JakeFusion

iTrader: (7)

Just wanting to make sure, since I don't think I've ever actually read it, but for some reason I assume the L92 heads have an offset 1.8 rocker on the intake. Am I Correct? Also, what's the stock length pushrods for the L92? Is it similar to the LS1/2/6 because it's a 15 degree head?

Wnts2Go10O

iTrader: (12)

no, both intake and exhaust are 1.7

JakeFusion

iTrader: (7)

Thanks. That makes selecting a cam a bit easier.

BlackHawk T/A

iTrader: (3)

I was gonna say, how will we work around that?

JakeFusion

iTrader: (7)

LSK lobes would be out of the question on intake if that were the case. I'm not real sure what lobes LS7 cams are running, but I think XE-R on the exhaust and maybe XFI/XE on the intake (or something else) from the specs I've seen.

I am glad the L92 is normal, however.

Vents

iTrader: (9)

concidering the "relitively" low exhaust flow numbers found in the L92 heads, a 1.8 ex 1.7 intake rocker would actually help out things in trying to close up the i/e ratio.

that would actuall be a pretty good idea, but i think that they are straight 1.7's across the head. we will probably start seeing some larger intake/exhaust splits in longer duration camshafts, circa SBC.

JakeFusion

iTrader: (7)

Well, if the exhaust uses the LS1 1.7, one could conceivable use an LS1 1.8:1 ala Crane Golds or 1.85:1 for the Comp Pro-Magnums. Might be worth a look.

Bring the Noise

There is 1 problem with that.

Both the Crane and Comp LS1 style rollers use push rod guide plates to keep the rockers aligned -vs- the stock LS1 / L92 rockers setups that use either a pedastal or tray to keep the rockers aligned. I don't think the comp or cranes would work to well in the trays that are used on the L92 heads.

Here's a shot from my head cam swap where I had the Comp 1.85's installed.


You can see in the photo that the rockers do not set on a pedestal or in a tray. The way they keep there alignment is with the push rod guide plates, It was a carry over from the Gen 1 stuff that Crane and Comp made. The newer Comp design is there Shaft mounted setup (which is a copy of Jessels setup to be honest).

And the Harland Sharps LS1 rockers are out of the question due to the shaft going between the intake and exhaust rockers.

thread Derail... Man I need to get some shots of the engine bay now with the SW tubes on her... okay back to the question at hand.

Currently the L92 intake rockers are only one that can be used with the L92 heads. The LS7's intake rockers don't align correctly to the L92's Valve tip.

You might be able to use the L92 intake rockers and the LS7 exhaust rockers (which are 1.8's) but you will probably need shorter length push rods on the exhaust side to keep the tip of the rockers in the right location on the valve tip.

I'm wondering how long it will be before Comp, Crane, Jessel, Harland Sharp, or someone else comes up with offset intake rockers that will work on the L92 heads.

With the L92 heads coming on the Vortec Max (L76 for 07 and later Chevy Silverado) and L92 Vortec motors (Escalade and Yukon Denali's) and possible in the next gen camaro and/or the 08 or 09 vette's (with active fuel management to meet federal regulations)... aftermarket rockers will come but it will take a little while.

BlackHawk T/A

iTrader: (3)

My point was it puts a real pain into designing a camshaft. Put that 1.8 ratio on the LSK lobe cam I speced and you get .687 intake lift. Sure you can go lower on the lift but you have to choose a different lobe which affects the duration as well...

Dragaholic

iTrader: (180)

Just curious, but why is it such a concern on rockers for the L92 heads? When I asked for suggestions on what rockers to run, I was recommended by many to use the stockers and have the Harland Sharp mod done to them. That of course was directed towards LS1 rockers, but they're not different than the L92, other than they're offset correct. So get 8 L92 intake rockers and 8 LS1 exhaust rockers, have the Harland Sharp mod done to them, and you have yourself a set of nice rockers. I've also been told that shaft mount rockers are really expensive and anything else is just too heavy.

JakeFusion

iTrader: (7)

At first, I didn't know what ratio the rockers were at, since it's based on the LS7 head but with a 15 degree valve, I didn't know what ratio it was running at stock and couldn't find that information. The Harland Sharp mod is great.

jdo6696

iTrader: (4)

thanks, I couldn't remember which rocker was the offset one, means I only need 8 L92 intake rockers.

DoesSpeedTurnUon

iTrader: (17)

So will LS1/LS6 rockers work? Intake? Exhaust? Both?

I'm about to order my rockers from SDPC and was curious what I needed.

LSX Wizard

LS1/2/6 rockers work only on the exhaust side of the L92 heads.

DoesSpeedTurnUon

iTrader: (17)

good deal, means i only have buy L92 intake rockers.

Juiced

iTrader: (2)

Has anybody measured what the offset is on the intake rockers?

Vents

iTrader: (9)

true. but really, until the aftermarket ante's up for a nice set of offset rockers, these heads arent going to pay off on BIG hp levels anyway.

BlackHawk T/A

iTrader: (3)

Stock rockers are fine.

Vents

iTrader: (9)

fine you say?

forgive me, but i dont think you understood what i was getting at.

from my experience most stock rocker arms will grenade around the ~850RW mark (and some sooner considering FI cyllinder pressure) personally i wont trust them for much over 650RW for any power adder. thats not to say that they wont work, just that i wouldnt use them. especially when you're looking at building 1100+ at the wheels, which seems to be the starting point for most "BIG" hp setups these days...

anyway enough of that...

looking at the LSK lobes they are VERY aggressive, and with stock 1.7 rockers, and an L92 head, these are going to hit the sweet spot in these heads. especially once ported. i'd be looking at 2127-2132 for the ported setups. did i mention that these will be VERY aggressive?

https://ls1tech.com/forums/generation-iv-internal-engine/616405-precision-race-components-ported-6-2l-cylinder-heads-almost-ready.html

Here's some flow data from the ported version: (taken from above thread)


.200 156 114
.300 226 154
.400 287 187
.500 325 207
.600 351 229
.650 357 234


https://ls1tech.com/forums/generation-iii-internal-engine/363688-comp-lsk-lobes.html

(taken from above thread)

Comp Cams LSK lobes
Lobe#, Dur. @ .006", .050", .200", & Lift w/1.7 rocker
2124 265 215 142 .629"
2125 269 219 145 .632"
2126 273 223 149 .636"
2127 277 227 153 .639"
2128 281 231 156 .643"
2129 285 235 160 .646"
2130 289 239 164 .649"
2131 293 243 168 .653"
2132 297 247 171 .656"
2133 301 251 175 .660"
2134 305 255 179 .663"
2135 309 259 183 .663"
2136 313 263 186 .663"


just dont forget the trusty 'ol XER lobes, those still make plenty of power with good duration, and not so much lift.

i suspect that here in the near future 600RW NA will be somewhat of a bottom line standard.

BlackHawk T/A

iTrader: (3)

Ok, for N/A use they are fine.

Not everyone shoots for 1000+ hp