
Warpspeed
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Everything posted by Warpspeed
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Yup, Disco, that is a pretty good explanation. A low boost setup only needs low compressor Rpm and tip speed, so velocities everywhere will be much lower, wheel, diffuser, and housing. High boost requires the turbo to spin much faster, tip speeds will be up, and so will velocities. Cubes, if the housing is all wrong, boost will be down, and turbo discharge temperatures will be higher. It is an efficiency thing. Which would make more acceleration, 10 psi boost at 180C or 12psi boost at 150C coming out of the compressor at identical compressor Rpm ?
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Spot on discopotato. The compressor cover should not really effect lag, but it possibly might if the compressor was forced to work in a really low efficiency part of the flow map during spoolup. There may be less boost and less exhaust flow and much poorer spooling if the cover is totally wrong for the engine. Think of the cover as a long gradually tapered pipe section that matches the wheel to the engine. For any given compressor tip speed and engine boost/airflow combination, there is an optimum taper angle or ratio of inlet size to outlet size. As disco says, it is like the turbine cover, but in reverse.
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The compressor cover a/r will have absolutely no influence on lag, how can it ? It is only the cover around the wheel, it cannot influence how fast the wheel accelerates. Lag is all due to the turbine end. Second point, compressor a/r changes the shape of the flow map. Small a/r covers give a tall skinny compressor flow map that leans to the right. Ideal for very high boost small engines. Large a/r covers give a fat round looking flow map, with big flow numbers at lower boost levels. Ideal for big cube engines running low boost. Take two engines both producing 350Kw, one is a five litre V8 in a boat running low boost. The other is a two litre high Rpm high boost race engine. Both make 350Kw, both have identical airflow, one runs about five times the boost pressure of the other. The two litre engine will have small a/r turbine cover, and small a/r compressor cover. The V8 will run large a/r covers at both ends. Small a/r is for high pressures, skinny passages, high air velocities. Big a/r is massive flow, low pressures, and low air velocities. That is the general way it works at BOTH ends of the turbo. In this example both engines are 350Kw, same airflow, same turbo, radically different turbo Rpm and pressure ratios.
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No need for a surge tank, just plumb both pumps in series. The big pump will suck pretty hard and relieve the small pump of just about all pumping pressure load. But the small pump is still required to raise fuel up to the big pump and prime it. Do some flow testing, you will find the 044 will not be restricted by keeping the original smaller in tank pump.
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True Cam Measurement (measurement Point)
Warpspeed replied to pnblight's topic in Engines & Forced Induction
Fifty though is probably your best bet with GTR solid lifters for several reasons. It is the historical figure that most cam grinders call the "advertised duration" and it is almost universally used as a yardstick when comparing different cams. The reason being that it is always going to be well beyond any known starting and ending ramp built into the cam. Hydraulic cams don't require an initial slow ramp to take up tappet clearance, but solid lifter cams do. Hydraulic cams can easily be measured "seat to seat" at five or six thou lift, because the cam lifts instantly off the base circle. But measuring at five to six thou lift on a mechanical cam is meaningless because the tappet clearance would not even have closed up. Fifty thou is also good because at that lift the follower will be moving pretty fast, and there will be a lot of movement per degree of rotation. That is good for accuracy. Trying to set a mechanical cam at five thou will be difficult because the lift per degree will be extremely slow at that point, and setting it will not be so accurate. -
Anyone Know How 'trade Prices' Work?
Warpspeed replied to SS8_Gohan's topic in General Automotive Discussion
To get trade price you need to be in the trade. All you need to do is register a Company name with corporate affairs. Any name will do, as long as nobody else has registered it, "Shonky Auto Repairs" or something like that would be fine. You then get some business cards printed and an official order book with the company name. You will also get a tax file number for your new business which will need to be shown on the order book. That enables you to get everything at trade price and escape paying GST. The only disadvantage is you have to fill out a tax return for the business each year and forward all the GST you collect off your customers to the tax office. -
The answer is very simple. Mandatory jail time if you exceed your points, but the idiots behind bars...........
