If you've been reading GMHTP lately, you know that the new L92 heads are superior to stock LS1 and LS2 heads. But what happens when you put them to task against one of the best 15-degree heads on the market? This is exactly what SLP Performance Parts wanted to know shortly after putting together its new L92 cylinder head package. The previous Air Flow Research/SLP 225cc cylinder head package is one tough customer, and the L92 package costs considerably less. So would the L92 setup be able to match up on one of SLP's ZL402 strokers? We tagged along while Director of Engineering Hank Daniecki conducted the test to find out.
SLP includes everything you...
SLP includes everything you need to complete the install with the L92 package (PN 12293 for cable throttle), and L92 Head Install Kit (PN 12507), for a total of only $2,445.90. The heads are fully assembled with COMP Cams' 918 beehive valvesprings, titanium retainers, and stock valves before being decked to maintain stock LS2 compression (and 11.0:1 on high compression ZL402s). The heads will also be available uncut for lower compression and increased valve clearance. Since the L92 heads require an offset intake rocker, eight GM 1.7 ratio rockers and accompanying pedestals are included. The unique head design also requires the matching L76 intake, which is fully assembled with LS7 39 lbs/hr injectors, fuel rails, and a 90mm electronic throttle. Cable throttle applications will have to purchase a different 90mm throttle body, such as the FAST unit used in this test. New GM gaskets, seals, and head bolts are included in the install kit.
An inconsistency in distribution...
An inconsistency in distribution of the L92 heads has some going to vendors with the rough combustion chambers and casting number seen to the far right, while others go with the smooth chambers and casting number below....
...SLP tries to use as many...
...SLP tries to use as many of the smoother castings as possible, and has the other versions machined to match.
Due to some engagement issues...
Due to some engagement issues with the clutch in the test car, as well as ease of install,...
...the motor and attached...
...the motor and attached T56 were dropped out of Steve Moffa's Collector's Edition TA as part of the front K-frame and suspension assembly....
...Disassembly of the top...
...Disassembly of the top end starts with the SLP headers, then the removal of the coil packs and valve covers by SLP Tech Hank Daniecki, Sr.