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Some of this week's Letters to the Editor, discussion group posts and other feedback!

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Speed Kills? #1

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I wont argue or comment on speed limits on LOCAL roads. If the study ["Speed Kills: Setting and Enforcing Speed Limits"] says driving the couple of minutes around my local streets at 50 km/h instead of 60 km/h will help save the lives of those stupid enough to roam into the street, then I can handle that. However, doing a blanket reduction of the speed limits (which are already too low on many roads) on general urban roads to reduce the number of crashes by about 5% overall (33% of 148 crashes out of 952 crashes that were included in the study) is just ridiculous! The numbers they talk about almost sound significant until you remember they didn't include the majority of crashes in their study and are referring to only 16% of the crashes they attended which were "free travelling speed" driving. What was the cause of the other 84% of the crashes?

I suggest they loosen the enforcement buffer so that I can watch the road, and not have to continually check my speedo every 5 seconds to see if my speed has crept up by 1 km/h. That would make me a much safer driver. That is the difference between drinking and speeding. Your speed is continually changing and must be maintained near the limit to prevent becoming a hindrance to other drivers. A minimal blood alcohol level is of no hindrance to other drivers.

Have the police use their judgement more, enforce tailgating and move-left-unless-overtaking more strongly, and concentrate on dangerous drivers. Stop the revenue raising from going to the government's coffers, and send it to charity as I heard someone suggest. Then we will see where the government's true interests lay.

Roger Canty

Speed Kills? #2

A major fault in the "50 km/h" South Australian study is that reaction times are assumed to be 1.5 seconds throughout the investigation. Is it not highly likely, that at the lower speed of 50 km/h, perceived risk - and therefore driver attentiveness - will be dramatically eroded? It might well be that increasing reaction time to just 2.0 seconds will indeed increase the severity of the collisions being investigated. Such a variable is easily calculated, but is not even considered.

We need dramatically more information, as well as studies looking at driver attentiveness - given that skill levels are apparently invariable.

Robert Lawrence
(former Learner, Advanced and High Performance Professional Instructor)

Speed Kills? #3

I have read, with much interest, the two latest articles on speed limits. It does seem to be a very complex issue, one that most of us interested in modifying cars would take some interest in. The study outlined in 'Speed kills: setting and enforcing speed limits' where the speed of free travelling cars hitting pedestrians and injuries such accidents caused, was compelling. If this study is accurate, then one would have to agree that a lower speed limit of 50 km/h in built-up areas was entirely justifiable. The study in some ways however, raises more questions than it answers. It states that:

"...the great majority of (these) free travelling speed crashes occurred on arterial roads or major traffic routes. Therefore, a speed limit of 50 km/h in local streets would be likely to have only a small effect on free travelling speed casualty crashes as a whole (a 6% reduction) due mainly to the small proportion of these crashes which occurred on local streets."

Yet the speed limit AFAIK on most arterial roads and major traffic routes is still 60 km/h, with almost all local streets having a 50 km/h limit. Does this mean that the reduction in local streets to 50 km/h limit is essentially a fruitless exercise?

In the discussion section of the report, the writer went on to say:

"The results of the study of travelling speed and the risk of involvement in a casualty crash show that the risk is twice as great at 65 km/h as it is at 60 km/h, and four times as great at 70 km/h. Proportional increases in risk of such magnitude would appear to be sufficient reason to justify the elimination of the current practice of applying an enforcement tolerance to speed limits, or at least a substantial reduction in such a tolerance. In South Australia there is a zero tolerance approach to policing drink-driving legislation. We have shown in the full report on the speed case control study that travelling at 65 km/h in a 60 km/h speed limit area increases the risk of involvement in a casualty crash by the same amount as driving at the speed limit with a blood alcohol level of 0.05 (Kloeden et al, 1997). As all cars are fitted with speedometers, and few if any drivers have access to a breath alcohol meter, it is incongruous that zero tolerance should apply to drink driving but not to speeding."

This argument ignores a couple of points. The first point is that a person generally knows how much they need to drink before they are close to the limit. Once they get into a car, they can concentrate (or attempt to, depending on how much they've drunk!) on driving the car. They don't need to and as the writer points out, can't, check their BAC once they're driving. A vehicle's speed on the other hand, needs to be constantly checked by the driver, especially if you are attempting to vary the speed of the vehicle as little as possible. Even with cruise control, a vehicle's speed can deviate from the set point down a hill by some km/h before the driver may notice.

