Warpspeed

There are also ways to cheat. You can sometimes place shim washers under a spring to increase boost, but usually the spring coils go solid long before you get to as much boost increase as you really want. It is a good way to make a small adjustment though. Another way is to leave the original spring in there, and fit a smaller helper spring inside the original. This works really well.

Not too difficult to work out really. But finding a suitable spring might be a challenge. First measure the diameter of the control diaphragm in inches, and work out the area in square inches (pi R squared). Then work out the seating pressure by multiplying the diaphragm area by the reqired boost. For instance, if the diaphragm has ten square inches, and you plan to run 15psi, the required spring pressure on the wastegate valve seat will be 150 pounds. When you get to 15psi, any extra boost will be enough to start the valve opening. But you need 150 pounds to hold it shut below 15psi. The next thing you need to do is measure the installed height of the spring when it is fitted into the wastegate. Suppose it is one and a half inches. The spring is going to be much longer than this when you take it out though. What you need is a spring that has a height of one and a half inches when it is loaded to 150 pounds (for 15 psi boost) in this example. Or the metric equivalent of 68Kg and 38mm. Now you start looking at what springs are available from your spring catalogue, and try to find something that has that load at that length. It could be a long soft spring, or a stiffer shorter spring. The softer spring will control boost better because the wastegate will open further for less change in boost. for instance one spring might start to open at 15psi, and be fully open at 17psi. A shorter stiffer spring might also start to open at 15psi but need 20psi to fully open it. Hope that helps.

There are usually two things that can go wrong with wastegates when you tweak up the boost. Either the exhaust back pressure rises so high in the exhaust manifold, it can blow the wastegate open too far, and you can then loose top end boost. Or else the wastegate passage is too small to bypass enough exhaust, and boost rises up out of control at the top end.

It is retarded. The pulley turns clockwise, and the cam that is attached is now lagging slightly behind the pulley, so everything happens just a bit later. The pulley has 48 teeth which is 720 crankshaft degrees. Each tooth on the belt is fifteen crank degrees. If you look you will see it has been retarded about one quarter to a third of a tooth. Pretty close to four degrees I would guess.

It is retarded. The pulley turns clockwise, and the cam that is attached is now lagging slightly behind the pulley, so everything happens just a bit later. The pulley has 48 teeth which is 720 crankshaft degrees. Each tooth on the belt is fifteen crank degrees. If you look you will see it has been retarded about one third of a tooth. Pretty close to four degrees I would say.

I am driving a Ford Laser at the moment, but had a similar situation, with a noisy cylinder head. If it is just one hydraulic lifter that ticks, it may be stuffed, and replacing it the only option. But I doubt if they are all faulty. Anyhow, the lifters should all pump up and remove all clearance from the valve train, and it should run quiet. BUT this assumes the cam is not bouncing around in worn cam bearing journals. When I checked the cam bearing clearances they were huge, like fifteen thou on some bearings. They should be more like one and a half to two thou. So even if the lifters are perfect, it is going to rattle something shocking. Now your mechanic is going to tell you the only way to fix it is to get a new cylinder head, because the cam runs straight in the aluminium casting without replaceable bearing shells. His eyes will light up as he tells you this is going to cost really big dollars, and be a lot of work. If you think about it, the valve springs are all pushing upwards, and all the wear is going to be in the bearing saddles, not the actual head. Now if you are adventurous, it is possible to take out the cam, remove the twelve lifters (from each side) and after degreasing everything, put the cam back in. Measure the cam bearing clearances with plastigauge by tightening down the saddles. You must remove the lifters and clean everything up first though, to get a true reading. You can then tighten up the clearances by rubbing the saddles on very fine wet and dry abrasive paper. Be very careful about this though. It is possible to get the cam bearing clearances back to factory specs. It will cost zero, and all the noise will then go away. Do not attempt this if you are not completely confident in being able to do it right. It certainly worked for me. I did it about a year ago on my Laser, and it has remained quiet. Just remember the saddles are very soft, and it is easy to remove too much material. Then you are stuffed. So go very easy and take your time. I know this is going to horrify some people, but it does work.

