Keith Addison wrote:
I see you still haven't looked at the page I referred to, which you
said needed updating (which it doesn't), so I referred you to it
again
Actually, I have read it and in fact have referred others to it on a
regular basis. I am quite aware that it refers to SVO and not BD.
However, *you* referred Mel to it when his original question dealt with
biodiesel, not SVO. You said:
Biodiesel's no problem, SVO/WVO is something of a controversy.
You're mixing up two emails.
I disagree, and feel that the page should be updated to include the fact
that US spec BD may not be appropriate in a PD TDI.
Why would anyone want to put information about biodiesel on a page
entirely about SVO? The reason I referred Mel to the page was that it
wasn't clear whether he was referring to SVO or biodiesel, and that
was obvious enough.
What isn't at all obvious, at least to me, is why you've answered a
question I didn't ask but not the one I did ask, and in fact snipped
it out. So I'll unsnip it back in again. You said this:
The Bosch designed unit injectors found in the PD engines get up
into the neighborhood of 20,000 psi. Questions have been raised on
whether BD use is appropriate at such pressures. My understanding is
that these pressures are much much higher than either the old
distributor pump or common rail designs used in other models.
My original point remains unchanged; do not assume that experience
with pre2004 TDIs and BD use can be extrapolated to new PD engines.
This is not to say that they won't be fine, but the history just
isn't there...yet.
jh
This was my reply:
http://journeytoforever.org/biodiesel_TDI.html
The TDI-SVO controversy
Please note, if nothing else, that it's about SVO. Anyway, this is
one thing you'd have found there:
"... Siemens, Delphi and Bosch all are ramping production of
sophisticated new injectors that can handle today's sky-high fuel
pressure, and inject infinitesimal fuel droplets so quickly that
upcoming diesels may at times employ as many as five distinct
injections for each cylinder's combustion 'event.'
"... the most promising advantage of common-rail technology is the
ability to deliver extremely high fuel pressures on the order of
23,000 psi (1,600 bar) or more. This type of pressure means that in
microseconds, astonishingly tiny fuel droplets can be injected;
these droplets more effectively mix with the induction air,
boosting power production and reducing emissions.
"Only Volkswagen AG, Europe's diesel volume-sales leader, has
resisted the common-rail development path, instead relying on its
unique 'unit injector' system that combines each injector with an
integral fuel pump, energized by its own lobe on the camshaft. This
system develops pressures of up to 29,300 psi (2,020 bar)..."
-- From "Super Diesels!", Ward's Auto World, September 1, 2001
http://industryclick.com/magazinearticle.asp?magazineid=50&releaseid
=8418&magazinearticleid=118355&siteid=26
23,000 psi, 29,300 psi... Note the date - 2001.
If you think a mere 20,000 psi is all-new for 2004, then you couldn't
have read the page, could you, as it refers quite prominently to much
higher pressures in 2001.
If you feel that particular page is focused on SVO specifically rather
than the overall controversy over what is the appropriate in fuel a
TDI, I can understand that.
It's not that I feel that way, it is that way. That's why it's called
"The TDI-SVO controversy" and not the TDI-appropriate fuel
controversy, and also why the only way to reach it is via the main
SVO page (and the Site map).
However, can you see from my perspective why I think a page on TDI
fueling controversy should include info about US spec BD in a PD engine?
That would be a different page. We wouldn't do such a page. The JtF
website had visitors from 187 countries last month, not just the US.
To claim that a page called "The TDI-SVO controversy" needs updating
because it lacks information on US spec biodiesel in a PD engine is
preposterous, it has nothing to do with running a TDI on Straight
Vegetable Oil.
After all, the url *is* /biodiesel_TDI.html, not /SVO_TDI.html Can you
see how this might be misleading as to the focus of the page?
Oh come off it John! You're clutching at straws. SVO is dealt with in
the Biodiesel section, as a sub-set. There isn't a separate SVO
section, nor will there be. That TDI page isn't even accessible
directly from the Biodiesel section, only from the main SVO page.
It's a url, the page has a Title, which appears at the top of the
browser window, far outweighing whatever it may say obscurely in the
url code, the title is "The TDI-SVO controversy", and there's a big
red headline right at the top saying the same thing. If you want to
think that's misleading, well, suit yourself.
Best wishes
Keith Addison
Journey to Forever
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