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Some of this week's Letters to the Editor!

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No Oxygen Sensor?

Firstly .. great site .. especially the DIY and Tech...and to Julian Edgar a very good book (21st Century Performance).

I bought an '84 ET Pulsar which has a Series 2 import motor in it, I've done the usual mods - 3 inch mandrel from turbo back, intercooler with water spray, relocating airflow meter and idle control valves, VL throttle body, hi-flow turbo, in-cabin adjustable boost up 20 psi . Car responded well to mods. The problem I have is that the oxygen sensor is not connected and there are no visible wires to connect it to. I have read the (original) Nissan service manual (based on an '84 model) and there is no mention of an oxygen sensor. If the pre-'84 engine does not use an oxygen sensor, how is a correct air/fuel ratio maintained? Can you please help me out here so I can fully understand the functioning of the ECU and plan further modifications to fuel system.

Gabriel Tarallo

All pre-unleaded cars don't run oxygen sensors. The air/fuel ratio is determined without any closed loop feedback, using just the pre-programmed maps in the ECU.

Improving the Immobiliser

Regarding the "The World's Best DIY Immobiliser" article, and the problem of it immediately killing the engine if it's accidentally tripped. With the addition of one more relay, wired so that the kill switch would open the relay only when the engine is not in operation, this problem can be solved. One source for that signal could be the fuel pump power, or the ignition primary, just to give a signal to the system that the car was already running, and to therefore not kill whatever circuit it normally would.

Joshua Allen
United States

Dodgy Workshops #1

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I thought I'd commend you on that article about dodgy workshops and dodgy modifications ["Greedy, Stupid and Liars"]. AutoSpeed has helped me take a smarter approach in modifying vehicles, namely taking a more scientific approach rather than simply trusting other car enthusiasts or workshops.

Recently I've used the knowledge gained from costly intake trial and error (in your article I think you may have been referring to my NA Impreza RX!) and I have applied it to my new Peugeot 306 GTi-6. With manometer testing, I discovered it is impossible to gain the claimed "3kW at the wheels" from a K&N kit sold by a local Peugeot performance outfit. I was immediately suspicious of the kit when I was informed it produced an extra 3kW at the wheels on many Peugeot models. The kit also breathes air from behind the radiator.

Recently at a dyno day, I discovered Peugeot's factory efforts have resulted in a virtually flat torque curve (a total variance of no more than 10Nm at the wheels!) from 60 to 180 km/h in 4th gear.

I'm sure many common modifications would detract from the results of Peugeot's extensive R&D.

Adrian Fisse

Dodgy Workshops #2

Re: Recent Article - "Greedy Stupid and Liars".

I was very pleased to see your recent article warning enthusiasts on the pitfalls of vehicle modification.

As a software test engineer and also a car nut, I have an understanding for strength of materials, solid mechanics, thermodynamics, kinematics and so on. Most mechanics I have met use the "suck and see" approach, and if you asked them to determine the inertial load on a main bearing at 7000rpm they wouldn't be able to do it - which has always been a mystery to me as to how they arrive at a RPM limit in a modified engine.

I'm currently working on a document that I am going to freely distribute on the Internet. It's designed to be a brief introduction to the real world of vehicles and how these machines can be improved, and some basic facts about the machines. I'm doing this because I see a lot of interested people get wrong ideas and become a bit disgruntled with their project outcomes as a result. I hope that my document will lead enthusiasts into researching the field more, and buying some detailed books on the subjects to understand it properly, which can no doubt help to weed out the dodgy performance shops.

Adam Howarth

Dodgy Workshops #3

Re: "Greedy Stupid and Liars". Sure there are many workshops which should not be in business because their work is so poor, but just because they do not have a dyno sheet on a 200B, doesn't make them a bad workshop. I am in the exhaust industry and I have seen work from other shops that is only half welded and hitting the body in numerous places. This is a bad workshop. The customer or workshop is not going to pay $160 for before & after dynos on a $200 sports system.

I have reams of dynos on Gen 3 Commodores, where we and the customers have paid for dynos. When the customer is spending thousands on a job, they are likely to spend a bit more for before & after dyno runs. When the cars come in volumes, like the Gen 3 Commodores, the workshops are more likely to spend their own money on R&D.

Although your criticisms may be valid in the camshaft issue, it should be put in perspective with volumes of a particular car.

It is hard to comment on your specific instance, however, your comments put a slur on all but 20 un-named workshops in the whole of Australia. I just hope we are one of the 20 good workshops in Australia!!!


