The folks at Berk were kind enough to refiddle their exhaust to fit the big VT muffler. Brian at Berk actually got it to fit under the tight confines of the G35, barely. We then proceeded to do a post install dyno test at our home shop Technosqaure's Superflow chassis dyno.
|We used Technosquare's Superflow chassis dyno to test the muffler. We first did a baseline on the car then switched the center resonator with the Dynomax VT muffler.|
The dyno results were interesting. Below 4300 rpm, the G35 VQ35 made about 4 more hp. This is probably the result of more back pressure at low rpm when the muffler flapper valve is closed which can sometimes help low end power. From 4300 rpm to around 4800 rpm, the power level stayed about the same as the straight though Berk exhaust.
From 4800 to 6100 rpm the muffler made 3-4 hp less than the standard Berk system peaking at about 1 less hp peak and roughly the same power to the fuel cut. We think that perhaps the flap is not open fully until 6100 rpm, hence the power loss. It’s probably not so much a backpressure issue but a loss of exhaust gas column velocity and scavenging until the flapper door opens and the straight exhaust gas path improves velocity.
|Technosquare's Howard Watanabe and Mike Kojima testing the G35 with the Dynomax VT muffler.|
We feel that on a forced induction motor or a larger displacement motor the zone of reduced power would be in a narrower band as the additional flow would open the flapper door sooner.
The most impressive thing about the VT muffler was how quiet it was. The muffler literally quieted down the big 3” exhaust to near the level of the stock G35, especially when driving at highway speed and within Frank's dreaded drone zone. The irritating drone was 100% gone. At wide open throttle the exhaust note was mildly performance sounding while still being pretty darned quiet. We think that perhaps if we experimented with a smaller muffler case volume we might have improved upon the zone of power loss, but we would have traded off some quietness.
We also think that the power loss zone will be much more narrow on a turbo engine that is less gas column velocity sensitive. Turbo engines are purely responsive to back pressure due to the effect of the turbine in the exhaust stream. The VT muffler is an awesome piece to have in the book of tricks when you need power and unparalleled quietness. Even though we lost a little bit of mid range power, please note this is over a 3” core straight through perforated core muffler, which essentially is a straight through pipe. The VT muffler will probably easily out power any baffled performance muffler on the market.
|The dyno results were interesting, a slight gain in bottom end power, a slight loss in the mid range and almost the same top end. We think that the mid range loss is due to the valve opening and causing turbulence and a loss of exhaust gas column velocity while the valve is part open. When you consider that the Dynomax VT replaced a 3″ core straight through perforated core muffler the results are not too shabby considering that the VT is only slightly louder than stock!|
Frank is now happy, his wife is happy and his darling baby girl is happy. We no longer have to worry about him unleashing his doom self- destruct code on us so ultimately you readers will be happier as well. Oh yeah, this muffler does have bearings…