TimZ

It gets even better... Apparently, that is part of an advertisement for bigchrome.com . They even have a video .

My initial thoughts were that they were all idiots. After getting over the lameness of the kid's driving skills, and everybody else's annoying preoccupation with the "Type R" , I do have to give those kids credit for not letting an already ugly situation turn into a violent one (at least not during the time it took to film the video). Let's face it - this could have happened to 99.9% of the Rice Boys out there. That kid's 'skillz' were probably not much worse than any of the other kids in that parking lot. Very few kids that age have had any kind of performance driving experience. What do you expect when you put a novice in a relatively fast, neutral handling car? The only reason that stuff like this doesn't happen more often is that most of the ricers are FWD.

What BlkMgk said. I think that this was the post he was referring to. I'm pretty sure that I know of a couple of people successfully using the stock Nissan knock sensor with the TEC II, and I'm also pretty sure that this interface was not changed for the TEC III. I'm using the GM knock sensor that E-motive specifies with a TEC-II, and it does not work for sh!t, BTW...

I'm sorry, but this is not correct. Pulsewidth is (as it's name strongly implies) simply the time measurement of the width of the pulse. It does not have any provision (nor does it need one) to accommodate the number of pulses that happen per second. This is specifically what duty cycle is for. Further, pulsewidth varies fairly linearly with the engine's intake manifold pressure, and it does so regardless of engine rpm. I know this doesn't sound right, but if you think about it it makes sense. For any given intake cycle, your engine takes in a pretty constant volume of air. The intake manifold pressure dictates how many air molecules are present in that volume of air, which dictates the amount of fuel that needs to be injected. The injector meters fuel by opening for a specific amount of time, so for a given manifold pressure, the injector pulsewidth stays pretty constant, regardless of RPM. As RPM increases, you are pulling in more air per second, but the amount of air per engine cycle is roughly the same (for a given manifold pressure). You are just pulling in that volume of air more times per second. Again, as the RPM increases, the spacing between the injector pulses gets shorter, so the duty cycle increases. This is a well documented behaviour for Electronic Fuel Injection systems. If you like, another way of looking at it is that pulsewidth dictates the volume of fuel injected on one cycle. Duty Cycle dictates fuel flow (volume per second). Yes, its accurate, but it has nothing to do with the pulsewidth itself, aside from the frequency determining the maximum allowable pulsewidth, which is due to the duty cycle (can't be > 100%). Sorry if this sounds like I'm nitpicking, but this distinction is fairly important in understanding how the EFI system works. That formula will give you time per 4-stroke engine cycle (i.e., 2 revolutions). This may or may not be what you need, depending on how your system fires the injectors.

Yes, it's a linear relationship, so long as the pulsewidths stay above the injector's minimum on-time - usually about 1 msec for low impedance injectors, and maybe 2 msec for high impedance types. In this case, at 4.2% and 800rpm, you should be at a little above 3 msec, assuming the injector fires every engine rev, 6 msec if it fires every other rev. So, if you do the math a 450cc injector will flow the same amount of fuel at 4.2% as a 270cc injector at 7%. However, it's not clear to me what you are trying to accomplish here - you do realize that the larger injector will flow that much more all the time, not just at idle, right? This equates to approximately a 67% increase in fuel flow, which will make the engine run stupid rich everywhere else, if it doesn't just die and foul the plugs.

Yes, you are correct - pulsewidth is a measurement of the amount of time the injector is commanded to be open, not the amount of time it is actually open, which is always a bit less due to the injector's mechanical properties. However, pulsewidth is independent of engine RPM in the context of the original question. Duty Cycle has RPM as part of it's definition, pulsewidth does not. The only linkage between RPM and pulsewidth is that the maximum allowable pulsewidth is determined by RPM, but again, this is because you can't have a duty cycle greater than 100%.

