Lockjaw

Thats why that transmission and 3.90s work like peanut butter and jelly, and thats why I always felt the thing was sluggish with 3.56s. I liked on the interstate in over drive while cruising, but I hated waiting for the boost with 3.56's. It is really one of the sweetest combo's out there for a Z, running the ZX tranny and 3.90s' it gives a really nice spacing between each gear. Check the gap between second and third, thats where the ZX tranny really shines. No big gap, like Z trans and T5.

I am not sure your math is correct. According to the link I posted, i ran some combo's. Running your trans with 3.90's and I guessed a 215/60r14 tire, you turn approx 3731 Rpms at 80 mph. The same everything except the ZX trans bumps the speed up to 92 mph at the same rpm. Coming down the line I got 80 mph at 3234 rpms, which is approximately a 500 rpm drop. Yes I realize this is not spot on accurate, but it is close enough to make a point. I don't really want to flame you or anything,you appear to be a nice guy, but you seem to have an opinion on everything, but nothing to base it on. You don't have the trans, and you have never tried it, as I have. Same scenario about webers. You haven't run them, I have. You have never tried to tune them, I have tuned them. I have a basis for what I say, and as far as I can see, you don't. Run a ZX trans and then comment on whether you think 3.90's are to much gear. I always found that to be a very balanced combination, and so have a couple of my friends, one ran mid 12's and the other has run very low 13's, both in excess of 110 mph. Both 280Z turbo transplants with stock ZX turbo FI. My best friend who has been fooling with Z's for probably 20 years also agree's with my assessment, in fact he put me on the combo better then 12 years ago. Anyway, sorry to digress Dane, I would like to see you try the ZX tranny and 3.90's if you have them, and see what you think. I think you will be pleased. If you can find a set of 3.70's, I think that would be good too.

I was kind of being a smart alec. Mudge is basing his comment on the fact he has the Z tranny with the lamest overdrive other then a 4 speed (with none) . His complaint is RPMS at freeway speeds, and he blames it on the 3.90's which is crazy when he has a .86 OD, and should be running a trans with a .745 OD. A simple trans swap would drop him down into the 3k range at 75mph, which is plenty sweet if you ask me. To me it seems unfair to blame the gearing in the diff when it was clearly intended for that kind of gear to be run with a .745 OD tranny. (Nissans intentions anyway) I guess it is like looking at a glass and arguing over whether it is half full or half empty. Neither is technically wrong. I hate that Z transmission, it is more like having 2 4th gears then having a trans with an overdrive. I have always been more pleased with the ZX tranny versus the Z tranny, and the ZX tranny is very balanced with 3.90's, and 3.70's are ok, but 3.56's are a little to tall for my tastes. I guess in the end it all boils down to personal preferences.

Is your stall high enough to leave on boost? Stick cars don't leave on boost without clutch slip. Also auto's don't drop boost between shifts, sticks do. You also have 1 liter more displacement, which hardly makes a comparison between your car and an L6 fair and valid. I cannot shift mine before 6k either, at least not at full throttle. Maybe in 3rd or 4th, but not in 1st and 2nd. And to follow the numerically lower gear content, my car would speed up if I put 3.56's or 3.36's in it, but how would it do that when it takes longer to get into boost? Its driveability will suffer since most of the time it would be operating below the boost threshold, and it would take longer to get there. As I said earlier, I really think there is more to it then just some general rule. There are alot of factors that determine whether it is beneficial to go higher or lower, and just because a car is turbocharged does not mean numerically lower is the best way to go. In my own experiences, I have not gotten slower by running a numerically higher gear, and while some people may have experienced different results, idicates that there is another variable involved that ultimately determines the outcome.

Just get a single fogger and go with it.

It probably gets "blown" dry. Actually I would say if you put ice in the water tank, you would get some condensation, but other then that, I don't think the cooling factor of the water is enough to create condensation, but hey I just some guy from Alabama, what do I know?

I use Bosch dual electrode platinums from a 98 BMW M3. They work well and are easy to index.

If you have a Z transmission, you don't have overdrive.

Well for starters, my car is not light, nor is it as rpm limited as a GN V6. Perhaps in your case Scottie, you are making enough power but are limited by RPM's. So in that case, you probably could go faster by having a numerically lower gear. I know when I break mine down, I was 2 tenths faster in the 1/8th, 1 good tenth faster in the 1/4 mile, on a hot day. My 60 foot was good considering I was spinning, and the only thing off was mph, but only by 1. And my turbo was on its last leg while I made these improvements. You also run an auto with a stall which helps with torque multiplication, which those of us with a manual don't have. I am not saying you are wrong and I am right either, I am just saying perhaps there is not a universal standard, or there is more to it then just the fact that the car is turbocharged. Sleeper I would like to know what you find out. I like the 3.90's in my car, but it does hamper me on the interstate a little. I know one thing, it goes thru the gears in a hurry. I can swap back and forth as well, but I have taller tires when I have the drag TA's on my car, so I was feeling a little sluggish, and I noticed I did not have that hard of a boost hit in first as I did with my regular tires on. I will update with my times when I get back too.

