effort. Its also the thing that lets you launch the truck. Don't cringe, they range ~$550-1200

[68shortwide]

Damn...thats perfect. So do I even need the L92 heads? If they're not needed would you still go that route since its gonna be a complete ground up build and the engines gonna be on a stand and accessible anyway? Got a few pages into your build thread, damn cool truck.

[BR3W CITY]

No you don't have any particular need for them. They aren't cheap per se, and tho they flow the best, that doesn't mean instant horsepower if you're not doing anything with that flow. If anything I'd just mill your heads a tiny bit if you only plan on running 93 and have a good tuner.
If you really want to spend some extra $$ for bulletproofing, you can get a new set of o.e lifters (ALL new GM v8 lifters are LS7 style, even into the new LT's, and they are a great replacement/upgrade for the lq4) and put them in while the heads are off...and you could upgrade the trunion bearings in the rockers if you wanted to.

[68shortwide]

Ok. Awesome. As for a tuner, there's a guy out here near Troy Mo that my dad sends his people to. I'll give him a call and see if he knows of any good complete 6.0s and what he'd charge for tuning. Thanks for the help man, I really appreciate it.

Edit: last question I swear! What are some intakes that fit the truck heads cause, as no offense to anyone running the truck intake, imo they're hideous and tall and annoying to fab a decent cover.

[BR3W CITY]

No such this as a "last question" on this forum, but thats ok...I mean I keep coming back so I'm doing it to myself lol.

Either just go with a car head (ls2/ls6) or get an aftermarket manifold. I run the 3 piece Vortex Max cover on my lq4, but I actually like the way it looks.

Car heads aren't 100% plug and play tho, as the fuel rail setups are different (either change to a car style system or swap truck rail on to car intake) and the throttle body opens up right into where the water pump outlet is. That needs to be modified to clear, or you need the car accessories.

[tony2tall]

Originally Posted by BR3W CITY

A few ways to achieve the same thing.

I.e. any of them will make good power, but it depends how far you want to go. You can make mid 400's in hp with a stock-head lq4 as long as you have supporting mods. You can mill the stock 317's for a little bump in compression without killing PTV, and with a good cam make a reasonable amount of power.

If you chose to do l92 stuff, that also means that you'll have to use the same ECM and DBW stuff on that manifold. You can't use the GenIII stuff unless you wanted to run a cableX which is expensive. I'm not sure about cable options for those manifolds, as gm stopped doing DBC largely at that point (someone else might know, I'm sure there is an aftermarket TB which will work).


.

So are you saying that in order to put l92 heads on a Gen III lq4/lq9, you would need an ECU and DW stuff from a Gen IV? Iv'e been researching this type of swap for a couple weeks now. Haven't seen anything to confirm or deny what you are saying. This is kind of the grey area I haven't seen a lot on.

[BR3W CITY]

The L92 heads need a different style intake with the same style ports. The L92-era DBW units don't use a TAC module, and are driven off of the ECM directly (the TAC does exist but its on the ECM board). IIRC, they also open in opposite directions.

You can use something called a Xlink, to convert the DBW signal from the L92 TB to the TAC drivers from the GenIII. If you use that, then you can keep the Gen III ecm stuff.

OR if you can find an aftermarket throttle body that is DBC, you can use the GenIII ecm set to use cable throttle and eliminate the DBW. AFAIK, there isn't an aftermarket DBW throttle body that fits the l92 manifold, but uses the GenIII dbw protocol.

OR go to a single plain and 4150, and you can run the l92 heads with that, or a carb the same way.


.....I know 3 short Tony's from my city, no Tall ones.

[68shortwide]

Its not that I don't like the Vortec max cover, I just prefer a cleaner more simple ls1 type look. Also, it'd cover up my new shiny black proform valve covers

[tony2tall]

Thanks Br3wcity. The l92 heads swap is a ways off for me, but this has got me thinking that this spring when I get my LQ4, maybe I should be looking for one from the Express van with DBC instead to make life easier once I am ready for the l92 heads

[BR3W CITY]

Not all vans had DBC just be aware. My lq4 was a late 2003 with DBW, which is a bit odd.

[68shortwide]

Ok....i think I'm gonna stick with truck intake and use this this cover is pretty badass....id almost feel bad painting it lol

EDIT: I can't make links work on my phone so here's the site via copy paste lol ill fix it tomorrow.

http://www.ebay.com/itm/99-06-GM-TRU...p2047675.l2557

[BR3W CITY]

I think someone here has that one, it looks really cool on the right truck (but it does seem large).

[68shortwide]

It does indeed. tomorrow I was gonna post a picture and ask if anyone had used it. Someone on Ls1tech.com pointed me towards it. The car one is better proportioned but the truck one is equally nice and cool. Also cheaper than an aftermarket intake.

[Super73]

Originally Posted by 68shortwide

i understand the higher the compression, the higher the octane fuel you have to run

You need to really look at more than just Static compression.

Dynamic compression is more important. 8.5ish is about the most I like to see with 91 octane. This is dependent on static compression + Intake valve closing point (.006 in a hyd cam application).

Keep in mind that Cyl fill and volumetric efficiency as RPM goes up change things too.

Originally Posted by BR3W CITY

Car heads aren't 100% plug and play tho,

If it is a stock 6.0 with cathedral heads, LS6 heads are a direct replacement and can use the truck manifold. These will gain flow and provide more compression.

Originally Posted by tony2tall

DBC instead to make life easier

IMO DBC makes a lot of things easier.



What ever heads you go with, I would consider a custom cam to maximize dynamic compression. It will help in low end TQ production which is a big thing in a heavy truck.

[BR3W CITY]

Originally Posted by Super73

If it is a stock 6.0 with cathedral heads, LS6 heads are a direct replacement and can use the truck manifold. These will gain flow and provide more compression.

I thought the question was about putting L92 style heads on a 6.0, which I assumed to be a GenIII. AFAIK, you can't put cathedral intake mani with a square port head. The LS6 uses the same port style as the 317 etc

[Super73]

Originally Posted by BR3W CITY

Either just go with a car head (ls2/ls6)

Car heads aren't 100% plug and play tho, as the fuel rail setups are different (either change to a car style system or swap truck rail on to car intake) and the throttle body opens up right into where the water pump outlet is. That needs to be modified to clear, or you need the car accessories.

I guess this is the comment that got me confused on your advice.

If a LS2/6 head is used, a truck intake can bolt right up to it. Then all the other truck things like accessories, fuel rails, injectors etc can be used.

Best bang for the buck head wise IMO for a LQ4/9 would be an LS2/6 head since you don't have to change a ton of things. No they don't flow the same as an L92, but they make great power.


Now if an LS6 intake is desired, yes, lots more to change.


I know you know this, but I guess to me the way you put it out there might be confusing.

Hope that make sense.

[BR3W CITY]

I get what you were saying, my bad. I had put that in there if he didn't want to go L92, as the LS2/6 is a great flowing intake just to get power on a stock GENIII head combo.

We're all on the same page right