Camber gain is a measurement of how the camber changes as the suspension goes through its travel. Basically, the lower control arm forces the bottom of the strut to travel in an arc as it goes through its range of travel. Since the top of the strut does not travel in an arc, the camber changes as the suspension moves. In our case, the camber is at its maximum when the lower control arm is parallel to the ground. When you lower a stock Z, you change the part of the arc that the control arm uses at the static ride height. Instead of angling downward, the control arm is usually pretty close to parallel to the ground. This means that since the maximum camber occurs near the static ride height, when the vehicle rolls in a turn and the outside suspension compresses, its camber actually decreases, which is not what you want for maximum handling. Relocating the pivot point upward, as in the JTR mod, does put the lower control arm back in the proper orientation (angled downward slightly) such that for the first few degrees of roll, the camber increases. The up/down relocation of the pivot point effects your camber gain and bumpsteer. In/out (lateral) relocation effects your static camber. The reason people move the poivot point out is to increase the amount of negative camber. I would shy away from trying to do them both at once, just because you really want to keep the static camber characteristics the same left to right. If you want more negative camber, move both slots outward by the same amount. I touched on this before, but this the reason that I don't like using the inner pivot point to adjust bumpsteer. Unless you are lucky and both left and right sides come out close to the same amount higher than the stock pivot point, you will have fixed your bumpsteer, but your camber gain will be different left to right. This is why on my car, I did perform the relocation symmetrically to get the camber gain that I wanted, and then adjusted the bump steer at the tie rod end, where you can adjust bumpsteer without effecting camber gain, or static camber.

Pulsewidth is just the amount of time that the injector is open for a given engine cycle. It is generally measured in milliseconds. Duty Cycle is the percentage of time that the injector is open during a given engine cycle. It is the pulsewidth divided by the cycle time (the total time between pulses), times 100 to get a percentage value. So, duty cycle is related to pulsewidth, but since the cycle time varies with engine rpm, duty cycle takes engine rpm into account, where pulsewidth does not.

I tried to make it clear that this was an example. I picked numbers that I knew from memory would be in the ballpark. They at not based on any particular setup. The numbers that I picked are irrelevant, anyway. The important part was the procedure that I was trying to lay out for picking your spring size, and getting the ride height to come out at the middle of the suspension's range of travel. That said, it won't hurt anything to have a 5" long adjusting sleeve, but when your range of travel is only 6", there is really no useful purpose for it. Once you have established the ride height at the center of your suspension's travel, you really don't want to adjust the ride height more than 1.5" up or down. If you do, you will be severely compromising your suspension travel in either compression or droop, which was the condition that you were trying to fix by going to all this work in the first place. Also, remember the caveat that I mentioned about making sure that the spring doesn't bind before the suspension reaches full compression? If you put the perch less than 2" (probably more like 3", depending on what your upper perch looks like) from the gland nut, it will pretty much be impossible to find a spring with suitable travel that will not bind before the suspension compresses. Yes you could do this, but as I have been trying to point out, the relatively small (+/-1.5" max, preferably +/-0.75") range of ride heights that will give you adequate suspension travel has already been set by the amount that you sectioned the strut. This is independent of which spring you chose, or how you adjusted the spring perch. You can probably adjust the spring perch to get you into this range, but I have no way of telling you whether this was the ride height that you wanted. You first need to determine whether or not the ride height that results from the suspension being in the middle of it's travel is what you want. Pull the spring out, reassemble the suspension, use a jack to position the strut in the middle of it's travel, put the wheel on, see if it's what you wanted. If it is, then use the procedure that I outlined above to figure out if your spring will work. If not, then we can help you figure out how to fix it. The eccentric adjusters that I had seen for the Z were offset bushings, which essentially move the inner pivot point around in a circle to make the camber adjustment. If this is the type of adjuster that you were referring to, I fail to see how this type of adjuster could not effect the bump steer. I have seen another type of adjuster that uses an eccentric washer which is held captive by the crossmember to allow adjustment back and forth in a lateral slot. If this is the type of adjuster that you are referring to, then I can see how this could work, assuming that you adjust the rack's toe setting out the same amount that the pivot point moved, so everything stays in the same orientation. If you take a look at your crossmember, you will notice that there are washers welded to it for the pivot bolt and nut to tighten against. To allow adjustment, you first need to remove these washers. Use a cutoff wheel to break the welds, then grind the remaining flash smooth. Then you can cut a vertical slot in the crossmember to allow the pivot bolt to be adjusted up and down. Start with a slot about 1" long, with it's bottom at the original hole's location. When you reassemble the suspension, use two new washers of dimensions similar to the originals. You can now move the pivot point where you want it, and tightening the bolt down will hold everything in place while you check the bump steer. Once you find the setting you like, tack weld the washers in place. Pull the suspension arm out, and finish welding the washers in place, and you are good to go. Well, almost - once you find the position that you like, you should also make sure that the suspension arm does not interfere with the crossmember through it's range of travel. Usually you need to grind a bit of metal away behind the bushing when you move the pivot point up. Not a very good description, but you'll see what I mean when you look at it. The reason that there isn't just one ideal place to move the pivot point to is that production tolerances just wouldn't allow it. Each car is different enough to make this impossible. This is essentially why they didn't come from the factory that way in the first place. Additionally, these cars are at a mimimum 25 years old. There's no telling what has changed on the car since it rolled off the factory floor. For instance, when one of these cars were damaged and the suspension was bent, it was common practice to move the inner pivot point in the manner that I described above to get the camber back in line. This was almost certainly done without any regard for the resulting bump steer characteristics, or anything else besides camber, for that matter.

