TimZ

Well, I'm not Bob, but yes the steel drums will hold more heat than the aluminum ones, and that is why you would want them. Bob already mentined it - the ability to absorb more heat without overheating is the name of the game. The aluminum will dissipate heat more quickly, but they also overheat more easily. Heat dissipation is a long-term effect - it's effect is negligible during a hard stop, or rapid fire series of hard stops. Heat dissipation comes into effect when you are not braking - having better dissipation means that you need less time between stops for the brakes to cool back down. The heat capacity of the rotor/drum is what you are using during a hard stop. The rotor/drum essentially has to completely absorb the energy of the vehicle's motion during the stop. So, higher heat capacity brakes let you stop safely from higher speeds, and allows more repeated brake applies before overheating. Finally, another reason that the iron drums are more desireable is that they are stiffer than the aluminum ones, and should allow a better pedal force to decel ratio.

The manifold is not finished yet - the wastegate will be fitted under the turbine inlet.

Probably not. Cylinders 3 and 4 are always seperated by 360 degress of crankshaft rotation, so they have the best pulse seperation of any of the pairings. Also, they have the shortest path to the turbine inlet, so 3 and 4 should have the least flow restriction.

I'll take that one step further, and say that once you figure in the considerable added system volume of an equal length setup, spoolup is probably a wash, too. This design was exactly what I had in mind - I didn't want a big 'exotic' looking header. They don't package easily, they radiate more heat to the engine bay, and they tend to crack. More complex isn't always better.

Actually, that one is for an on-center. Abid and I were working out some packaging issues with the tangential housing, and he sent me some pics of one of the manifolds that they were currently working, with the tangential housing thrown in as a reference.

I'm using a clutch from Clutch Specialties - it uses ACT's heaviest pressure plate, and an sprung center, iron friction disk. Rated for 500 lb ft, and engages very smoothly - no chatter. You need the 240mm flywheel for this, BTW. With any of the Datsun transmissions and high torque, it's a pretty good idea to keep shock loads down as much as possible, so I didn't want to go with a solid hub. It's pretty expensive, though (~$500).

At least on the first gen, the springs were single rate, linear. At least according to the Factory service manual.

No, it isn't. Because the spring is compressed farther, it exerts more FORCE on the spring perch. Force is RELATED to spring rate AND the amount the spring was compressed. Again, force is related to spring rate, but not the same as. Further (and this is about the tenth time this has been covered), because the longer than stock spring will be supporting the same weight as before, it will act exactly the same as the stock spring (remember that the spring rates are the same - only the length is different), except the ride height will be higher, and the shock will reach the end of its travel sooner. That's almost right. A free length spring (by definition) does not support any load. If it did (by definition) it would be compressed. The spring rate for a linear spring is determined by measuring the amount of force it exerts at a given amount of compression. The rate is the force divided by the amount of compression. You just have to remember that the force exerted is not interchangeable with spring rate. Ride height is determined by the spring rate, it's position on the strut (assuming you have a strut), the spring length, and the amount of load supported by the strut.

My car is a 280Z, so it's rear bar mounts from the front. I used the solution that alsil sugggested, and it has worked fine. As I recall, there was a slight interference at full compression, but I believe that it only involved reshaping the 'flange' on the leading edge of the suspension arm a small amount. I did do some quick calculations, as I was worried about this mod causing too much deflection in the end link, but as I recall, the total deflection worked out to about 0.45", which I deemed liveable. The clearance is pretty close, but so far, my suspension does not bind, and my CV boots are intact. BTW, kudos to Ruben for searching the archives, instead of asking the same question for the millionth time...

I guess I don't know what engine controller you are using, but cold start is pretty much always run open loop. The O2 feedback usually doesn't start until the engine is warmed up. In fact, even on warm start, there is usually a fairly large delay (30 sec or more) before the feedback gets enabled. Also, both the 3-wire and 4-wire sensors have the heater. The extra wire is a dedicated return for the sensor signal, for reduced signal noise. The 3-wire uses the engine block for the return (common ground).

Before I open a whole can of worms here - what is your intended purpose for doing these mods?

On my '93 Taurus SHO, you have to pull the intake manifold off to get to the rear cylinder bank.

...Is it just me, or was somebody trying really hard to make that car into a Corvette? Also, interesting wording under "Vehicle Condition". "Know Known Problems" - did this mean there are problems and the seller knows about them, or is it a typo, and the seller meant "No known problems". I can understand somebody having problems knowing when to use "there", "their" and "they're", but "know" and "no"? Come on... sounds like weasel words to me.

I think the point of all this was that you can use either head and get satisfactory results. If you don't want a lot of hassles with machine work, pick the head that comes closest to the compression ratio that you want for the pistons that you will be using.

good god, whats with the turbonetics **** ? deltagate is 100% crap. The Deltagate flange is a pretty standard size flange, and I'm reasonably sure that several other wastegates can use that flange. That said, I'm not sure why he told you that - the manifolds that I know of are being built with flanges for the 60mm HKS gate. That's a pretty big difference. Abid has basically jigged the unit up, so that he can do several different designs, and make the wastegate and turbine shaft centerline come out in the same place/orientation as was on the manifold that I sent him. This gives me the best chance of successfully packaging the system, since we are doing this long distance. My original manifold was a Cartech cast manifold, as was mentioned above, modified for the 60mm HKS gate. I used an on-center turbine housing, so the turbo sits fairly high. With the orientation that I gave Abid to copy, a T64 turbo (9-inch compressor housing) was still able to fit under the stock FI intake manifold (just barely). This will be a semi-log style manifold. It will have the same basic form factor as the cartech manifold, except with ample flow paths for all of the exhaust ports. So, if you are looking for a big, snakey-looking header, this is not for you. Actually, Abid could quite possibly make one for you using the dimensions that I gave him, but it will most likely cost more. There was no 'group buy' in the traditional sense of the phrase. As it turned out, we got 4 people to buy manifolds at pretty much the same time, so Abid gave us a discount. If any of you want in, just call Abid - so far (knock on wood), he has been pretty easy to work with.

