02-21-2008, 12:34 AM
|
#1 (permalink)
|
Batman Junior
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,527
Thanks: 4,078
Thanked 6,976 Times in 3,612 Posts
|
Article: adding a turbo to improve efficiency
Yet another good AutoSpeed article: Turbo'd for Fuel Economy - The way of the near future
A good overview of the issues around turbocharging.
The writer compares two 2.0 VW motors, one normally aspirated, the other turbo, and concludes:
Quote:
In the comparison shown above of the two 2-litre engines, the turbo engine has better fuel economy, better CO2 emissions, 50 per cent more bottom-end power and 34 per cent more top-end power.
|
Of course, to gain the most from the lower end torque, you really need better gearing.
|
|
|
Today
|
|
|
Other popular topics in this forum...
|
|
|
02-21-2008, 12:50 AM
|
#2 (permalink)
|
I'd rather be biking
Join Date: Feb 2008
Location: New Orleans, LA, US Minor Outlying Islands
Posts: 127
Thanks: 0
Thanked 4 Times in 4 Posts
|
A turbo is definitely high on my wish list.
Quote:
Of course, to gain the most from the lower end torque, you really need better gearing.
|
Not exactly. You'll still be taking advantage of the increased low end grunt while accelerating, which is when most of your high fuel consumption rates are. You can shift at 2k and get good acceleration.
Of course, having higher gears would add even more benefit.
__________________
My bike runs on dihydrogen monoxide.
I like to use these acronyms
|
|
|
02-21-2008, 01:29 AM
|
#3 (permalink)
|
MP$
Join Date: Jan 2008
Location: SW Ohio
Posts: 595
Thanks: 5
Thanked 19 Times in 14 Posts
|
good article, i noticed that they never did actually tell you that when your going 0 to 60 in 7 seconds, that you are getting terrible mileage.
|
|
|
02-21-2008, 01:45 AM
|
#4 (permalink)
|
nut
Join Date: Dec 2007
Location: Southen West Virginia
Posts: 654
Thanks: 0
Thanked 37 Times in 26 Posts
|
I think most of the gains they got in mileage is from the gearing. The turbo just let the higher geared car drive more like a normal car. If they can find identical cars one with a turbo and one without there probably wont be any difference.
Adding a turbo to a car and not changing gearing or going to a smaller motor is not going to help anything but acceleration really. Kind of a similar problem of doing aero mods and not changing gearing. The engine load decreases but the rpms are high enough you are still using a lot more gas than you really need to.
|
|
|
02-21-2008, 12:17 PM
|
#5 (permalink)
|
MP$
Join Date: Jan 2008
Location: SW Ohio
Posts: 595
Thanks: 5
Thanked 19 Times in 14 Posts
|
Quote:
Originally Posted by Coyote X
I think most of the gains they got in mileage is from the gearing. The turbo just let the higher geared car drive more like a normal car. If they can find identical cars one with a turbo and one without there probably wont be any difference.
Adding a turbo to a car and not changing gearing or going to a smaller motor is not going to help anything but acceleration really. Kind of a similar problem of doing aero mods and not changing gearing. The engine load decreases but the rpms are high enough you are still using a lot more gas than you really need to.
|
"or going to a smaller motor"
that i would like to see, two engines same power, one NA, and one turbo'd.
that would be interesting, OK who wants to do it?
PS. power and economy are usually inverse.
Last edited by diesel_john; 02-21-2008 at 12:54 PM..
|
|
|
02-21-2008, 12:35 PM
|
#6 (permalink)
|
Batman Junior
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,527
Thanks: 4,078
Thanked 6,976 Times in 3,612 Posts
|
Oh, and let's not forget Autospeed's series on " The Story of Turbo'ing a Hybrid Prius" (1st gen. model.)
Where the author concludes:
Quote:
So it’s been lots of work and there have been a helluva lot of problems to overcome along the way – but now, finally, what’s the turbo Prius like on the road?
In a word – fantastic.
The turbo NHW10 Prius now has better than standard fuel economy. And performance? Well, the key aim has been realised – country road hill-climbing performance has been completely transformed.
|
He points out that, not surprisingly, the car's CVT contributes to the gains because it permits the revs to stay lower for a given road speed.
Parts 1 through 5:
http://www.autospeed.com/cms/A_2658/article.html
http://www.autospeed.com/cms/A_2659/article.html
http://www.autospeed.com/cms/A_2660/article.html
http://www.autospeed.com/cms/A_2661/article.html
http://www.autospeed.com/cms/A_2664/article.html
---
I'm vaguely aware of a couple of Honda Insights that have also been turbocharged.
|
|
|
02-21-2008, 01:33 PM
|
#7 (permalink)
|
EcoModding Lurker
Join Date: Feb 2008
Location: SF Bay Area
Posts: 6
Sippy - '07 Toyota Prius Package #6 90 day: 45.58 mpg (US)
Thanks: 0
Thanked 0 Times in 0 Posts
|
The turbocharger itself modifies the thermodynamic cycle of the engine and increases efficiency.
|
|
|
02-21-2008, 01:49 PM
|
#8 (permalink)
|
Banned
Join Date: Feb 2008
Location: california
Posts: 1,329
Thanks: 24
Thanked 161 Times in 107 Posts
|
Quote:
Originally Posted by Coyote X
I think most of the gains they got in mileage is from the gearing. The turbo just let the higher geared car drive more like a normal car. If they can find identical cars one with a turbo and one without there probably wont be any difference.
Adding a turbo to a car and not changing gearing or going to a smaller motor is not going to help anything but acceleration really. Kind of a similar problem of doing aero mods and not changing gearing. The engine load decreases but the rpms are high enough you are still using a lot more gas than you really need to.
|
You can change mileage without changing gearing. The whole point of the article is to point out that a turbo will increase low end torque therefore the driver can upshift much earlier while maintaining the same acceleration. The 97 Volvo 850 is a good example of this. The non turbo 850 produces 168lb/ft at 4700rpm while the low pressure turbo produces 190lb/ft between 1800-5000rpm. While the fuel economy between the automatics is identical (LPT was only offered with auto in US) a manual trans car would give you the ability to upshift at much lower rpm.
|
|
|
02-21-2008, 02:01 PM
|
#9 (permalink)
|
Batman Junior
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,527
Thanks: 4,078
Thanked 6,976 Times in 3,612 Posts
|
I'll go out on a limb and say that while the ability to upshift sooner while accelerating is good, it's going to have a very small impact on overall fuel consumption, simply because we spend so little time accelerating, vs. time spent cruising (assuming you're not pulsing & gliding).
So unless you're driving a garbage truck or mail delivery route, better gearing matched to the turbo's good low end torque is what will return the largest fuel economy improvement.
|
|
|
02-21-2008, 02:03 PM
|
#10 (permalink)
|
Administrator
Join Date: Dec 2007
Location: Germantown, WI
Posts: 11,203
Thanks: 2,501
Thanked 2,587 Times in 1,554 Posts
|
I'm going to second Metro's comments and agree with Coyote X. Turboing increases power density. That will allow small gains if you can take advantage of increased low rpm power. However, the main gains are from regearing and using a smaller engine.
|
|
|
|