The second point is that because vehicle speeds are inclined to vary, it would seem that if you removed the tolerance level from speed enforcement, we would become a nation of drivers with their eyes glued to the speedometer, not the road!

This concept of speed variation is often used by police in the placement of speed cameras. Is the placement of a speed camera in a position where vehicles are most likely to speed in the best interests of road safety? Or is there placement got something to do with the amount of income the governments of this country are addicted to collecting?

The two articles also raise the question of why we speed in the first place? It seems that in a land without speed limits, we would just go as fast as we liked everywhere! The human species just likes getting to where it wants to go as fast as it can. I guess that's why Germany has Autobahns. If the study in 'Speed kills: setting and enforcing speed limits' is correct and to decrease fatalities with our current road infrastructure would mean lowering speed limits, then why don't we try a different tack - improving the infrastructure to sustain higher speeds!

It would seem that today's roads are nothing more than modern, tarred-over versions of the tracks once used by horse and cart. There are ways to exclude pedestrians from roadways, remove obstacles from the sides of roads and methods to keep cars from hitting head-on. Are these methods too expensive, or are we going to perpetually argue about one factor contributing to fatalities? Perhaps governments know this already, but also know if they spend money on improving the infrastructure, then their arguments for speed restriction enforcement (read: revenue collection) would simply hold little water.

Phil Barnett
Sydney Australia

Micro Gas Turbines

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Good article about MicroGas Generators ["Micro Turbine Power!"]. Here in New Zealand (Christchurch) we have buses that use them to generate electricity to run. Developed by Designline in a small centre to the south of Christchurch called Ashburton. The generators are run all of the time and supply a constant charge current to a bank of batteries. The turbines are American built and run off LPG. I think the rating of them is around 30kW. When standing next to the bus you would not know they are operating.

Keep up the good work!!!

John Reveley
New Zealand

R31 Skylines, Please

It's all very well having articles on R32/3 Skylines and other exotic turbos, and very interesting, but largely irrelevant, as most of us have more mundane cars. Could we please have some articles on the R31 Skyline, and how to get more from the RB30E, without turbocharging.

Raoul Stogaus

The RB30 is now getting so old - more than 16 years - that we are unlikely to do a story on getting more power from it. After all, a starting point of 118kW from a naturally aspirated 3-litre six isn't a terribly good beginning these days. That said, we've run articles on mufflers, exhausts, intakes and so on that would all be relevant to it. R32 Skylines are now available so cheaply that they can hardly be called an exotic car.


Just wanted to say I think you guys are doing a terrific job. Informative, balanced, and topical. I think the 'hard-copy' mags could learn a thing or two from you.

Jamie Everingham

NACA Resource

I've been a member for the last few months and I think the site is excellent.

I read the "Patents Files" piece on turning vanes ["The Patent Files: Turning Vanes"] and it reminded me of a document I downloaded some time ago from the NACA reports site. I came across it when looking for information on NACA ducts.

The article is naca-tn-1148.pdf and the title is "Flow Tests Of An NACA-Designed Supercharger Inlet Elbow and the Effects of Various Components on the Flow Characteristics at the Elbow Outlet". It outlines some similar points in the turning vanes article and indicates general design considerations for the design of elbows etc.

Although these guys were dealing with superchargers bigger than motorcycle engines I think the principals involved in good flow design etc are the same whether you're looking for more power or better economy. Some criteria for good flow around bends are some and I found it very useful.

The reason for this email is, I suppose, that I want to share what I think is an excellent resource that's available free on the internet. Although the information dates from the 1920s through to the 1950s there's a lot there that's relevant for the engines are aerodynamics even today. It's all from the era before computer power so generally the reports are targeted at providing design rules rather than simulation model inputs.

The site is and I normally use the NACA Reports (full text) option. The problem with the site is that there isn't enough time to read all the interesting stuff!

Keep up the good work!

Paschal McEnroe

Good Article

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What a good article about the AU Falcon ["The Forgotten Bargain? AU Falcon"]. Your comments are about exactly how I'd describe mine. While sadly they are roughly finished, they do have cheaper parts and cheaper insurance, and I know two locals who have walked away from 70 km/h head-ons. Do that in your budget Korean.

Shane Quinn

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