Negative Boost
In
Negative Boost Revisited, Part 5 there is a before and
after dynoplot proving a 3kw gain from the intake mods on an EF Falcon. More
interesting is that the graph also shows the AFR leaning out across the rev
range by 0.4-1.0, averaging about 0.75. This raises two questions for me. 1) Did
the mods increase fuel economy? 2) Did the AFR remain lean, or did the ECU
"learn" and adjust the fuel trim back to the original AFR?
Roger
New Zealand
(1) Fuel economy was improved but that testing
also included other modifications, including leaning-out the lean cruise
air/fuel ratio. In the past, we have seen fuel economy improvements from running
free-flow intakes, in both MAP-sensed and airflow meter cars. (2) Dyno runs are
at full throttle; this car cannot learn around full throttle mixture changes.
Measuring Exhaust Flow
Julian's method of using a weed blower to act as a
device to measure back pressure for exhaust testing is not really correct. I
measured my exhaust , off the car, in total, in part connected and then the
individual components. These are cat, interconnecting pipes, and muffler, hence
three parts. The output of the blower is such that it doesn't find the limit of
each component. Hence the results are confusing.
If you subtract the head rise as Julian does, you
get one answer, but looking at individual results of head gain you get a
different perspective, and most confusing result. Hence difficult to interprete.
Reults: full cat/pipe/muffler gain = 240mm water,
pipe & muffler=215, cat+ pipe=200, cat only = 185, muffler only = 190. I
suspect blower capacity needs to increase substanially. Any comment?I would like
to measure the actual flow rate at 28" water to see if Vizard's formula of HP at
the flywheel * 2.2 = flow rate necessary for a muffler to have zero power loss;
but this is a bit expensive to test. cheers from (a confused)
Ron Sutherland
Australia
By far the best way is to do the measurement on
the car at full throttle, measuring the back-pressure at various points. We have
covered this technique in many AutoSpeed stories.
Leaning for Economy
I have read a few articles in Autospeed about
improving fuel economy by leaning out the mixture. Has there been any
measurements of NOX levels and oil temps before and after the mods?
Justin
Australia
No there have not.
Forget Kilowatts
I've just read with great interest your article
Forget the kilowatts
Firstly, I must declare that I am not a car
enthusiast per se, nor a great potoring press reader. (I am thoroughly put off
by the thinly veiled rev head behind many car reviews. I simply don't identify
with a purely performance basis for evaluating cars which seems to attract the
attention of many motoring writers.) This is why I found your article both
refreshing and well informed.
For some years I have been wondering why the
motoring press don't use a different benchmark for reporting car power and
torque. I agree 100% that peak power and torque figures give almost nothing
useful for the average driver.
I'd like your thoughts on this idea for a new
standard on these specifications: What is needed are specs that match real
driving circumstances, eg. a table of power and torque values for, say driving
on level ground at 60km/h, 80km/h and 110km/h in top and second top gears. Then
add the curves over the rev range and everything is covered.
In traffic, these are the times when I may want
high acceleration to pass a vehicle, or maintain my speed up the next hill.
Forget maximum specs, forget excessive revs - just give me real scenarios at
realistic rev values. I want to be able to balance considerations of power,
energy efficiency, road and engine noise etc., as well as other more slippery
statistics such as durability and break down rates as best I can.
Unless car manufacturers and motoring press adopt
a useful common alternative standard, we'll be stuck with the current useless
sets of peak specs. Will that ever happen? BTW I happily drive a 2001 Mazda 121
Metro and feel no shame about being overtaken! And I still have very fond
memories of my first car, a very pedestrian but durable 1970 Isuzu Florian.
Peter Spolc
Australia
The easiest way of showing this data is to
measure in-gears acceleration figures (sometimes referred to as ‘passing’
acceleration.) These figures used to be widely available in enthusiast
magazines.
Aurion Test
Toyota Aurion AT-X
The most convincing point you made to me was: 'The Aurion was hired for this
review.' I cannot say where else I have seen this. For the relatively small cost
involved to rent a car I think any motoring review journalist can increase their
credibility by using this 'no favours' method where a random sample is tested.
Here you gave a good report from testing a fleet vehicle without options and
which is was not new.
Shane
Australia
Wet Tyre Grip and Downforce
I just read your article
The Slippery Stakes - Wet Road Tyre Grip and it definitely
provides some interesting information. One relevant factor that I thought could
have been mentioned was the effect of vehicle aerodynamics at high speeds. While
the tests show that tyre grip is significantly reduced at high speeds, vehicle
aerodynamics also come into play to provide more downforce.
It would be interesting to see the tests redone
using a downforce that increases with speed, using the downforce vs speed
profile of a number of commonly mass produced cars. (These results could also be
simulated or calculated theoretically)
Alex
Australia
There are almost no road cars that develop
downforce, so at speed, things would only get worse....
Measuring Boost
Basic Hands-On - How to Fit a Boost Gauge
I enjoy much of this magazine, and, as a writer and researcher, I have learned
much from this site, so thank you.
