getoffmyinternet

Part 1: I took off a rear wheel and verified that the distance between the wheel well lip and the shock strut is just over 9" and furthermore the offset of the rim should be .5" to center it just about right. That would make the tires I want to get fit pretty darn snug. The tire width is 9.2" but that should be neither at the base of the spring nor the well lip. However, the suspension might have to be fairly tight to keep the wheel from bottoming out because it would only have a few inches of positive loading. I might be pushing it... Part 2: I drove around at various speeds to test the signal coming out of the speed sensor to determine what would be necessary to convert the tach to a speedo if that is the route I can take. If the range is mainly in voltage, then a frequency controlled oscillator would be needed as the tach input is based on frequency. However, if the output is in frequency, then a simple signal divider can be made, which my teacher says would be simple for him to do once I figured out the ratio. The interesting conclusion is that both the VAC and Hz vary directly with speed, I suppose it should have been expected since the little generator doesn't have any sort of field control unit. Giving it my best approximation, the voltage varies about 14% between 20-65mph however, and the frequency varies only 4%. Of course there is error in my readings, but the Hz seems to be the ticket. Even if my data is dead on, the greatest deviation when the circuit is at the average ratio would be a mere 2mph at 65. I'm not sure how must speedos work, but this would suggest that they are also frequency counters, unless my data is wrong--the voltage reading is too unreliable. I shall remove the sensor and bench test it for a more accurate Hz reading. The only problem is that I don't yet know how fast to spin it for any given speed. The only thing I could do at this point is spin it based on the data I already have, but that would make the new findings just as inacurate. The alternative is to somehow figure out what the gear reduction ratio is between the transmission output and the sensor. Does anyone know what final gear options the skylines came with vs. what pinions on the speed sensor? I might be able to figure out the ratio that way, the match to how many teeth correspond with each diff.

Mine is a salvage

I'd take it just to rip off the vin! Edit: I wonder how illegal that is.

Is the cat's name giggles?

Huge overkill...

Well if I had cash flow right now, my posts would be less trivial, but just to clarify... The lazer gauge apparently came with the wrong instructions. I called msd and the guy was very helpful, said he owned the same gauge, and yes the cyl count is programable, so I hooked the tach driver back up to the negative on one coil only and set the gauge to 1 cylinder, apparently it comes set to 4 or something, unlike my instructions said (ie. 1 cyl non programmable.). Now I just have to figure out how to fix the needle. I probably won't be able to send it back since I got it on ebay, so I'll have to take it appart and hope it will go back together and work. That is on the assumption it's just dirty or rubbing against the lense, something of that nature, and is fixable.

FUELISH ftw!

Well that's what you want. 13lbs > 15lbs. This is one of those mathematical anomalies.

Hmm, that doesn't sound cheap, but worth looking into.

Update on the msd tach: looks like it's inaccurate at higher revs, I don't understand it. Also, the needle gets stuck sometimes right when I turn it on and I have to flick the gauge face to get it to start spinning. The good, or not so good, news is I bought it cheap off ebay, so if I can't get it to work properly it's not a huge loss. I'm going to see if the tach driver will power my stock gauge for curiosities sake. If not, I guess I'll have to stop beating around the bush and get one of those dis tach adapters for like $80. Super annoying.

I'm getting bored with realistic goals. I read the whole tech thread on the garrett website to figure out how to map out a turbo. The only thing they didn't mention is how to map a dual setup. I assume that the flow rate would be half of the total for each, while the pressure ratio would have to be the same. I'm not sure if it works exactly like that in real life though. I plugged in 500hp just for fun, and it comes out to 24psi of boost, meaning 64lb/min flow @ 3.0 PR total. What I don't get is their equations don't seem to account for the engine configuration. I mean there's obviously much more to it than displacement, as illustrated by the fact that stony probably has twice the power with the same engine I suppose that you can look at it like modifying the engine other than displacement or compression increases the VE and stuff like that, which is included in the garrett formulas. I put in estimated BSFC and stuff like that too, but there are so many factors it is hard to see how each one affects the outcome. That aside, I browsed their midsize turbo list and found this one to be pretty ideal (it's acually the only one within operating limits), aside from making a hybrid or something. I haven't figured out how to guestimate the lower revs yet based on what boost is below peak hp. I didn't even realize until after that this one says direct replacement for skyline, along with 8 other models. There is also a larger turbine option, but it doesn't have an accompanying map. A pointless endeavor I know, but a fun one nonetheless.

What's your backspacing? For the tires I want, the rim has to pretty much dead center the tire in the wheel well.

Wow, so many questions. First, what the hell, why? :'( Also, I thought the black car was the 260... Second, which parts are viable, ie to sell as unscathed? Is the airdam urethane? What specs are the rims? Does the hatch glass have horizontal defrost intact? Any nice chrome parts or emblems for cheap? What's the story on those coilovers? Are the door window squeegies in one piece? Do you still have the louvers?

Oh I know, I just like to fast forward to the parts where stuff blows up.

Yeah, that'll do it. Did you clip all those other wires or where they like that as well? Man, what a mess. I was losing power once because the battery holder was bouncing up and hitting the terminal, my sister was losing power because of a rat chewing on the wires from it's nest under the hood, and a friend's car decides to lose power for a few days out of the year even though we can't find any problems yet. Long story short, you're in good company.

