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Quick Gear Changes

I just wanted to say thanks for the 'Quick Grab' article on changing gears. I have a 91 MR2 Turbo, and have already undertaken a few of the items in the article, but was very interested to learn a few of the racer's tricks (lightened gearsets and such).

I'd like to add one point to the discussion as well. While the MR2 never really saw much in terms of homologation specials, but the sister car to the MKII's (the Celica) have some mighty trick bits for the turbo cars. Included in this is an anti-lag system for the rally cars, that works on a principle not mentioned in the article. There is a rare exhaust manifold for the 3S-GTE that incorporates a set of air jets that are tied into the recirculation valve on the intake side of the engine. When the recirculation valve is activated, the pressurized air from the intake tract is forced over the turbine. This has the advantage of a longer service life for the turbo charger compared to the typical fuel driven anti-lag kits.

Adrian Irwin


E85 Conversion

I have been looking into the E85 fuels as an alternative to the normal unleaded I'm currently using. So far the only data I've found on a conversion is through a US Mob called 'Flex Fuel International'.

From what I can tell, all that is done to turn a 'normal' EFI engine into one that can accept E85 is to change the injector cycle and timing - along with fuel pump/line suitablity issues. The system FFI supply looks like an intercepter type between the injectors and ECU whilst taking power from the battery.

Do you know of any Australian companies that are doing a similar modification, if not I'm thinking that the Digital Fuel Adjuster would be able to do the same job? I know that the DFA doesn't intercept in the same way, but I'm thinking that it would still be able to do the job? That way there could be two maps for E85 and normal unleaded.

The car I'll be modifying is a 1.8 KJ Laser (Mazda BP engine) and I'm told it's not worthwhile to fit LPG to it, so E85 might be a viable alternative. I'd just rather use the DFA or the DPA to do it. What piqued my interest is that the SA Farmers Fuel co-op (SAFF on Salisbury Hi-way) on my daily drive to work now sells E85 at the pump apparently for some fleet vehicles that are using it.

Darren Roles


The DFA should be able to change fuelling without much problem. However, to get best results, you’d also want to alter ignition timing, so really a full three-dimensional interceptor would give potentially much better results. We don’t know of any company in Australia performing E85 conversions.

Driving Direct Injection

What a great website! Your articles are well researched, thorough, and above all, good reading. My two interests (like yours I expect) are performance when I want to enjoy my driving AND economy when I am driving gently. To this end I have an Astra with the 2.2 direct injection engine. Zippy performance with the added economy of direct injection.

To aid perf. & economy I removed the baffled muffler at the rear. This gave me an immediate improvement in fuel consumption (on steady cruise I saw about a 1 to 2 L/100km drop in the instantaneous consumption figures). Just as you said in your articles.

Finally to my question. A direct injection engine runs ulta lean on light throttle. Conventional wisdom states that economy driving is in a high gear and a wide open throttle (to improve the volumetric efficiency). But what about a direct injection motor? Open throttle gives the richer mixture map. Can you write an article on the most economical way to drive a direct injection motor? (ie do I go up a slight hill in 3rd gear with light throttle or 4th gear with a more open throttle).

Keep up the good work, I love your articles.

Tom Burke


In cars with a trip computer, the easiest way of finding the best driving techniques (eg up the slight hill you describe) is to try various techniques and see which gives the best fuel consumption. However, we are currently working on a project that will give a useful fuel mixture read-out from cars that can run very lean and are fitted as standard with wideband oxygen sensors. That will provide a good on-dash indication of when mixtures are at their most economical.


G'day - love reading your publication, look forward to it arriving in my inbox every week. I drive a 1989 Nissan Z32 300ZX, manual, imported from Japan 2 years ago.

Regarding the Technical Feature from 20th May 2008 - 'EGR Comeback', I found it very interesting, because a common suggestion during major servicing by knowledgeable owners of the Z community here in Australia is to disconnect the EGR, as it's apparently useless. Now, the 300ZX has an external type EGR, feeding through pipes to recirculate the gasses. Would a more effective solution be to develop a cooled EGR system that would link in with the existing Airflow Meter? It is typically a strong unit and the 300ZX AFM is used as an upgrade on a wide variety of cars. Do you know if this has already been developed in the US?

