Article: adding a turbo to improve efficiency

[Cowspots]

Gentlemen,

A little FYI here for you.

One Variable Vane Turbo Diesel in the US was all Volkswagen TDI from '99 to '06. I believe Mercedes and Jeep Liberty Diesels also employ this technology; however, Jeep and VW diesels are no longer in production for the US market due to new for '07 particulate and NOx emissions standards. The Dodge Sprinter Van uses a Mercedes VNT TD and is currently in production.

I owned an '02 Jetta TDI with the VNT Turbo Diesel and had it boosted up to 18psi with Upsolute re-maping of the fuel curve. It rocked! Smoked the tires, did 130mph and then you could get 53mpg with high cetane diesel.

In 1990 VW launched the Corrado G60 which was a gasoline-powered, Comprex Pressure Wave Supercharged, fuel injected, 4-cylinder engine. I work with a woman that owns one. She just got it running again this Winter as parts are rare.

Goodnight,
Cowspots

[tasdrouille]

Originally Posted by Cowspots

[...]One Variable Vane Turbo Diesel in the US was all Volkswagen TDI from '99 to '06.[...]

It's a detail but the MKIV Jetta started as a '99.5 model. I have a '99 MKIII Jetta TDI, pretty rare, with a wastegated KKK03 turbo.

[Cowspots]

Tas,

You are correct on the 99.5 TDI info. I was just being lazy on that little VW TDI detail, but that was actually a mid year introduction. Insurance companies don't seem to care though. It's just a little VW marketing trick like building 2006 TDI's way past the normal model year cutoff date to avoid complying with the 2007 emissions laws. I understand that both VW hybrid technology and VW diesels will arrive by late '09 as 2010 models. VW also has a turbocharged & supercharged, direct fuel injected gas engine lurking about out there. It has the power of a six with the economy of a three. It electrically shuts off the supercharger when turbo boost builds. Kinda reminds me of Mad Max! I'm not sure if it ever made it here to the US.

I have a DC Motor and a small regenerative air compressor to experiment with some day on my Metro 3-cyl.

THX!
Cowspots

[tjts1]

[steensn]

Did anyone come to a conclusion whether putting a turbo on you hypermilling car would be a benifit? Even if it is a couple percentage points, isn't this a sport where everry little thing counts?

[Daox]

It will increase fuel economy IF it is tuned for fuel economy.

[JohnnyGrey]

From fueleconomy.gov

02 Jetta:
2.0L 5spd
Regular fuel
21/28mpg
Cost to drive 25 Miles: $3.76

07 Jetta
2.0L 6spd Turbocharged
Premium fuel
21/29mpg
Cost to drive 25 Miles: $4.00

Sorry, but that article is full of crap. Turbochargers allow for more power out of smaller engines. If you turbocharge the same size engine, you'll get more power out of it. To get more economy, you'll have to pick a smaller engine and turbocharge that. Then you have to ensure that doing so improves economy enough that cost per mile is significantly lower than the N/A engine despite the premium fuel requirement. Also, you can expect reduced longevity from the turbo motor.

[Daox]

You can increase fuel efficiency by turboing an engine of the same size. The gains will definitly not be as large as going to a smaller engine, but there are gains to be had. It may not be worth the money of course.

For example, lets use this BSFC chart from a 1.9L Saturn engine.


With a turbocharger, you could vastly increase low end torque and widen the peak BSFC area to much lower rpms. This would necessitate a different type of tuning system than what is conventionally used on turbocharged engines. The system would aim for peak torque while keeping the engine in closed loop always. This would require a way to dynamically alter boost pressure based on rpm and load (hey, I never said it would be easy). This would allow you to always have optimal cylinder pressures. The only variable left really would be RPM (more specifically piston speed).

[JohnnyGrey]

With a turbocharger, you could vastly increase low end torque and widen the peak BSFC area to much lower rpms. This would necessitate a different type of tuning system than what is conventionally used on turbocharged engines. The system would aim for peak torque while keeping the engine in closed loop always. This would require a way to dynamically alter boost pressure based on rpm and load (hey, I never said it would be easy). This would allow you to always have optimal cylinder pressures. The only variable left really would be RPM (more specifically piston speed).

You don't want more low end torque for economy. Most cars can cruise just fine in top gear. If you aim for peak torque, you'll be doing 90mph on most cars before long. Most of us can't take advantage of peak efficiency, because it causes us to cruise at aerodynamically inefficient speeds. A turbo does nothing to solve this problem.

[tasdrouille]

Originally Posted by Daox

You can increase fuel efficiency by turboing an engine of the same size. The gains will definitly not be as large as going to a smaller engine, but there are gains to be had. It may not be worth the money of course.

For example, lets use this BSFC chart from a 1.9L Saturn engine.


With a turbocharger, you could vastly increase low end torque and widen the peak BSFC area to much lower rpms. This would necessitate a different type of tuning system than what is conventionally used on turbocharged engines. The system would aim for peak torque while keeping the engine in closed loop always. This would require a way to dynamically alter boost pressure based on rpm and load (hey, I never said it would be easy). This would allow you to always have optimal cylinder pressures. The only variable left really would be RPM (more specifically piston speed).

Here's a pic showing what turbocharging does. It's clear from this pic that downsizing it the way to go, but there are still some gains available in some regions for same displacement. It's just a generic pic as results can vary a lot depending on the turbo used, but you get the big picture.