shutternuts

I have a iron 6.0 LQ4 that I'm building. Going to make it 408.
The power goals are 550 rwhp, want torque and throttle response for frequent drivability.

Tremec 6 speed.
1 7/8 LT headers, 3" dual all the way.

I'm an old school guy trying to get caught up in this world. Here are my questions that I'd like your opinions on:

I acquired a set of 862 heads that have been CNC'd. I don't know who did them, but I measured them. They are fresh with new valves/springs.
Chambers 67cc
Int. runners 233cc
Exh runners 87cc
Int Valve 2.05
Exh Valve 1.56
How would these heads fit in my plan, or do I pass them on and get different? If so, what?

Also, which intake would be best for this? How well do the single plane 4150 type flanges work?
Camshaft tbd.

Thanks in advance for your comments.

Ls7colorado

iTrader: (3)

There are no aftermarket vendor/shop markings at all on the heads?? Most sets ive seen that were CNC ported had markings from who did it.
550 at the wheel is gonna require some good heads (witch you may have) or 821 or 823 heads would also work with the right cam.

shutternuts

Ls7colorado. Thanks for reply.
Only markings on heads are stamped: S253243 and 13181.

G Atsma

Those heads are the same as 706 heads. Someone really hogged them out. Chambers are normally 61cc, intake ports 200cc.

Che70velle

iTrader: (6)

As G stated, the 706/862 castings are the same dimensionally. Different casting process, but numerically/dimensionally the same. Here’s the numbers as cast...
Combustion Chamber Volume: 61.15cc
Intake Port Volume: 200cc
Exhaust Port Volume: 70cc
Intake Valve Diameter: 1.89 inches
Exhaust Valve Diameter: 1.55 inches

shutternuts

So with the mods that have been done to these heads, are the “hogged” out dimensions beneficial for my goals? How do these specs compare to other aftermarket heads? Just trying to understand what the goal was for the shop that did this work. Cosmetically, they are gorgeous....

Ls7colorado

iTrader: (3)

If you dont already have an Intake I would just buy some 821/823 heads and Ls3 intake. That would be the cheapest route to get you to 550 rwhp.
A FAST 102 for the cathedral heads will cost about the same as the whole rectangle port topend setup.

Che70velle

iTrader: (6)

Post some pics please. Close ups of the ports with good lighting would be great. Someone did a ton of work to those heads.

shutternuts

Intake port. Will be able see chamber and exhaust later