Xnke

I'm not entirely sure yet, but I know the A/C compressors that come on the newer LSx motors in the vette and camaro are variable displacement. I would think something similar to what you are suggesting.

TonyD, most new MVAC systems are using a variable displacement compressor now...Not that hard to find in the junkyard.

You really don't *need* to do anything at all to that engine for your power goals. If you have never tuned a turbo motor, you WILL blow a headgasket, so don't put in anything more than a stock gasket. Even the fel-pro gasket is going to risk damaging internal components before blowing; so run the stocker. It will hold your power goals no problems, with a good tune. If the engine had good compression, and good oil pressure before you stripped it apart, don't mess with it. It's in good shape. If you absolutely have to tinker, go with ARP rod bolts and new gaskets, and CHECK all your bearings for clearances, check your bores, chances are they will be pretty dang close to tolerance. The weak point in the stock bottom end is the rod bolts; everything else is pretty damn stout. Now, if you are swapping parts from block to block, i.e, moving the turbo pistons/rods into the nonturbo block/crank (pointless to do this, unless the turbo block has a hole in it or the crank is twisted, yadda yadda) then I'd go with new bearings, as you are changing the wear surfaces. In the end, It's your engine, and your money. But for your power goals, there are folks on this site running factory assembled 150,000 miles motors making that amount of power.

Well, the compressor I have is what will get used, for now. It may last a long time, it may last six months; we'll see. I am gonna hit the junkyard in a few weeks again; I'll take a look at any variable displacement compressors I find and see if anything would fit up nicely. Tony makes good points; but I still think I can get a measurable improvement with what I have now. Eventually the variable displacement/fixed orifice system will get switched out. More emails back and forth from VA and myself; I'm looking into smaller compressors with the same footprint as my current SD-508. There are several, and I could trade for an SD-503 or SD-505, however I'd have to modify the clutch a little. VA thinks that going to a variable displacement system would be a bad idea; but then again they sell variable-orifice systems.

In the end, it will be less work to start with the ZXT harness, not to mention less component cost. All he has to do is change the ECU connector, really. Yes, if you go with the LC-1 controller, follow the directions EXACTLY. I bought my controller used on Ebay, which is why I had to send mine off to get repaired; it was replaced for free by Innovate. DO NOT try to cheat the grounds, or you will either burn it up or it will read funny. Yes, the LC-1 controller does not need a gauge. You'll be reading it in Megatune/Tunerstudio, you just need the controller and the LSU-4 sensor. The thing with the 240SX throttle body is that the TPS bolts up, and you might have to fiddle a little with it to bolt it onto the ZXT throttle body.

I'd see such a character in a Crown Vic PI package, or perhaps a rough-and-ready '88 S10 with a shiny-built 4.3. More likely the S10, no rust but dings here and there, paint is good but not great...He's a little busy working on customer's stuff to be fixing his own.

