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.

Exhaust port tested without pipe (4.155” bore).
Lift ___.100 _.150_.200_.250_.300 _.350 _.400 _.450 _.500 _.550 _.600 _.650_.700_.750
#1 Exh.63.1 94.7 121.1 140.6 156.9 165.8 176.1 182.8 187.9 191.4 193.7 195.6 197.6 199.5

Valve dimensions:
Intake = 2.160” X 4.870” X .314”(8mm)
Exhaust = 1.590” X 4.920” X .314”(8mm)

Seat/throat diameters:
Intake = 1.870”
Exhaust = 1.355”

Volumes:
Intake runner = 260.6cc
Exhaust runner = 90.0cc
Chamber = 69.8cc

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.

Happy hot rodding.

Richard

 

Do you guys have any intention of putting a CNC program on these heads?

Also when did they go static? .625" ? And do you have a .625" flow number on a 4.03 bore?

Nate

 

At the moment I have too many projects on the front burner. I'll consider a CNC program when more support parts (ie. intake manifolds and valves) become available.

The flow rolled over gently between .600" and .650" There was no definitive flow drop at a particular lift.

Richard

 

Deffinatlly disapointed in the exaust port volume/valve size and the lack of flow. Intake looks great. Nice view of how much you can gain by increasing bore as well. Thanks for the results.

 

u the man thanks for doing the flow test.

 

Thanks for the test. Great info!

 

WOW! Those things are going to be in high demand in a few years when some start showing up in junk yards.
Great work!

 

The L-92 intake manifold part # is 12580678, just FYI, I told Richard I would post it.

 

Is that the truck or holden mainfold #
b/c it's only $144 from GMPartsDirect

 

thats the truck manifold number.

 

you can build a full set of heads w/valves and rockers for less than 600$

 

wow.

i hope these show even better gains once ported...

 

Damn, man. Just install a 1.60" exhaust valve, blend the throat, and polish the port. Then clean up the intake port with a 120gt flap wheel and you are done!!!! Killer information!!!!

 

Richard,
Like I said before, the L92 and LS7 heads are all anyone is ever going to need for 370 cid on up. This is going to be great for you to clean them up, maybe even do full turnkey assemblies. There is no doubt it is going to put real pressure on the aftermarket heads considering the price point.
Brent

The Warhawk heads will be for the big number f/i crowd.

 

OH MY GOD, and they are what around 200-300 each brand new.

 

160 a pop from GMPartsdirect.com. They are bare though. You'd need ls7 rockers, rocker stands, valves, springs, retainers, seals, and keepers but that stuff is probably only another 900 bucks.

Nate

 

i priced out a full set yesterday using the L92 valvetrain....less than 600 total for the set.

 

You're still going to need the LS7 rocker set for the heads. Thats 350.

Stock springs are good to what lift? Wouldn't think them to be that high. Maybe .550" max if you're lucky.

Also would probably want stainless valves in high hp applications (what most people would be using these for).

Nate

 

Yeah, the overall cost will be cheap to setup these heads. Now an intake manifold is all that's needed. I understand that Wegner is working on a carb style aluminum one. I have no idea when they intend to release it.

Richard

 

could you elaborate?

why wont the L92 valvetrain work with L92 heads on a diffrent shortblock??