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Some of this week's Letters to AutoSpeed!

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Get it Cheap at...

Do you know about Yahoo Japan Auctions? The biggest on-line auction in Japan! Very often prices are much cheaper than retailers! If you are looking for new and used JDM parts, you should check this site...

Masa -

Awesome Honda Engines

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Great article on the H22 Honda engines (The Honda H-series Engine Guide) - a great in-depth look at these awesome engines. Well done!

Joey Chau

Enjoying HPV Articles

I am enjoying the HPV articles. In relation to the front suspension, another way to reduce roll is - rather than run an anti-roll bar - run a monoshock with quite soft springing and you will have soft suspension in bump but extreme roll stiffness. See and specifically this page...

You can see the links coming from both wishbones feeding via common links to the monoshock. That three-wheeler will out-corner a Type R Honda Civic on a skid pan and, when it finally runs out of grip, it ends in mild understeer, with throttle induced oversteer available. I think 0 - 100 km/h is sub 5 seconds. In relation to bobbing rear suspension, you may find this page interesting as this rear suspension does work very well to remove pedal bob.

Craig Vincent
New Zealand

More re Davies Craig Pump Testing

I was very interested at the Davies Craig water pump NON article (Testing the Davies Craig Electric Water Pump - Part 1... I’m keen to know if you recommend this piece of "interesting" equipment or not? PLEASE REPLY - I can’t seem to get any professional opinions on this.

Scottie Young
New Zealand

If you have any concerns regarding the performance of this (or any other product) we suggest you negotiate a money-back guarantee before purchase. For legal reasons we won’t be revealing any of the findings of our tests.

How Many Zs?

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Re Straight Six Z31... I have a Nissan 200ZR import with 80,000km and a factory top-mount intercooler. I just want to know how many came to Australia.

Kane Buttress

We’re not sure - but not many! Readers?

Gauge Duel

Could we get an article on aftermarket gauges - a comparison of the accuracies and features? Compare the expensive Defi and HKS gauges to more reasonable gauges from other companies. I work in a calibration laboratory for the US Air Force here in Japan and, after checking the accuracies of a few of my gauges, I thought that this might be a good article for you to have on AutoSpeed. You could make it a multi-part story with boost gauges one issue, temp gauges the next, etc.

Shawn Pantall

If you haven’t already, check out Giant Gauge Test - Part 1and Giant Gauge Test - Part 2 But, yes, it’s probably about time we looked into something similar again!

Alfa Assessment

Love your work. I would like to see your considered assessment of the new Alfa Romeo Brera - preferably the 3.2-litre manual.

Nicholas Croft

We’d love to provide it but, unfortunately, Alfa Romeo (Australia) hasn't supplied us with press cars since our 166 review.

More on Rubbery Figures

Responding to the Rubbery Flywheel Power Figures letters - Response...

That Puma Racing link posted by Simon Nieper is very good, and the text refers to another helpful Canadian article. With regard to transmission losses, there is an inescapable loss when transferring torque through gears. Referring to straight-cut gears, the gear teeth engage such that the force transferred from one tooth to another is at an angle (the pressure angle). Typically 20 degrees, (I can't confirm the angle for automotive gears – does anyone know? - but usually the case for motorcycles) the force vector then has two components, one (Force x Cos20) is tangential to the gear and is passed to the mating gear, the other component (Force x Sin20) is actually pushing the two gears apart (so the greater the torque, the stronger the transmission casing needs to be to prevent this bursting pressure).

To get to the point, ignoring frictional losses which are covered in the aforementioned articles, the force received and the resultant torque is approximately 94% (Cos20) of the input torque. In the case of helical gears there is another component lost to axial thrust, so the torque post transfer will be even lower than 94 percent. With a typical diff (90 degree change in drive, helical gears), transfer loss is likely to be greater. This is the case for any gear set, so multiplying the torque or power by the loss factor by however many gear sets are driven at a given time will result in the net value ignoring friction, tyres, etc (refer articles). This loss is proportional to torque and, since power is torque x rpm, stating a static power loss for an engine when power is increased from standard is not logical. I hope this helps factually explain some of the reasons for drivetrain power loss. (It really needs a diagram to help explain but the web should provide something). In general, since rear wheel power is what you end up with, flywheel power is just academic.

PS - Pressure angles affect the size of the tooth, the smaller the angle the less torque lost but the more slender the tooth and increased risk of failure. Ducati used to use (and may still do) a 15 degree pressure angle.

