Inertia Motorsports Ported Heads for 5.7l Hemi

Our 5.7 and 6.1 Hemi CNC ported cylinder heads. The heads are CNC ported by a shop that supplies heads for numerous Top Nextel Cup, NASCAR Truck and Pro Stock teams. To assure longevity, in the development process after the port was developed the test heads were cut apart to inspect for areas that may have gone too thin during the porting process. With hand ported heads it is impossible to tell if there are thin spots because no two ports are the same and you only know for sure if you break through so there may be 0.250? of material at a point or there may be 0.010? which will fail over time. Our CNC hemi heads are provided with a 5 angle valve job on the intake and a proprietary radius valve job on the exhaust. These seats are optimized specifically for the 5.7 or 6.1 Hemi and not just a standard performance cutter that most shops use. Used 5.7 heads are inspected, cleaned and rebuilt to spec using the heavier better quality 6.1 exhaust valve springs on all valve locations. The 6.1 heads utilize the 6.1 intake spring on the intake and exhaust springs on the exhaust. Manley springs and retainers are available as an extra cost option. Although flow numbers are not necessarily the best indicator of performance gain (it is possible to flow less and make more power due to many other factors in the head) and flow numbers are often inflated or misrepresented. People often are interested in the numbers, so. Our CNC ported heads with the stock valves have yielded the following flow numbers during our testing:

CNC ported 5.7 hemi flow numbers, flowed on 3.935? bore with no exhaust tube

CNC ported 6.1 hemi flow numbers, flowed on 4.0? bore with no exhaust tube

Although, performance gains can differ depending on modifications and vehicle differences on most installations we are seeing right at 30 RWHP gain from replacing the Stock 5.7 heads with our heads and 35 RWHP between the stock and ported 6.1 heads.

We have also been noticing measurable fuel economy increases (1-2 mpg) with the ported 5.7 heads and are in the process of substantiating this on the 6.1 head also. This is probably due to two reasons. A more efficient cyl head from the porting and in the port design the ports were done to intentionally keep the low lift flow (0.100?-0.250?) lower than we could actually make it. Some would consider this crazy. The reason this was done was to reduce the natural tendency of the hemi head to over scavenge and pass excess raw fuel out the exhaust valve during overlap. This is the same reason that the hemi cams run a wider lobe separation angle on the cam than similar performance wedge motor cams. The truth is in the power production not the flow numbers.

The stock 6.1 combustion chamber is approximately 72 cc so if you put the standard 6.1 head on a 5.7 block that normally has a 85 cc chamber it will yield approximately 11.25:1 compression ratio which is too high for most street applications. With this and forced induction 6.1 engines in mind we came out with an optional large chamber 78.5 cc CNC?d chamber 6.1 head. This head will yield approximately a 10.4:1 compression ratio when used on a stock 5.7 block. The 6.1 head on the 5.7 engine is a good option for people that are looking to make over about 365-375 RWHP naturally aspirated with a 5.7 engine and contrary to popular belief our dyno testing has not shown a low RPM power loss with the ported 6.1 head vs the 5.7. Our testing has shown the ported 6.1 head to make between 10-15 more HP than the ported 5.7 head on a typically moded 5.7 engine.

Large chamber option on ported 6.1 head additional $150

We are working on large valve heads at the moment they would be 2.02 in/1.57 ex on the 5.7 and 2.10 int/1.62 on the 6.1 heads. I will get you a price on these as soon as I know. They are the Manley pro flow design.

This is a before and after showing the gains from a 6.1 cam and ported 5.7 heads on Rob (2 Avoids) truck. It lost some bottom end due to the cam. We could only run it to about 5300 because it kept shifting right at that point so the peak power normally is at about 5800 with this kind of combo but it still shows some pretty good power gains 38 RWHP would have been about 50 if we could have run it up to 6000 RPM

This is a dyno of the 6.1 heads and intake on a 5.7 engine 6.1 cam with a very rich a/f ratio (10.5:1) and a bad headder mismatch with the 6.1 exhaust port which can easily be taken care of with a die grinder. It made 368 HP. With a proper a/f and the mismatch corrected I bet it would have been around 390. We are recreating this one with a bit bigger cam on Scotts truck right now and should be running in a few day with it so I guess we will see.

5.7 with superchips and mid length headdars vs 6.1 cam, 6.1 intake, ported 5.7 heads with 6.1 port window, long tubes, dual exhaust.

**Price includes a $350 refundable core charge. Cores must be returned within 30 days.**