There is no reason that this idea wouldn't work - the staged assymetrical throttles would help give a more manageable tip in response, and if you could get the total cross sectional area to be the same or greater than a single 60mm, there is no reason that it wouldn't flow as much or more. That said, it looks like the throttle body that you pictured has a 20mm and a 40mm throttle, and their cross sectional areas do not add up to be the same as a 60mm. Believe it nor not, this combo only works out to an equivalent ~45mm single throttle. The idea could work, though, if you can find a suitable combo. Assuming, of course that you can fab a suitable mounting flange for it, which would require considerable modifications to be made to the intake.

Depends on how much fuel got dumped into the exhaust, but yes - especially if you have it set for fuel cutoff on high vacuum.

Yes, you are correct - the damping will effect the resonant frequency. My bad. I still can't find the equations for it, though - left my Gillespie book at work. I was pretty sure that the resonant frequency usually ends up somewhere in the same ballpark as the natural frequency, though (could be wrong). In other words, I was viewing damping as being used to fine tune the response, once the spring rates and mass have put you in the ballpark. I acknowleged this in my second post. After the first time you said it. And for the THIRD time, it doesn't do any good to talk about spring rates if you don't know what mass they are supporting.

Okay, now I'm going to have to get the physics book out to be sure - unfortunately, I don't have time right now so I'll post a quick response... As I recall, damping is not strongly coupled to the natural frequency (if at all - that's what I don't remember) - it primarily determines how closely the suspension follows the forcing function. If the system is underdamped, the car will oscillate for a period of time after perterbation. If it's critically damped, the car will follow the perterbation without oscillating. If it's overdamped, the car will not oscillate, but will lag behind the perterbation. Hopefully you were just pulling my chain here, but the oscillation reference was to illustrate the point. Regardless of damping, there is an underlying frequency that the suspension wants to oscillate at. The point that I was trying to make was that when you are talking about spring rates front and rear, what you are really trying to talk about is the balance of the natural frequency front to rear, and you can't get there without knowing the mass being supported (and a few other things, like the installed leverage ratio. The reason that I was trying to make the point in the first place was that questions like "how come the Camaros can run these spring rates when we can't" were cropping up. Remember the original discussion was related to preventing bucking.

Guys - You are focusing on the wrong thing - close but not quite... The thing that you are trying to tune is the natural frequency of the suspension - that is, at what frequency will each corner of the car oscillate (move up and down) when it is perturbed. The spring rates are what you use to tune this parameter, BUT the natural frequency is dependent on the mass that the spring is supporting (heavier mass = lower frequency). They can be used interchangeably in this case, since John mentioned a 50/50 weight distribution, so the mass is assumed to be the same (or nearly the same) at each corner. You also have to assume equal install ratios, as somebody already pointed out. In a camaro, for instance, the front might be heaver, so a stiffer spring would be required to keep the natural frequencies equal. Saying what the spring rates are front to rear without knowing the weight distribution does not tell you enough information to do anything useful.

The flame out the back thing is caused by a rich-to-lean transition. In the cases mentioned, it was due to the mixture changing when you go from WOT to closed throttle. A rich mixture, by itself, cannot burn in the exhaust pipe. By definition, if it's rich, there is no oxygen left to burn the fuel with. On many fuel injected cars, when the throttle is lifted, the injectors are turned off, and the mixture goes dead lean. If there was a hot, rich mixture in the exhaust from before (such as what you are likely to see at WOT), it now has oxygen to allow it to burn. The idea with the air vent in the tailpipe followed by a spark plug would work, for the same reason.

Seeing as how crankshaft vibrations are a known problem with the L-series (or any inline six, for that matter), I wouldn't recommend this, unless you find a way to incorporate the dampner function. Wierd coincidence - I just got done posting about this on another forum: SHO Forum - crankshaft dampner post

...So which one did you decide on? Might as well put one on that card for me, while you're at it.

...was that supposed to be a pun?

Yes, we did. Ever made a spooky halloween brew by putting dry ice in your punchbowl? Did you notice that the punch didn't freeze before the dry ice evaporated? The same will happen in your intercooler. Just having a chunk of something really cold in the tank doesn't mean that it will be able pull any heat from the heat exchanger. You need a liquid medium in there in order to make full contact with the heat exchanger surfaces in order for it to work. The problem is that the dry ice is frozen CO2 gas. When it 'thaws', it doesn't spend much time (if any) in the liquid state, where it could absorb some of the heat from the water around it - it just goes straight to a gaseous state, and bubbles out. Hence, the water doesn't get very cold at all. Another thing, in case you don't believe me and want to try this anyway - DO NOT seal the system with dry ice in it! As I mentioned before, dry ice is frozen CO2 - when it thaws, the gas that results from a pound of dry ice will occupy probably several thousand times the space that it did when frozen. If your system is sealed, this will result in a SHITLOAD of pressure (probably several hundred psi), and at best will blow a hose - at worst it could ruin your expensive intercooler. IMHO, you would be much better off running a simple glycol antifreeze/water mix with water ice frozen as cold as you can get it. Since the glycol won't freeze, the entire mix will take on the temperature of the ice (max 32F), until the ice is entirely melted. One more thing - if you try to make the mix in the intercooler too cold, you could run into problems with moisture in the intake air charge freezing inside the intercooler, and clogging it, or at the very least dramatically reducing it's efficiency - ice is a very effective insulator.