Supra drivers excuses = a cover for driver error. Having a ton of horsepower is great, putting it to the pavement is something else. Drag racing is about going from a dead stop, if you want a roll, go to a restaurant. Thats my take on it.

Did you change the rocker arms? In other words, are there new one's to go with the cam? If that is one of the MSA schneider cams, they are supposed to be adjusted 8 thous intake 10 thous exhaust, cold, I believe, and I would not go tighter then that. I just put a cam in my ZX flat top motor, new crower, and used some of the resurfaced rockers from Delta Cams, and it is quiet. I used the proper lube and broke it in. I will be putting one in my turbo engine soon, using more resurfaced rockers, and expect the same result.

Could I have those 5 minutes of my life back please? And FWIW, I figured out early on what the scoop was.

I am close enough that if I had the cash, I would go and get it.

You can make the injectors work, you just have to adjust the spring pressure in the AFM. Its not that hard to do, but you should mark your original position in case you need to return it to where it once was. You will want to tighten the spring.

I want a turbo Hyabusa, then bring on your cars. Nice kill there Scottie.

Linky no worky.

The fuel pressure regulators are the same.

There are slight differences. I would run the ZX cam from the P79 if it were me. I know I have run an NA cam in a turbo engine before and I did not like it, but I could have been off on timing or something, it was a long long time ago.

As far as an opinion, what would you rather have, a nissan or GM? I like the maxima one, and I have heard you have to get over 2k in the rpms to energize the GM one. Not to mention you have to come up with some sort of bracket to mount it. The nissan one is a direct bolt in, and I made a little two wire harness to connect the ZX plug to the maxima alternator, and it was good to go. It is a very clean looking unit too. I hate those external fans.

You could get a core one from a Junk yard for cheap. Or just take yours back, its not like the parts place is likely to notice.

I disagree with the concept that a turbo needs a numerically lower gear to work properly. Think of it this way. What exactly is a turbo engine? Is it not a very high compression engine when under boost? If your turbo boost is chasing the tach, you don't have something dialed in right on your set-up, or you have to big a turbo. I run a T5 with 3.90's in my ZXT. I dropped a solid tenth of a second in the quartermile over the stock 3.56 diff, and did this on a hot day, versus the cooler evening with the 3.56 times. In addition, my 60 foot times were better and so was my 1/8th mile. I run Drag TA's so it is not a traction issue. Even though I was spinning the hell out of the DR's on the hot day. Same boost levels, so the gearing helped. Also something to consider is this. Turbo engines are generally lower in compression, and the numerically higher gear helps with off boost drivability. Nissan put the T5 in turbo cars, and it has decidedly different gearing in first and second gear then it did in other applications. They must have had a reason for doing that. Also a friend of mine has a 280 turbo, and he ran the T5 and 3.90's, but swapped it for a ZX trans, but kept the 3.90's. His warped logic for swapping? He had to shift into 5th gear before he finished the 1/4 mile with the T5, but did not with the ZX trans. Since they both have a 1:1 4th gear, which transmission was faster in his application? The T5. T5's can also use a hurst short throw shifter for a Mustang T5, lets see you get one for a ZX trans. I am sure I will have some naysayers say I am full of crap, but my times have proven that numerically higher gears do not hurt my performance, and with this bigger turbo I have now, I expect even faster times. Thats the LJ stand on the matter.

Yeah the maxima one is nice. I have an 87 model maxima one, and it is easy to wire up, puts out 90 amps, and has an internal fan, so it just looks cleaner. They bolt right in too. Just have to swap the pulley. A side benefit is I swear my car runs better with it then the stock 60 amp one.

Fuel pressure regulators tend to just go out, so don't rule out fuel pressure as your culprit. You should also check the filter located in the inlet to the fuel pump and see what is in there. You could have some trash in the tank. The fact that you are getting 10 mpg tends to indicate a seriously rich condition.

I agree with the 2+2 flywheel or one from a turbo car will also be sufficient, however I would run the 84-85 300ZX turbo clutch from Nissan. It is stouter then a stock one, and will handle your mods'. Plus you should be able to get it at any nissan dealership, so if you were out and about, and your clutch broke, you would not have to mail order one. I would start with a CAI and an exhaust system. Run a header and mandrel 2.5 in system, and you can make your own CAI. Keep it out in front of the radiator. You can also put on a bigger throttle body and do the turbo AFM mod if you are feeling froggy. Adding the N42 head and a mild cam would round out the mods, and the car should run well.

I would like to have one just to drive around when the Talladega 500 is here. That would rule. Any you can put a big fat person on the superbird wing, try that with one of these stupid APC ricer wings.