Description:
Our CNC-porting of GM LT4 heads significantly improves airflow of these heads. The stock LT4 heads are known to have valve guide wear issues. We replace the factory guides with CHE valve guides made from CHE's proprietary bronze alloy. This extends the heads' longevity.
We know what makes power and also survives the beating of competition. It's not chasing peak air flow at max lift by excessively cutting away the metal around the valve guides. Peak air flow occurs at only one instant in the cycle. Our focus is more on average air flow across the entire cycle. For spring packages with 0.650 inch max-lift, quoting a peak airflow at 0.800 inches is irrelevant.
Of paramount importance for us is that our heads don't break and wreck our engines. We therefore do not chase flow at the expense of weakening the heads mechanical integrity. That's a concern that non-engine builders don't share.
We will disassemble and clean your heads upon arrival. Our process for machining these heads starts with CNC porting on our 5-axis. This is followed by CNC valve jobbing and bowl blending in a single operation on our Newen CNC seat & guide machine (see video down below).
The air flow results we get are as shown in the Table immediately below.
| Valve Lift: | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 | 0.75 | 0.8 |
| Intake | 91 | 160 | 240 | 297 | 335 | 358 | 375 | 382 | 382 |
| Exhaust | 69 | 126 | 180 | 198 | 221 | 236 | 246 | 249 | 249 |
| Intake Valve: | 2.126" |
| Exhaust Valve: | 1.590" |
| After Intake: | 296cc |
| After Exhaust: | 110cc |
| Max Lift | 0.65" |
| Chamber Volume | 65.5cc |
The heads are then reassembled with your original hardware (if useable), or with the optional parts as discussed in the next papragraph.
We offer a variety of optional valve & spring packages for these heads. Our standard spring & valve package comes with GM titanium intake and Manley stainless steel exhaust valves. These are paired with a BTR dual spring kit and titanium retainers. A variety of other hardware options are available.
Call us at 815-725-2727 to discuss your requirements. Pricing is per pair. Shipping charges are not included.
NOTE & DISCLAIMER: GM LT heads have a known issue of dropping valves seats, particularly under extreme conditions. While rare, any such occurrence will cause serious or irreparable damage to the engine. Borowsi Race Engines, Inc. disclaims any responsibilty for such issues as these would be GM factory defects. We offer our CID CNC-ported LT4 heads as an alternative, particularly in race applications.
Payment Types Accepted: Cash, Credit Card, Wire Transfer, ACH
Built by people who love motorsports for people who love motorsports