Looks like a permanent fix to me. Problem solved, on to the next project. On a side note, I dream of having the time to take apart my interior and cut the fat like you're doing, really puts your mind at ease I'm sure. That said, I don't envy you one bit.

Dang, I guess I should stop complaining about ground clearance. Those tires look almost fake, I mean they are so tight in there it seems impossible that they actually fit, like an idealized version that could never be. Nicely done.

For a second I was thinking that the common wire to the coils is hot all the time, so it wouldn't work, or it wouldn't work because the instructions said you can't hook it up to all the coils at once (supposed to hook it to one coil and set the tach to 1cyl). But then if it were easy to find a common wire, what the heck, I might as well try it. And then I remembered exactly where the common wire was, because last time I left it unplugged, the car wouldn't start. So I hooked the driver to the middle wire on the plug leaving the coil loom (wired just like the coils themselves) and wouldn't you know it, the tach works. I'll have to hook up my laptop to be sure it is reading accurately, but I don't see why it wouldn't. The moral of the story, don't always follow the directions, because sometimes they are completely wrong. Now I just have to figure out what to do about the speedo. Maybe I should just give in and get the cable-x or whatever.

Nope, there's a custom plug on it and a headphone jack input (for the software--a serial port from pc to fine tune the shift light). The custom plug has three wires for map, +12, gnd, and green input. The adapter/driver, that this exact tach calls for when employing distributorless (coil on plug) ignition, has +12, gnd, and green. It makes me mad because it seems foolproof, yet dozens of attempts have failed. Plus, nowhere in the manual for the tach does it mention even the word "cylinder" so, ugh. I think I realized how the original z tach works now that I have it off. It's just like the tach driver, it senses rpm by the emf pulses from a wire you clip through. That wire was the distributor power source routed all the way through the dash and back out to itself. Basically, if you don't have the tach plugged in, your car won't start. I wonder if I can either wire in the driver to that, or better yet, run the main ignition wire through the firewall to mimic the original setup and clip it on. It's even made for the same number of cylinders, I just don't know if the pulses resemble each other enough, ie. the emf will be strong enough to drive the tach. FWIW there's also a strange screw on the original z tach that almost looks like an adjustment, I wonder if they needed to be fine tuned to be precise because of the way they work, does anyone know? There is also a spot next to the power source that says +6v but there is no stud there. Could be a sensing signal for a different variant of the same tach housing, who knows. I'll take a picture of it later.

I got the gmr pickup today from summit. STILL DOES NOT WORK. It's doing exaclty what it did when I tapped straight into on ignition wire, reading like 150rpm. The instructions say for distributorless ignitions hook the thing up to a +12v on one of the coils. It also says to set the tach to 4cyl, that part doesn't make any sense. The tach doesn't have a setting anywhere for # or cylinders, I don't know how the hell this thing is supposed to work. It says something about it being 1cyl operation in the options for the software, but this is not editable. It's some kind of single pulse sygnal then from one cylinder apparently, but then it seems like the gmr pickup would work perfectly because it is only hooking up to one cylinder. So why does it only read 1/6 of the actual rpm?????

I went ahead and ordered the gmr pickup so it should be here in a few days. I got the map sensor installed so now the boost gauge portion works. I think it would look really nice to have the other lazer gauges to go with this one, man I wish they made a speedo. I also got some marine style 12v pin lights that I'll use as blinkers etc. The only ones I can find right now are red. I gunned it a little today and the boost peaked at precisely 15psi. I thought the stock setting was like 8psi or something. Unless it was something I did or didn't do... Not that I'm complaining, just baffled. It's possible someone removed the restrictor beforehand, or that I didn't hook up the wastegate controller properly, or that the stock boost is only a nominal value and it just spiked past that for a second when I loaded it? In retrospect, I still think the ultimate question is how much boost can you run on 91 octane (or whatever is readilly available for a street car in your area)? That is, putting aside how much the engine or turbos themselves can handle-- let's just say that wasn't an issue . The compression ratio is about 8.5:1, and I know they pump up to 175 psi (low miles) in the chamber. Also, I found an equation for effective compression = (boost / 14.7 + 1 ) * c/r. Not sure how solid that is though (in a perfect world I guess if you were boosting 14.7 then you're essentially doubling the ratio...). I guess I'd like mythbusters to see how much you can pressurize 91 until it explodes. ...Given I'm sure there are other things at play here, like chamber shape, spark, a/f, etc. We should tell them to do it on an rb26 then, the myth they are testing will be that it is indestructible. Two birds with one stone.

Billet or bust! Are you going to solid mount the diff in the rear as well, or are you going to put rubber insulators on the front mount?

The only thing unique about mine right now is that there's no air dam or tail bezels, nobody seems to notice, they just ask what happened to my license plate. ...That's not quite as touching though.

Awesome thanks for the info.

Sorry to hijack, but speaking of which, do you guys know how thick those come? I had one just like it, appeared to be fiberglass, but it looked like two layers. Like a thin plastic mold with fiberglass slathered on top or something. It broke pretty easily too...