Hehe yes 25GTT it does make a similar sound doesn't it. I have had several supercharged cars with toothed blower belt drive and know that it is not a simple thing. Trying to convince yourself that it is more efficient and "makes power" is bullshit. If you do some research you will find conventional vee groove pulleys are around 92% to 95% efficient depending on power transmitted, belt tension, and belt speed. If your alternator and waterpump takes say three horsepower to drive, the belt loss is going to be around 5% or 0.15 Hp. If you discover a 100 % efficient drive that extra 0.15 Hp is really going to make your car haul some ass at the saturday night drags, eh !

Very true......... Surprisingly one of the hardest things to make brake quickly is a motorcycle. High centre of gravity, and short wheelbase. They are awsome in every way except braking capacity. You would not want to lock the front wheel, or go over the handlebars I think. I have not looked at figures, but I would not be surprised if a top bike could stay with a formula one car in acceleration, but the formula car would kill it for braking.

Naaaaaaaaa. The best way is to tap into your alternator before the rectifier diodes. There will be an ac voltage that varies with engine RPM. You feed the 14v at 55 amps into your stereo speakers. There will be over 700 watts of whine, that should be loud enough for you. The frequency is several hundred hertz, the pitch goes up and down with engine RPM, and sounds just about the same as whine from a timing belt. Sounds really cool.........................

Impossible to say, not enough information. Assuming both braking systems are powerful enough to easily lock the wheels at any time during the stop, and do not fade significantly during the stop, the size of the brakes makes no difference. This assumes that front to rear brake bias is correct for the vehicle, and the driver has reasonable skill. The next biggest factor is tyre grip on the road. What about unsprung weight and suspension rates ? What about wheel camber and toe under heavy braking ? And what is the front to rear weight bias of each car ? What is the centre of gravity height of each car ? Tyre pressures ? A formula one car with low centre of gravity, very high rear weight bias, and very good suspension geometry is going to easily outbrake a tall front engined production car even with identical total weight, tyres, and brake specifications. Then there are technical aids such as ABS and 4WD which can make a big difference if traction is very uneven in wet slippery conditions.

I have been told that brand new ones from any Nissan dealer are $1600. Secondhand, who knows?

I think this is really the thing. Some nineteen year old drug dealer that gets himself a GTR is going to thrash the crap out of it, then expect to hustle the buyer when he gets tired of it. On the other hand you have the 50+ year old executive type going through a late mid life crisis, that probably has a four million dollar waterfront home and a yacht. He wants a really nice GTR because he cannot be stuffed fiddling around with it. $50K or $75K does not really matter to him. If it developes a problem, he takes it around to the same mechanic that looks after the Merc, the M3, and his wife's Porsche. If it costs a couple of grand to fix that funny noise, that really does not matter either. Most young guys in their twenties lust after a GTR, but for most it is financially well out of their reach. They are COMPETING with people that do have a lot of cash to spend. So its no good crying that a particular car is not worth sixty grand. It is worth whatever people are prepared to pay for it.

Ahhhhhhhh, but some people have a kinky fetish about aluminium pulleys. Bright and shiny, smoooooooth to the touch. Nudge nudge, wink wink, know what I mean.

Exactly. I am thinking of non stressed, non structural parts. Things like plenums, pipework elbows and reducers for intercooler pipework, intercooler end tanks and so on. Things that do not require precision machining, but can be hand finished. I think it is the sort of thing you would need to practice at to get your technique spot on. I guess it is like spray painting or welding, you can only learn so much from books. You must actually do it yourself and get the technique right. The beauty is, that the metal, and the casting sand is very cheap and can be re-used. Its not like it is going to cost a fortune every time you try it. I would love to try a custom plenum.

Some people have had a fair bit of success, the main thing being to de-gas the molten aluminium just before the pour. Otherwise you end up with porosity and other problems. Yes you must know all about metallurgy, heat treatment, ageing, and so on. A person can learn to weld without knowing anything about eutectic states and binary phase diagrams. Its like driving a car. You cannot learn to drive unless you have ten years experience in combustion chemistry, thermodynamics, mechanical engineering, oil refining, and bearing technology. Without a very deep understanding of all the technology, just turning the ignition key can kill you. I don't think so. People have been successfully casting metal for at least five thousand years. It is basically a very simple process. Hobbyists are doing it at home all over the world. Check the internet.