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It sounds to me like some wanker screwed some GTS-T badges onto his GTS ?
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Yup, GTS, no turbo GTS-T has turbo. What could be simpler than that ?
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All you really need to change is the pistons. If you are going to rip it all apart, why not fit RB26 crank, rods, and pistons ? They will all go straight into your RB25 block.
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You cannot fit the front drive sump onto a normal RWD turbo engine, the blocks are very different around the pan rails (much wider). The only replacement engine that will drop straight in is the RB26. If you want a turbo 4WD RB25 you will need to rebuild your existing engine with turbo pistons to lower the compression ratio.
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Exactly, Buying all the parts individually will always cost far more, and it is all the little things that make the difference between a neat factory looking job, and something that looks homemade. The correct moulded hoses, factory brackets, and bolts make a very big difference. If you get a GTR front cut, you get absolutely everything, and afterwards, you can sell the original parts, it will turn out costing even less. The only real down side is storing the front cut, because it absolutely must be under cover. I have half a spare car here, and yesterday saved myself a few dollars and a trip, by scrounging a replacement globe. Small thing, but it all adds up.
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The trouble is that once you start down the path of that kind of modification it just goes on and on. It becomes a total money pit without end. I still think the best way is to get either the real thing and restore it to better condition (maybe minus it's GTR badges). Otherwise you will be doing clutch upgrades, brake upgrades, suspension upgrades, and all the rest. Another thing is the law. If you have a real factory standard GTR they cannot touch you. But if it built up from all sorts of non standard parts, it could become a very big issue if some noxious little Hitler decides to run you over the high jump.
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Well, a lot has been said on other threads, but time marches on, and things change. The price of genuine GTRs is still falling. At one time it was a great way to build a poor man's GTR with considerable cash savings, but with a lot of hard work. These days if you buy a GTS-4 and a full GTR front cut, for the cost you could damned near buy the real thing. The problem comes when you need to sell the car. Even genuine GTRs can be hard to sell, a home made GTR may be impossible to sell. It could be a lot of work, and in the end money down the drain. Five years ago maybe, but not today.
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No
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I was flashed while overtaking someone. As there were two cars side by side in the picture, they cannot prove which car was actually speeding. I never heard anything from that either. Lat time I was caught by a speed camera the fine arrived within a couple of days. Apparently the mailing is now all computerized and automatic.
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The police can stop you and search you or your car any time that the officer feels a crime is/has been committed. If he searches you, and finds drugs, stolen property, or illegal weapons, he was right, wasn't he ? If he decides to go right through every inch of your car and finds anything illegal, he can do that too. Best policy is say nothing, admit to nothing. He then has to produce the evidence. Later on a smart lawyer might make things sound not quite so bad, and you may get lucky. But if your car is illegally modified, or the copper discovers a murdered corpse and a shovel in the boot, too bad......
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I have been all through this myself. You need to take a bit of time and do it properly, otherwise it's a complete waste of time. The first thing you need is a decent dial indicator with the little screw in ball in the end, and it must also have enough travel to work over the full valve lift (obviously). Next get a small flat metal strip, and drill a suitable hole in one end and fit it under the screw in ball on the end of the dial indicator. It should stick out a right-angles, like a foot sticks out from a leg. That way, the projecting metal "foot" can sit on the very edge of the cam follower without the lobe hitting the stem of the dial indicator as it rotates past. Until you have tried this, you will not realise how little room there is. The last, and most important thing is to make up a very solid mount for the dial indicator. It absolutely MUST be mounted parallel with the axis of the valve stem, otherwise the metal "foot" will slide around on the follower and the readings will be all over the place. I made up a special fixture that bolts on top of the camshaft bearing saddles. It requires a couple of longer bolts, but it is extremely rigid, and mounts the dial gauge exactly true. If you are clever, it can be turned around and used on both inlet cam and exhaust cam. Another handy little gadget I fabricated from an old spark plug body, is a fixture for very accurately finding TDC. It has a long threaded bolt that hangs down inside the combustion chamber, and it stops the piston coming up at exactly 90 BTDC. With the degree wheel fitted, the engine can be turned both ways to hit the stop, and it should show exactly 90 BTDC one way, and 90 ATDC the other. If the bolt length is not exact. both readings should still be identical. When they are, remove the spark plug fixture and TDC should be exact on the degree wheel. If you take the time to set it all up and make some special tools, cams can be dialed in very quickly and accurately. This might be important if you are trying a few different cams and have adjustable pulleys. A really convenient way to turn the engine over is to place the car in fifth gear and just roll it backwards and forwards. It is the easiest way.
