Unique application, L92/LS3 build with truck intake, ported throttle body, and stock exhaust manifolds, no cats or resonator, twin 2.5” into single 3”. Will be wanting more cam than my LS3 cam after break in. Vehicle is 2009 Colorado V8 4x4, 4100lbs. Trans will be 6L80 with 2k rpm ZL1 converter, stock gear ratio is 4.10. Vehicle is daily driver, fuel is nearly free. Caveat is there is really only room for stock iron exhaust manifolds. There is one single small company that offers long tubes for the 4x4, but they are $1,000. Will be able to do 4x4 launches if the t-case survives. I have CNC’d a custom adapter to mate the 6L80 to the Colorado transfer case, but also looking at others if need be.

Looking for any suggestions, dyno charts, or 1/4 mile times for 6.2L engines with cam swaps and stock exhaust manifolds. Wanting noticeable idle lope yet good manifold vacuum for tuning to reduce decel stall risk. Also wanting to keep idle exhaust reasonably clean. Power priority is more toward upper RPM end vs low/mid range torque, pulling hard up to a 6,500rpm shift point then repeating.

Offerings from Lingenfelter, Livernois, BTR, LS7/9, others? I have read the infamous yet now older LS3 cam shootout article as a foundation.

Thank all.

 

I'll take a stab at it, but there are few things to hit. Now I know you've been on here a while, so no need to go into too much bullshit. But the one thing to worry about is wanting both good vacuum and a noticeable idle. The thing that makes the idle noticeable is the same thing that makes intake vacuum go up. It's unavoidable. So you really cannot go too crazy on the chop and maintain good manifold vacuum. Also, your limitation of stock manifolds prevents you from running a nice choppy cam and still having it perform well due to back pressure increasing the likelihood of reversion.

What I propose is this:

With a 6500 shift point, IVC at 42 degrees, overlap at -3 to give it some bark, but not kill your vacuum or make your exhaust stink too bad, and some lift to take advantage of your heads...

222/232-115+4, .625/.618 lift. Based off of cam motion's little chopper, but a wider LSA and less advance to gain vacuum and bias it more for higher RPM. Now, to really wake it up, mill your heads to 67cc and run a 0.041" head gasket. That will get your dynamic compression up to 8.7 and greatly improve throttle response. You'd need to run PSI1511 if you prefer beehive or BTR dual plat or equivalent dual springs with that cam, but you'd be able to set those straight up to work with the cam, no issue. I'd have no dynos, 1/4 mile, etc, as that is a very unusual spec for a somewhat unusual build

As to choppy idle, in your tune, make your adaptive spark very aggressive, which will give it the characteristics of the random misfires of idle chop without hurting the stability of your idle. Your idle spark will just look like a saw blade on a trend line. I truly think that is your best play for a noticeable idle given some of the limitations you are stuck with (stock manifolds, etc)

 

Noted. Thank you very much to consider my unique case regarding the stock exhaust manifolds and taking the time to write. I know I did ask for everything, and therefore none can be optimized, more of just a best fits-all. I didn't consider the head mill and gasket thickness, will strongly consider that and try the cam you suggested. It still has the L9H VVT pistons in it, which have valve reliefs in them, so the compression is even a pinch lower. I do have the option to run premium fuel exclusively even as a daily driver, so will really study the compression situation as well. Thanks again, ears still on for anybody else that has ran cam+stock exhaust manifolds.

I have been on here a long time, but have not contributed much, as I did so to learn as much LS foundation as possible while doing this first build by reading nearly thousands of posts and threads. Forums are an amazing collection of real experience. The upper hp area under the dyno curve people, high mileage reliable runners, and mishap builds of infant mortality are the ones I have been specifically targeting. Going to assemble my first LS3, and seeing the main caps are stamped opposite of others when correctly assembled, told me to simply start over on knowledge and just be a good listener as compared to most everything I have known of other engines.

Thanks again to all here.

 

Lingenfelter GT11 will run awesome w/ that package, but will have zero lope. It idles like stock, but great power w/ stock manifolds.

 

I was initially looking at the Lingenfelter GT11, due to the cam shootout test showing high manifold vacuum at idle, but then a lot of people were barking about their valvetrain sounding like a sewing machine using it. This was a while ago, so I was hoping some more modern grinds since them have come out to resolve this.

 

That lingenfelter cam is ****.
I had it.
It made my low and mid range very lazy compared to the stock camshaft.
A wide split and wide LSA combined is good for boost.
Not for NA.

 

https://www.summitracing.com/parts/sum-8719/

 

I disagree, I have the GT11 in my daily TBSS right now. Tons of torque and power for what it is, and I even still have the stock converter. Your combo must have really been off for the application, that happens, there is no absolute in any of this.

​​​​​Yes, mine is sure noisy at idle, but I am also running LS7 lifters w/ light preload(should have run more).

Note: There is another version of this cam on Ebay called a "Comp Cheater" . Same specs, but a little less lift, probably on different lobes. It's a trade out w/ making power w/ stock manifolds. In general, you want no overlap or very little to make max power on manifolds, but to get the chop, you need overlap. Also, w/ the 823 exhaust ports, I would want at least 12-16 degree split or more on the exhaust, it'll want it for sure. The more exhaust dur you add, the more power up top you will make, but it'll lose torque in the midrange near peak.

