Go Back   EcoModder Forum > EcoModding > The Unicorn Corral
Register Now
 Register Now
 


Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 10-17-2015, 01:30 AM   #1 (permalink)
EcoModding Lurker
 
Join Date: Oct 2015
Location: Great White North
Posts: 9
Thanks: 1
Thanked 2 Times in 1 Post
Exhaust valves

There is some merit to this although it's effect on mileage has yet to be credibly tested but here it is; exhaust valves create backpressure at low RPM's (when the engine is cycling smaller volumes of exhaust per minute) but open to allow full use of the cavernous exhaust pipe, it allows the engine to get a small bump in hp lower in the rev range, my question is has anybody tried exhaust valves to nurse the engine during acceleration at lower speeds for the purposes of mileage/fuel-conservation? I intend to give this a go on my next vehicle but would like to know what others know/have experienced about this subject.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 10-17-2015, 04:12 PM   #2 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 16,225
Thanks: 24,372
Thanked 7,354 Times in 4,754 Posts
exhaust valves

Quote:
Originally Posted by GreenSquirrel View Post
There is some merit to this although it's effect on mileage has yet to be credibly tested but here it is; exhaust valves create backpressure at low RPM's (when the engine is cycling smaller volumes of exhaust per minute) but open to allow full use of the cavernous exhaust pipe, it allows the engine to get a small bump in hp lower in the rev range, my question is has anybody tried exhaust valves to nurse the engine during acceleration at lower speeds for the purposes of mileage/fuel-conservation? I intend to give this a go on my next vehicle but would like to know what others know/have experienced about this subject.
At least one production motorcycle incorporated a 'smart' muffler which had a computer-controlled butterfly valve inside.
The motorcycle engine underwent a full-spectrum dynamometer test to evaluate it's best performance at all rpm's as a function of exhaust back-pressure,then a look-up menu was burned into the ROM chip which allowed the computer to modulate a servo motor linked to the muffler's valve; enabling the engine to always remain in the sweet-spot.
If you've got a loose $100,000 you want to throw at a chassis dyno,you'd be able to do this to your car.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
The Following User Says Thank You to aerohead For This Useful Post:
niky (10-18-2015)
Old 10-17-2015, 04:35 PM   #3 (permalink)
Master EcoModder
 
Join Date: Nov 2012
Location: San Diego, California
Posts: 982
Thanks: 271
Thanked 385 Times in 259 Posts
Or you can use in-cylinder pressure sensors.

Quote:
Originally Posted by aerohead View Post
At least one production motorcycle incorporated a 'smart' muffler which had a computer-controlled butterfly valve inside.
The motorcycle engine underwent a full-spectrum dynamometer test to evaluate it's best performance at all rpm's as a function of exhaust back-pressure,then a look-up menu was burned into the ROM chip which allowed the computer to modulate a servo motor linked to the muffler's valve; enabling the engine to always remain in the sweet-spot.
If you've got a loose $100,000 you want to throw at a chassis dyno,you'd be able to do this to your car.
For roughly 10,000 USD, you can purchase an array of pressure sensing spark plugs and the attendant data logging. A set of well thought out acceleration runs will get you most of what you desire.

If you are doing a single cylinder engine, you can purchase the sensing spark plug for about $1K and cludge your own data logger using slower commonly available electronics and do multiple cycle overlays.

But, that's just what I would do.
  Reply With Quote
The Following 3 Users Say Thank You to RustyLugNut For This Useful Post:
aerohead (10-21-2015), oldtamiyaphile (10-17-2015), pgfpro (10-21-2015)
Old 10-18-2015, 10:02 PM   #4 (permalink)
Master EcoModder
 
Join Date: Aug 2010
Location: Philippines
Posts: 2,173
Thanks: 1,739
Thanked 589 Times in 401 Posts
You could actually do the same thing with a piggyback chip like the UniChip-Q, to which you can add auxiliary maps to precisely control things like extra injectors, nitrous and even a flapper valve.

Just tune it once on the dyno, you're done.
  Reply With Quote
The Following User Says Thank You to niky For This Useful Post:
aerohead (10-21-2015)
Old 10-21-2015, 04:10 PM   #5 (permalink)
EcoModding flying lizard
 
Daschicken's Avatar
 
Join Date: May 2012
Location: Georgia
Posts: 743

Cibbie - '88 Honda CBR 250R
Motorcycle
90 day: 48.49 mpg (US)

Rarity - '06 Honda Accord EX V6
Team Honda
90 day: 29.88 mpg (US)

Baby viff - '86 Honda VFR 400R
Motorcycle
90 day: 42.15 mpg (US)

Latios - '08 Suzuki SV650SF
Motorcycle
90 day: 64.56 mpg (US)

Mazda 3 - '14 Mazda 3 i Sport
90 day: 43.25 mpg (US)
Thanks: 618
Thanked 263 Times in 175 Posts
Quote:
Originally Posted by aerohead View Post
At least one production motorcycle incorporated a 'smart' muffler which had a computer-controlled butterfly valve inside.
The motorcycle engine underwent a full-spectrum dynamometer test to evaluate it's best performance at all rpm's as a function of exhaust back-pressure,then a look-up menu was burned into the ROM chip which allowed the computer to modulate a servo motor linked to the muffler's valve; enabling the engine to always remain in the sweet-spot.
If you've got a loose $100,000 you want to throw at a chassis dyno,you'd be able to do this to your car.
My grandpa's 1999 yamaha r1 had an exhaust butterfly valve, but I doubt it was computer controlled as the thing had carbs. Although it did have a MIL system that had codes for the exhaust valve, so it could be.
__________________
-Kaze o tatakaimasen-

Best trip in V6: 52.0
Best tank in V6: 46.0
Best tank in Mazda: 49.9
Best tank in CBR: 61.3
Best tank in SV: 83.9

Quote:
Originally Posted by MetroMPG View Post
You can lead a fashion-conscious horse to unusual-looking water...