Martin Sainsbury

IEBC to be Used for...

Can you think of any other uses for the IEBC? I bought one for a turbo conversion but am no longer going down that path because of the myriad of problems encountered attempting the ‘turbo'd for torque’ approach. I am having trouble offloading the kit and have advertised it on many forums without success - I was wondering if there are other uses for such a kit, as most of the other kits you helped to develop can be used for all sorts of applications?


The IEBC typically receives an injector duty cycle input and, once programmed, outputs your desired duty cycle to drive a boost control solenoid. However, there’s no reason the IEBC can’t be used to drive an extra injector/water injector or toluene injector on the basis of injector duty cycle.

Re Vortex Generators #1

Re Driving Emotion... Mike Chadwick from VG Fuel Savers’ reluctance to take part in a scientific test of his product may be because of me. After seeing his product on New Inventors and recollecting a previous ABC program referring to it being the product of university research, I agreed to purchase a set if he would agree to refund me my money if a scientific test failed to show any measurable improvement. He agreed. I fitted them. They failed to show any improvement. I sent them back and received a refund.

I'm not saying they don't do anything. But while their website says they work on ALL body shapes, the explanation referred only to cars with sedan-like rear windows. The way they worked, it was claimed, was that the vortex generators prevented separation of the airflow. The air flowed down the window without turbulence rather than separating turbulently at the trailing edge of the roof. My car is a hatchback - a Renault Clio Sport - with a spoiler at the trailing edge of the roof specifically to get clean separation. I saw New Inventors and the website, but I couldn't see how it all related to the body shape of my car.

So what I did was use the trip computer on the car to measure litres/100km every 15 km/h from 55 to 115 km/h on the same car on the same road in the same weather before and after fitting the VG fuel savers. It would have been easier with cruise control - it turned out to be very hard to maintain a very precise speed at low speeds. And it turned out that the cold start mixture enrichment stayed on well after the water temperature gauge was up to normal. But the testing showed there was no measurable difference between before and after. On my car.

So if you're going to test, be fair and test various body shapes. The demo on the ABC was a BMW sedan or coupe with a fairly flat rear window. You could see there was an effect. But VG Fuel Savers claims significant benefits on ALL body shapes.

Gordon Drennan

Interesting stuff. However, as mentioned in our article - and as you say – the manufacturer’s claim is a fuel consumption improvement on ALL body styles. It appears this is not the case and, as a result, we would not have validated the claims in our test (that now appears won’t be happening)....

Re Vortex Generators #2

Re: Driving Emotion 18th June 2006 - Fuel Saving Vortex Generators (Driving Emotion...

You mentioned you had found another source of vortex generators for your future article. You may also be interested in whose product has been specially designed for trucks. But I guess, may also be suitable for cars? They claim an average four percent fuel saving on their website. Hope this is of some use.

Glen Kable

Thanks for the lead - you’ve found our second source!

Re Vortex Generators #3

I read Julian Edgar's 18th June, 2006 ‘Driving Emotion’ article on vortex generators (Driving Emotion) with interest. This may provide him with some ideas for his further experimentation...

I too have experimented with vortex generators, but not for the purpose of fuel consumption reduction. I am Editor of my local car club Bulletin (Peterborough Motor Sports Club,, which appears on-line at between monthly and bimonthly intervals - depending on how busy I am at the time. Much of the technical content I add results from experimenting with my track car, a 1989 RX-7 Turbo II, which I use to compete in time trials (which we call Solo 1 or SoloSprint).

My approach has been to increase rear spoiler to the point that I can feel the car becoming aerodynamically unbalanced and the adding front air dam/splitter until balance is regained.

Meanwhile, I have been keeping an eye on top speed on a fast straight to see that I have not added so much drag that lap times are detrimentally affected. I was prepared to accept some reduction in top speed as long as cornering speeds and lap times improved.

As the 2nd generation RX-7 has a cusp in the roof line at the start of the rear hatch, I expected flow to be separated over the entire glass and I expected this to reduce the effectiveness of the rear spoiler. This got me thinking about vortex generators to reattach the flow and, when I saw a picture of VGs on the Evo, I realized how sensible the idea was. The VGs were very effective in keeping the flow attached – but how exactly this has affected drag or downforce or lap times, I can't say. The car is definitely more planted at high speed, and given that no significant reduction in top speed has been observed, the VGs definitely can't be doing any harm.

You may also find this link of interest

James Mewett

Some very interesting info – thanks for that.

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