First off, the formula above is a bit too simple. The free length of the spring is only part of the picture. You also must know the spring rate before you can make a generalization like that. You should also know the weight that the spring is supporting, and the dimensions of the strut (including the installation ratio), but since those are known relatively well for this example (and the installation ratio for the Z's suspension is 1:1 for our purposes), I'll give you those two. You don't need to stock up on a crapload of springs to come up with a workable setup, but you do need to do some basic engineering homework. For the sake of keeping this thread to a readable length, I'm going to skip most of the process of determining a spring rate (we already had a lengthy discussion of that here). Instead, let's assume that this work has already been done - the original poster's combo of 175 front and 225 rear are known to be in the ballpark of combos that work well on the street for the Z. Again, for the sake of argument, let's just look at the 175#/in springs in the front. Also, let's say that this Zcar weighs 2600lbs with the driver, and it has a perfect 50/50 weight distribution. So, each front wheel is supporting about 650lbs. From this, you can see that the spring will compress by (650lb/175lb/in) = 3.7 inches. First, let's take a look at the travel of your strut insert. Let's say that it's range of motion is 6 inches (this is about normal). Notice that to get the shock in the middle of it's travel, you will need to compress it by 3", but the spring will compress by 3.7". No problem - this just means that the spring will have to be preloaded by 0.7" when you install it. The springs are almost always preloaded - this keeps them from jumping off the perch when the suspension droops. Now, given the dimensions of your strut, you will have a range of positions where the lower spring perch can be located. The trick here is to pick a spring length that will allow the spring to be preloaded by 0.7", and still be in the adjustment range of your adjustable spring perch. As an example, let's say that your perch has a 3" adjustment range, and it's placed 3" below the gland nut. This gives you 3" to 6" of adjustment range below the gland nut. Next, let's say that at the strut insert's full extension, the upper spring perch is 7" from the gland nut. This means that you need to pick a spring length of somewhere between 3" + 7" + 0.7" = 10.7" and 6" + 7" + 0.7" = 13.7" ... to get the suspension to come out at the middle of it's travel at your static ride height. One last caveat - you also need to pay attention to the spring's fully compressed length - if the spring binds before full compression, then you have lost that amount of suspension travel. Also, please notice that these rules apply, regardless of the length of the strut (i.e., how much it was sectioned). Just to reitterate, you should determine the amount to section the strut by placing the center of the strut travel at your desired ride height. Of course, you will still be limited by the lengths of the strut inserts that are available. Conversely, if you are 'stuck' with a specific spring, you should be able to use this same technique to figure out what ride heights are possible with your spring, and section the strut with this value in mind (i.e., you might not be able to go as low as you wanted, but you should still be able to determine the right amount to section the strut by).

Hey - I wasn't trying to make you feel bad - just trying to make sure that I hadn't missed something.

