Warpspeed

Ronin, if you want to be pedantic........... One watt is equal to one volt multiplied by one amp, that is a measurement of electrical power. And a joule is one watt per second, which is a measurement of energy flow. With total energy, the time element comes into it as well. By the way, there is no such thing as a joule per second. Now please explain how volts and amps are relevant to measuring mechanical power ? While it is true that heat energy, mechanical energy, and electrical energy have equivalents, and the study of thermodynamics is based on this fact, it is usual to measure in units most suited to the task. Light bulbs are usually rated by wattage. A really large bulb in killowattage. In the film and television industry we commonly used individual bulbs rated at up to five kilowatts each. Please explain how the output of a rotating machine can be converted to volts and amps, with a resultant power in watts (or kilowatts). Please tell me, I would dearly love to know. I would also be really interested in how many foot pounds of torque, and at what RPM my Eveready lantern puts out ? I still say it is a silly concept.

Actually horsepower is the rate at which MECHANICAL work is done. Kilowatts are the rate at which ELECTRICAL work is done. It has nothing to do with metric or imperial measurement.] Who ever heard of a one horsepower light bulb, or a one kilowatt petrol engine, it is just plain silly.

Have to agree there Mick. The best springs for ANY car are those that just allow full suspension travel for the type of driving you do. If the tyres leave the road (airborne), or you hit the bump stops, tyre grip immediately goes to zero. The trick is to get best tyre adhesion at all times, and increasing the spring rate does exactly the opposite. What the springs do is press the tyre against the road. If you stiffen the springs the tyre forces go up and down far more violently with every little bit of suspension movement. Now sometimes stiffer springs will help, but there are only two circumstances where this is true. 1/ The suspension geometry is so terrible, that limiting the suspension movement keeps the wheel more upright This is often the case with very old cars with badly designed suspension. Simply because the suspension cannot move around much, you might have prevented all the terrible camber angles, and unwanted steering effects of individual wheels. 2/ You have reduced the available suspension travel so much, that you must now increase the spring rate to prevent you hitting the bump stops all the time. You will lose roadholding by doing this, but it will be far more predictable when you hit a mid corner bump. In both the above cases, stiffening up the springs is a band aid approach to a geometry related issue. Fix the geometry first, it will feel a lot better. I assume you want real performance, not just that cool low car look. If you really want to improve things, you cannot really better the original spring rates. But the original dampers would have been specified for comfort rather than the ultimate in roadholding. Get the best fully adjustable dampers you can afford, and play around with them. It will feel a lot firmer, probably as firm as you really want it to be. Then try some stiffer antiroll bars. As the original suspension is almost certainly set for a fair bit of understeer, try increasing the rear roll stiffness first. All you friends will tell you this is not cool. You must lower the car 100mm, fit twenty inch wheels with 30 profile tyres. It will look like it should corner really hard, it will not.

What do you hope to achieve ? What is wrong with stock springs ? If you can answer that, there is no need to ask anyone.

A lot of things still originate from America, like text books, software, dynos, turbos, and so on. So you buy a book like Corky Bells Maximum Boost, he is certainly not anti turbo ! But his book has inches, horsepower, and temperatures in degrees Fahrenheit. Just about all of the engine dyno simulation packages come from America as well, you can specify things in millimeters, but the readout is always in horsepower and foot pounds. Garrett turbos are imperial as well. Try and buy metric tyres to fit metric diameter wheel rims though .......... You find something like 255/60/15, where the 255 is tyre section in millimeters, 60 % profile, but the 15 IS IN INCHES. So you get a bastard mix of metric and imperial measurements on the same item. And this is now the world wide standard as well !

Well the best of luck. His dad was probably driving before he was even born, and as you grow older your perspectives change quite a lot. (I am an old fart myself). While "junior" is probably getting all excited about power to weight ratios, and standing quarter mile times, "granddad" just wants to get there safely, and without breaking down, or having to completely refill the fuel tank every three days. After a while you are just happy to sit on, or just below the speed limit, and watch the crazy hoons tear past, followed three cars back by the uniformed copper in the unmarked police car. Hehehe. You see the poor young guy pulled up a mile down the road, with the bonnet up, and the copper with his foot on the front bumper, busily writing on his clipboard. Been there, done that. You become very philosophical in your old age.

It can be made to fit with an adapter plate, but it is a still pretty difficult thing to do though. A complete GTR head is a much better solution, and quite possibly no more expensive if you have to pay for all the machining involved in making up an adapter. But it can be done, and has been done.