We think it's easy for you to judge yourself with regard to where you fit into the industry. In our opinion, a good exhaust shop should:

  • Have access to a dyno
  • Have a noise meter
  • Measure exhaust backpressure
  • Have computer exhaust modelling software
  • Closely follow the SAE engineering papers on exhaust and muffler design
  • Cut apart OE mufflers to investigate changing new car designs
  • Have flow-tested the mufflers that they sell

Dodgy Workshops #4

I really enjoyed your article "Greedy Stupid and Liars". I've found out what you wrote is true, the hard way. Keep up the good work.

PS: perhaps the consumer website (ie: could be used to keep dodgy mechanic/workshops in check.

James Empson

Twin Boost

Thank you for showing twin-charging for what it really is in the "Response" section. I think it is an often misunderstood area and I have read some incorrect information from magazines before about it. I would love to see a late model engine like a SR20 with a 4AGZE supercharger where the air-con compressor was and a massive ball bearing turbo. I think the resultant power curve would be amazing.

Samuel Quadflieg

Yes, well wait a few weeks and you'll see in AutoSpeed a twin-turbo, supercharged V8!

Airflow Meter Screens

Good morning from Chicago. I'm a new member and just wanted to let you know you have excellent articles and information! Pertaining to the Negative Boost enlightening articles [starts at "Eliminating Negative Boost - Part 1"], please advise on the following:

I've an '01 Audi S4 Bi-turbo (U.S. spec) and am attempting to allow the engine to breathe easier (delete negative boost) above and beyond 4k revs, i.e., upper rev range, without upgrading the turbos. However, my airflow meter is a Hitachi with only one mesh screen, which is welded onto the body of the meter.

1) Will removing mesh screen by itself (without performing other intake modifications done in the article) actually reduce neg. boost? Noticeably?

2) If so, how do I actually remove it? By using wire cutters??

3) Realistically, what is chance/probability of sizeable debris entering the meter, i.e., a pebble/rock??

4) Am I correct in the following 'reasoning': the greater (or less restrictive) the airflow BEFORE the turbos, the LESS hard the turbos have to work (less boost); hence, longer turbo life??

John Benjamin

If the meter has only one screen and it is welded into place, we would leave it there. There may be a reduction in wear with a reduced pressure drop in front of the turbos but even if it does occur, it would be negligible.

Gen III Engines and Tyres

I think you're doing a great job and I wanted pass on a compliment and make a suggestion for a future article.

I completely understood your point on the Gen III Commodores with respects to their fuel usage ["From the Editor"] and agree. It is quite possible to build high performance and get better economy than this. Although I do love V8s and have driven a friend's Gen III SS, which I love, I had the following concerns over personal ownership of a Gen III. Having built a large capacity V8 (5.9 litres) many years ago for both power and economy, I was very surprised at how much fuel the Gen III used and how doughy the throttle was on this car. I expected much more crispness in the throttle response; my turbo car has better response.

At first I thought it could be low compression, but at 10:1 this is right up there for pump fuel. Then I realised it must be the intake volume and design. My old V8 had extremely large intake ports and valves, with a 750 Holley vacuum secondaries carbie, but had a much smaller intake volume and didn't have to be muffled heavily on the intake for ADRs. It achieved 360hp and 25 mpg if driven gently, all with a carb, but if the foot was heavy that economy would drop.

My point is that it would not take much by Holden to improve the engine response and therefore economy of the engine but for the need to comply with the drive-by noise rules of the ADRs, amongst other rules.

My previous car was a 2.2-litre Vectra which had a modified intake after discovering, to my horror, two very large restrictions in the intake path. From the airbox to the engine, the pipe was about 3 inches in diameter, but within the airbox was a removable trumpet that brought the diameter down to about 1.25 inches! The intake to the airbox was also restrictive with a three-way branching from multiple sources. I immediately removed the standard airbox and placed a K&N rampod in its place. The performance increase was quite noticeable, but the induction noise was unbearable, even at idle. I ended up modifying the standard airbox and found this to be slightly better again. The noise was not much more than standard, but it was higher than an ADR test would allow (75dB I think)! The car was much more responsive, had better fuel economy and I kept up with a lightly modified A4 Turbo Quattro off the line in first and second gears, to his visible horror.

Holden have to compromise on so many aspects in their vehicle design, but why fuel economy? My reasons for buying my Nissan S15 200SX were primary for sporty performance, but of almost the same importance was its efficiency at doing so.