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You only really need a high flow waterpump for slow idling in bumper to bumper traffic with the airconditioning going in mid summer, or maybe for towing. At any reasonable operating Rpm the water flow will be controlled by the engine thermostat. What the waterpump does do at high power outputs is pressurise the cylinder head. By having 30psi to 50psi water pressure in the head, it greatly increases the boiling point of the water around the combustion chamber and exhaust ports at high power output. It prevents steam bubbles from forming. What you require on a high power engine is not a high flow waterpump, but a pump that will generate very high pressures at high Rpm without cavitating. A pressure gauge connected to the cylinder head before the thermostat will tell the story. If pressure peaks at mid engine Rpm, then falls off of near redline, something needs to be done about the waterpump. Slowing it down may help, or different shaped fins, like the N1 pump has. Going to a bigger pump, or speeding up the stock pump is exactly the wrong thing to do. We all know what happens when you spill water on a red hot barbecue plate. It spits and balls of water run off the hot plate. Now picture a turbo engine on a dyno flat out at full load, with glowing bright red hot exhaust manifold. Think about the exhaust ports and combustion chamber deep inside the head. If there was little or no water pressure, steam bubbles would rapidly form and push all the water out through the radiator cap. The head would then over heat to destruction in seconds. So think more about pressure than flow. If it needs more flow, the thermostat will always quickly open up and give it the flow it needs. The waterpump that generates the highest measured pressure without cavitation is the one to use on a high power performance engine.
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Actually Mark you raise a very interesting point. All four wheel drive systems are definitely not created equal. The perfect system probably does not exist, and the characteristics of different methods of torque splitting can make a huge difference to how it behaves, and the advantages/disadvantages.
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Many things have really impressed me over the years. the first time I drove on radial ply tyres (a very long time ago) I thought, wow this is really terrific. Then I was pretty impressed with disc brakes and multi-point EFI when they became available. My first drive of a turbo car also was pretty memorable too. After owning a couple four wheel drive road cars I would NEVER now consider owning anything else. If you have to ask the question, you have never driven a 4WD road car for any length of time. Sydneykid has it exactly right (as usual). Even in something really slow like a 4WD Laser, the traction and stability in the wet is awsome.
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Have to agree with Sydneykid, this is not an easy or cheap thing to do, and you will not be happy with the results. If you want a front entry plenum on your 25, get yourself a Greddy inlet manifold. If you want the six throttle body induction, it is easier and probably cheaper to fit the whole GTR cylinder head complete.
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Yes, first of this month no more import duty on American imports. GST only (if applicable).
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I am curious Chris, why do you require more pumped oil volume ? The oil pump volume increases directly with engine speed. The only time it really becomes an issue is with a very low idle speed setting ? As others have said the N1 pump has the same swept volume as the standard GTR pump. A high RPM engine can really use a SMALLER oil pump if the idle speed is suitably increased.
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Hey...... you could always get a GTR and jack it two metres up in the air and fit REALLY big wheels to it. Use it like one of those monster trucks for crushing little cars. *** Warpspeed runs away and hides *****