Hey, I'm not taking too much offense at this; I just see Tony get all over folks about just about any field of work in the Z's and it does irritate me at times; the downfall of a text-based information exchange. I can't always tell when he's being snarky, or if he's forcing me to proove my point. (yes, I realize that it's a two-way street.) I was hoping to hear about that JDM evaporator system a little...hoping to coax some info out of Wiki. I knew it would fit in the early S30 dash, but I don't have one, and have a pretty low chance of getting one. Yes, BUT you are also moving more CFM of refrigerant, with a greater condenser area, and less restriction to flow: less head pressure is required from the compressor, and while you are still going to be changing state, you are not spending as much energy heating and cooling...rather than the fluid being heated to 150F hot side, and 32F cold side, you're seeing the fluid heated to 100F hot side, and 35F cold side...which is plenty, and takes less energy input to do. You still have the high side and low side, but instead of 280PSI high, you are down to around 150PSI or so being required for proper exchange. BTU's are BTU's, You're exactly right on that point. (mostly pulled those numbers out of my butt...but they are not too far out of line. You get the idea.) Really, I would LOVE to have a variable displacement compressor to work with...Set up a controller to aim for temperature or pressure targets, and minimize the overshoot on the high-temp/low-temp. Maybe after I have a working and tested system. The other way to go is to use a variable expansion valve...which is where I'm starting. The variable valve's range is limited, however. Also, variable displacement compressors are generally more expensive and a bigger a pain in the ass to keep running correctly compared to the more reliable fixed displacement types. Again, you're missing a point...the condenser (Ideally) WON'T have to dissipate as much excess heat, because it won't be working as hard. An airflow increase WON'T be raising the temperature of the airflow through the condenser...think about it. One CFM of air through a given heat exchanger can carry away X amount of energy with Y temperature increase. Let the energy be fixed, and let two CFM's of air flow through the exchanger: The temperature of the air flowing through the heat exchanger will drop. More airflow, at the same energy, results in lower air temperatures through the exchanger. I won't say the temperature will half, because it won't...nothing is perfect, and I don't have enough data to figure out what percentage of half would occur. So, let's combine those two thoughts: Less head pressure means lower upper temperature: The condenser is cooler for the same volume of refrigerant being condensed; ideally we would only have to deal with the heat of evaporation, and no more. More condenser capacity: the refrigerant is giving up the heat of evaporation to a larger volume of air, resulting in an overall lowering of air temperature through the condenser. This doesn't have to mean that we're not exchanging the same amount of energy! Now, before you attempt to shoot down the "lower head pressure" argument (It's the weakest point I've made, so far) In any heat exchange system like this, we want as much of the high pressure side to be the same pressure as we can get, and we want it to be no higher than we really need. If the compressor can flow more CFM than the condenser can, then the pressure in the segment from the compressor to the condenser is higher than the segment from the condenser to the orifice. We are wasting energy in compressing the working fluid to a higher pressure, and thus a higher temperature, just to ensure we have proper pressures present at the orifice. If I get around to taking the hood back off the car (won't happen for a bit because I'm still doing bodywork on it for at least two more weeks) I'll try to show the difference in the two condensers a little better. I'm also going to be ducting them together, and sealing off the remaining holes in the core support to try and reap some aero benefit as well, and I think that having the radiator and condenser closer to the same size will help keep both heat exchange systems taking advantage of the ducting, instead of just one.

ah, that makes sense. I'll make that change and see if i can get it to straighten up and fly right.

It is a better system for a modern installation. It takes less power to drive the compressor to produce the same amount of cooling, it offers less restriction to the airflow through the core, it offers less restriction to the refrigerant flowing through the core, it produces with the same 37 degree center vent temperatures with higher airflow through the evaporator core, allowing hot, outside air to be drawn through the core in a non-recirculating fashion to be cooled to the same temps as the recirculated air. Yes, I will be running both vented and recirculated air with my install. It also does not use the draw-through system of the old dealer-installed aftermarket air conditioning, which while it may have worked, did not work as well or as reliably as a differently designed blow-through system. It also matches with the evaporator system that I am using, and is recommended by that company. The original system in good repair, used with the design-specified R12 refrigerant, can perform very well. I have a complete Late S30 system that I could use. You know as well as I know, that the early S30 dash in a USDM will NOT allow the later USDM S30 air handling system to fit correctly. I would have to change the dash and console to a 1974-1978, which I am not willing to do. I am choosing to NOT use 35 year old components when I can take advantage of 35 years of automotive air conditioning technology advances, AND design my system from the start to run with R134A. For the same size evaporator, R134A requires a condenser with approximately 30% higher capacity than an equivalent R12 system. R134A just doesn't have the specific heat of R12, and the systems are designed and optimized differently. I'm not saying, at any point, that this system is the ONLY way to do it. I am saying that I am using these parts, for these reasons, and that's it. If you don't like it, TonyD, then you don't like it. Do it your way, which works too. I'll dig up my references and PM them to you, Tony, complete with maths, after I have the system installed and can take good measurements. After it's installed and running, I'll actually be (In theory, I'm still looking at the math for this part) able to measure the efficiency, and (In theory) calculate the power usage, and, with a little handwaving, estimate shaft-horsepower needed to run the system.

