Was a great video, ill clean up the ports without enlarging them, keeping a somewhat rough texture on intake, will polish up the exhaust port. Video also talked about cleaning up the port but not so much changing the size, because port size is equally as important as these CFM numbers, because intake and exhaust velocity are crucial to efficient operation, and if you hog out a port, it kills velocity, which kills low end torque (but can see improvements on the high end). Seems like he spends about 3-5 seconds talking about "lowering the floor on the intake and raising the roof on the exhaust" but doesn't elaborate on it sadly. AKRA (racing) rules don't let you jack with it too much, hence the talk about dont touch the guide etc. Now from what I get in the video where the port transitions to the bowl, there are sharp edges that need to be blended into the bowl. 3-.5 hp increase in HP for the honda gx200 clone engines, or about a 7.6% increase is awesomeness, mainly found in the mid to high RPM range. A mild port job on the clone engines - according to ARC Racing video here: Okay, so the more I am learning about this, the more reserved I am going to be with material removal. I think I leave the intake at 80 grit, the chamber at 320 grit, and the exhaust as polished as I care to make it (which is also usually 320 grit - because I'm lazy).īelow is the exhaust port on the NR Racing Hemi Head. They start out kinda big and are tight in the port, but after a few minutes they get small enough to fit in some of tighter nooks. 180g, 280g, 320g abrasive finishing buffs. Ohhhh, I really like these for finishing up the exhaust and combustion chamber. Post added at 08:48 PM - Previous post was at 08:38 PM. I'll have to take their written word on that, I'd love to see if a valve job make noticeable HP difference on a DYNO or flow difference on a Bench. I've read that a good valve job also really helps the flow a bunch on these small engines.
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