DC Performance does it again! Over the past year we have been looking very closely at the Gen 4 Viper engine. With superchargers, turbochargers and big engine builds not practical or economical for most customers with this new engine, we were looking for another 100hp without major internal modifications.
The production bottom end on these Gen 4's has proven very stout with good tri-metal bearings, ARP rod bolts and decent rods. The only limiting factor has been the pistons, so we did not want to increase the piston speed or compression. Another big consideration is the sensitive engine computer, the Venom engine controller is very sensitive to mechanical engines changes and we did not want any check engine lights or "limp" in conditions.
Our performance gains with exhaust and intake modifications have worked really well, the final step for the 100hp gains would need to be in the heads.
With changes to the VVT, cam and compression not viable options, we focused on the cylinder. There has been quite a bit of technology in cylinder head testing with wet flow benches and injector spray pattern analysis, so we thought a good look at the heads would yield some big power gains.
Our big focus on a head modification was to maximize air-velocity through the primary choke area of the intake and exhaust ports. Engines runs on velocity and not just cfm numbers. The area under the seat is critical and can be improved dramatically.
With our ported heads done and ready to test, our next concern was clamp load on the head and block. We wanted to do everything possible to keep the bore straight. The production head bolts are inexpensive and are borrowed from the passenger car line, so we opted for an ARP bolt set to finish off our package.
Our last concern was oil pull through in to the intake manifold from the PCV system. These engines are very sensitive to knock. On many engines that we tested, we have data-logged the knock control and found the computer retarding timing. This hurts power and can lead to piston issues. Oil in the intake and related carbon deposits increase knock (detonation). Our solution was a air-oil canister that does not allow the oil to migrate into the manifold.
Our testing was done on a 2008 Viper with Belanger headers and exhaust, Arrow intake and Mopar controller. Gains were 30-32rwhp in an AB test. Futher testing with our intake and better fuel added another 7rwhp. Air fuel was very safe and no check engine lights or "limp in" conditions were encountered.
For those of you who want the most from your Gen 4 Viper engine with good reliabilty, this is THE option! I will be posting dyno sheets, videos and pricing this week!