Just been catching up with this thread, some very interesting views expressed here. I still feel that a plenum with a front mounted throttle body can be designed to give pretty reasonable air distribution, but if you try to push it to extremes well beyond that for which it was originally designed, it is going to create some problems. By the same token, a stock centre fed plenum is going to be a lot more tolerant of extreme power upgrades as Sydneykid says. But I could never imagine anyone with a GTR replacing the stock six throttle body induction system with an RB25 induction system because it was "better". It all really comes down to designing for your intended purpose, and realising that however you finally go about it, there are going to be some compromises and disadvantages.

Bwaahahahahahaha......... Too True.

If you are a slow sensible driver, FWD works fine. The handling characteristics are safe and predictable, and there will be more traction in the wet because most of the weight is on the driving wheels. The main disadvantage is chronic understeer, which is actually good. Even a poor driver will instinctively back off before the car goes totally out of control, so its safe for granny to drive. The main disadvantage is very high front tyre wear compared to anything else. RWD is a better performance setup though. It will have more ultimate traction in the dry and better handling characteristics. For a young guy far better than FWD. But this assumes an IRS, rear disk brakes, and probably an LSD as well. It is going to be better for an enthusiast, but not so safe for a poor driver, especially in the wet with a lot of power. 4WD is by far the best overall package. Yes, it weighs about 80Kg more, but the drivetrain loss is very misleading. I can tell you for a fact that converting a FWD car to 4WD (Laser) resulted in an improvement in fuel economy and a massive reduction in tyre wear. I have read somewhere that driving all wheels consumes less power than trying to push or pull a pair of undriven wheels. It has something to do with the hysteresis losses in flexing the rubber in the tyres. On a dyno, 4WD show lower power output than 2WD. But if you put your 2WD on a 4 roller dyno and coupled the rollers somehow, so the driving wheels were forced to turn the loaded non driven wheels, net power output would be greatly reduced. And that is exactly what happens on the road. You gain more from reduced tyre losses than you lose through a few more ball bearings and an extra diff. Few people realise this though.

Great work guys......... There is a lot of mystery about plenums, different people tell you different things. But an awful lot depends on the state of tune of the engine. A lot of the big horsepower guys tell horror stories of how the stock GTR plenum is crap, and how the rear cylinders run lean and how the resulting detonation blows up your engine. Well yes , maybe...... On the other hand I cannot believe the Nissan engineers screwed up so badly, and that they never actually bothered to measure air distribution or test full throttle mixtures on the dyno when they developed the GTR engine. Duh. It all really depends on the power levels and the air velocity in the induction system. If you are running nearly stock power you can be pretty sure the stock plenum will work fine. And as Gradenko says, moving the throttle body is probably going to do it a world of good, especially with a really nice FMIC. But suppose you decide to increase engine power from 250 BHP to 500 BHP ? The air velocity is going to double, and all the pressure drops go up four times. You just might start having a few air distribution problems then. Now what about a 750 BHP car, three times the airflow, nine times the pressure drops in every bend, that stock plenum is just not going to be up to it at all. On the other hand putting a huge drag race plenum on a stock engine is not going to be all that terrific either. You just cannot test plenums on a flow bench, steady state flow through one intake runner at a time, will tell you nothing of how six pulsing cylinders are going to behave at different RPMs. You really must do it on a dyno.

One little trick that often works when you see the police following immediately behind, and you know you have done nothing wrong. Adjust your internal rear view mirror, the cop will see you do this and realise he has been seen and lost the element of surprise. He also realises you are wide awake, watching all around, and not about to do something really dumb. In every case, the cop has suddenly changed lanes and accelerated off into the distance (hehehe). This has worked for me quite a few times. The police just cruise around looking for something a bit out of the ordinary. They will just sit behind someone waiting for them to change lanes and fail to indicate, or clip double lines or something. On the other hand if you want to go for a fang, and you get spotted, you are going to get done no matter what. Simple.

It seems to me, that to be racing there needs to be more than one car doing the same thing at the same place and time. If you were going a bit quick ALL BY YOURSELF that is obviously not street racing. But if the cops pull over two cars and nail both of you for racing, I think you would be stuffed.

Then how you passee road law teest ?

I live in Victoria, and drive every day. I have had zero points now for over four years. Six months ago the cops pulled me over, said I had an illegible front numberplate. He was quite right about that actually. Driving sensibly and within the law is not difficult, and I drive a modified car as well. Some of you guys have a real attitude problem, that is all it is.

You guys are just so funny, really................. Just because you like driving fast, racing each other, and having heaps of fun on the roads, you call the police idiots and ass holes. I bet if you get your car stolen, you might think a bit differently about the police if they caught the thief and recovered your car for you. Grow up kiddies. you want the police to respect you, why the hell should they. Any police officer reading this thread is going to nail the next one of you he sees breaking the law. Do you people seriously think the cops don't read these threads? they like cars as well you know. And NO, I am not a cop, I am an engineer.

The only problem with white writing is that you only need one little gutter scrape, and they then look really horrible.

