Hopefully by this point, you have watched our other Mahindra Roxor ECU and dyno testing videos. To continue our product development, we wanted to see how the turbo diesel engine acts with no exhaust restrictions. Our Agency Power turbo back exhaust did not yield huge gains like you would see on a turbo gas engine. The small power gains result from a small turbocharger and small displacement. As with all product development, it requires lots of testing. The Roxor didn’t see big power gains with our Agency Power exhaust, but an even larger diameter exhaust might show greater power gains.
To see if exhaust pipe diameter was or wasn’t a factor, we created two test products to compare to our previous results. Exhaust performance is a balance between flow and scavenging, and diameter effects both of which. To see if diameter makes a measurable difference in power on the Roxor, we built two turbo-dump exhausts: one 2.5″ and one 3″. By comparing the two different sized exhaust turbo dumps to the Agency Power exhaust and the stock exhaust, we can see if size matters.
2.5″ Dumped Exhaust Testing
Most exhaust systems include one or more muffler/resonators to tone down the sound and the exhaust is routed to the rear of the vehicle. With a dumped exhaust, there are no mufflers, and the exhaust is not routed to the rear of the vehicle. This design provides the most flow and least restriction possible, but it’s loud.
Once we fired the Roxor up with the 2.5″ dump, it greeted us with some exhaust soot and lots of turbo noise. As our dyno testing showed, the Agency Power 2.25″ exhaust and the 2.5″ dump exhaust made no difference in power when compared to each other. When overlaying the dyno graphs, they are nearly the same throughout the power-band. Now we knew the 2.5″ dumped exhaust made virtually no power difference, it was time to test the 3″ dumped exhaust.
3″ Dumped Exhaust Testing
We knew if the 3″ dumped exhaust made the same power as the 2.5″ dumped exhaust, restriction wasn’t an issue. Just as before, the dumped exhaust was very loud and produced a bit of exhaust soot. We put the Roxor on the dyno and began our 3″ dumped exhaust testing. Interestingly, the 3″ dumped exhaust made slightly more power than the 2.5″ dumped exhaust. The power difference was tiny (around 1hp), but it was still a measurable difference.
Summary
The tiny difference in power between all the difference sized exhaust systems means aftermarket Roxor exhaust systems will be designed for a great sound rather than an increase in horsepower. With a larger turbo the diameter of the exhaust might become more important, but diameter doesn’t really matter for a Roxor with a stock turbocharger. Be sure to check out the video below!
