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Get your own Free Home PageOnce I got my car to the point where it was working as new, the next step was to take it to the stage that the engineers really had in mind, before the marketing and accounting types made them act more responsibly. (I'm a design engineer, I know how it works.)
The results of all this work are listed here. Modifying a car without measuring the performance at each stage means you don't know what you are doing. You can't tell whether the car is even getting faster or not. You can't go on feel as once you have performed some work you expect to feel a difference, and so you do. Especially if the modification has done something like increase the noise level it is very difficult to tell what is happening without hard numbers to compare.
Following the recommendation of just about every reference on hotting up cars that I've ever seen, my first mod was to chuck the standard exhaust in favour of a 75 mm (3 inch) custom made, mandrel bent, system with high flow catalytic converter and muffler. I eschewed such frivolities as chrome tips and stainless steel, as they cost more and don't help performance. Indeed a chromed exhaust will attract attention, and there are at least 2 sorts of attention that I don't want to attract if you know what I mean.
The next modification recommended by all and sundry is to have a free flowing intake provided with lots of nice cold air. However, there seems to be some confusion about how to do this in a Zed. The standard way is to replace the airfilter box and resonator with a filter pod as described here. However a simple check with an indoor and outdoor thermometer reveals that the air in the air filter box is a relatively constant 8°C cooler than that in the chamber outside, so ditching the box would not necessarily be an improvement. However as the temperature in the airbox can be as high as 42°C and that outside as high as 50°C, all when the ambient temperature is at a nice cool 10°, it is clear that both sources are unsatisfactory.
Examination of the front of the car revealed a long, rubber flap, the sole purpose of which appeared to be the prevention of cool air from entering the air filter chamber. So this was temporarily moved and the temperatures measured again. But this sadly made no difference.
The next step was to get a piece of flexible tubing and run it from a forwards facing intake up into the air filter chamber. Once again, this proved to have no affect whatsoever on the intake temperature. I suspect that the problem may be that the air also needs to escape from the chamber in order to develop a cooling flow.
At this point I take the car to the Autospeed.com track day at Wakefield park. Where I managed to be beaten down the straight by worked WRXs, corner badly compared to the good cars and come of the track entirely at the corners. (Take a good look, my car is facing in the right direction but it is well and truely in the mud.) For a more detailed description go here.
Back to the cold air intake. In the standard car the filter-box is fed air from a plastic tube that in turn is fed from a sheet metal duct that ends in the engine bay. However if one side of the metal duct is removed then the interior is open to air that is forced down the side of the right hand head light. By taking the headlight out I was able to unbolt this metal duct and voila! fresh cool air can now make it's way into the air-box.
Providing the car is moving... no great loss except for the traffic light grand prix.
And the headlights are in the up position...Doh!
Actually the air supply does work to some extent all the time, the temperatures appearing to be 5-8°C below the previously recorded results. But pop up the headlights and the temperature will fall another 10-12°C in a matter of seconds. The readings on the air-temp thermometer changing about as quickly as the thermometers reaction time.
This is where we start to get serious. To start with I used a simple setup as pictured here. 
as you can see this has two adjustments, Valve 1 is a course adjustment that controls the restriction on the main line, and Valve 2 is a fine adjustment that controls the bleed. The idea is that the course adjustment is modified until the fine adjustment gives you the range you want. Then the course adjustment is set and the fine adjustment is used to vary the boost from day to day.
Ideally the fine control would be changable from a little knob in the cabin, but as yet I have found no suitable hole to feed the tube through. There is one hole, but with the accelerator cable, temperature probe wires, fuel mixture meter wires and burglar alarm wires all going through it there is no room for a pipe. Especially as I'd need to feed another pipe back out unless I wanted high pressure oily air to be sprayed out in the cabin.
As is described in the performance section the initial boost increase from 5 to 6.5 psi did produce a measureable performance increase. As expected and desired. However a further increase to 8 psi produced a terrible sound and fluctuating boost levels. Obviously I had reached the overboost dump valve level where the overboost dump valve was just dumping all the excess pressure.
This problem was solved by taking the dump valve apart and increasing the dump pressure. The Dump valve consisted of a simple diaphram held closed by a spring. Increasing the seating pressure of this spring will increase the pressure at which the boost will be dumped. I measured the seating load at 3.6 kg and increased the spring seating pressure until the load reached 6.9 kg. This should give a dump pressure of about 12.5 psi which is the max recommended boost level for the Zeds stock fuel system.
So how do you increase the seating pressure? If you look at the photo and then compare it to the sketch you can seen how it works. You just place spacers under the spring so as to make it more compressed in the seated position.
Now that the Dump valve has stopped leaking pressure I could start upping the boost again. Going to 9 psi produced... a drop in performance. This time it appeared that the car was detecting detonation and retarding the ignition. Time to fill up with optimax and octane booster I feel.
LaterHmmm, not really that great, even with optimax and octane booster I am still getting detonation. This is not helped by the fact that it is now summer and so everything is hotter. Time to get to work and really install that intercooler I think.
