TFS-R Cylinder Head Install and Test - Trick Flowing Casts - Tech

While the 0.700-lift airflow figures were impressive, the reality is that most enthusiasts run cams of less than 0.700-lift. Not a problem, as the TFS-R heads offered much more than big peak flow numbers. At a slightly more realistic lift of 0.600, the out-of-the-box heads flowed 296 cfm, which means they worked perfectly well with smaller 0.600-lift cams. Having tested TFS-R heads time and again, they have never failed to produce exceptional power. Even more impressive is they respond so well to porting, with TFS literature indicating that a simple cartridge roll can unearth an additional 20 cfm on the intake side and 30 cfm on the exhaust.

With the TFS-R heads working so nicely right out of the box and responding so well to porting, it was only natural that TFS offer a ported version of its own head. Maybe it got a look at the results of the tests we ran on the ported R heads from Total Engine Airflow, but whatever the reason, TFS now offers CNC-ported versions of the famous R heads.

Using the same 2.08/1.60 valve combination, the porting has improved peak flow from 305 cfm to 341 cfm. Since man does not live on peak lift values alone, the porting performed by TFS improved the flow rate of the heads from 0.300-inch on up, with only a slight trade-off at 0.200-inch lift. The CNC program also opened up the combustion chamber volume from 61 cc to 65 cc, but this can be adjusted by milling. The exhaust flow took a serious jump as well, from 235 cfm to 271 cfm, with sizable gains offered throughout the lift range. Naturally, the port volumes increased as well after porting, from 206 cc to 225 cc on the intake and from 92 cc to 100 cc on the exhaust.

While we all want heads that flow 341 cfm on our stock 302, the reality is the larger port volumes are best suited to larger-displacement motors or very high-revving ones. The often-used calculation for the relationship between airflow and horsepower is:

Horsepower = Peak Airflow x 0.257 x Number of Cylinders

This equation shows maximum power available from a given amount of airflow. Obviously this formula is helpful for determining the power potential of a set of cylinder heads, but it is not a predictor.

The airflow formula does not take into account the other engine components that may affect the power output, nor does it consider average airflow. Just for grins, we applied this formula to predict that the new CNC-ported TFS-R heads can support 700 hp in normally aspirated trim and a great deal more if equipped with forced induction. Again, just because you run these heads on your 302, 331, or even 351 stroker, it doesn't guarantee that your combination will produce anywhere near the 700hp potential offered by the new R heads. While we didn't go all out on this build, we did equip them for use with a solid roller cam. TFS offered the CNC-R heads with valvespring packages for either hydraulic (up to 0.680-lift) or solid (up to 0.720-lift) roller cams. We chose the latter.