extended intake for more low end power

  • Thread starter Deleted member 12676
  • Start date
Pipe length

Did you know that the exhaust pipe length affects power also?
Look at this graph plotting changes in delivery ratio (.8 means the cylinder is filled 80% with air/fuel mixture which equates to engine power) and pipe length. It's from the same crankcase_volume pdf.
I measured my stock pipe to be 9" from cylinder to muffler.
Between 30 and 40 inches really boosts the delivery ratio for mid-range rpms and probably 20 inches would be best for high rpm power.
I'm going to start experimenting on pipes.
Also some airplane engines utilize straight pipes that slowly taper outward. They supposedly give the best power over the whole spread of engine rpms.
 

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Man I wanna revive this post! I have been looking to extend my intake as well just like everyone on this thread. I was told I can use heater hose 3/4” ID 1” OD for my extension. I am just looking to get a good boost at my low end but will my top end suffer a lot?
 
I doubt it would alter top end by much. Do it and see! You can always undo your change. That’s the value of this hobby: we are all experimenters and we can learn from others. Let us know your results. Thanks!
 
I doubt it would alter top end by much. Do it and see! You can always undo your change. That’s the value of this hobby: we are all experimenters and we can learn from others. Let us know your results. Thanks!
Alright will do thanks!
 
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Okay so I got the heater hosing and cut myself a 4.5” section of it just to test out first. I took a spare intake manifold and cut the mounting bracket off the end because Furry was correct there would not have been enough room for the hose clamps to bite onto. Here is how I currently have it rigged. I’ll have to cut a longer piece of fuel line to attach to the carb but I think it’s looking pretty good so far. Do you all see any issues with how it’s setup? The fuel line won’t be running downhill as much now is that alright? I have it zip tied to the frame for the moment just until I come up with the length of hose I’d like to use and then I’ll come up with a better way to stabilize the carb on the frame. And I’m not sure why my photos are posting sideways I’m sorry!
 
Ok, so, what would be an ideal intake length for a zeda 80 (ported, 40mm intake, 40mm stroke, 40mm exhaust), nt speed carb, 36t sprocket and a zeda 66 pipe for the 3k-8k rpm? Would it still be at the 8 inch total length?
 
You’ll just have to experiment! Start at about 4 1/2” and work up. You’ll hit a point of diminishing returns when your intake gets too long.
 
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