05-29-2018, 09:47 PM
|
#1 (permalink)
|
|
Cyborg ECU
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,299
Thanks: 2,373
Thanked 2,174 Times in 1,470 Posts
|
Potato power
"Spherical back pressure oscillation" he calls it. I would post this in the lounge or the unicorn corral but he has it on a dyno, so it must be science! 
I looked it up in the Google without much success. Something called the Helmholtz effect comes up, but it seems unrelated.
__________________
See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.
|
|
|
|
|
The Following 2 Users Say Thank You to California98Civic For This Useful Post:
|
|
 Today
|
|
|
|
Other popular topics in this forum...
|
|
|
|
|
05-30-2018, 03:02 AM
|
#2 (permalink)
|
|
Master EcoModder
Join Date: Aug 2010
Location: Philippines
Posts: 2,173
Thanks: 1,739
Thanked 589 Times in 401 Posts
|
That was mighty fun. And funny.
It's likely that the straight pipe is a bit too big, and adding the potato increases the exhaust velocity at the tip, allowing for quicker exhaust flow.
But the rest of the results, 49.9 to 51.6 kw is not a big difference, and without A-B-A testing, it could simply be an old motor shaking the cobwebs out on successive runs... especially if the previous owner never really revved it out.
|
|
|
|
|
The Following User Says Thank You to niky For This Useful Post:
|
|
|
05-30-2018, 06:06 AM
|
#3 (permalink)
|
|
Not Doug
Join Date: Jun 2012
Location: Show Low, AZ
Posts: 12,240
Thanks: 7,254
Thanked 2,233 Times in 1,723 Posts
|
|
|
|
|
|
06-01-2018, 09:16 AM
|
#4 (permalink)
|
|
EcoModding Lurker
Join Date: Oct 2017
Location: Virgina
Posts: 19
Thanks: 3
Thanked 1 Time in 1 Post
|
Will I make more power with a cannon on my car?
That'll be a rocket car.
|
|
|
|
|
06-03-2018, 04:04 AM
|
#5 (permalink)
|
|
Master EcoModder
Join Date: Aug 2012
Location: northwest of normal
Posts: 28,719
Thanks: 8,151
Thanked 8,933 Times in 7,375 Posts
|
One run per modification is a small sample size.
They should've tried the potato half-in and half-out of the tail pipe. Or in a bellmouth.
__________________
.
.Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster
____________________
.
.Three conspiracy theorists walk into a bar --You can't say that is a coincidence.
|
|
|
|
|
The Following User Says Thank You to freebeard For This Useful Post:
|
|
|
06-03-2018, 12:09 PM
|
#6 (permalink)
|
|
Cyborg ECU
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,299
Thanks: 2,373
Thanked 2,174 Times in 1,470 Posts
|
Totally, freebeard. In a way, their potato test might prove tha their methods are not reliable more than anything about "spherical oscillation" or whatever. In general their approach to testing needs more thought about sample size, mods, and what sorts of gains "count". I like some of their stuff a lot, but if it is not a giant gain from a single mod, Moog in particular seems unable to see the point.
__________________
See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.
|
|
|
|
|
06-03-2018, 12:49 PM
|
#7 (permalink)
|
|
Master EcoModder
Join Date: Aug 2010
Location: Philippines
Posts: 2,173
Thanks: 1,739
Thanked 589 Times in 401 Posts
|
Yeah. I would've expected at least three runs, then a final "back to stock" set at the end to check.
You can get a variance of one or two kW in successive runs with nothing done to the motor in between.
|
|
|
|
|
06-05-2018, 07:02 PM
|
#8 (permalink)
|
|
Master EcoModder
Join Date: Feb 2010
Location: Elmira, NY
Posts: 1,790
Thanks: 320
Thanked 360 Times in 299 Posts
|
LOL I sold truck parts to potato farms for a decade. What a moving obstruction does is alter the effective length of the pipe. The timing of the reflected exhaust pulse can be used to tune the scavenging. So the trick is to move the reflection point to match the instantaneous RPM. A stainless steel potato and a linear motor.. oh bother.
|
|
|
|
|
06-06-2018, 12:10 AM
|
#9 (permalink)
|
|
Master EcoModder
Join Date: Aug 2012
Location: northwest of normal
Posts: 28,719
Thanks: 8,151
Thanked 8,933 Times in 7,375 Posts
|
If you used a mild steel potato it would weather to a nice Russet brown. 
__________________
.
.Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster
____________________
.
.Three conspiracy theorists walk into a bar --You can't say that is a coincidence.
|
|
|
|
|
06-22-2018, 03:28 AM
|
#10 (permalink)
|
|
EcoModding Lurker
Join Date: Jan 2018
Location: Atlanta, GA
Posts: 27
Thanks: 2
Thanked 2 Times in 2 Posts
|
Fascinating stuff though.
|
|
|
|
|
