30th t/a

iTrader: (51)

I bought a L92 engine and sold the L92 heads to go with the cathedral design. Since im on a budget, im probably going with a stock set of 243s milled to give me 11.5:1CR, and a FAST intake and a nice cam. I dont like the giant 260cc runners and horrible PTV clearance. I know L92/LS3 heads make good top end power but I want crisp throttle response & awesome low/mid range power. The plan is to add a set of TFS heads on the engine in the future.

bozzhawg

Your running the wrong camshaft timing events or your combo is off.

I am not saying what you have done is not valid in your experience, but I will say you can make power and there are many 6.2's making 400rwtq around 3300-3800rpms it depends on the combo.

There is 1 common mistake that a few make over and over and it is constantly repeated here even by the same cam guessers. A few people see the dyno or cam and repeat the same mistake over and over. Doing something the same way expecting different results is neurotic behavior.

To me I don't care what head a guy brings me with his combo from cathedrals to square, I can make it work and will chose the camshaft timing events to match the combo. I cannot make blanket statements and say either cathedrals or square ports are crap. They all work and can work well when you know what your doing.

Tainted

iTrader: (9)

With the big bore of the ls3 the ls3 stuff is great. Your valves arent shrouded, youve got room to mill and run a decent cam. But some tfs heads will certainly do very well. Pat g has shown us what l92 vs afr 230s are worthy of on 6.0s.

bozzhawg

I keep seeing you post this same thing over and over on multiple threads.

Did you run L92/LS3's on a 6.0 combo and it did not workout for you?

30th t/a

iTrader: (51)

Agreed, and it was a tough decision, I know im going the opposite way of what most people would do but I rather make more low & mid range power since its mainly a street car. I really dont even race that much anymore so below 5000 is where i'll spend most of my time.

Tainted

iTrader: (9)

Ive had a l76 g8 but it was fine.

Ive never debated the fact you cant make good power with them. In fact I post plenty of dynos showing the opposite. BUT I think if youre willing to spend a little more you could have a better setup.
Hell if I didnt like ls3 stuff I wouldnt have a set of $2400 ls3 heads waiting to be put on a 408 (and thats a 4.030 for tbose who dont know or come across this).

I feel like its a split between getting the appropriate valve events that the ls3 stuff is very sensitive to and people using hogged out ported heads with huge runners on stock cube motors that could never exploit the heads potential.

And its in scenarios like that where I believe a aftermarket casting (prc for budget afr tfs etc for big rollers) or quality ported ls6 heads would be a way better match.

KCS

iTrader: (20)

I assure you that's not the case. This isn't a conclusion based on the results of one or two cars, but a sampling of dozens of combos with different cams.

onefast84

So I think you will be very happy just running the stock lq9 heads. Just get a custom grind cam for it, and supporting mods. My camed lq4 ran 11.60s with less compression. If anything just mill the 317s down a bit to get comp up. Anyways you will have on bad *** street car!!

Avenger02

iTrader: (1)

sweet!

mannyfresh

Heres the numbers on my lq9 swapped m6 z28, i pieced together this combo as a daily driver also so this might help you out. Stock Lq9 block ported and polished 317 heads ls6 intake custom pat g cam (230/234 .600"/.612")pacesetter LTs .040" cometic head gasket 10.5:1 cr CMS tuned. Put down 398rwhp 406rwtq..has me grinning ear to ear everytime i smash the gas pedal.

Avenger02

iTrader: (1)

sounds awesome

Avenger02

iTrader: (1)

So would a set of ported 243 heads and an ls6 intake with the appropriate cam make a better street combo? I care more about how it feels on the road than dyno numbers at an rpm i wont ever get high enough on a regular basis to use.

I keep hearing that the 243's are hard to beat for the $$. How would they compare to my 317's ported?

kainedogg

iTrader: (23)

In for the answer

Tainted

iTrader: (9)

The 243 or 799s will flow slightly more and have a smaller chamber so you can get your compression up more.

30th t/a

iTrader: (51)

Here is what my research have shown. Most cammed LS3 setups on a 6.0 shortblock will be in the 450-460rwhp/ 415-435 rwtq.
Most cammed 6.0’s with a LS6 intake will be in the 425/410 range. Now if you install a FAST intake & mill the 243 heads and you will
be in the 450-460 range/425rwtq with better low end & mid range over the cammed LS3 setup and make the same or very close to the same
top end power of the cammed LS3 setup on a 6.0. If your like me and just want a fun street car that stays below 5000 (most of the time) I vote milled 243s to get 11.5:1 CR, nice cam & a FAST intake. Then when you get some money, install a set of AFRs or TFS heads. I’m doing this setup on my 6.2 shortblock.

milled & ported 317s would get you even more power over unported, milled 243’s

Avenger02

iTrader: (1)

Isnt there more than one fast intake? I think theres a 90 and a 102? If this is correct, which one would I be better off with.

And just so I understand this correctly about that last comment on the 317's.
A set of ported and milled(how much 0.030"?) 243 heads will out perform a set of ported and milled 317's, but you were just letting me know that I can port and mill my heads and they would outperform unported but milled 243's correct?

From what I gathered the 243's have the smaller chambers to bump up the compression so Ideally those would be the easiest starting point right?

30th t/a

iTrader: (51)

FAST has made a 78mm, 90mm, 92mm & 102mm. Id look for a 90 or 92mm. The 102 will make more power but you got to buy new fuel rails to go with the 102 making it $$$$$.

The stock 243s with the smaller combustion chamber (more CR) & tad better flow will make more power compared to stock 317s. Once you start milling each head & porting them, their basically the same head. You will get away with milling the 243 less to acheive the same CR. As far as how much to mill them, that depends how much compression you want.

Note: If you mill the heads, always check piston to valve clearance.

Tainted

iTrader: (9)

When comparing the 317 and the 243 ported the are very close. The ls6 heads only get maybe 2 or 3 cfm better if that which is negligble, but the real advantage is the chamber cc. You can only mill so much before you have alignment issues.

Generally .0030-.0040 is the max amount you can usually mill and get away with. For reference .006 = 1cc

KCS

iTrader: (20)

I wouldn't say they're mutants, but the ported heads, higher compression, and the fact that's on a DYNOJET versus the MUSTANG dyno I'm on, surely inflates their numbers.

Avenger02

iTrader: (1)

OK, So here's my current plans with the help of some of the wonderful people on this forum.

-Stock Lq9 bottom end (408 in the future when its rebuild time)
-LS3 heads bowl blended, titanium retainer with dual springs .660 lift, milled 0.030"
-Stock LS3 intake complete with stock fuel rails and injectors
-Custom cam grind 223/231 .610/.617 113+4
-Pace Setter long tubes ceramic coated not sure to go 1 3/4 or 1 7/8 (any ideas?)
-90mm cable driven throttle body, I'm assuming I'll need the bracket for the cables from SDParts.

Going for a 91 octane tune since there is no 93 around here. The tuner is going to tune it Speed density with a micro-squirt unit so I wont need a MAF.

Will get a dyno tune at a later time.

How does this sound to the majority of you guys?