6carmello8

Hi Guys,

I'm about to upgrade my Lq9 with new heads and cam

It looks like l92's and a "smaller" cam is a great combo for the street, however I've never seen a Lq9 or LS2 running a ported set...

The ported l92's are mostly seen on 408's and 418's.

Is this because you won't see any gain with porting them or with 2.20 valves on a 6.0L?

Thanks in advance.

briancb1

Of course you can can run ported LS3's on a 6.0.

Just make sure if you mill them, you have the port roof clearanced so it doesn't block the top of the intake port alignment.

Beyond that, having experience with a LS3 6.0, run some TFS heads and be done with it. It's worth the extra cash.

Rise of the Phoenix

iTrader: (27)

They would be a great upgrade with a matching cam. Plenty of guys running the LS3 heads.

low2001gmc

iTrader: (148)

I run an Lq9 with porting on exhaust only Ls3 heads. Ls3 intake is already overkill but exhaust can benefit from porting. My Ls3 heads are milled .015 and in conjunction with Cometic .040 gaskets for 11:1cr. I also run a lunati 232 238 cam and love it.

6carmello8

Good to know and thanks, I'll have to see what static compression I want to go with first...

When you say the Ls3 intake is already overkill do you mean the overall L92/l76 intake flow is overkill?

I thought for sure if anything, the exhaust flowed too much especially at low RPM's. That's why people run smaller cams with the l92/l76 combos with amazing results power through out the band.

Always2Slow

iTrader: (8)

It's very much worth porting a set of l92 on a stock 6.0 even on the intake side. L92 heads pick up nicely from bowl work and a valve job with some modifications to the SSR. I would recommend doing that with having the exhaust side fully worked. Then have the intake l92 manifold ported for a nice gain across the board. Just make sure you run a healthy cam with plenty of lift to access the flow.

low2001gmc

iTrader: (148)

The Ls3/L92 intake port is already at 260ccs stock. For a 6.0, overkill. On a 408 maybe not. People like to get greedy with porting and flow numbers, and porters make more money porting both intake and exhaust. Advanced Induction has a basic porting in which they only do exhausts for a reason. Spinmonster only ports exhausts on his ls2/ls3 builds. When i researched, i went with actual proven combos and sources. Im on a budget and gotta get most for bang, get it right. No money for trial and error. Since no funds to send to Advanced Induction, i spend 14 hours on mine porting the exhausts. Good luck with your project.

redtan

iTrader: (5)

I don't think you can fit that valve size even on a 4.030 bore.

6carmello8

That's a good point and that's the very reason why I'm asking here on the boards before talking to shops because like you said, they'll always recommend doing both side to make more money. What's frustrating is that I can't get data or 6.0 with L92 (ported non ported) not to mention cam specs here. Back when L92's came out, people swore by cathedral ports because of they performed better (port velocity yada yada) but they had the came specs all wrong. Big head big cam right? Wrong! "Smaller" cams with closer LSA's worked much better not to mention the power curve. Maybe I really have to dig into the search and find out. Now whats confusing is what you said and what the guy above said...two different things. You say just exhaust and he says there's benefit from porting the intake side too. Maybe you're not against it but jut going with whats been proven?...which is smart but I wonder if porting the intake side is beneficial.


Huuum interesting. I'll have to look into this. I'm wondering why it wouldn't or better yet if it's even necessary. I know you have to run 4.125 gasket to run the l92's on the 4" bores. The guy above said that l92/l76 combo on the intake side is overkill so at that point larger valves would be unnecessary on a 6.0. I just read about it on West Coast Cylinder Heads site and maybe these are for the ls7's which would make sense.

low2001gmc

iTrader: (148)

There is plenty of data on 6.0 with l92 or ls3 heads, even on proven cams. The biggest factors in my opinion are:

Which 6.0 you plan to use? lq4, ly6, l92, l76, lq9, ls2. They have different compression ratios.

Do you plan to mill heads? This is
critical to compression, ptv on cam selection, etc.

What are your goals? Daily driver, weekend, strip only? Driveability manners? Budget?

From builds and dynos i researched and evaluated a fully ported head didnt necessarily make more power. Thats why i didnt port intake. If it had, i wouldve since i can port my own. Intake ports are already overkill for 6.0, referred to lazy ports due to being too big at 260ccs and some people try to compensate with smaller cams to improve bottom end. Consider cathedral port heads range in 205-255ccs, 245 and 255s considered max effort all out race heads and we are starting with 260ccs. I recommend ls3 heads with lighter valves and Advanced Inductions exhaust only porting.

If you can provide more info, answers, to questions, ill gladly help you with answers. I share what ive learned in an effort to keep folks from misspending money and being disappointed. But it is your money to spend as you choose.

yonerhottlt1

iTrader: (21)

I'd have to agree with low2001gmc on this one. The intake ports and valves are already overkill for the bore on a 6.0 motor. If anything I would just go with stock sized lightweight LS3 valves and do the exhaust side. Your cam selection and compression ratio will be far more important when it comes to making power.