My suggestion [for AutoSpeed] is this: with the need for new tyres shortly, I can't gather enough information on tyre specifications to make a remotely informed decision. Could a test comparison of performance tyres be done by AutoSpeed on a yearly basis? A test of friction, wear, noise and an opinion on driver feedback would be invaluable.

I've devised a device to measure the co-efficient of friction of a tyre, but it cannot determine its relative longevity, noise or wet performance. The device is simply a measured mass (1kg) with spring scales attached to it to measure the sliding tension of the mass as it is dragged across the top of a tyre. The ratio of the tension to the weight of the mass of the gives a relative co-efficient between the tyre and the mass. Not all tyres indicate their treadwear and trying to make sense of that stupid traction rating to give quantifiable results makes life quite difficult. Both the Falken Azenis and FK-451 have the same treadwear rating of 200, but isn't the Azenis a better gripping tyre?

Wouldn't it be a nice world if tyres traction rating was stated as a co-efficient and sun block SPF ratings specified what % of UV they filtered out. Maybe I'm just an idealist.

Adrian Veasey

Much of the doughiness in the response of the Gen III is the fault of the engine management - Nizpro's MoTeC Gen III engined ute has far better response than standard, and is mapped very densely at low rpm. A tyre test big enough to yield useful results is unfortunately beyond our current budget.

ChipTorque CV8 Monaro

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You guys recently used my Monaro CV8 for an article ["Real Time Re-Mapping the Monaro CV8"] at ChipTorque.

I have something further to add with regards to the recent comments made by Julian about fuel consumption ["From the Editor"]. Since having the car re-programmed by ChipTorque, my fuel consumption figures are considerably down. It appears that when you open the throttle with the standard Holden maps the fuel is simply dumped into the system without any regard for the amount being used.

I have noticed a dramatic drop in "normal driving" consumption compared with the car in standard form. Where previously I could easily average 16-18 litres/100km, I now cannot get above 13 no matter how much hard acceleration I use in normal city driving. Lean cruise highway is down to 9-9.5 l/100km from an average 11-11.5 which shows the unnecessary fuel-hungry nature of the standard engine maps.

Is Holden trying to preserve at all costs the engine and alleviate any warranty concerns and damn the fuel? I have heard of problems with these engines as the K's creep up. Is Holden hiding bad engineering with more fuel in an effort to save costs? Who knows what thinking has gone into the overly fat mixtures - I don't care! I at least have a solution in ChipTorque and I am very pleased with the results that have been achieved with my car. I have a mate with an SS Ute and the fuel consumption alone is sending him to CT to get the mods done. With the K's he does dragging a trailer full of gear, the mods will be paid for within six months and you get more power!

Chad Johanson

More on Magna Noises

Re: Darren Roles letter "Magna Noises" ["Response"].

The scraping noise coming from the front axle of his TJ VR-X is simply the ABS unit and its diagnostic check at start-up. It has nothing to do with lowering the car or the tyres. Having bought a Limited Edition VR-X, I also thought it was caused by the new 17-inch wheels. It is a very annoying noise but reference is made in the owner's manual. Disconnect the ABS and the scraping will disappear... a fairly drastic move though.


Noisy Exhausts

In NSW the law is being changed to fine and lose 2 demerit points for undue noise - loud stereos and exhaust.

How often do you change lanes and run into a car with a noisy exhaust? How often do pedestrians walk out in front of a car with a noisy exhaust? Sure, there are dickheads of all descriptions and they create a nuisance, that's a part of nature. There is always a dickhead that spoils it for the rest of us. Noisy exhausts by themselves are not a problem. They are a safety measure which cuts down the number of accidents.

Are we going to give in to this, or are we going to complain to the NSW Government about there changes. Who wants a fast car with a dead quiet exhaust?

The exhaust laws are pathetic. 90db at 450mm from the end of the exhaust is a joke, it's dead quiet. 1 in 5 cars are over the limit and you will lose your licence if you are not careful. It is another revenue raiser that is a lot easier than catching drug dealers, car thieves and murderers.


"Noisy exhausts are a safety measure that cuts down the number of accidents?" We'd love to see the evidence for that statement.

X-Trail No Good

I just finished reading the X-Trail review ["New Car Test - Nissan X-Trail Ti"]. I've been 4wding competitively for some years, amongst other 4wd activities.

Julian Edgar, could I suggest you might gain from some insights into what I think 4wding is about and what constitutes a good 4wd. I do not believe the X-Trail is a good 4wd.

