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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?


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


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?



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


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.



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)



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.


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.


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


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,4771.0.html


United States

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