I'm not sure I understand why the weight of the vehicle should effect the amount of sectioning needed. This is purely a function of getting the suspension in the middle of it's travel at your intended ride height. Weight should not enter into it. If the vehicle sits too high, then you either have too stiff a spring, too long a spring, or your spring perch is too high. Or some combination of these factors.

Me too. I thought I was the only one - maybe we should both respond at the same time more often. That's pretty much exactly the setup that I use - it's in the "How to Make Your Car Handle" book. To make it even simpler, I don't even use a dial indicator. I just have two 10-32 bolts placed where the dial indicators would have been, basically situated 17" apart, so they match my rims. To make the measurement, I remove the springs from the suspension, disconnect the sway bar, and jack the car up until the suspension is at full droop. To allow travel to full compression, I place to 4x4s under the front tires, centered approximately on the kingpin axis, so that they offer as little resistance to change in toe as possible. I then position my homemade 'gauge' such that the ends of both bolts are an equal distance (laterally) from the rim. The camber of the wheel changes as the suspension goes through its travel, so you don't want the bolts to actually touch the rim at any point during the measurement. I usually start with the bolts about 0.5" - 1" from the rim. Then I just drop the suspension in approximately 0.5" increments, and use my caliper's depth gauge to measure the change in distance to the two bolts. As I mentioned, it's normal for the distance to change, but ideally, the distance to the front and rear bolts should change by the same amount. If they differ, then the toe is changing. Make sense? I hadn't thought of it, but the method Jim mentioned should work just fine, just substitute the laser pointer for the gauge. One more thing - I use Heim-jointed tie rods, and do the adjustment with spacers to locate the rod end with respect to the steering knuckle. The nice thing about this is that it decouples the bump steer adjustment from the rest of your suspension geometry. You should still be able to get to zero bump steer by relocating the inner pivot point (ala JTR), but now it's quite a bit trickier, since the inner pivot point also effects the static camber, camber gain, and roll center. It's generally preferable to have these parameters symmetrical for the left and right sides.

Yes, I do know of struts being sectioned that much and still having enough travel. However, these were most likely on applications where the car was lowered about 2", so the 2" section made sense. Just remember that sectioning the strut does not add or subtract the amount of travel available (assuming you didn't have to change to another strut with more or less travel) - it merely changes the ride height at which you are in the middle of the available travel. For instance, if you are only going to lower the car 1", it doesn't make sense to section the strut 2". You will gain bump travel, but you will lose rebound travel, which can result in literally pulling the wheel off the ground when the shock tops out. Do your best to keep the suspension withing 0.5" of the middle at your static ride height. Stiffer springs will limit the travel as well. If you are lowering more than 2", you probably would want stiffer springs, just to keep from bottoming the chassis out. In this case, however, you won't need as much bump travel, either. For the street, I think the spring rates that you have chosen will work very well. I wouldn't go much stiffer, unless this is a track only car, or unless the streets in Australia are much smoother than they are here in the states. Yes, that's right - I would just shoot for minimizing the change in toe through the suspension's travel. You might be shocked when you see what the characteristic looks like before you change it - my car had over 1" of toe change (this was measured at one wheel only, so double that for a traditional toe measurement ) I origninally tried using the 'bump steer spacers', (very similar in principle to the JTR mod, BTW) and found that these actually made the problem WORSE. That said, it should be possible to come up with a bump steer curve that is very near zero. It sounds like you are clear on how to measure this - if not, let me know, and I'll explain it.