Great stuff, and jolly good fun making your own parts. Anyone looked into making their own aluminium sand castings ? I have been doing a bit of a net search on this, and it looks to be a bit of an interesting new challenge, and not very expensive to try either. Golly, people have been sand casting stuff for thousands of years, it is not high tech. Should not be hard to DIY in the garage either. Check out google "sand casting" absolutely fascinating. I had no idea it would be so easy to build a furnace using natural gas and a hair dryer used as an air blower. Plenty of scrap aluminium car parts around to melt down as well. Anyone here actually done this ?

All the exhaust back pressure will now have gone away, which means that the ignition timing and fuel mixtures will be way out. Get it tuned properly and it will go better than it did before EVERYWHERE. There is a lot of BS around that engines need back pressure to run. That is simply not true, but just changing the exhaust as you have done, can just make it seem that way. Get it tuned, and it will be fine.

I am still driving a Laser I bought brand new 19 years ago. I have had other cars, but still keep my Laser. It is a great little car, turbo, 4WD, and it is fun to drive, and economical to run, and parts are easy to find. The only real problems are the engine is fairly small, and the gearboxes can give trouble if you hot them up and then thrash the daylights out of them. But driven sensibly the gearboxes do not give trouble. As has already been said www.fordlaser.com is a good place to visit to learn more about these cars.

Is there any reason why you could not try a stock computer. It might not be great, but it should at least start and run. That will tell you for sure if the problem is inside the PFC or outside.

Measure the exhaust back pressure before and after the cat. That will give you a good idea of how much total exhaust restriction is in the cat, and how much across the cat back system. Only then can you make a logical decision on how good the cat is. If you work on the basis that each psi back pressure is costing you 1% power, that is a good rule of thumb to work with. Realise though that noise increases faster than power when you unblock the exhaust. Probably about 10 psi is reasonable, and 5psi is very good indeed, but you gonna have trouble with the cops if you try too hard.

Sydneykid is spot on as always. If you are not actually valve bouncing, leave the damned springs alone. Fitting expensive heavy duty springs is not going to improve anything, it just increases the contact pressure of the already highly loaded cam face and follower. Everything is going to just wear out that much faster. A lot of cam suppliers make cams in the 9.0 to 9.5mm lift range which will work fine with stock springs. If you are worried about coil bind at full lift, turn the cam until one valve is fully open right on the cam nose. See how much further you can push the follower down until the spring binds solid. 1mm extra is plenty. If you can move a 40 thou feeler around under the cam nose, you are o/k. Really high lift cams DO need special springs to allow the extra lift. They might also might need relieving the head around the cam follower bores so there is enough clearance. Unless your head has been significantly ported, the extra lift is going to make almost zero difference and is a complete waste of time.

I need about a three metres of bowden throttle cable for a project. I do not need any special ends fitted, just a bulk length of bare cable and sheath. Anyone know where in Melbourne I can get the stuff ?

One question, does the front diff have its own separate oil, or does it rely on engine oil in the sump sloshing around? A properly sorted dry sump system is going to be a very good thing if you can afford it. Developing your own system, or using untested components might lead to all sorts of unexpected problems and unreliability. It would be a pity if you burned down several engines before you finally had your dry sump system fully sorted. I would be a bit cautious of someone who says, yes we have never done a GTR before, but we can supply you what you need. I have never run a dry sump system myself, so cannot speak from experience, but I have seen knowledgeable people lose engines after fitting something as simple as an external oil cooler because "something" went wrong. On a drag car, would it be possible to just use a very deep sump, and keep the oil right away from the crank ? Simplicity is often a virtue. The Japanese seem to know all about making GTRs go really fast, do they use dry sump systems ? No answers I am afraid, just questions............

Some of you guys might be really surprised that he probably owns more than one car. Guys like him often own and fly their own aircraft, have a couple of boats to mess around in at weekends, and a garage full of fast and exciting machinery. Too bad he nailed some poor bastard in his wife's Porsche eh.

Inlet and outlet pipe sizes are three inch. There is no possible answer to your question. At how much pressure drop ? How much ambient airflow, and what temperature drop through the core ? It is not possible to say a cooler works very well at 299Kw, and is total crap at 301Kw. It does not work that way. I have heard a lot of experienced and knowledgeable people say 400 BHP (300Kw)is the point where you should start seriously thinking about something bigger. At that flow there would be a boost pressure loss of about 4 psi to 4.5psi, that might be o/k, and it might not be.