Hope you might have some ideas for our 300ZX Community to consider -

Thanks heaps and keep up the good work! ;-)=

Kris Gall


Other than in our stories, we’ve never seen anyone modify the EGR for a greater flow in order to achieve better part-throttle fuel consumption. As we said in those stories, people just normally rip EGR systems off the engine! Re cooled EGR, we think it’s worthwhile experimenting with a manually controlled system. If that is effective, then you could look at linking its action to engine load.

Electronic Relays

I was just reading your article on Solid State Relays in issue 480. You stated in the article that these type of relays can never wear out. I work for an ATM maintenance company, in particular we service a brand known as NCR and these all use the same solid state relays as you are talking about. I wont go into boring detail but I might add a word of caution, we see these relays reguarly after a period of a few years, go closed circuit on the LOAD side. This causes big problems as it burns out certain components. So while they are reliable, they are not 'bullet proof'. I would say from experience, a well made mechanical relay is just as good, reliability wise. There are some out there right now that have been switching hundreds of times a day since 1994!

Michael Dahlenburg


Silly Blog Ads

Oh the irony! At the bottom of your blog article 'Being less circumspect' I see an advertisement stating: 'Double any vehicles mpg!  Secret Technology THEY want to ban! Plans, Sources, Complete kits! only $50'Could this possibly be any less circumspect, I ask myself? Following the link takes you to a website selling cosmetci car care products and offering a free report 'How to modify your car or truck to save gas using water!!!'. I'm surprised at Autospeed hosting this kind of garbage. Perhaps a suitable subject for a technical article along the lines of the Twin Turbo Zet supercharger???

Ben Garside

United Kingdom

We have literally zero control over the ads that Google chooses to serve in the blog.

Measuring Intake Restriction

My interest in reading AutoSpeed is in practical moderate modification that can improve the driving experience without sacrificing fuel economy.  With this in mind I must say that the two Negative Boost series' are my favorite articles.  Today I just just reading up more on cold air intakes, and was at some point direct to "Free-Flowing a Miata MX5."  It's at this point I had a bit of a revelation.

When diagnosing the restriction of an existing intake system, measurements are taken from points inside the intake versus 'atmospheric' pressure (from inside the cabin where the pressure gauge is).  It occurred to me that there may be several minor issues with this method.

There is, I think, an additional factor in accurately assessing intake restriction; that is pressure right around where the intake picks up the outside air (out of direct flow or air into the intake, for accuracy's sake).  For example, in the case of the Miata MX5 pressure was measured just after the snorkel, giving 8cm of water. But what if, say, under the hood right where the snorkel picks up air the pressure is less or more than our base pressure (in the car)?  Not measuring the air pressure right around where the air is picked up means that 8cm of water is actually the measurement of the restriction of the snorkel and under the hood pressure, which could mean that the snorkel itself is actually only offering a restriction of 6cm of water, for example, if pressure just before the intake pick up is 2cm of water less than out base (or vice-versa of course).

Taking this further, I don't think that measuring vacuum right before the throttle versus a base pressure of inside the car can be said to be measuring the intake restriction.  It also measures the pressure created by the vehicle moving forward (or vacuum if your intake in in a really bad place).  (sorry if I'm being redundant, it's 3AM)  The measurement is still useful, of course, but to measure solely the intake duct work restriction the 'base' measurement needs to be right around where the intake picks up, as I said before.  So, in summary, to measure solely the restriction measuring the pressure difference between the beginning and the end of the intake work.  Alternately you could just measure the intake restriction while the car is not moving and I just realized how incredibly self-defeating all of this is shit fuck dammit.  I've just totally missed the point of why we take these measurements the way we do.  *sighs*

Dammit, well, I'm not letting this stuff I just typed go to waste. *Submit*

John Sarris

United States

We covered your first point in detail in the second Negative Boost series, where the restriction of the closed bonnet (ahead of the snorkel) was measured. Re the second point: you can directly measure the pressure difference between the inside of the cabin and atmosphere - we’ve done so in the past. If the car ventilation system is working properly, it is a very small value – far smaller than the pressure drops typically measured in the intake system.


Hey guys, just wanted to let you know that I enjoy the site and it's contents. I recommend the site to all my students as a good source of information and the fact that it is Australian is fantastic. I recently plugged your site on the ABC 'under the pump' segment on morning radio, hope you get some more traffic. Keep up the good work.