As mentioned in the Diary section, I had purchased a water/air intercooler about a year ago. Since then: I had not done anything except gradually collect a bunch of hoses and pipes that together could probably be made into the required connections to join the intercooler in between the turbo and the throttle. In this I found it very helpful to go to a large plumbing supply store and check out their collection of joins and bends. I also found it useful to raid the garden shed of my friend Mykl who had collected some large diameter hose bends when he was planning on intercooling his RX7.
The first attempt at actually fitting the intercooler was made in September 2000, during the Sydney Olympics. Sadly this did not work. After taking the existing piping out I found that the space available was not as large as I thought. So I had to put everything back together. This was very annoying as I had put aside a whole week for doing the intercooler installation, and now I was only able to install an air/oil separator.
While I had all the piping out I was able to work out a way that the Intercooler WOULD fit, but I found that I actually needed a lot more piping. It also meant that there would be more bends in the pipe, which means more pressure loss, which is bad. This new, complex, piping arangement is shown to the right.
So then it was a matter of installation. I was planning on spending a whole weekend on this but I had a date on the Saturday night (Damn! :) and so really couldn't afford to have my car out of action by then. So it was on Sunday that I set out to install an intercooler. Unfortunately this really was a 2-3 day job and by Sunday night (11.30) The intercooler was in but I found that there were a couple of problems.
So after having to catch the bus to work the next day, I got to work again. The first problem wasn't too much trouble, I had just made the pipe that runs to the idle control valve too small, and so the motor wasn't getting enough air. After a few different tries I was able to get the plumbing so that it would flow enough air while still fitting into the engine bay. The starting problem was now solved.
The second problem was more difficult. The various parts of the intercooler and piping only protruded above the line of the bonnet by a couple of cm. (I did after all try to get it to fit in the first place.) But this protrusion occurred at the rear of the engine bay. By the principal of leverage this meant that the front of the bonnet failed to close by 10 cm, which is a bit of a gap.
The good side of this is that reducing the obstruction by a tiny amount made a big difference to the amount I could close the bonnet.
Because I had already put a reasonable amount of work into making sure there were no real high points in the intercooler, there was no one area that was responsible for holding the bonnet open. So the fitting process was a long series of finding which bits were holding it up, lowering them somehow, the bonnet dropping 5 mm, and then looking for the next one. Finding which bits are hitting is made a lot easier if you get a sheet of newspaper, lay it on the intercooler, and bounce the bonnet on it a few times then look for where the paper is damaged.
Eventually some work was needed to raise the bonnet level. The easiest move was to get at the hinges and losen the bolts that held them to the car body. This enabled the hinges to lift off and get another 5 mm of clearance. Now that I could see this worked I put some washers under the hinges to hold them firmly in their new, higher position. This higher bonnet also created a big gap at the rear of the bonnet that allowed a lot of hot air out of the engine bay. This accidentally solved the problem that I had been working on, off and on, for over a year.
It was also neccessary to remove patches of the underhood insulation and in two cases, some small portions of the stiffening ribs. But overall the bonnet was left stock and it looks much the same and it always did, but with a bigger gap all round.
It is standard proceedure in a modern car to run a pipe from the rocker covers to the intake. This enables the blowby gases and vapours from the oil to be sucked into the intake and burned. This is not ideal in a high performance turbo car.
Therefore it can be a good idea to stop the oil vapours from entering the manifold. The easiest way to do this is to remove the pipe leading to the manifold, but then you will get oil condensing all over your engine bay.
The next step is to pipe them out of the engine bay and let them escape into the outside. The problem with this is that it is illegal, and without some actual suction (Previously supplied by the manifold) the vapours aren't cleaned out as much as they are supposed to be.
The best way of dealling with the problem is to make an oil/air separator. Then the blowby gases can still be sucked into the engine but the oil is condensed out and caught before it reaches the manifold. The separator merely has to be some sort of expansion chamber to allow the mixture to cool and the oil to condense out, possibly with some sort of filtration media to further clean the air.
In practice, I used a jar as shown here. There are two intake pipes, one from each cam cover, and one output pipe that leads to the intake manifold. These pipes are built into the top of the jar. The oil collects in the bottom of the jar and the jar itself can be unscrewed from the fixed lid and emptied.
About two days after I finally got my bonnet to close nicely on top of my intercooler, it all decided to go wrong again. Naturally that very day I had been wandering about telling my friends that I had finally gotten the intercooler set up and was ready to start upping the boost.
That night the car broke down 3 times. In 3 different ways. And didn't start for some days afterwards.
I got to where I was going (Dinner with a cousin) and was relieved to find the car started easily when it came time to leave.
To solve thithis I was forced to put my battery on a charger overnight, which left it still flat as a pancake. So I concluded that it was dead. Killed by the short. Hence I got a new one.
I also replaced the plugs which were totally fouled by the rich mixtures.
Sure enough it started right away. It still is a bit rough on idle, especially when cold, but I think that is due to minor airleaks from the oil/air separator.
This still leaves the problem of ensuring the pipe doesn't come loose again.
It is a pipe with a rubber connector held on in by a hose clamp. It is one of the 2 connections that are difficult to get at, so it probably wasn't done up as well as it could be AND the pipe does not have a ridge or lip, it is just a smooth pipe. Plus I was stretching that very connection to move the IC up by 5 mm to get at the short.
It wasn't a surprise. I had that connection down as probably the one that was causing the problem just by thinking about it.
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