In your part of the country, yes, get another shell. Z cars in good condition are common enough in cali and arizona/nevada/oregon that there is not much reason to spend the money to get a rusty one fixed properly. If you were on the right coast, sure, you can fix that, but You CAN NOT just cover it up with bondo or fibreglass. If you choose to cover up the rust, it will be right back ruining your paint in a year or less. Strip the paint off, strip the interior out, and inspect both sides of the panel. This will show you the real extent of the rust damage. It would be much, much easier to replace that roof skin, than cut the pillars. NEVER cut the pillars, in my opinion, because you will not get the new roof back on right...it just won't happen. Drill out the spot welds along the top of the windshield, drill out the spot welds at the top of the hatch, and along the rain gutters. melt out the leaded seams at the top of the A-pillar and B-pillar, and carefully cut the welded seam found there.

Uh, I do belive I stated I DO have an original 280Z condenser, but that's a non-issue. I've got my reasons for running the Mazda unit, so I'll run it. (another reason I'm using it: I have been talking with the good folks at VA for a while about this...they are recommending using the parallel flow condenser for a lot more reasons than I am.) Anyway, Placed the order for the plumbing parts, and some pre-swaged aluminum hardlines. I ordered: 1 90* -10 beadlock O-ring (condenser high side) 1 90* -10 beadlock Flare (compressor high side) 1 foot -10 barrier hose (compressor to condendser high side) 1 48" -6 pre-swaged aluminum hardline (drier to firewall) 1 straight -6 bulkhead fitting (firewall) 2 90* -6 beadlock O-ring (evaporator fittings) 2 foot -6 barrier hose (evaporator feed) 1 72" -8 pre-swaged aluminum hardline (firewall to compressor low side) 3 90* -8 beadlock O-ring (evaporator fittings and compressor low side) 1 90* -8 bulkhead fitting (firewall) 3 foot -8 barrier hose (evaporator return and compressor low side to hardline) 1 90* -8 beadlock flare (compressor low side) Also ordered a standard drier, with -6 fittings in and out and a high/low pressure switch.

The condensers that are commonly fitted to the S30's are effective, yes, but not even close to the level of the newer designs available. Would you run a turbocharger intercooler designed like the S30 condenser? No, of course not, because there are more effective designs available. The condenser in an A/C system is the same thing, a charge cooler located after a compressor. As I said, the Mazda condenser I chose to use is more effective, has a greater capacity, and I was able to fit it in space available. Not to mention it is lighter weight, and offers less restriction to airflow than the old tube-and-fin type. Also, the S30 is not the most ideal situation for climate control...lots of window area, and little to no insulation, except what you install after you pull out all the old thin rotted stuff and replace it. Another issue for me is the flow through the core...I will eventually have a turbocharged engine with intercooler infront of this, and then the radiator is behind this. They will all be ducted together, with a fan shroud, but that is a LOT of flow restriction possible! This is why I chose this core over the old style core.

The Mazda condenser is a MUCH MUCH MUCH more efficient design than the 280Z condenser. It is a parallel flow condenser, built similar to an intercooler. It is also actually a little bigger than the 280Z condenser, which is what is called a tube-and-fin serpentine condenser. I had both condensers available to me, and the Mazda unit is not only newer, more efficient, less restrictive to the air passing through it, and bigger, but it's also about 3lbs lighter, to boot. PS...PLEASE don't quote big posts complete with photos...

Ok, I am going to chronicle my experiences installing an A/C unit pieced together from junkyard parts, and a Vintage Air evaporator unit. You won't save a TON of money, but it IS less expensive than buying the whole system outright, and you can get BETTER performance. My Z is a '72 S30, so it has the least amount of room under the dash and infront of the radiator to mount parts. First up, the Condenser Coil. I used one from a Mazda 626: The aluminum lines need to be re-bent, and this is a real job. Use a GOOD tubing bender, go gently and easily, and be careful. Aluminum tube likes to collapse, and you DON'T want to put any stress on the brazed joins where the tubing meets the end-tanks of the core. To mount the condenser, it has rubber feet on the bottom of the tanks, like newer style radiators. You will need to drill two 5/8" holes in the lower core support, to let the rubber feet sit down in. I am probably going to end up notching my front core support to set my condenser down a little lower, but this is not required on the Later S30's with the lowered core support. a few aluminum brackets later for the top mounts, and waaaa-laaa! it's in. See how nice the high side line of the condenser matches up with the compressor location? Compressor: I used a new SD508 clone, mounted to a ZX compressor bracket. The idler pully needs to be moved rearward 1/8" for use with the stock 2-row L24 damper, and the idler pully bracket has a steel boss on it that needs to be removed to fit the compressor in the correct location. Both of these modifications involve cutting and welding the steel idler pully bracket. No need to drill/grind/weld the aluminum casting. A few bits of 5/16" all-thread and a short piece of 3/4" angle steel, with thick washers welded into place, are next up and are also, pretty simple. Or you could just use the original ZX air conditioning compressor. Next up on the list of parts is to buy the evaporator unit, and get it installed in the car.

