Aaron
DC Performance does it again! One of our good clients brought us his ACR to upgrade his intake manifold and upgrade to our Supertuned Stage 4 engine package which includes our high velocity ported cylinder heads and intake manifold. Our customer tracks his car on the weekends and this is a great power upgrade for his setup.
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 7 rear wheel horsepower. Air fuel was very safe and no check engine lights or “limp in” conditions were encountered.
Our criteria for testing was very controlled, each test was performed at the same engine coolant temp and heat soak. Our initial test was a before and after test of the heads. The only variables other than the head change was the removal of carbon from the piston tops, new plugs and an oil-air separator for the PCV system.
Initial Test with Ported Heads:
34 hp and 26 lb-ft torque
Next test was to remove the Arrow intake and install our ported intake.
Ported Heads + Intake:
5 hp and 6 lb-ft torque (increase on top of Ported Heads)
Our final test was to raise the octane level to about 95
Ported Heads + Intake + Octane:
3 hp and 7 lb-ft torque (increase on top of Ported Heads and Intake)
For those of you who want the most from your Gen 4 Viper engine with good reliabilty, this is THE option! Please feel free to call us with any questions you may have. I am always available via PM.
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