On the subject of how much to section the struts - you are leaving out the one essential piece of information. How much are you lowering the car? Until you supply that piece of information, you can pretty much disregard any suggestions that you have received so far. Also, as has already been mentioned, depending on which suspension pieces you are using, adding camber plates alone can drop your ride height by as much as 2", without sectioning the struts, or losing bump travel. There is no exact amount to tell you to section your struts by. You want to end up with the strut being as close to the middle of its travel as possible at your static ride height. This is the only thing you should be worrying about. My best advice to you would be to assemble your suspension (before sectioning) without the springs, and use a jack to bring the suspension to the middle of it's travel. From there, you should be able to see how much you still need to lower each end (you might be fine as it is, BTW). If you still want it lower, then you need to section the strut by the amount that you want to lower it by. Bear in mind that you will still be limited by the length of the insert that you plan to use. On the bump steer issue (I cringe every time this comes up, BTW), I've said this several times before and it never seems to sink in: the "bump steer mod" as outlined in JTR almost certainly will not "fix" your bump steer characteristics. It will definitley change it, but it won't necessarily make it better. If you've ever tried to actually dial out bump steer, you'd realize that this is a much finer adjustment than could ever be covered by a rule of thumb, such as "up 3/4", out 1/4", or not". The mod is still worthwhile, because it yields a better camber gain characteristic, but don't expect it to zero out your bump steer. If you really want to get rid of bump steer, you will need to slot the mounting holes, and move the pickup point around until you get the right characteristic, then weld the washers in place. To measure this, you will need to (again) assemble the suspension without the springs, move the suspension through it's travel, and graph the change in toe-in, say, every half inch or so. It's pretty tedious, but not rocket science. Finally, the eccentric bushings for adjusting camber will blow any bump steer adjustment that you have done out of the water. Better to change camber at the top of the strut, where it has a minimal effect on bump steer.

I generally agree. Until I started working for Ford, I never would have bought a new car, and still drove my paid-for Jeep for several years before I replaced it. The employee discount does make it a bit easier to swallow, I must admit. The employee price is the price - no haggling, and a new car purchase generally takes about an hour out the door with a new car (assuming they have it in stock). The reason I brought this up is that I thought I should mention that if any of you are in the market for a new vehicle, I can get you the "Friends and Neighbors" (X-Plan) discount on any Ford family vehicle (Ford, Mercury, Lincoln, Mazda, Land Rover, Jaguar, Volvo, Aston-Martin ). The X-Plan price is usually 4% over the price that direct employees pay, and I have yet to see anyone out-haggle this price, and I have seen some try. It's very little work for me, and I am allowed to give out four of these per year. Okay - spamming over. Just thought I'd offer that up, in case anybody was interested. ed... Oops - this post made more sense when I thought it was following the posts talking about not buying new cars. Didn't see the second page of posts.

Agreed. I flared my fenders last year, and went to 255/40-17s on 17x9.5" wheels in the front. For them to fit at all, I had to reduce the caster to approximately the lower limit of the stock spec. Otherwise, the wheels were too far forward in the wheel well. Even though this is contrary to the prevailing logic for Z suspension setup, I am very happy with this configuration. The wheels are centered nicely in the wheel wells, high speed stability is fine, and the steering effort is noticeably lower than it was with my old 245/45-16s.

I completely agree. Especially considering the added pressure requirements of forced induction, it's really a crapshoot as to whether the pump will supply any additional fuel, let alone enough to keep the mixture correct when you add the nitrous. For this reason, I was going to suggest going with a wet system as well.

