Hi all,
Now that the 2019 steam show season is over, we have time to reflect on some lessons learned and re-learned.
Lesson Number One has to do with exhaust and power.
We all know that mufflers cause back pressure and restrict the flow of exhaust out of the engine. If we remove the muffler and 'let the engine breathe', we will get more power. Many motorcycle riders also claim, "Loud Pipes Save Lives."
Last summer (2018) at a show a young fellow came to the Blue Brake with an H International that had a straight pipe. I don't remember how much power we measured. After the run we started talking about mufflers, back pressure, cylinder filling and power. I commented that often times engines will produce more power with a muffler than without.
This year (2019) he brought the same H back. He had replaced the carb with one from an M and was using a K&N style paper air filter instead of the factory oil bath filter.The straight pipe was in place and he had a factory muffler with him. I thought with those two changes, maybe he will get more power with the straight pipe.
The results of the two runs are below.
Straight Pipe
Pounds . . RPM . . . Horsepower
50 . . . . 322 . . . 16.1
53 . . . . 317 . . . 16.8
55 . . . . 313 . . . 17.2
58 . . . . 309 . . . 17.9
60 . . . . 306 . . . 18.4
62 . . . . 295 . . . 18.3
65 . . . . 230 . . . 15
Muffler
Pounds . . RPM . . . Horsepower
50 . . . . 319 . . . 16
52 . . . . 314 . . . 16.3
55 . . . . 312 . . . 17.2
64 . . . . 313 . . . 20.0
70 . . . . 311 . . . 21.8
71 . . . . 302 . . . 21.4
75 . . . . 285 . . . 21.4
77 . . . . 267 . . . 20.6
When he entered the tractor pull later that weekend, he was running with the muffler.
Later,
Jerry Christiansen
Now that the 2019 steam show season is over, we have time to reflect on some lessons learned and re-learned.
Lesson Number One has to do with exhaust and power.
We all know that mufflers cause back pressure and restrict the flow of exhaust out of the engine. If we remove the muffler and 'let the engine breathe', we will get more power. Many motorcycle riders also claim, "Loud Pipes Save Lives."
Last summer (2018) at a show a young fellow came to the Blue Brake with an H International that had a straight pipe. I don't remember how much power we measured. After the run we started talking about mufflers, back pressure, cylinder filling and power. I commented that often times engines will produce more power with a muffler than without.
This year (2019) he brought the same H back. He had replaced the carb with one from an M and was using a K&N style paper air filter instead of the factory oil bath filter.The straight pipe was in place and he had a factory muffler with him. I thought with those two changes, maybe he will get more power with the straight pipe.
The results of the two runs are below.
Straight Pipe
Pounds . . RPM . . . Horsepower
50 . . . . 322 . . . 16.1
53 . . . . 317 . . . 16.8
55 . . . . 313 . . . 17.2
58 . . . . 309 . . . 17.9
60 . . . . 306 . . . 18.4
62 . . . . 295 . . . 18.3
65 . . . . 230 . . . 15
Muffler
Pounds . . RPM . . . Horsepower
50 . . . . 319 . . . 16
52 . . . . 314 . . . 16.3
55 . . . . 312 . . . 17.2
64 . . . . 313 . . . 20.0
70 . . . . 311 . . . 21.8
71 . . . . 302 . . . 21.4
75 . . . . 285 . . . 21.4
77 . . . . 267 . . . 20.6
When he entered the tractor pull later that weekend, he was running with the muffler.
Later,
Jerry Christiansen