LPG Fuel Consumption
In your recent article "LPG vapour injection' the engineer suggested that
there would be up to a 20% INCREASE in feul use over petrol using LPG. However
the article goes on to indicate that over a standard test procedure there was
actually a reduction of 6% feul used.
How can this be so?
Are there some situations where the LPG ECU allows the car to run lean? or
are there situations (like low loads for example) where LPG is more efficient
that petrol?
It certainly would be good if the reducation in feul use was true – it would
be like having your cake and eating it too..... And i hope that it wasnt a
calculation error, or inconsistant testing or otherwise different testing
situation, but it would certainly be great to have any sort of definitive answer
you can suggerst as to weather feul use will increase of decrease using
LPG.
Craig Dunn
Australia
John Parnell indicated to us that there is usually a 20 per cent increase in
LPG fuel consumption. However, the emissions test he provided us showed that on
that particular car, in that particular test, this was not the
case.
Ferrari Engine
Nothing wrong with recycling old stories - especially stories on old Ferraris
- but recycling the errors? I am pretty sure the Testarossa and 512TR were FLAT
12s not V12s!
Robert Mitchell
Australia
As described in the story, the car has a 180-degree V12. Many people
incorrectly call this a flat 12.
LPG Turbo Skyline
hello i read your article on vapor injection. you mentioned Parnell doing a
turbo gas conversion.i installed a prins kit on my 98 R34 GTT skyline about 6
months ago and its the best mod i have ever done.
The car is a R34 GTT 5 speed with a stock turbo @ 14psi or 244rwhp.
Power FC piggy backed by a Prins gas ecu running 6 x 75cc injectors
I think probly the greatist thing about this car is that the stock
computer has been ditched and replaced with a apexi Power FC. The skyline was
then tuned agressivly for 98 octane fuel. this made the car run much better on
LPG but still allow the dual fuel set up. In reality there could be more power
made if it was tuned solely for LPG but i enjoy knowing that i probly own 1 of
maybe only 3 knowen LPG skylines in aus that can drive 700 klm's with out seeing
a service station.
there are many Pro's and Cons to a setup like this.
PRO's being a massive increase in driving range.you dont normaly have to
worry about what brand or octane the gas is, exactly the same power and
mainly the price per litre.
Con's being very few people will install a kit like this, some times
hard to diagnose EXACTLY were problems lie, also it can take a while
to tune and set the car up proply and no spare tire.
There are a few things i would love to tell people or companys who are
thinking of installing any gas kits. what they must do is wire in 2 relays for
there petrol pump. 1 to initaly kill power to the fuel pump when ever the gas
lock off has power or gas flow and the 2nd to over ride and apply power to
the fuel pump when the petrol injectors have power. you have to wire it this way
for when the car changes over fuel types as the gas computer turns the petrol
injectors off 1 at a time.
If something like this isn't done the fuel pump never turns off and
constantly is supplying pressure to the fuel rail and heating it up, i know for
a fact that when i have a full tank of petrol and run on gas that alot of petrol
is lost.
and lastly LPG is a waist of time IF you are planning for over 300KW @ the
wheels. LEGAL tanks simply can not supply enough gas flow. you can get around
this by running duel tanks but simply cost vs effect just doesn't add up.
I hope my experience with my car can help some people out. i would deffinitly
do it to my next car.
chris
Australia
Diffs
Hi, I'm a very happy reader of your website from Singapore, keep up the good
work! Anyways, I would like to suggest an article about LSDs (especially torsen
ones)? I'm very intrigued by them, and how about a before and after test thrown
in as well?
Todd On
Singapore
Keeping Memory
I read your articles on batteries. Very good. My question is this. when you
remove and replace a battery how do you maintain the electronic(computer) so you
don't lose the computer. Would appreciate an anwer. thank you
Dennis Scanlon
United States
The most common way is to use a diode and a small battery (eg a 9V one) and
plug it into the cigarette lighter, such that the battery powers the radio and
ECU memories but cannot be charged when the car battery is
reconnected.
Battery Developments
Thought this may be of interest to autospeed http://www.csiro.au/science/ps15a.html
Robert Seymour
Australia
Step by Step for Insight Mod
I very much enjoyed Julian's article, my wife and I both drive Insights.
Would it be possible to get a little more detail on his circuit and its
installation in the car? I'd be happy to report back on any mileage changes we
see; good or bad.
1) part numbers for the capacitor and pot, or a suggested fixed resistor
2) loom wiring color to attach to
John Heller
United States
There is enough information in the article for anyone with even a tiny
electronics knowledge, and with the ECU pin-outs, to install the modification.
If you can't understand the installation, and can't source the parts, it's
probably not a do-it-yourself mod for you.
Intercooler Maths
In your recent artical "Intercooler Maths" I don't get the part of the
formula that is suppose to equal 1.236, what is the (2.1) to the 0.286 is it the
power of or what. Theoretical outlet temp = 293 x (2.1)0.286 = 293 x 1.236
appriacte your help, great magazine love it.
Anthony Parle
Australia
The number is raised to the 0.286 power.
DIY Hydrogen
Have there been any articles on hydrogen generators, "Joe Cells", "Browns
Gas" or HHO gas used in cars? I've read loads on the net, and there's a Range
Rover here in Toowoomba with "Powered by Hydrogen" stickers on it and a phone
number, but I've never been quick enough to get the number.
From the web pages, it seems relatively easy to home-make a hydrogen
generator and run a vehicle on it, or in some cases, use the hydrogen produced
to supplement the existing fuel, be it petrol, diesel or LPG. As there's no
problem with storage of the produced hydrogen (only works when the engine's on),
this is a huge advantage.
Can you investigate and produce an up-to date article for us?
Paul Engelhardt
Australia
We haven’t covered this topic but we’ll put it on the list of possible
stories.
Errors
A couple of small glitches with your recent story on the Corvette ZR1's LS9
engine:
You blokes should know that with roots-type supercharger, "incoming air is"
NOT "squeezed between the rotors and pushed under pressure into the engine".
Incoming air is carried in the cavities between the outsides of the rotors and
the inside of the casing "and pushed under pressure into the engine".
Also, if the charge cooler drops the inlet charge temperature by 140 deg F,
that's equivalent to a temp drop of 77.8 deg C, not 60 deg C. To convert a temp
DIFFERENCE between deg F and deg C you just multiply by 5/9, WITHOUT first
subtracting 32 from the deg F value. You only first subtract 32 when converting
an actual measued temperature of an object from deg F to Deg C, not temperature
differences.
Hope you will accept this as constructive criticism.
Ian Petersen
Australia
Re the description of the supercharger, we’ll let the description penned by
GM ride. However, the slip-up on the temp conversion was our fault – it’s now
been corrected.
Throttle-less Engines
RE: Brake Specific Fuel Consumption, you comment that diesels are more
efficient than petrol engines due to reduced pumping losses at part throttle
since the diesel engines lack a throttle. Am I right to think BMW also
eliminated a throttle butterfly from their valvetronic engines, such as the four
cylinder units used in the 3-series? I assume these use valve timing and/or fuel
injected to control engine speed?
Ben Garside
United Kingdom
They use variable valve timing and valve lift – see
http://autospeed.com/cms/A_1083/article.html.
Wankel History
Pertaining to 'The History of Mazda's Rotary Engine', "By this time, no less
than 49 years had already passed since young Felix Wankel dreamed of the rotary
engine..."
Do you mean 39 years?
Gary Ng
Malaysia
Well spotted - fixed
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