Porsche Nomenclature
Isn't the 993 Porsche designation just like saying a "VN" Commodore? 993 was the old model, 996 is the current. The turbo is a 911 993. It's still a 911.
Mark Pakula
Reading the article "Something Better - A Porsche 993 twin-turbo with around $100k spent in mods? This is one hell of a car!" you state that the 993 is a 911 with twin turbos and all wheel drive. That is very incomplete and partially inaccurate information. The 993 is a generation of 911s that included the Carrera 2, Carerra 4, and the Turbo, among others. If there is a number designation that refers to 911 Turbos, it would be 930. The 993 was the last generation of air-cooled Porsche 911s and has been replaced by the current 996 generation water-cooled 911. The 996 series includes a Carerra 2, Carerra 4, and Turbo. In addition to the Coupes offered in each of these trim levels, there are also Cabriolets for the C2 and C4.
Nicholas Luhr
Thanks for the correction we have made a change to the article.
Intercepting the Oxy Sensor
Just a thought I had re modifying engine management systems (caused by the observations of a faulty oxygen sensor on my mixture display).
You have noted several times that an interceptor or chip won't work at part-throttle settings because the oxygen sensor signal causes the ECU to adjust the mixture back to stoichiometric. Has anyone done any work to intercept the O2 sensor signal and adapt it to suit? I realise this would probably be tricky due to the high non-linearity of its response, but surely someone with the nous could give it a fair go... if not altering it completely then at least off-setting it a little bit with a potentiometer...
Anyway, any comments (positive or negative) would be appreciated.
Matt King
We have considered developing a product that intercepts the output of the oxygen sensor. The application that we thought best would be to force a lean cruise mode by suggesting to the ECU that the car is running just a little rich, even when it is at 14.7:1. If such an interception occurred only after a certain period of constant throttle, and above a certain road speed, it could be quite effective. Lean cruise is of course a function that some cars already have. However, we dropped the idea when we decided that there would be insufficient interest in such a product.
In terms of intercepting the signal to negate the affects of the ECU learning its way around another interceptor, to be blunt we think that would be piling too many bodgy things on top of one another. At least with an interceptor and a functioning oxygen sensor, the air/fuel ratio will be sufficiently correct in closed loop that the cat converter will still work and decent fuel economy will be retained. Start altering the oxy senor output in order that the mixture will stay much richer in closed loop, and cat converter efficiency will be ruined. In that case, it would be simpler to just disconnect the oxygen sensor permanently. If the conditions which cause the ECU to enter and exit closed loop need to be changed, it is much better to do that by altering the original management system software - and then the fuel and ignition can be changed as required at the same time.
Not Enough Fuel
Hi there! I'm currently driving a Ford Laser with a converted Mazda GTX 1.8 Turbo engine. I have also installed the electronic equipments such as Apexi Super AFC & Apexi AVC-R on to my car. I went for a car tuning via dyno machine and it was noted that my car can run a maximum boost of 0.8 Bar which would generate about 220hp. I was advised by the workshop that it is not safe for me to boost further because that is insufficient in the supply of fuel after 0.8 Bar.
Recently, I decided to upgrade my fuel pump to Vortech fuel pump (180 litres/hour) which would have a fuel flow rate of 3 litres per minute (ie according to the supplier). After installation, I realised that it might be too big for my car as the petrol burst out from the old fuel hose in several occasions. Subsequently, I replaced all the old fuel hoses with more reliable hoses. Besides, I understand from the 21st Century Performance written by Julian Edgar that if the fuel pump is too big, it will increase the frequency of the fuel flow and at the same time increase the temperature of the petrol.
1. If that's the case, is there any method that I can use to reduce the fuel flow rate? By installing an adjustable fuel pressure regulator, would it slow down on the return of fuel to the fuel tank?
2. If I want to increase the fuel supply when I increase the boost up to 1 Bar. What is the best way? Can the Apexi Super AFC do the job? Do I need to install the adjustable fuel pressure regulator to assist super AFC in carrying out the job? Can super AFC have the same function with adjustable fuel pressure regulator in increasing the flow of fuel to the injectors?
3. Could I know what is the difference between the Apexi ITC and the HKS Twin Power Ignition aftermarket products? Is it advisable to install?
Sorry to inquire so many questions at once. Hope you can enlighten me. Thanking you in anticipation.
Chong Wee Ng
1. You can reduce the fuel flow by dropping the voltage to the pump. In fact, we have a project in the pipeline that will be suitable for just this application, but in the mean time just keep running it at full power - it won't be a major problem on its own, so long as you have good quality fuel hoses in place!
