[Vwdiesel] Turbo vs. Non-turbo [was My TURBO test (more scientific)]

[Tyler "Casioqv" Backman]

Please correct me if I am wrong about any of the below. I have also
noticed another very significant difference above and beyond the
horsepower/torque increase when turbocharging a diesel, as I own 4
diesel vehicles, a turbo and non-turbo 6.2l suburban, and a turbo and
non-turbo 2.4l (VW engine) volvo. A turbocharged diesel responds much
more like a gasoline car, because the turbocharger spins up quicker than
the engine, and causes the motor to rev much more freely, and is able to
utilize more throttle without just converting the extra fuel to soot. On
a mechanically injected non-turbo diesel at lower rpms there is a point
(between half-full) throttle where more throttle just makes it smoke
more, but won't put out more power, because there is no more air. A
Turbo Diesel seems to produce maximum boost only at full throttle at
these rpms, and will therefore respond to the entire range of throttle
input, just like a gasoline engine with a throttle body. A non-turbo
diesel revs and responds so slowly, that I think under a light enough
load, a gasoline engine with less horsepower would outperform it, while
a turbo diesel responds much more like a normally aspirated gasoline
engine. A normally aspirated Volvo 2.4l Diesel puts out 80 horsepower,
while a Jetta TDI puts out 90, only 10 horsepower more, in cars that
both weigh about the same. The TDI feels like it has twice as much
power, while if they were both pulling heavy trailers and had to rev
very slowly, I would assume that the TDI would only be about 15% faster.
I wonder if that could account for some of the very low horsepower
readings on non-turbo diesels? Perhaps most dynometers cannot measure
the full torque of the diesel, because they do not put sufficent load on
the engine, and are being biased by the huge rotating mass and slow
combustion of the diesel engine. Anyway, other than cost I don't see any
good reason to not get a turbocharged diesel. It doesn't seem to affect
engine longevity with properly increased lubrication and cooling, the
turbos last virtually forever because of low exhaust temperature, and
they seem to get better fuel economy, especially under heavy load. Your
chances of getting rear-ended by a fully loaded semi truck climbing a
long grade are also greatly reduced ;)

-Tyler

Shawn Wright wrote:
> There is definitely a difference, so if you're not feeling it, perhaps your boost
> enrichment valve on the inj pump is not working. In this case, you should get about
> 59HP, which is the spec for the ECOdiesel, which was a TD without the boost
> enrichment. Your 1.6TD should see around 68HP, so a 15% gain in HP over the non-
> enriched 59HP should be noticeable.
> I know it is on my '85 Jetta 1.6TD - twice in the past 10 years I have forgotten replace
> the boost enrichment hose after having the VC off, and found I cannot climb our local
> mountain pass in 5th gear. With the hose on, I can easily climb the steepest part of
> the pass in 5th at around 100km/h. Until you try a steep climb, the difference may not
> be obvious though, as there is still a boost from the turbo, just not as pronounced
> without the extra fuel.