Date: Mon, 22 Sep 2003 09:24:16 +1200
Reply-To: Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Andrew Grebneff <andrew.grebneff@STONEBOW.OTAGO.AC.NZ>
Subject: Re: Propane Fueled Turbo Diesel Injection
In-Reply-To: <3F6DEBA3.2000605@charter.net>
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>Just watched a program on the tube called "Trucks". Featured this week
>was a modification of a Chevy diesel engine to accept propane fuel.
>
>Didn't catch the whole thing, but this is what I did get.
>
>Chevy diesel engine was dyno'ed at 190 BHP. A bolt-on propane injection
>kit was added and the engine dyno'ed at 400 BHP, ran totally clean, and
>specific fuel consumption was reduced, equating to improved mileage per
>gallon.
Everyone I have talked to has said that Chev V8 diesels are best
avoided. Not reliable.
Most diesel engines will not last for more than a few minutes when
the power-output is multiplied in this way without major
modifications; they are not designed to handle the stresses.
Collapsed pistons, head and conrod damage will likely result.
Propane doesn't have a huge calorific value, and I very much doubt
that such a power increase will result from merely converting to the
different fuel. Now, if the diesel was running GASOLINE it would be a
different story.
Small diesels are racing and winning against gas care on European
racetracks (2.0 Golfs & BMWs), putting out 400hp, so high outputs ARE
possible from diesels. BUT these racing engines will gulp fuel,
negating the main reason for having a diesel in the first place. Now,
IF it were possible to have a 400hp economical reliable diesel, I'd
certainly look at modifying my Corolla diesel...
Someone mentioned getting more power from a diesel just by turning up
the fuelpump. That's a BIG NO-NO!! All this will result in is high
fuel consumption, obnoxious black smoke and increased engine-wear due
to fuel-dilution of the sump oil (and cylinder-wall wash). Bad news.
In third-world countries the bush mechanics chronically wind the
pumps up, hence all the smoke-balching diesels. I drove about 80km in
Fiji once in an airconditioned car... with the windows open because
the Indian passengers don't like aircon... and when I wiped my face
afterward the towel was very dirty. Diesel-derived soot. Guess why
there are so many stuffed diesels in these places!
>Yeah, you can burn any combustible gas in a diesel. Since ignition doesn't
>occur until the diesel is sprayed it's simply a matter of keeping the gas
>mixture lean enough to prevent preignition.
Yes, but injection-timing is critical, and will differ between fuels.
Higher-flashpoint fuels will require timing to be retarded compared
to distillate (so-called "diesel" fuel). Such fuels will require a
lowered compression.
Here in NZ gasoline costs about $2.40US/imperial gallon. Diesel is
about $1.76, plus a "road-user charge" which you buy in km, still
makes diesels far cheaper to run.
I believe diesels make up over 50% of new-car sales in Europe, where
(with the exception of England) it's less expensive than gas.
LPG (propane)? Low calorific value, so a gas car run on LPG will lose
power... and though the unit price of LPG might be cheap here in NZ,
the car will gulp the stuff (experience here with taxi fleets). A
diesel car here is way cheaper to run than a gas car of the same
model running LPG. The Ford BA Falcon (Aussie) is now available as a
dedicated CNG (compressed natural gas) option.
Besides, an LPG or CNG car is a bomb. Saw a video of a CNG Holden
Commodore in Australia burning... when the tank went up, you
wouldn'tve wanted to've been closer than 100m away. These things
don't give a gentle "whump" and a hiccup of flame as a gasoline car
would (such cars' tanks do not explode).
>I'm not sure the VW diesel block and head can stand much more output when
>used in the heavy vanagon. The oil temp in my TD westy
>would go through the roof on long hills. Exhaust gas temp would get too high
>as well. Water temp would be normal.
>I would suggest to anybody who has modified their turbo diesel to get a
>pyrometer for the exhaust. On hills, I would basically drive only as fast
>as the pyrometer
>told me I could.
>
>Intercooling worked as expected, for every degree you lowered the charge
>temp, the EGT would be lowered by the same amount.
Water-injection to lower temperatures? And add further complexity...
LPG, CNG or hydrogen however in a way is an ideal diesel fuel... no
carobn particles, so oil will remain clean and not score bores,
bearings etc... and no more indelibly carbon-blackened hands!
--
Andrew Grebneff
Dunedin, New Zealand
64 (3) 473-8863
<andrew.grebneff@stonebow.otago.ac.nz>
Fossil preparator
Seashell, Macintosh & VW/Toyota van nut