 

I also disagree.
My combination was well sorted when I fitted the camshaft.
The wide split might make it hang on a touch better up top but the difference is small.
But it comes at a cost of a reduction of low and mid range torque.
Off idle to about 3500rpm the engine is lazier.
if you had more intake duration like a 224/230 with a lower LSA you would have far stronger low and mid range power and your top end will also be stronger too.
adding a ton of exhaust duration does not make more power.
​​​​​​it is all to do when the exhaust opens.
i used to believe like you do.
You should read iskenderian's camshaft information sheet.
There is a great article explaining about single and dual pattern camshafts and what the effects are.

 

Don’t need any fights, just opinions, and all considered. Especially for any that used stock exhaust manifolds. I’ll look into each one objectively, but they each give me a good starting point vs nothing. Thanks.

 

i don't disagree your suggested cam specs are better, but I had read enough reviews and gave it a shot. Pretty happy with it overall, but I would have wanted a narrower LSA, probably 114 or so. I have read Isky sheets and study cam timing constantly, as you do.

I can tell you absolutely though, that with my local well ported 243's, stock compression on a forged short block, .005 over, stock intake/manifolds/tb/etc, it runs way better than it should. I can break 295/45/20's on heavy 20x10 wheels tires loose pretty hard from a roll at part throttle. Stock def didn't even close to that. Like I said, they are all different. What heads did you run yours with?

 

I had 243 heads also back then.
Ported also and I was running the stock LS2 intake.
The GT11 camshaft made an extra 35rwhp more which was good, however the max torque was not much different from stock.
On the dyno the curve was almost exactly the same at where engine peaked and the peak torque.
Immediately when I drove it I noticed throttle response was lazier and felt kind of soft throughout the whole rpm range.
Only after 6000rpm it felt a little better than before.
It just didn't drive as good with this camshaft just killing under the curve power.
However I never changed to a better camshaft after this because I went straight to the LS3 heads.
I am very certain if you changed camshaft, kept the same amount of life narrowed the split to half and had similar valve events you will be surprised how much better the vehicle will drive.

 

Without headers and a good stall all those cams are too big imo. You'll be pushing through the converter at every light and it will be lazy down low plus the manifolds will choke it out right where those bigger grinds come into their zone.

RPM range/converter/gear/supporting mods ( headers/exh/intake) learn it, live it, match em ALL well or pay the price of lazy. Miss one component? Crap build.

With cams? A small cam can outperform itself easy with a good tune up. Even sightly too large of a cam for your supporting components? It will be a sluggish unfun relative junker.

 

Interesting, probably the difference is the LS2 intake vs my TBSS. Who knows. I am going to an LS3 combo after this also, in the parts/build phase now.

 

Ok cool.
I might be able to throw you a few cam specifications depending on what you want to do with the car.

 

Big grinds? Are you reading the same blog? 220@.050 is not big, just depends on specs behind it. A stock LS1 cam is not much smaller than what we are discussing. Camming his combo is not that hard, just may take 1-2 tries to get it perfect. As in actually spending $$$ on a cam, I wouldn't bother w/ anything less than 215@.050 on the intake. Otherwise you may as well stay stock unless it's some sort of specific rocker crawler build and has to make massive torque at 1500rpm or something weird. Nobody ever mentions it on this site, but putting an adj timing set and just advancing the cam some will let you tune a cam that's close, but want a touch more low-end.

 

Looking at a pull of a stock LS3 cam, it appears the power peaked at 5,800rpm.

http://www.superchevy.com/how-to/eng...ick-boomerang/

SAE curve of the LS3 shows the same hp rpm peak, but of course nearly 70hp lower power level (430 vs 497) due to stock tune, no headers, and SAE rating methods.

I liked their cams #2 and #3 for power, hp rpm peak, and idle vacuum. I know I will lose some by having my stock iron exhaust manifolds. Factory V8 Colorado is rare to begin with, let alone to find headers to fit a 4x4 one.

No doubt even a stock LS3 into my Colorado will be fun regardless as it is adding 130hp over the 300hp 5.3L it came with. I’ve so far done a K&N filter, removed cats/resonator, and a ported throttle body, and dropped a full second off my 0-60 time with only those 3 changes. Swap in a 6.2L should knock some more time off it.

I’m really just looking to move that power peak a little further downstream to 6,300-6,500rpm range, and have a pinch noticeable idle through the non-cat exhaust I already have.

 

http://www.cammotion.com/camshafts/l...222-232-108-3/

 

215 could work but might be trouble with stock stall. 220 or bigger on 6.0L or smaller needs a converter change imo or its no fun. Then add manifolds choking it down, not much sense in spending a grand on a couple of cams when headers are a couple hundred bucks and a stall is 600. Add those and some gear and sure 220+ duration all day but for what the OP lists the cheap cam I linked will work well imo

 

Just a thought on the header which seems to be part of the question..
Stepped Tri-Y header is an option,, It will give a lot of upper end for a relatively short header.. At least they work for me..

I've also in the past found a set of shorty headers, cut them on the band saw about 3 " up stream from the collector and welded in 4 extension pipes,, easy way to ad 12 to 14 inches of pre-collector tube and it starts with a $100 set of cheap headers..

I was able to find short headers that dropped far enough to get under the trans and such but just were not long tubes..

Good luck