This was exactly my point. 40psi of fuel pressure is most likely what you will be running at zero psi of boost. The output flow of many pumps drop dramatically as pressures rise above this level. For 300hp, your flow requirements are considerably less than 155L/hr - more like 100L/hr. Problem is - MSD NEVER SAID ANYTHING about this pump's capabilities at 75psi. They don't have to stand behind it - they never claimed it would do that. If I had to guess, I would say that the MSD pump will 'probably' still flow 100L/hr at 75psi, but that opinion is worth exactly what you paid for it. Your best bet is to call MSD and ask a tech assistant specifically what the pump will do at 75psi. BTW, if the tech says it will 'probably' work - then he doesn't know either. They will either have the spec or they won't. Finally, I thought that you wanted nitrous in addition to this. I'm assuming that your 300hp goal did not include the nitrous. You still have to account for the extra fuel flow required by the nitrous. And, if you are planning on using a dry manifold setup (i.e. pinching off the regulator for added fuel flow), then you will need to be able to go to 100psi (possibly higher, depending on the amount of nitrous you are adding), and still meet your fuel flow requirements. I did some quick calculations, and assuming that your injectors were flowing 300hp worth of fuel at 75psi, you would need to jump to 100psi (minimum) at the injectors for a 50 shot, and 120psi (minimum) for a 75 shot of nitrous. This means that for a 75 shot, the pump would have to be capable of supplying 375hp worth (~115L/hr) of fuel at 120psi. In this case, my guess would be that the MSD pump will 'probably not' meet your needs, as many pumps just don't go that high at any flow. One more example, then I will shut up... Kinsler sells a pump which I'm pretty sure is the same pump as the big Aeromotive or Paxton pump. You know - the big, billet cylinder, monster looking thing that is rated for craploads of power (this one...) . According to Kinsler, this pump flows: At 0psi, 445L/hr (i.e. just squirting into a bucket). At 50psi, 291L/hr. At 70psi, 199L/hr At 100psi it's down to 95L/hr. At 120psi it is not rated, presumably because it does not flow anything at that pressure. This pump is most likely rated at 1000+hp (Summit says 1200hp), due to it's flow at 43.5psi (around 320L/hr or 519lb/hr, which correlates quite well with Summit's rating of 500lb/hr at 45psi). At 100psi, however, it's only good for about 300hp. To put a finer point on it, that pump would not meet your requirements, assuming you want to add dry manifold nitrous to your existing 300hp setup, even though it's rated for 1200hp.

I was originally going to go with 300zx hubs up front and redrill the rears for 5 lugs, as many have done. Once I started looking into things, I found that I needed to have a pretty thick spacer made up for my front discs, and had to adapt the 5 bolt hub back to 4 bolt for my AZ ZCar brakes to work (I've had them a long time - long before anything else was available). In addition to that, I was still going to need pretty sizeable 1 piece spacers to get an off the shelf wheel to work. It was at this point that I decided that a well engineered 2-piece 4 to 5 lug adapter was a better solution than going with actual 5 lug hubs, looong studs and spacers. Since I didn't have to mess with spacers for the front discs, I actually had less mass than I would have had with 5 lug hubs. The thing that cinched it for me was the fact that I could now go to a 5 on 4-3/4" bolt pattern. This allowed me to use C5 Corvette wheels, which I was able to find for a reasonable price. Anyway, I did check his website at the time, and if Ross would have had them available I would have bought them from him. Also, I have not had any problems with balance with these adapters.

I have a 6hp Sears oilless compressor, and like everybody says, it is LOUD. Mine did crap out on me a month or so ago - the 'rings' gave out, and the compressor just couldn't get the pressure up to the shutoff point - if I had not been there to shut it off, it would have run like that forever. I will say that the replacement parts were relatively cheap - an entire piston/rod/bearing/sleeve assembly cost about $30 as I recall. Also, it's all pretty modular - I was able to take it apart and replace both cylinders in about 15-20 minutes. ~$75 total. That said, I would never buy an oil free compressor again. It was just quicker and cheaper to fix this one at this point.

Thank you Scottie. I thought I was the only one that felt that way. IMHO, not only is that amount of wheelspin not cool, but demonstrating it at speed on a non-divided public highway with oncoming traffic is downright stupid. So the stock computer will just figure out that it has bigger injectors and 500hp worth of airflow? Really? Show me documented and independently verified proof (dyno plot, 1/4mi times, whatever) of somebody actually achieving this for under $5k, and then we can talk. Until I see that, I'm going to remain really skeptical on this one.

okay, who the hell wants to stop and change out the water in the I/C every other light? most racers change the fuild after every run AFAIK. second, does'nt ford use the engine coolant in their "intercooler"? how is 180+ deg water going to cool air? it cant cool it below 180deg can it? The OEM systems do use engine coolant, but they do this to keep the water from freezing. They DO NOT share the coolant with the engine. I'm pretty sure that the OEM engineers aren't that stupid. Racers most likely change their fluid after every race because they are using ice water, the ice melts after every run, and they need new ice. I can't think of any other reason to do this. There is absolutely no reason to do this in a production air to water IC - they need their fluid changed about as often as does the radiator.