2. You don't say how much duty cycle the injectors are running at peak power. If they are flat-out (ie 100 per cent duty cycle) then electronic interceptors like the AFC won't increase the fuel flow - you'll need to either increase fuel pressure or use larger injectors. It's quite likely in this application that you will need to increase fuel pressure and then use an interceptor like the AFC to fine tune mixtures.
3. At this stage just get the fuelling side of things sorted out first. However, if you intend going a long way with the project, you might want to consider fitting good quality programmable engine management and larger injectors instead of taking the AFC and ITC routes. "Fitting Programmable Management" is an example of this approach.
Getting Cars Featured
Hi just wondering about what are the criteria it takes to put one of the car on your website? As Singaporeans studying overseas in Australia we have got several good and powerful WRX and 200SX that run 11s and 12s together with impressive dyno-proven horsepower figures. Just wondering, are we able to feature our cars in the AutoSpeed website...thanx a lot for your effort to reply :)
Gavin
We are always looking for good quality cars to feature in AutoSpeed. The best approach to take is to send us some photos of the car - exterior, interior and underbonnet - together with a description of its modifications. If we like what's been done, we'll then either use it in one of two ways - in Readers' Cars, or have the car shot by one of our photographers and then run as a full feature.
When is a Rex Not a Rex?
I thought you might want to know (and I'm pretty sure on this one) the car featured in your "WRX with the Worx" article is actually a Subaru Impreza GT, not a Subaru Impreza WRX. The WRX is the replacement for the GT (and is the Subaru with the round lights).
Cameron Waldron
The names that Subaru has used for its models vary around the world. In Australia, where the story on the car was produced, it is definitely a Subaru Impreza WRX.
Subaru Liberty RS Intake
I've been reading with great interest your articles on eliminating negative boosts on the Audi (starts "Eliminating Negative Boost - Part 1") and now the VL (["Modifying the VL Turbo Intake").
As an owner of a Liberty RS, I'm particularly interested to know if you made any similar mods to the Liberty's induction system. In Part 4 of the Negative Boost article, you mention the Liberty has a very significant pressure drop which suggests to me that one of you perhaps experimented with this at some stage.
If so, any info or tips you have would be greatly appreciated. I've done a big search on AutoSpeed but there doesn't seem to be any specific info relating to this.
Nick Robinson
You're right in that we have done it, and you're also right in that the specific information doesn't appear in AutoSpeed (it was all done well before AutoSpeed began). Basically, fit a large diameter cold air duct flowing into the airbox through its standard opening. Remove the very restrictive in-guard resonant chamber and discard it. Don't worry about making any other changes to the intake prior to the turbo (ie leave the post airbox resonant chamber in place, and use the factory airfilter). Making these simple modifications improves intake flow substantially.
Turbo Technology
I think very highly of AutoSpeed and will renew my membership shortly.
I have a small request. There has been much talk of VATN (Variable Area Turbine Nozzles) turbochargers. Having bought an S15 Silvia and eventually wanting to upgrade the turbo I stumbled on this technology in Corky Bell's Maximum Boost. The only company that activity sold this technology was Aerodyne in Texas. Unfortunately their turbocharger (the Aerocharger) was quite unreliable although it did live up to its performance expectations. Garret has developed this technology for diesels and are in development of the gasoline-engined version.
Would it be possible to write an article on this technology, explaining its pros and cons. But more importantly to me, when will it be available for regular Joes like me ;-)
Adrian Veasey
There are a number of new turbo technologies that will hit the market in the next 12 months or so. These include variable nozzle turbos, electric assist turbos (the Garret prototype unit is pictured), turbos with air bearings, and turbos with sheet metal housings. When enough good quality information is released on these designs we will certainly be running a story. We have already very briefly covered variable turbos at "Turbines to Speed".
Incidentally, excellent power increases can be gained from the Nissan S15 Silvia, even when the standard turbo is retained - see "S15 Silvia Power!" for further on this.
New Car Assembly - DIY...
Mister the Editor,
I am proposing you a synopsis. My aim is to write an article upon the reality of easy-to- assemble cars. Although the automobile industry is not already aware of the advantages of such a car, I want to present your magazine its eventuality. This case study is very complex. Just facing the changes of habits created by a car that would become affordable to new owners is enough. So, if you are interested in a complete article, just ask for a description that could fit in your special magazine.