I want to point out a different train
of thought when it comes to citing the location for boost readings. With
todays variable vane geometry technology, and closed loop feedback for
boost control, the boost set point relies on the oem MAP (boost) sensor
typically located at or near the intake plenum, where you have suggested the
sensor should be located. This has one very important drawback: you will
never know if a leak develops in your system, or if a problem develops in boost
sensing.
If the gauge sensor is located near the compressor discharge,
you then have the added knowlege of knowing exactly how hard the compressor is
running. This is very handy when doing your own tuning also.
An example: Say you are accustomed to seeing 15
psi of boost at the plenum. With normal frictional losses, this would
typically require around 17 psi at the discharge. But if you develop a
leak, the oem MAP sensor will require the turbo to produce more boost, and you,
with your colocated boost sensor may never know you have a problem. Why?
Because the boost at the plenum will be the same. If the sensor, instead,
is located at the discharge, you would normally see 17 psi. But if
you get a 5 psi leak, it will jump to 23 psi (assuming the turbo is
capable)...and this will alert you to an issue.
Obviously there are multiple schools of thought
here, and this one, from a technicians point of view, should be
considered. The only way to gauge the compressors workload, is locating
the sensor at the compressor discharge location, upstream of any possible
trouble spots. This will not give an accurate plenum boost number, but you
will know when you have a malfunction.
Michael Patton
United States
Painting Concrete Floors
In
Building a Home Workshop, Part 9 you mention that you
weren't painting the floor, with two of the reasons against given as cost and
effort.
When I had my first house built my wife and I were young and
broke, so we had to economise of various things. One way of doing this was to
gradually do the finishing of the house over time. So, we lived for a couple of
years with the concrete slab as the floor until I got around to tiling. A
workmate who had been in the concreting industry advised me to use Bondcrete and
water to seal the slab before we moved in. The method was fairly easy - mix
Bondcrete with water (1 part Bondcrete : 10 parts water) in a bucket, apply
withan old indoor broom, and let dry.
That place was about 80sqm, and a four litre tin
of Bondcrete was enough to do my house, and the guy next door's. So it should be
OK on cost, even if you did decide to up the mix to give you better protection
given the harsher environment of a garage.
The application is similar to washing a floor with
a mop. There's plenty of scope to "push" some of the mixture under low shelves
and cupboards, and since it soaks into the concrete and dries clear you've got
no worries about patchy coverage looking daft when you eventually move things
around. It's not exactly hard work either.
We only tested the longevity of the resulting
floor for two years, but we certainly didn't have problems with concrete dust at
all.
As for curing the concrete first, the slab would
have been five or six months old I guess from being laid to me coating it just
before we moved into the finished house.
Jason
Australia
Toyota 2000GT
I just finished reading
Toyota 2000GT because a co-worker
looked it up after I showed him some pictures of the one I owned from 1972 to
1978. It was one of about 50 or so imported to the U S A and it most
assuredly WAS a LHD model. It was white and carried serial # 141 as I
recall (of the 200 reportedly built) and it was a 1967 with the 2.0 litre engine
as described and NOT the "Crown" engine that was used later and up into 1970 or
so.
Carroll Shelby had been hired by Toyota to turn some of the unsold
cars into race cars but they weren't very successful, so he modified a few of
the remaining ones but left them fully streetable. Mine had been
"Shelby-ized" and had CHAIN driven cams instead of BELT driven ones and the cams
had a bit more lift and duration. That, coupled with having 40 mm Solex
carbs, yielded an estimated 185 HP. I actually achieved 152 MPH with it on
level ground once. That was with the optional 4.11 third member. It
would return 20-21 MPG at speeds in the 85-90 MPH range, but with our silly
speed limits that was difficult to maintain without drawing attention.
I
owned it for the years mentioned above and was showing pictures of it with my
1971 Datsun 240-Z (that I had purchased new and STILL own and drive today after
523,000 miles) to show the similarities between the cars.
Thank you for
bringing back memories of a nice car that I didn't fit in - it was built more
with Japanese people in mind and at 6' 2" I had to kind of "fold" myself into
it.
W. Allan "Butch" Skaar
United States
Holden Poised for Success
With the falling Australian dollar relative to
most other currencies, Holden's strategy of pursuing large cars for sale
overseas is about to look spectacularly successful. And Japanese and American
cars are about to get very expensive. The Australian car industry isn't dead
yet.
Grant
Australia
Electronic Auto Trans Mods
I have a been a long time reader (and paying
subscriber) of Autospeed. The DIY tech content is fantastic, but I want to see
more projects involving automatic transmission tinkering. I read
Electronic Trans Controllers - Part One,
however, DIY tramission modifications are more interesting (and cheaper). I
would love to see Julian do a project using an Arduino programmable board to
modify an automatic transmission's signals to achieve, for example, improved
torque converter lockup, faster shifts, or even throttle blips on downshifts!
Even if the modifications didn't work, it would be interesting
reading.
Keep up the good work!
Michael Paszti
Canada
Watch this space...
Inflammable Coolant?
Regarding Issue: 462 Section: Technical Features
11 January, 2008
NanoFluids!
Improving the performance of engine coolant by up to 40 per cent. No mention of
fire hazard. See http://www.landracing.com/forum/index.php/topic,4771.0.html
Gary
United States
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