I'm happy to explain why in an email or on the phone. I'm actively involved in the 4WD community and if you guys are in Sydney I could arrange a drive to Menai in my comp truck or something else to show you, if you want more practical insights.

Adam Howarth

For the purposes for which it was designed, we think that the X-Trail is a very good car. As far as we know, driving in off-road 4WD competitions (or, as your later email suggests, to Cape York) weren't part of its design criteria.

The Story Behind Whiteline's No-Show Commodore VT-VX Rear Toe Link

I would very much love to report some good news but unfortunately not... our development program for this item is now officially dead!

Why? Mainly cost, but first we'd like to at least share some of the information we have learnt during the design stage that may help you understand the positives and negatives. Using this data, you may decide to still proceed with this modification - however somewhat better informed as to the costs.

This information pertains to the VT series I/II IRS and VX series I with this range referred to as the earlier model. Only exception is the VT GTS that was supplied by HSV with the toe control link modification as standard. The latter models we refer to are VX series II onward.

The main issues with VX II or VT II GTS (HSV) using toe control link as compared with earlier models:

  • Latter models use unique cross-member and lower control arms with relocated pickup points and different inner bushings. This is done to achieve a better base line camber setting as well as providing mounts for the toe control link. New inner bushings are specially directionally voided for controlled compliance.
  • Using our data, base camber at standard ride height has been pulled back from a range of -1.75 to -2.25 degrees on the earlier platform, to -0.75 to -1.25 degrees on the latter. Factory lowered models like SS and S will have higher base readings due to suspension movement arc. (Holden's claims that up to the VX I chassis, rear static camber averaged -1.5 degrees. However, VX II average should be around -0.5 degrees *Source was Polk Autospec vehicle data.)
  • Contrary to Holden's claims of better camber control for towing, we did not find any significant improvement to dynamic camber using the new link other than a reduced base line.
  • Base toe setting at standard height used to range from -1.0 (toe out) mm to +3.0 (toe in) mm per side! VX II models are adjustable via the toe
    control link with a very broad range to cover toe in and out.
  • The toe control link's main advantage is in holding the toe setting through the suspension movement arc (wheel travel). For example, earlier vehicles with a base setting of 0.0 mm or neutral toe would swing between +2.1 mm (toe in) at 40 mm bump to -3.8 mm (toe out) at 40 mm wheel droop. Later models with a base setting of 0.0 mm have next to no change on bump and will toe out by -1.8 mm at 30 mm of wheel droop.

So the overall technical results of the later model suspension are good and make a significant difference. Anyone serious about maximising their Commodore IRS's performance would find these changes very worthwhile as they allow for much more predictable and stable rear dynamics while delivering a great deal more traction potential.

Assuming you wish to proceed, here are the issues (costs are lowest prices found at time of writing):

  • VX II uses a new crossmember with separate part numbers for V6 and V8. Holden spare parts retail price quoted as $280
  • VX II uses revised control arm assemblies with new style bushing fitted. Common to both V6 and V8 and retail for $395 each from Holden. Note that VX series I control arm assemblies do NOT have machined section on hub to mount toe link. VT series I and II do however have these mount points machined.
  • Toe control links seem to be common to VT GTS and VX II and retail for $305 each. Allow an additional $5 to $10 for some high tensile mounting hardware for the cross-member end of the link.

The crossmember is relatively cheap from Holden and holds the key in delivering the static camber improvement while featuring the very elaborate welded mounts for the control link. Whiteline could not offer these mounts as DIY weld options for that much less than the cost of a new cross-member and that still doesn't address the changed pickup point issue.

There is some opportunity in Whiteline developing alternative toe links and we could probably supply them for half the price but this is a relatively small part of the cost equation as the overall labour component would be huge. The crossmember would need to be removed completely so that the new mounts could be welded to it. This in itself would necessitate an engineer's inspection, as it would qualify as a "major change" to the suspension. That would still leave a problem with the VX I cars as the hubs would need to be removed and machined with a taper to accept the ball joint style toe link end.

Considering all the variables, we therefore concluded that it was simply uneconomical and unviable. We calculate that our parts plus those you would need from Holden would still total in excess of $700 with around $350 in fitting labour IF the hubs do not require machining. Even then you will not end up with the improved static camber.

In all honesty, our suggestion would be to wait for a wrecked complete VX II rear-end and have that fitted to your earlier series car. It would probably be the cheapest and easiest solution.

We'd like to thank everyone for their patience on this issue. We hope that you might find this information useful and apologies for any inconvenience.

Jim Gurieff

Whiteline Suspension

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