Bayden Clissold


Nano Health

The article on nano-particles in plastic body panels does not mention the concern that nano-particles are the new asbestos. We already know that most of the deaths from air  are due to fine particles, whether they come from heavily-loaded diesel engines or bush fires. The finer they are the worse they are. Now we're looking at the widespread use of a whole new class of even finer particles, ones so fine the body's defences can't see them, and they pass straight through the the body's natural barriers like the blood-brain barrier and cell walls. Concern about them might turn out to be a false alarm, but the possibility they could be a risk is very plausible.

Gordon Drennan


LPG Diesel Pug?

Just checking to see if you will be installing an lpg gas injection system into you diesel peugot? I would be very interested to read how it performs as well as how economical it is. Otherwise keep up the good work.

Jason Seagg

It’s possible – we haven’t yet decided.

Old Intakes

Re: Cold Air Intake:

The Alfa Romeo Giulietta Spider Veloce was designed in 1955 and had a cold air intake at the grill, with a duct through to a large air filter cannister and then into a plenum to the two twin-choke Webers. The 1964 edition-the Giulia Veloce -had the intake set up such that a panel provides some ram effect at speed. The 1963 GTZ, known as the Tubolare, had an intake that generated so much ram that tubes were designed to balance the pressure on the float chambers.

Bob Hoye


Improving Low Beam

re: driving lights

great article but i was just wondering what improvements can be made to low beam lighting (if any)



More efficient bulbs are the simplest option. We also find that aiming the low beam carefully can make a great deal of difference.

Ignition Timing Change

Issue 482 - DIY Bigger Squirts

Hi, I have been a long time reader and never replied about an article before.

HOWEVER: the article on DIY bigger squirts, shows fooling the air flow meter or map sensor by changing the output before it reaches the ECU. (This can be used to lean out the overly rich mixtures when changing to bigger injectors)

Just a point I think you should add to that article: When fooling the map sensor OR airflow metre to read less load (therefore less pulse width) think about what it’s also doing to the ignition timing.

All cars run more timing at less load, as load increases (or manifold pressure) the ignition timing decreases. (i.e. 37degrees at cruising speeds, down to maybe 20degrees boosted at high load, some cars even 14 degrees or less at high load!) Many N.A cars will run 24-30degrees of timing high load.

So as a result: you put in big injectors, fool the map sensor or flow metre. The ECU is now reading a lower load cell in the map so your fuel may not be as rich, but your timing may be MUCH too high depending on how far you have compensated for your bigger injectors.

This could result in heavy detonation especially on boosted cars. Slight tweaking MAY be ok but changing from say 270cc on a RB20DET to 440cc you would have to tweak the POT's A LOT. Therefore running dangerously high ignition timing on full load.

Sam White

New Zealand

The point you make is valid. However, in the example you give, there will be a heap of other problems as well - cold start likely being one of them. The described techniques are not applicable to increasing injector size by over 60 per cent! In fact, we said in the article to "not go up massively in [injector] flow capability".

LPG Water Injection

A question re water injection with the intelligent contoller which I am using. I have a turboed dual fuel XH Falcon . Is it advantageous to use the water injection on gas as well as petrol? I have asked Gas people, they don't seem to have the answer.


We haven’t seen water injection being used on an LPG engine but we’d expect the same benefits to apply as for petrol and diesel.

Water Electrolysis

is there any articles on running petrol engines with the gas obtained from water electrolysis, eg. using the technology espoused in the WATER4GAS website. this technology uses the HHO gas obtained from the water, fed into the intake air pipe or manifold while still running the engine on petrol as well.  Do you have any opinions on this ?? just a matter of interest -- don't want to waste your time unnecessarily.

I find your AUTOSPEED website very informative, and agree with your steady shift away from high performance modifications to economy modifications while still accepting any improvement in power that results from it.

John Bartholomew


We haven’t ever explored this topic but we’re getting an increasing number of emails about it so we may take a look. Thanks for your positive comments.

Infamous Zet

Thanks very much for the article on the twin turbo zet, absolutely fuggen awesome. very cleverly written... I'm gunna be laughing about it for weeks. Thanks again.



Google " vertigro" It is an accelerated growth process. If it is all true then it could be a winner.

Kevin Davis


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