Edited July 2007: It is confirmed that the LS3 shares the same cylinder head castings and block casting as the L92 truck engine. The main difference in LS3 complete heads is that they have lighter valves and better valvesprings than standard L92 complete heads.
Ok here is all the info I have so far.
L92 Part numbers
GM #12590771 2.16 intake valve
GM #12582719 1.59 exhaust valve
GM #12582714 L92 Bare Cylinder head
GM #12600936 Rocker arm pedestals
GM #12569167 Intake Rocker arm
GM #10214664 Exhaust Rocker arm
GM #12590124 L76 Style Intake manifold
GM #12499225 LS Series lifter kit(newly designed for high RPM LS7 usuage)
Here are the details and photos of the L92... my only question is, when could I actually have one in my hands!
The main things everyone needs to know about the L92 engine...
6.2L
Aluminum block and heads
LS7 design heads with the offset rockers
Variable Valve Timing
Forged stock crank
Richard@WCCH Did the flow testing of the new L92 heads.
I just finished flow testing a new stock L92 head. All I can says is…….WOW! What a nice part.
I’d like to publicly thank StreetnStrip for the opportunity to test this head.
The test head has casting number 5364. Here’s the tale of the tape……..
4.030” test bore
Lift ___.100 _.150_.200_.250_.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650_.700_.750
#1 Int. 74.9 109.4 154.4 193.5 225.3 252.8 274.6 292.7 308.8 321.0 328.7 326.6 310.0 316.6
#1 Exh. 63.6 97.9 126.1 148.7 162.3 178.6 189.6 197.6 205.5 210.7 214.6 217.8 221.2 223.5
The intake was tested with a radius plate and the exhaust was tested with a 2 ˝” stub pipe.
4.155” test bore
Lift ___.100 _.150_.200_.250_.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650_.700_.750
#1 Int. 73.8 108.7 153.2 192.6 225.2 253.6 277.0 296.7 313.0 326.0 335.8 326.9 327.3 317.1
#1 Exh.61.1 97.9 125.7 148.1 162.0 179.5 191.8 200.1 205.9 213.3 218.4 220.9 221.9 223.2
The intake was tested with a radius plate and the exhaust was tested with a 2 ˝” stub pipe.
A few observations………. These heads have the best seat/port lineup for an as cast GM head that I’ve seen. Their casting precision is VERY good. The fit and finish of the valves are very nice as well. The intake port is large, especially the area above the short turn radius. The intake cross section starts at 3.1sq/in at the intake flange and grows to almost 3.7sq/in forward of the guide boss!
I’m a bit disappointed with the exhaust port flow. IMO it needs to be at least 25 peak cfm better. I’m sure the engineers at GM know what they’re objective was and they were satisfied with the final product but I think for hot rodding especially blown applications, the exhaust port needs to be improved. Looks like head porters will have something to do after all………
I understand that there is a company working on a 4bbl carb style intake, but I’ll leave the intake manifold subject for another thread.
Most of the info I got was from here and from my local GM garage. Im sorry if I didnt give the people who psoted up pics or part numbers the credit they deserve. Also can I get a sticky and also if anyone has more info to add please do so. i also will have rocker arms soon and I will psot of pics of them on a head.
Great post, Im glad someone finally made a thread with all the part numbers in it. Also are the lifters sold in sets or is that each, its like 100.00?
Do we know yet, will regular LS1 springs fit in these heads? Like a set of PRC's?? Also the vlaves, can aftermarket ones be used, and is there room to put larger valves in there? These heads are going to be amazing, pretty big chambers but flow a shit load of air.
thanks
ed
ok, I noticed there is no block number that has been put up yet.......here it is:
12584727
hope I'm not too late to the game. BTW its a good part number for the bloc, but no pricing info has been released cause GM is waiting for a vendor for the block. Any more info wanted?
__________________ "So let's see.
I can get 400 rwHP (50 rwHP gain) for $700-800.
I can get 35 extra rwHP if I spend an additional $2,000.
Holy Law of Diminishing Marginal Returns, Batman"
Quote:
Originally Posted by bigredexpress99
If I have sex with my best friends girl because she was lonely and maybe a LITTLE drunk, and I was asked by him to take care of her while he was away on a business trip, does the phrase "That's what friends are for!" still apply?
ok, I noticed there is no block number that has been put up yet.......here it is:
12584727
hope I'm not too late to the game. BTW its a good part number for the bloc, but no pricing info has been released cause GM is waiting for a vendor for the block. Any more info wanted?
I was told that we can only get that block in a long block is this true?
12584997 - crank part number - availability is somewhat limited, just a bit longer wait for it.
12577583 - con rod number - availability is no problem, almost next day.
__________________ "So let's see.
I can get 400 rwHP (50 rwHP gain) for $700-800.
I can get 35 extra rwHP if I spend an additional $2,000.
Holy Law of Diminishing Marginal Returns, Batman"
Quote:
Originally Posted by bigredexpress99
If I have sex with my best friends girl because she was lonely and maybe a LITTLE drunk, and I was asked by him to take care of her while he was away on a business trip, does the phrase "That's what friends are for!" still apply?
Is that for sure the intake part number, looked on GMpartsdirect.com and its less that $200.00.
is it out of quality control already thought it wasnt supposed to be cleared to be sold until may 11th, and now their listed?
just want to make sure as the description isnt specific enough for me to order already, lol
Is that for sure the intake part number, looked on GMpartsdirect.com and its less that $200.00.
is it out of quality control already thought it wasnt supposed to be cleared to be sold until may 11th, and now their listed?
just want to make sure as the description isnt specific enough for me to order already, lol
thanks
ed
yeah there suppose to be out next week on the 12th. I know my guy said i need to get a vin so i could get it quicker so hopeful it will be here soon. I do have an australian Vin do any of u guys need it.
THE HEAD ON THE RIGHT IS THE L92 HEAD AND THE ONE OF THE LEFT IS THE LS7
This is a great thread! Thanks to everyone for your contributions.
Is it me, or are the heads in the above picture on opposite sides? The L92 heads should have the intake bolts holes low on the intake flange.
Trivial stuff...........
Great job here guys. Keep up the nice work.
Richard
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gmpartsdirect says the con rods are 80 bucks each, seems kinda high for a factory rod, maybe they are a forged piece like the crank, which is only 174 bucks. I sure wish they would release the price for the block, im starting to think that with these prices for this engine, that im going to build a 6.2 for my Sonoma GT instead of a reg LS2.
Id be willing ot bet that even though the L92 block is aluminum the fact that its not a corvette part will make it cheaper than the grand for the LS2 block.
LS3 & L92 Info 
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Thanks to everyone for your contributions. 