It is definitely not a worn engine...It hasn't got 30 hours run time on it yet, and has about four street miles. Valves are adjusted to .010 intake and .012 exhaust hot. I'm jumping between one or two boxes at idle, and as soon as the throttle plates open it goes smooth. Getting idle mixture is not a problem, it is idling at 13.7-14.4 at all conditions, and idle is set at 900RPM. I'm getting an inconsistent idle now, I've noticed...I can start it up and it will run at 900RPM one start, and shut it off and four hours later start it up and it will idle at 750. Try again later, and it's 825, on and on. I'm really starting to think it's my timing curve. I'm running about 17-18 degrees at 54kPa and 900RPM, I'll fiddle with the timing and see what I can come up with.

Getoffmyinternet...the 95 maxima uses the same type of speedo cogs as the F4W71B and FS5W71B and C manual transmissions...they use the same R180/R200 rear ends...the rear end ratio for a '95 maxima can be determined and the appropriate speedo cog obtained. It's just like when you swap rear end ratios, and keep the cog matched to the rear end. zBigTim, what color speedo cog is on the sensor? how many teeth are on it? What rear end ratio are you running?

Tony, you think if I send you a datalog of the car, you can tell me if what I think are pulsations are normal or an actual problem? I still can't get my MAP down to the 40's at idle, although part of that may be my ignition timing. I have not even started to play with the timing yet, although I do have my fuel maps dialed in a little better every time I drive. If I had 40$ to spare right now for a piece of software that is violating the GPL, I'd buy it, just to get a good working autotune function, to get things closer than they are now. I can't really drive the car around too much, as it's not even titled. Stupid, stupid laws in KY about titling an out of state car...I've had it three and a quarter years and they STILL will not title the car, because it does not pass the state inspection. I'm probably going to get slammed with a HUGE tax just to get it titled, whenever I finally get to the point that it passes inspection. Whoa, i totally forgot to ask...about what size would be a good starting point for that 'small oriface?' .023"? .035"?

dude, If I could have found that nice of a tan interior, I'd have totally painted my Z the OEM 70-73 dark green color. VG30DETT sounds like fun, gonna be a WIIIIDDEEE bay.

you just push the side windows out, after the screws are out. it's pretty tough. The rear hatch is the same as the windshield, just a different shape.take the chrome trim out, carefully to keep it from kinking.

Also, if you go the Z31 route, you have Nistune as an option as well. Not a bad choice, and about the same cost (IIRC) as a complete megasquirt system, and you get a decent base tune too.

I think I was doing better without the O2 sensor...I finally got it working so I could see my AFR's, and now I can't get a decent idle under 1000RPM. That, and my idle is bouncing around from 950-1150RPM....not cool. Ok, Idle fixed. I watched a datalog and saw my MAP data was bouncy...lawnmower filter fixed that a little better, then I bored my throttle bypass screw ports out from 4mm to 9mm, to gain more range for setting the idle a little better. It worked, and doesn't whistle as loud now as it did with the radiused port opening, so that's good too.

As far as Megasquirting a stock engine, It is not difficult at all. I am considering building S30 Megasquirt standalone harnesses, as when I built mine it took me about 4 hours to go from having nothing at all to a complete harness, Including the time I spent in the junkyard harvesting connectors, and the time it took me to figure out how to disassemble all those connectors, remove the old wiring, solder in new wiring, and then rout it through the firewall. I've been meaning to write up a complete MS-harness-sticky for the forums here, complete with wire lengths and stuff. PM me if you want/need help building the whole harness.

cold lash should be 8 and 10 thousandths of an inch, intake and exhaust.

0.060 is about 1.5mm. I would either run the stock gasket and some head-saver shims, Or the 1.5mm thick gasket.

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