Yeah, you have to weigh up the odds. You can stand on your rights, and act like a noxious little prick, and if the copper is having a real bad day, you are going to get done one way or another. If the offense is minor, and you can BS your way out of it, you go for the "what is the problem officer ?" routine, and agree with everything he says. You might just get let off with a warning. The situation on the side of the road when you are all by yourself with no witnesses, is quite a bit different to being in a police station, or in court. Never forget that.

So now you are a little older, and a little wiser eh !

franks, the exact power where your AFM maxes out is never going to be exactly identical on a whole series of differently modified engines. Tune may be a factor, as would dyno accuracy. Rear wheel figures can be a bit suspect as well. The figures I gave were ballpark figures only, just to give people a rough idea of the capabilities of the three available flowmeters. You are right about cat converters, they are a legal requirement these days, and they also reduce noise to a certain extent as well as toxic crap. I do not think totally removing the cat is very smart at all.

You have to find the power by other means, just changing the airflow meter and management to suit a different AFM is going to do nothing for you. The only time fitting a Z32 is going to help is if your engine is already making more power, and the stock AFM has reached the maximum flow it can measure. This will be when you are making about 220 rear wheel Kw or more. A Z32 will allow about 260 rear wheel Kw before you are in trouble again. A Q45 airflow meter is good up to about 300 rear wheel Kw. Please try to understand the difference between making power, and the parts needed to support that power.

It is a waste of time. The Z32 is the same size as the AFM you already have, so it is not going to increase power. It will read higher airflows though. Putting a 300Kmh speedometer in your car is not going to make your car go any faster. Fitting a flowmeter that can read higher airspeeds through the same sized hole is not going to increase airflow.

White is best. Cooler in summer, more visible at night, looks like a million other cars going down the road so the cops don't pick you out. Also if someone keys it, or you get a scrape, the paint is easy to match. You want trouble with the cops, get a bright red sports car.

What you say is possible of course, but just having a pipe coming out of the supercharger into what looks like a blank aluminium cap on the end is not any sort of workable twincharge system. It still looks like a very desirable dual turbo installation, onto which a supercharger has magically appeared. If it is a mock up, or a photoshop trick I cannot say. After playing with these things myself, the only workable system is to place the turbo and supercharger in series. One way valves do not work. I have never seen a working twincharge system on a car that had the turbo and supercharger operating in parallel, I cannot see how it is even possible. The reason being that a centrifugal compressor requires flow before it can generate any pressure. Air is accelerated through the impeller. If flow is zero there is nothing to accelerate. That is why all compressor maps have a surge line. Below a certain flow, operation becomes violently unstable. You cannot just fit a flap valve that stays shut until a certain boost is reached and then open it. The turbo would be destroyed very quickly that way, either from overspeeding, or the violent pulsations would kill the bearings. The noise it would make would be pretty objectionable as well. By placing the turbo in series there is always airflow through the compressor housing, even below boost threshold. The two boosts just add. The wastegate can be set to the final required boost level, so the turbo makes up the difference, controlled by the wastegate in the normal way. It is simple and very effective, and it is how all these systems work. That picture is total BS, sorry.

Well maybe someone built it up as a dummy display engine for a car show. It would never actually run though. I can tell you that for an absolute certainty. If you do a search under twincharge/twincharging, here, and at Performance Forum, you will find I have made many previous posts on this particular topic, I have built and driven my own twincharged 4WD Laser around for eighteen months. So I am in a position to know just a little bit about twincharging. The supercharger definitely rotates the wrong way, it can never work. How do I know, LOOK AT THE PICTURE. The lower rotor turns clockwise as viewed from the front of the engine. Air trapped between the rotor and casing will go from right to left. There is nothing to stop air blowing back out through the turbos either. Think about it ! In America unlike just about any other country on the planet, the majority of cars are V8s, probably of about five litres or more. With these, low end torque is never a problem, they just do not like to rev. So a centrifugal blower is the ideal answer. It is also the best for Commodore V8s as well. Fitting twin turbos into a modern V8 engine bay can be very difficult indeed. This does not mean that centrifugal blowers are better than turbos though. Just better for certain particular installations. If you have a small four valve DOHC four cylinder engine that will rev its tits off, what you want is more torque, especially low end torque. A positive displacement supercharger will be best, and far easier to install on an inline engine as well. Turbos are pretty good, but you decide, do you want good midrange, or strong top end ? Forget about tyre frying torque below 2000 RPM, it is not going to happen with a turbo. It all depends on the type of engine and type of car. Twincharging is the best solution possible for a small engine. It is just too complicated and expensive for most people. Lancia and Nissan have released factory twincharged cars by the way. So thy do exist. The Nissan March, and the Lancia rally cars each had a roots blower, and a turbo plus an intercooler. Do a Google if you are interested.