New GM LSA CNC Ported Cylinder Heads - Set (12675872)
XCFM-10374Brand New. Ready to Bolt On
The ultimate upgrade for your GM LSA engine - our brand new LSA (GM part: 12675872) XtremeCFM CNC ported cylinder heads.
CNC Ported, Decked and Ready-to-Go
These stock LSA heads have been taken to the next level with our 5-axis CNC porting program, strategically removing material from the intake and exhaust ports and contouring them for maximum airflow. The stock LSA/LS9 cylinder head and engine combo yields a 9.1:1 compression ratio. After porting we deck the head 0.026" yielding a 9.38:1 compression ratio (when using the stock engine configuration). The stock springs are replaced by BTR 0.660" lift dual springs with titanium retainers for your larger-than-stock camshaft application.
No Cores, No Fuss
Note: We don't require any return core. These are brand new heads and if they are listed as IN STOCK they will ship within 24 hours.
Again, these heads are brand new (never used) and are run through our standard LSA head porting procedure which includes:
- Disassembly and inspection.
- A pre-clean using our ultrasonic parts washer.
- XtremeCFM 5-Axis CNC treatment using our Centroid A560.
- Hand blending of intake and exhaust ports as needed.
- Resurfacing / decking removing 0.026" of deck surface.
- De-burring, cleaning and washing.
- Upgrading to BTR SK001 .660" lift springs with titanium retainers.
- Reassembly and final inspection of your ported LSA heads.
The following is flow data from our LSA/LS9 cylinder head porting profiles:
|
Lift |
Intake (Stock) |
Intake (Ported) |
Exhaust (Stock) |
Exhaust (Ported) |
|
.100” |
73.2 |
83.4 |
63.8 |
69.8 |
|
.150” |
110.9 |
121.2 |
88.6 |
98.8 |
|
.200” |
145.7 |
165.1 |
114.1 |
129.4 |
|
.250” |
188.8 |
206.4 |
135.7 |
153.7 |
|
.300” |
215.6 |
239.7 |
157.3 |
180.6 |
|
.350” |
236.4 |
263.4 |
172.4 |
199.7 |
|
.400” |
257.7 |
283.7 |
184.7 |
220.5 |
|
.450” |
275.8 |
301.7 |
194.5 |
231.8 |
|
.500” |
290.3 |
321.4 |
201.6 |
239.9 |
|
.550” |
299.8 |
336.2 |
207.2 |
246.6 |
|
.600” |
303.6 |
351.9 |
211.6 |
252.8 |
|
.650” |
293.2 |
366.3 |
213.4 |
254.9 |
|
.700” |
292.5 |
372.3 |
215.7 |
257.7 |
|
.750” |
377.2 |
259.9 |
These ported LSA cylinder heads come direct from GM with the following configuration:
| Intake Valve Material | Stainless Steel (Hollow Stem) |
| Intake Valve Dia. | 2.165" |
| Exhaust Valve Material | Stainless Steel (Solid Stem) |
| Exhaust Valve Dia. | 1.590" |
| Valve Spring Style |
BTR 0.660" Lift Dual Spring |
| Valve Spring Seat Pressure | 155 lbs. @ 1.780" |
| Valve Spring Open Pressure | 380 lbs. @ 1.180" |
| Stock Deck Thickness | 4.750" +- 0.003" |
| Post-Porting/Decking Deck Thickness | 4.724" +- 0.003" |
| Chamber Size | 65cc |
Frequently Asked Questions
Q: Do I need to ship you my cores?
A: NO, these are a brand new set of heads completely CNC'd, assembled and ready-to-go. No cores needed!
Q: Will you buy my old (LSA, LS3, LS9, LS2, etc) cores?
A: MAYBE, please contact us with your LSA (or other LS heads) that you're looking to sell!
Q: Will these LSA heads work with my big cam?
A: More than likely yes. With upgraded dual-lift 0.660 lift springs we've given you extra headroom for your larger-than-stock camshaft.
Q: All else being equal what's my final compression ratio with these LSA heads?
A: 9.38:1 (after we deck them 0.026") all other internals being stock or of stock dimension.
Q: Are these heads used or remanufactured?
A: No, these are BRAND NEW. We have nothing against used/reman at all but these are in a brand-new never-used state.
GM Part Number: 12675872
Cylinder Head Material: Aluminum
Number of Cylinder Heads: Set of 2