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Testing The New GM L92 Cylinder Heads - 550 hp for Under $4,900

Beat this! With a cam and head swap with pump gas on a Gen III 6.0L we made 550 hp for under $4,900

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Cam Specs
CamshaftDuration @ 0.050Lift (inches)Lobe Separation Angle (LSA)
GMPP Hot cam, intake2190.525112
PN 12480033, exhaust2280.525 
 
Comp Cams XR281HR, intake2280.571112
PN 54-428-11, exhaust2300.573 
  • Testing GM L92 And LS7 Cylinder Heads Intake Manifold
    The new cylinder heads also require a different carbureted intake manifold because of the wider but shorter intake-port design. GM Performance Parts has already filled that void with a brand-new casting.
    Testing GM L92 And LS7 Cylinder Heads Intake Manifold
    The new cylinder heads also require a different carbureted intake manifold because of the
  • Testing GM L92 And LS7 Cylinder Heads Comp Cams
    The cam change to the Comp Cams hydraulic roller was again, very easy, and we reused the production GM hydraulic roller lifters.
    Testing GM L92 And LS7 Cylinder Heads Comp Cams
    The cam change to the Comp Cams hydraulic roller was again, very easy, and we reused the p
  • Testing GM L92 And LS7 Cylinder Heads Intake Plenum
    This is the plenum area of the new GMPP intake manifold. Most modern single-plane intakes tend to extend the port-runner dividing walls into the plenum area. This manifold does not. We might experiment with this to see if there is some power hiding in this manifold.
    Testing GM L92 And LS7 Cylinder Heads Intake Plenum
    This is the plenum area of the new GMPP intake manifold. Most modern single-plane intakes
Dyno Day
Test 1: is the best power curve from last month's story using the stock LQ4 6.0L iron heads, GMPP Hot cam, GMPP carbureted intake manifold, Holley 750-cfm carb, and Kooks 1-3/4-inch headers.
Test 2: is where we jump directly to the big L92 heads combined with the larger Comp hydraulic roller camshaft. We also increased carburetor size to an 850-cfm Holley to make a little more power at the top while retaining the Kooks 1-3/4-inch headers.
 Test 1Test 2DIFF
RPMTQHPTQHPTQHP
2,200399168378157-21-11
2,400392179378172-14- 7
2,600393194386191-7-3
2,800401214396211-5-3
3,000414237406232-8-5
3,200427260414253-13-7
4,300435281419271-16-10
3,600438299422289-16-10
3,800437315423305-14-10
4,000434331424323-10-8
4,200434347427341-7-6
4,400436366432362-4-4
4,600441387438385-3-2
4,80044740844740800
5,000450428455434+5+6
5,200450444462457+12+13
5,400444456464478+20+22
5,600436466464494+28+28
5,800430475459506+29+31
6,000423483451515+28+32
6,200 -- --443524----
6,400 -- --438535----
6,600 -- --435546----
6,800 -- --425551----
Avg.428336427364  
Power/ci(peak)1.231.321.271.51  
Comparing peak numbers, the torque gained only 14 lb-ft, but the horsepower jumped a staggering 68 hp with the combination of the larger cam and the L92 heads.
SOURCES
COMP Cams Kooks Custom Headers
North Bayshore
NY
866-586-5665
www.kookscustomheaders.com
Federal-Mogul
26555 Northwestern Hwy.
Southfield
MI  48034
248-354-7700
www.federal-mogul.com
LKQ
Chicago
IL
GM Performance Parts
www.gmperformanceparts.com
Scoggin-Dickey Parts Center
Lubbock
TX
N/A
www.sdparts.com
Holley Performance Products
1801 Russellville Rd.
Bowling Green, KY 42101
KY  42101
270-782-2900
www.holley.com
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