INTENSE™ Stage 3 CNC Cylinder Heads (pair)

INTENSE™ Stage 3 CNC Cylinder Heads (pair)


Part Number: CHP-xx3

Shipping Weight: 76.00 pounds

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Sorry, we are currently out of 'INTENSE™ Stage 3 CNC Cylinder Heads (pair)'.
Stage 3 Cylinder Heads Core Charge:
Add $500.00 refundable core charge
I'll send you my heads for porting beforehand
Please select your application:
3800 Series II L36/L26
3800 Series II/III L67/L32
Please select your paint color:


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1996-2008 3800 Series II or Series III engines

‘The INTENSE Stage 3 CNC ported heads were a very good investment. When they arrived at Havlik's Auto shop on the southwest side of Cedar Rapids they were speechless at how well they were ported, and how clean and beautiful they looked. INTENSE-Racing does good work. And I am impressed.’ – Nick Trask, ’98 Grand Prix GTP

There are good reasons why INTENSE™ Stage 3 CNC Cylinder Heads currently power many of the fastest 3800 cars in North America!

We have now studied and flow-bench tested more than a dozen different 3800 Series II/III head porting designs, and are convinced our Stage 3 heads outperform any other heads on the market without exception. In addition, they're the only head design good enough to use a CNC program for unmatched repeatability from cylinder to cylinder, that just can't be rivaled with hand porting.

These 3800 Series II/III cylinder heads are now available for both L36/L26 and L67/L32 engines. They should be used in conjunction with the more aggressive camshaft profiles (such as our INTENSE™ Stage 2 or Stage 3 Blower Cam or INTENSE™ Stage 2 or Stage 3 Turbo Cam), and boost levels up to 30 psi.

Each head is disassembled, inspected, cleaned and extensively ported. Each head is checked and typically ends up being milled ~ .005" for perfect flatness. Then top quality solid bronze guides are installed and a competition valve job and bowl blending is performed. 1.90" (intake) and 1.57" (exhaust) Manley Severe Duty Generation II Valves, custom made of NK-844 Stainless and XH-428 Stainless respectively are installed. These valves feature hardened tips to prevent mushrooming, even when used in conjuction with stock rockers, and are subjected to a competition valve job and multi-angle radiused. Heavy duty (130 pound) PAC Racing valvesprings installed at 1.80" along with Manley titanium retainers. These springs and retainers are STANDARD on all INTENSE™ Stage 3 CNC Cylinder Heads. Our heads are machined to handle valve lifts up to .600". And the combustion chambers (stock = 62 cc, Stage 3 and Stage 4 = 61 cc) are fully polished.

Each head is then painted with your choice of 1966 - 1970 Pontiac Metallic Blue, 1970 - 1975 Buick Red, Aluminum, Black, or Bright Red high-heat engine paint and reassembled (see additional pictures here). By utilizing valvesprings with the stock conical shape, we completely eliminate thepossibility of rocker arm to retainer interference found in some other head designs. By properly machining the heads to handle increased valve lifts, we are able to prevent oil seal and valve guide damage that can be caused by cams with gross valve lifts in excess of 0.525".

From an airflow standpoint, these heads are without question the best 3800 Series II/III design we have seen:

Intake (28" of water, clay radius to repeat)

.100" - 69 cfm
.200" - 127 cfm
.300" - 175 cfm
.400" - 208 cfm
.500" - 224 cfm
.600" - 235 cfm

Exhaust (28" of water, 1.75" pipe to repeat)

.100" - 60 cfm
.200" - 117 cfm
.300" - 172 cfm
.400" - 199 cfm
.500" - 212 cfm
.600" - 222 cfm

Look for horsepower gains to be in the 30-60 HP range with these heads, greatly dependent on other mods. Good results will be seen on engines with maximum airflow (induction and exhaust), and the best results will be seen on engines with higher boost and/or intercoolers.

Click here to read about Robert Silva's 366WHP pull with INTENSE™ Stage 3 CNC Cylinder Heads!


- INTENSE Stage 3 CNC Cylinder Heads are built to order. Please allow 4-6 weeks for machining and assembly when ordering.

- When purchasing preassembled heads, a core charge will be placed on this item. The core charge will be fully refunded after your original cylinder heads are returned, disassembled, cleaned and inspected. The returned cylinder heads MUST be from a late 1998 or newer engine as prior to mid-1998, GM used smaller valvespring pilot seats and the heads were prone to cracking at these locations. The core heads must be in rebuildable condition but need not include valves, seats, retainers, springs or keepers.

- INTENSE Stage 3 CNC Cylinder Heads are warranted for a period of ninety (90) days from the date of purchase against defects in materials and workmanship. The warranty provides for replacement cylinder heads only, and does not cover labor or any other costs. Purchaser and Installer assume all liability with regard to any and all damages in any way related to the purchase, installation and/or use of these cylinder heads.

- Click Here to see cross-sections of 3800 Series II/III cylinder heads

- We strongly recommend the ARP Head Stud Kit with these cylinder heads.

- We strongly recommend the Cometic MLS Head Gaskets with these cylinder heads.

- Click Here for important information on VSR (Valve Seat Recession) for very early Stage III heads

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