Scottie-GNZ

I expect to see it at Reynolds next month.

Here is what I would recommend FOR STARTERS. I emphasize for starters because you will probably end up doing some fine tuning. In the RPM IGN map, start with 20*btdc initial and ramp it up to about 36* at about 3300RPMs and carry 36* all the way out. In the MAPRESS/IGN RETARD map, start retarding the timing at about 3psi and approximately 1* for each psi up to 15psi, assuming you have a 2-bar MAP sensor. That should give you pretty snappy off-idle/low-boost response and about 23* total at full boost.

Tom, I think you can take better advantage of the race gas by focusing on running more boost vs more timing. You can increase the timing also but more boost will net more HP. E.g., I run 18* total (after retard) and about 16-17# boost on pump gas. At the track I run 24* total and 25# boost. I have only run my car once at the track with low boost and street timing and that was to test a fuel problem but I would venture a guess the difference is about 100hp. This is where an EGT comes in handy. Not sure what you are using to retard the timing, but here is how I would approach it. Right now I am assuming you are running 19* total derived from 37* advance and 18* retard (1* for 1#). If you can, start retarding at 5# with the race gas giving you 23* total at the same 18#. With that as a base, start turning up the boost in small increments so 19#=22*, 20#=21*, etc. Of course, as you turn up the boost you also have to supply more fuel. With SDS, I can tell you how to do that as all that would be very SIMPLE I hate to sound like a broken record, but when you start doing this type of tuning, you really need and EGT or WB and not have to rely on your ears. However, IMO that is a simple and safe approach. If you follow this approach with the right tuning tools, do not be afraid of boost. Just turn it up in small increments and monitor your mixture. Remember, it is detonation not boost that kills engines. Also remember there is no magic amount of boost or timing that you can run as there are too many variables. You run the max you can w/o detonation.

quicker240, nice car!! Please RSVP for the HybridZ event and send a pic of the car so we can post it. http://z31.com/sezs/s That underhood shot (pic #3) would do nicely . Look forward to meeting you and seeing that ride of yours.

I bet you could not touch one of those drivetrains for less than 5-figures. That would be one expensive swap.

As I have stated in previous posts and to folks in private emails, you cannot fit the C4 IRS under the stock fenders w/o cutting it more than 1.5" on each side like I did. A C4 Vette, when measured from the outside edges of the tires is 70" wide. They use very wide wheels and tires (255/50-16 on 16x8.5) but the wheels have a deep 5.5" backspacing. If you used the Z-28 wheels (16x8, 6" BS) and narrower tires you could probably reduce that a little over 1". Even if you could, you need to ask yourself - Do you really need this? I will admit the benefits are many with Camber, Toe, bumpsteer adjustments, some trick lower arms that keep the rubber planted, coilovers and adjustable shocks, the handling is great. BTW, the last 3 are my own mods and if you are familiar with the C4 IRS you will see that my mods make mine radically different from stock. However, it is not like the Z, when properly modified, is a slug in the twisties. I did not go to the C4 for what I just mentioned. I went to it because it was available cheap, was an enginering challenge and presented a solution to getting a final drive ratio in the 3.0 to 3.1 range. If it was not so damned costly to upgrade the R200 with stronger axles, NISMO 3.15:1 ratio and LSD, I would have stayed with the Datsun IRS. If you are not a skilled fabricator, cannot do most of the work yourself and could possibly be intimated by this challenge, you do not want to go this route. Unless you are running a low-revving torque-monster like my engine and cutting 130mph in the 1/4-mile, you should not have the gear ratio problem. I am also sure there are Z folks who can make the stock suspension match the performance of a C4. Sounds like I am talking you out of it? No, just trying to make sure you understand what you might be getting into. If you still plan on doing it, I will certainly offer help.

Look here: http://www.y-t-g.com/turbo.html

That looks like an NPR I/C. Wonder how much HP it is really making? Wonder how much pressure drop he is experiencing? No comment on the down(up?)pipe

Curious to see how it runs. Thats a lot of work but I am fascinated to see how the V-8 world is catching on to forced-induction.

Thanks for verifying what I have been preaching about gearing for turbo cars.

Lets see. You would need the following: intake, TB/TPS, upper plenum, fuel rail, FPR, injs, coilpack/ign module, various brackets for the above, MAF, (possibly) cam sensor & crank sensor, EFI harness, ECM, L & R side headers, crossover pipe, turbo, turbo support bracket. Not certain, but I think the 86-87 cam might also be different. This is a little like trying to turbo an NA L6 except with more components and very few donor cars.

Summit part# GRI-1-25202-X "Chevy, 24x19". Be aware that it has no mounting tabs and drain petcock, so it is not a simple drop-in, but I have been using it for over 2 yrs and it is great.

I simply answered the question "does it have as much potential as the later ones". Given the choice of a Buick V-6 carbed-turbo and an L28ET, I would go with the L28ET and avoid the swap hassles. You can only squeeze so much out that engine and if there is not much gain, why bother, even if it only cost $200? You end up getting nickel & dimed to death when you get done. Trust me on that.

If it has a carb, it is not an 84. 84-87 were EFI with the 86-87 being intercooled. Not worth pursuing IMHO.

If you intend to take a GN to the track and have some fun with it, you probably want a 86-87 Intercooled. The 84-85 model, referred to "Hot-Airs" do not have the same HP potential. For mere pennies, you can get an I/C'ed model in the 12s. Sometimes 86-87 engines are swapped into the early models so check for that. The stock 85 engine has the turbo sitting right on top of the intake.

I still have the fronts and set them to "1" for the strip and "3" for the street. If I recall, the rears were set the same way. Can't believe I have already forgotten. Must be having "senior" moment . I currently run -8 inlet and the stock 240 inlet for my return. I would imagine 5.5" BS should work but maybe someone who has that same combo can chime in.

Didn't say you could not use them but "you don't need them"

Don't know that any GN ever got 30mpg. My buddy Mike (red RX7/GN) gets mid-20s with his 3750lb GN that runs 12.0s with 50Lbers. I get ~26mpg also with 50lbers running mid-10s. BTW, from what I gather, that GN will weigh in about 2200lbs and is shooting for hi-6s @ 180+. That will require about 1150hp so he will have to pull off 1 spark plug wire to slow it down .

Not surprised about the gas mileage. A 12-sec street car does not need 75# injs.

I think you might have answered your own question. I would suggest you try and correct the rear suspension. As Katman says, a 325hp 1st-gen Z is scary enough.

Just curious. What are you doing that requires 100psi of fuel pressure? I am cutting back on the boost level I run by going with a different turbo but until recently I ran up to 26psi boost. With 43psi static FP, that amounts to only 69psi FP at full boost.

IMHO, with your mods and intended use, the stock engine management system IS NOT AN OPTION. Do the research on aftermarket systems and get the opinion of folks who are using them, not the speculators.

All lower case.

If this is a car that is primarily for the track and sees the street every once in while, it is a cheap solution that works well on the strip as long as you are willing to make the sacrifice on the street. If this is driven a lot on the street, you will not like the welded diff.