| Build Name | Static CR | Dyn CR @68° | HP Range | TQ Range | Notes |
|---|---|---|---|---|---|
| 347 TFS 11R 170/53 Flat-Top | 11.39 | 8.86 | 420–450 hp | 400–430 lb-ft | High comp, CNC heads, pump gas 93 required |
| 347 TFS 11R 170/53 Dish | 9.95 | 7.77 | 395–425 hp | 380–410 lb-ft | Safe pump gas, still strong street combo |
| 347 Liberty 180/64 Flat-Top | 9.95 | 7.77 | 410–440 hp | 395–420 lb-ft | Non-CNC, lower comp, safer but slightly softer |
| 347 Liberty 180/64 Dish | 8.86 | 6.95 | 375–410 hp | 365–400 lb-ft | Very safe CR, better for boost than NA |
- TFS 11R 170/53 Flat-Top is the hottest setup at ~11.4:1 static CR and ~8.9:1 dynamic CR. This pushes the edge of pump-gas streetability but maximizes NA torque and horsepower, especially with the CNC ports that flow very well at mid-lift.
- TFS Dish drops to ~10.0:1, giving a very pump-gas friendly combo while still maintaining good power. Excellent choice for a street-driven NA motor.
- Liberty 180/64 Flat-Top runs ~10.0:1 static and ~7.8:1 dynamic CR. This is safer on 91 octane fuel and more forgiving to tune, but leaves some torque on the table compared to the higher-compression TFS build.
- Liberty Dish at ~8.9:1 static is extremely conservative for NA. This is more suited to a boosted application than naturally aspirated performance.
- Trick Flow 11R 170 CNC: Smaller 170cc intake runners paired with CNC porting yield excellent velocity, strong midrange torque, and efficient combustion. These heads take advantage of the higher compression and work very well with the Comp XR282HR cam.
- Liberty 180cc As-Cast: Larger 180cc runners but not CNC ported. Flow quality and consistency won’t match the Trick Flow 11R heads. While the larger chamber volume lowers compression and makes tuning easier, the as-cast ports give up efficiency, especially at mid-lifts.
- With higher compression (TFS Flat-Top), the XR282HR cam’s 230/236 duration and 110° LSA are well-supported, producing a lopey idle, big torque in the midrange, and solid pull to ~6000 rpm.
- With lower compression (Liberty builds), the same cam is less “snappy.” Dynamic compression is in the 7s, so low-RPM torque softens, though still streetable.
- Max NA Power: TFS Flat-Top wins, estimated at 420–450 hp and 400–430 lb-ft, but demands 93 octane and precise tuning.
- Best Balance: TFS Dish at ~10:1 CR makes 395–425 hp with good torque, fully pump-gas safe, and very street-friendly.
- Forgiving Setup: Liberty Flat-Top ~10:1 CR with 180cc runners makes ~410–440 hp. While peak power is competitive, torque curve and efficiency won’t match the CNC TFS heads. Safer for 91 octane markets.
- Boost Candidate: Liberty Dish ~8.9:1 CR is under-compressed for NA but leaves plenty of margin for forced induction.
- If chasing maximum NA power → 347 TFS Flat-Top (93 octane, careful tune).
- If wanting street/strip reliability on pump gas → 347 TFS Dish.
- If limited to 91 octane or hotter climates → 347 Liberty Flat-Top offers a safe alternative, but at some efficiency cost.
- If planning for boost down the road → 347 Liberty Dish is best suited.