  Reply With Quote
The Following User Says Thank You to Daschicken For This Useful Post:
aerohead (10-21-2015)
Old 10-21-2015, 04:59 PM   #6 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 16,225
Thanks: 24,372
Thanked 7,354 Times in 4,754 Posts
in-cylinder sensor

Quote:
Originally Posted by RustyLugNut View Post
For roughly 10,000 USD, you can purchase an array of pressure sensing spark plugs and the attendant data logging. A set of well thought out acceleration runs will get you most of what you desire.

If you are doing a single cylinder engine, you can purchase the sensing spark plug for about $1K and cludge your own data logger using slower commonly available electronics and do multiple cycle overlays.

But, that's just what I would do.
The thing about the dyno though,is that you can get BSFC data as you go,which is of great importance,and a dyno's the only place to scientifically acquire the data directly that I'm aware of.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Old 10-21-2015, 06:28 PM   #7 (permalink)
Master EcoModder
 
Join Date: Nov 2012
Location: San Diego, California
Posts: 982
Thanks: 271
Thanked 385 Times in 259 Posts
On-road data collection.

Quote:
Originally Posted by aerohead View Post
The thing about the dyno though,is that you can get BSFC data as you go,which is of great importance,and a dyno's the only place to scientifically acquire the data directly that I'm aware of.
It is used daily in industry. Lay people see it as "unscientific and variable". Granted, the lab dyno does allow control of certain variables, however, in the case of exhaust back pressure versus load and fuel use, all one needs is a set of accurately mapped fuel injectors/pump for fuel flow and an in-cylinder pressure sensor to see power potential as well as an exhaust pressure sensor and position sensor on your exhaust backpressure valve.

A baseline run followed by a set exhaust valve run yields a pair of pressure traces that allow you to determine a gain or loss. No need to calculate BSFC as combustion pressure is all the feedback you need. A pair of runs takes 5 minutes or less. A well thought out set of runs can yield a reasonably extrapolated pressure map with which to program an engine map.

Again, there is no need to carry the burden of a dyno cell instrument set. In-cylinder pressure will tell you if the exhaust back pressure is beneficial or detrimental. I would probably add a stepper actuator to the exhaust back pressure valve to make "fanning" the back pressure during runs possible. This reduces the number of runs during your data gathering.

Last edited by RustyLugNut; 10-21-2015 at 06:30 PM.. Reason: Spelling
  Reply With Quote
The Following User Says Thank You to RustyLugNut For This Useful Post:
aerohead (11-28-2015)
Old 10-21-2015, 09:09 PM   #8 (permalink)
...beats walking...
 
Join Date: Jul 2009
Location: .
Posts: 6,190
Thanks: 179
Thanked 1,525 Times in 1,126 Posts
...or, you can buy software programs that simulate just about 100%-functions of an engine in operation...at any load...under any weather conditions.
  Reply With Quote
The Following User Says Thank You to gone-ot For This Useful Post:
aerohead (11-28-2015)
Old 10-21-2015, 09:20 PM   #9 (permalink)
Master EcoModder
 
Join Date: Nov 2012
Location: San Diego, California
Posts: 982
Thanks: 271
Thanked 385 Times in 259 Posts
This.

Quote:
Originally Posted by Old Tele man View Post
...or, you can buy software programs that simulate just about 100%-functions of an engine in operation...at any load...under any weather conditions.
None of the software programs found at your corner bookstore will be able to do the job, but there are several commercially available programs that would allow you to do most of your ballpark work. Of course, there is the issue of computational power. Some titles need a Cray class computer to run on, while others can run on lesser mainframes or desktops though with very slow results. And in the end, you must vet your model with actual data.
  Reply With Quote
The Following User Says Thank You to RustyLugNut For This Useful Post:
aerohead (11-28-2015)
Old 10-22-2015, 03:20 AM   #10 (permalink)
Not Doug
 
Xist's Avatar
 
Join Date: Jun 2012
Location: Show Low, AZ
Posts: 12,230

Chorizo - '00 Honda Civic HX, baby! :D
90 day: 35.35 mpg (US)

Mid-Life Crisis Fighter - '99 Honda Accord LX
90 day: 34.2 mpg (US)

Gramps - '04 Toyota Camry LE
90 day: 35.39 mpg (US)

Don't hit me bro - '05 Toyota Camry LE
90 day: 30.49 mpg (US)
Thanks: 7,254
Thanked 2,229 Times in 1,719 Posts
Aerohead, do you remember approximately what kind of a difference that setup made for that motorcycle?

  Reply With Quote
Reply  Post New Thread






Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com