Synopsis:
An easy-to-assemble car, costing forty per cent less than the actual vehicle market price and delivered at your home. You, as a car buyer being responsible for its assembly. This would be the reality of the next decade and a potential market for the actual automobile industry. The text describes the eventuality of a home industry of car assembly, resulting from the standardization of car parts. Any advised home-mechanic would find it advantageous to assemble by himself a personal vehicle. A kit needing no welding, but rather simple tools accompanied with assembly instructions, would then be provided.
The reality of car parts standardization would lead to several advantages. Modernizing a car instead of buying a new one would be the rule. Since you have owned a car, and assembled it, you could later restore old parts and give your car a new shape. Complete availability of standard parts on the market would allow the consumer to buy at almost every store, convenient parts. Garages would find it easier to respond to a driver's demand. Stocks inventory would be enormously simplified. Tyres, spark plugs, lights...
These vehicle can however be personalized. A number of models, of types, of different qualities would be accessible. The result would still be a fleet of standardized cars, assembled by their owners, and receiving repairs and maintenance. We can only imagine the impact on automobile industry, even of a prototype, of an easy-to-assemble car. What we are trying here is to state clearly the possible result of an exploitation of such a market in America.
Marc Everell
The modern car is the most complex mass-produced electrical/mechanical device in existence. We can't see too many people wanting to assemble their own...
ATTESA Systems
Correct me if I'm wrong, but the ATTESA system used on the Bluebird and GTiR has absolutely no similarities to the ATTESA system used on the GT-R, apart from that they are in essence both 4WD. The GTR system uses a RWD setup, which when overcome by slip/torque (detected by G meters) it transfers torque to the front wheels, therefore giving 4WD. Whereas, the system used on the Bluebird and GTiR is your simple centre LSD with a 50/50 split front to rear with no electronic variation in torque split (on the auto there was??). In fact, the Bluebird is even worse off then the GTiR as it doesn't come standard with a rear LSD (could be wrong on that). I know I'm probably stating the obvious, as you have fiddled around with your G-TR's system, but the article on the Bluebird ["Family Hauler"] gives the impression that the ATTESA system used is the same as the GT-R, and the only thing the same is the name.
Filip Kemp
That is correct - the ATTESA 4WD system in the Bluebird is just a common viscous coupled design. That's why the "he thought" bit is in the sentence: "Sure it wasn't Godzilla, but it had - he thought - similar characteristics with an SR20DET ATTESA 4WD". But yes, perhaps we could have made it clearer.
The Honda HRV Handles!
Just read your Honda HRV review ["New Car Test - Honda HR-V"]. I think the unit you used must have had suspension damage or some such (lousy tyres? alignment?). Regardless, I found the HRV one of the best handling cars. As part of my evaluation of 12 cars I took it to a large asphalt area and tried my damnedest to unseat it - managed to get it to lift inside rear tyre (duh!) but couldn't break traction no matter how I tried - remarkable. Suggest reviewer have enough mech knowledge to know if vehicle may need repair. No undamaged HRV would handle as he describes.
PS tried Forrester - way too uncomfortable and noisy, unlike HRV.
Dave Barry
Press cars are supplied by the national distributor of the car company concerned. They are standard in all respects, including wheel alignment and tyres. Further, the cars are workshop checked between each media road test, and any maintenance is carried out as required. Are you suggesting that we should know more about the mechanical condition of a car than the company that manufactures and distributes it? And, further, that we should change the standard tyres and wheel alignment? We are glad that you like the car - we didn't.
VL Turbo Fuelling
I am looking to construct a extra injector controller using the Hyperform Shift Indicator ["Simple DIY Rev Switch" ]linked to a vacuum switch for my VL Turbo. The basic design uses two extra injectors, each being controlled by a pressure switch and a light dark relay (from the shift light) in series. Hopefully this will allow individual control of each injector to come on at a set boost pressure and rpm (eg injector 1 comes on at 3000 rpm, 8 psi boost, Injector 2 comes on at 4000 rpm, 11 psi boost). Do you think this system is appropriate for a VL turbo looking to run a maximum boost of 15 psi with intake, exhaust and intercooling modifications?
Graham Treloar
What you are suggesting will work, however, it is really using an approach which is now rather crude and old fashioned. Firstly, is the car running lean anyway? Most VLs with relatively small mods are actually over-fuelled by the standard system. Secondly, if the car is in fact running lean, could a simple rising rate fuel pressure regulator provide enough extra fuel through the standard injectors? Thirdly, have you priced upgrading all six injectors to larger ones and having the ECU chip re-programmed to run them (perhaps with a modified airflow meter as well)? Using pressure-switched extra injectors (even with an rpm input as you have indicated) is not a particularly elegant way of doing things.
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