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Response

Some of this week's Letters to AutoSpeed

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Barina SRi Updates

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I am a subscriber and love your work.I have recently bought a new Barina SRi (I read your 2002 review - New Car Test - Barina SRi) and would like to know what technical changes were made for the post-2004 model - I know they tweaked the steering, deleted traction control and upgraded to 16 inch alloys. I tried talking to Holden but they said they could not give me any press release information and that I should try a motoring editor.

Bruce Carter
Australia

Aside from the changes you mention, the only other major alteration to the ’04 model was the introduction of brake assist.

Re SR20DET Guide #1

In your SR20DET article The SR20DET Guide you say...

"Inside, the GTi-R engine has numerous improvements over conventional SR20DETs. The bottom-end boasts piston oil jets, a larger capacity oil pump with a water-to-oil cooler as well as stronger main cap bolts and conrods. The top-end features beefier head bolts, sodium filled exhaust valves, a revised exhaust cam profile, solid lifters, an improved head design and different piston crowns providing a static compression ratio of 8.3:1 (down from 8.5:1). "

The SR20DET from my S14 had piston oil jets, sodium filled exhaust valves and a water-to-oil cooler. I believe all SR20DETs have the squirters and sodium valves but the S15 (5 speed) engine that replaced mine doesn't have a water-to-oil cooler.

Avner Bronfeld
Israel

Thanks for that – interesting stuff. Can any other readers identify the internal differences between the regular SR20DET and the GTi-R version?

Re SR20DET Guide #2

Re your SR20DET Guide...

Being a past Pulsar GTi-R owner this article captured my eye immediately, so I had a look (as I always do at lunch time) and I noticed you omitted one SR20 engine variant.

Although not a SR20DET as such, you forgot to mention the last of the SR20 turbo engines – the SR20VET, as fitted to the Japanese-spec Nissan X-Trail (GT, I think). From memory, this motor puts out around 206kW and has Nissan's NEO VVT technology.

Gino Espinosa
Australia

You’re right. As far as we can determine, the SR20VET (fitted to the 2001 J-spec X-Trail GT) uses a relatively high 9:1 static compression ratio and NEO VVL (variable valve lift) to generate a massive 206kW and 309Nm. Unfortunately, we are yet to see this engine at the import wreckers.

NVH Shootout?

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I was wondering about the possibility of a "NVH shootout" - a quest to find the smoothest, quietest and most refined driving car. I'm sure Julian Edgar’s Lexus LS400 would be a likely participant!

Peter Parianos
Australia

Such a test would be very difficult – you’d really need to have all cars together at once for SPL measurement and subjective testing. The Lexus would be easily outclassed by some current cars.

Speed Signal Problems

I have just purchased a Nissan Skyline R33 (1993) which was originally an automatic. It has been changed to a manual, but the problem is that the speedo only shows about half the speed you’re really doing. In addition, the odometer and trip meter readings are out. Can you help us sort this problem out and let us know what is required to fix it?

Greg Dixon
Australia

We suggest altering the vehicle’s road speed signal using the Silicon Chip Digital Speedo Corrector (as sold through Jaycar outlets.)

Electronic Kits Separable?

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I just bought High Performance Electronic Projects for Cars Book Review - Performance Electronics for Cars. I know that I can buy the kits from the AutoSpeed shop and build them myself, but the problem with that approach is that I might have to pay 60 percent import tax.

I did some research and found out that all the electronic components that I need can be purchased here – however, I noticed that for the PIC projects I need the assembler program that goes inside it. So my question is... Can I get these assembler files for all projects or do I have to buy the complete kit?

I know that there are advantages to buying the complete kit approach (the PC board will be much cleaner that the one I will build) but, still - to have the book and not be able to build yourself the kit (by purchasing the parts myself over here) is a bit frustrating.

For a long time I wanted to sign up to AutoSpeed and I’ve now been able to do it. Congratulations for the nice papers you guys put together - always very technical. Keep doing the good work.

Carlos Dagher
Brazil

The assembly code is not available so you will need to purchase the complete kit. Glad you like the articles!

Diesel Myth

Hi there! I am driving a diesel vehicle and there is a myth going around saying that it is not advisable to drive until your fuel tank is near empty. This is because diesel (being a lower quality fuel) leaves deposits in the fuel tank and driving ‘til near empty will pick it up in the fuel pump. This is the common cause of fuel pump damage.

But is that true? The pump’s fuel inlet is located at the bottom of the tank and thus everything will be picked up - no matter if the tank is full or empty.

Please enlighten us and smash the myth!

Lee EK
Singapore

We can’t offer a definitive answer, but we believe a low diesel fuel level and high humidity encourages the growth of algae. This might be the reason for this ‘myth’.

More on Plumbing

Reading your article Plumbing Basics, Part 3 brought back memories of adding an intercooler to my 1986 Mazda 626GT. The intercooler was mounted almost horizontally (30 degrees) beneath the battery - a scoop directed airpassing beneath the car into the core. A single length of 1 3/4 x 24inch BellowsFlex hose was used to connect the turbo to the intercooler and a second length of 1 7/8 x 36 inch hose connected to the throttle body. There were no sharp bends or material transitions to disturb the laminar flow along the way - just a smooth continuous hose. How many other systems can say that? BellowsFlex (yellow stripe) and other similar brands come in many sizes and, despite having an interior spring coil, the interior wall is smooth. The inner liner is oil-resistant Nytrile B, capable of withstanding pressures of 30-50 psi and has a working temperature of 110 degrees Celsius. At the time I payed US$3 a foot (about 30cm). Turbo and High Tech magazine also published my 626GT as a Readers Car in May, 1989.

P.S. - I've built your fusion IC which will be installed along with a BPT engine/tranny in a ‘88 Mazda 323GTX this winter. I'll write you when it's running! Thanks for all your thought-provoking articles!

George Barrett
USA

Interesting stuff. Let us know how you go with the fusion IC!

More on Prius Fuel System

I would like to say well done on the modifications to increase fuel pressures in the Prius. I would just like to put forward a simpler idea that I believe would increase the fuel pressure - but possibly not as much as you achieved. Does the Prius have a constant voltage sent to the fuel pump? If so, I’m sure you could increase the flow and pressure to the fuel rail by increasing the voltage to the pump up to, say, 20V. This might not sound safe for the pump windings but I’m sure for street cars (since boost is not held on for long compared to a race car) that the increased heat in the windings should not be an issue. Furthermore, products already exist from MSD that use a boost signal to ‘overvoltage’ the pump, such as this one... www.msdignition.com (the 22V 10 amp output one).You could add some additional circuitry to cut out the oxygen sensor signal or make the fuel pressure increase in a step change from baseline. Furthermore, you could use the Silicon Chip PIC based micro-controllers and adjustable fuel tables to modify the voltage coming out of the voltage booster to the fuel pump.

Jim Katsis
Australia

Check out the article Modifying Returnless Fuel Systems, Part 1 - the MSD Fuel Pump Voltage Booster is mentioned there. Certainly, these units can be used to bump up pump output, but you’re still limited to the fuel pressure which is dictated by the pressure reg. We needed a way to increase fuel pressure from around 44- 50 psi to around 85 psi - a big difference.

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