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

[James Hansen]

> > Accelerating quicker does not save energy. Period.
>
> It does if you are accelerating quicker on energy that would otherwise
> be wasted.

Lol! okay, okay.  It never happens in the land of boost enrichment, but for
the sake of argument, yes.


> I am sure your
> jetta gets better fuel economy, I get 36.5mpg with the turbo, and 30mpg
> with the non-turbo, and hope to raise to 40mpg with some modifications.

Yeah, it does. But with the fueling set like it is, it is very speed
dependant.  I would like to find a chassis dyno nearby some day.  It's a lot
of fun to drive. It can pull with the Passat tdi through the first three
gears, then the longer legs of the tdi take over.


> Yes, but there is still some tradeoff with turbo size, but clearly it is
> less so with a diesel, and especially with modern turbochargers (such as
> the variable geometry turbo on a TDI). Turbo lag is almost a non-issue
> at normal operating rpms.

Even with the old technology 1Z tdi, lag is not there.  If it is a factor,
slight driving style changes usually address this.  You should wedge a tdi
into the volvo for fun. Shouldn't be too difficult really, lots of room
under the hood...

 At low rpms 10psi would put the compressor on
> the stock turbocharger above it's surge line, and does not occur with a
> big enough turbo. This is the reason that you can't inflate your car
> tires with your turbocharger, it is designed to only produce certain
> boost levels at sufficently high flow rates (requires higher rpms or
> more engine displacement), this is why the surge line on a compressor
> map often resembles a "Y=X" graph within it's normal operating range.

Tell ya what.  Next time I drive the Jetta, I will stick the boost gauge
back, and log what rpm and boost it gets. I was very surprised. Once I tuned
it, I yanked the stuff out, no room for it really anyway.
Still trying to figure out where to stick all the gauges I want in my 1.9td
into caddy project...
-James
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