6carmello8

Basically my car will be a weekend and sometimes a weekday car and will only be driven on the street on street tires (325/30/19) with a t56. I don't wan't too much torque because I have the luxury of gearing with the 6 speed. That being said, I want the engine to have not too much low to mid but more mid to high end power. I'll just roast the tires. Obviously my power band would look very differently if I were running slicks or it was a strip only car. I can run 4.11's with a t56 so I think I would benefit with less (still already tons with a healthy 6.0) torque and more high end.

What do you think?

Cam will definitely be the most important and thanks for the opinion. Look slike most agree on the exhaust side only.

low2001gmc

iTrader: (148)

I designed my lq9 with milled and exhaust only ported ls3 heads 11:1cr build with mid to top end power as the goal. Why? Cause my truck is light in the rear and i run street tires. So i figured i trade off some low end for a more useful mid to top end where i wouldnt stay roasting my tires plus fly on the freeway. With the Lunati 232 238 cam, 4l80 with 3800 stall and 4.10 gears, no doubt i accomplished my goal. It pulls and keeps on pulling. 😀

6carmello8

Your set up is exactly what I'm looking for. People talk about power under the curve being really important and it is depending on your type of driving but I'm looking for more mid to high power...nice to see another on here that traded some low/mid for high end. Like I said, I have the luxury of a six speed to make up for the "lack" of low/mid with gearing.

My type of driving has always been when the car is moving, canyon runs, freeways... LA roads are long and lots of Freeways. I basically want to be able to drive the car like my Turbo M3.

BTW do you have a dyno on your engine? What kind of power are you making? I'm sure you're happy with you cam but if you had the opportunity, would you run something slightly different? 11.1:1 with 92 or 91? Cali only has 91. Are you happy with 4.11's? I can't decide to go with 3.89 or 4.11 with the t56. I'm leaning towards the 3.89.

My future plan is for a 408 so I'm leaning on the L92's over the other heads you recommended.

Much appreciated

low2001gmc

iTrader: (148)

No dyno numbers as they can vary with type of dyno, can be altered, weather can be effect, too many factors, etc. Would i change cam to some (slightly) different, i have to say no because i love my cam and slightly would only make slight difference positively or negatively so not worth money and labor. Im in Texas and with my 11:1cr, i run 93. Ive run 91 and no issue though, just feel safer running 93 and wanting to maximize power output. On 91, i would say i would consider maybe just running Cometics .040 gaskets without milling for 10.6:1cr. I still recommend Ls3 heads with the lighter valves over L92 heads. Lighter valves with help valvetrain stability. And i still recommend Advanced Inductions porting for 408 stroker.

6carmello8

Not sure how good the the ECU is detecting knock but I can only get 91 so most likely run the .040 without milling for sure. 10.6:1 is still high. How's the drivability with that cam? Throttle response with that cam and compression ratio? 10.6:1 is still pretty high so should be crisp.

Without a doubt, I will get the hollow stems and won't skimp out on springs retainers, etc. These castings are very affordable so I can put it towards good components.

Are you running 1.8 rockers? And what is your redline set at?

You always recommended that Advanced Induction porting even for the 6.0L, did you mean do the intake when going with the 408 and not just the exhaust?

lil john

BTW if you do have the heads ported get the bowls & combustion chambers done if you would like 2 keep stock intake runners. Let it breathe.

low2001gmc

iTrader: (148)

With 10.6cr and better drivability, i will suggest the Spinmonster Comp Cam 230 234, 612 598, 114+4. A lil less cr, so a lil less duration but will offset with a lil more lift on intake.

I run Harland Sharp trunion upgraded Oem 1.7 rockers. Oem are lighter and upgrade helps upper rpm stability.

As for porting intake ports for 408 stroker, since i havent dealt with or researched, i will suggest consulting with Phil at Advanced Inductions.

lil john

Getting the bowls and the runner will only help the TQ.. opening the runner more for a stock size engine will hurt down low TQ for a combo as this.. The bowl & chamber job will promote better air flow and fuel burning which in turn adds 2 more HP. with out touching the runner.
AI has a program just for this I think.. bowls/chambers. I was looking and emailed them about there 267cc program sometime back. They do darn good work.

6carmello8

It won't be a daily driver so the drivability doesn't have to be super smooth... I wouldn't mind compromising a little (not too much) drivability for more power.

Yeah the OEM 1.7 are the lightest and strongest and will def run the Trunion or Comp upgraded bearing kit.

I want better mid to high and if I can spin 6500, I'd be happy. I'll most likely swap out the rod bolts too.

Man I wish I could run the L92 intake but won't fit under my 68 Camaro so I'll be going with the BER ported L76.