Hey guys, I'm new here and I've been thinking of getting a 1986 z31 non turbo. It looks to be in very good condition and only has 113k miles on it. Now I've heard a lot of things about these cars and I'm looking for some help.

First off I hear everybody say they are hard to work on mostly because the engine bay is cramped. I have a H6 Subaru and that is extremely cramped to work on as well. However, I'm just curious as to how reliable the Z31's are.

Next is the performance aspect. I'm interested in buying it as a fun car that I am planning to throw money into to make it handle better and maybe go faster. What kind of performance can I expect out of a stock Z31? I saw the 0-60 is around 9 seconds, does this sound about right? Eventually I might be interested in swapping in a turbo and I'm wondering what kind of performance I can expect if I were to do that?

Also as far as handling goes, would this be a good car to autocross with? Does anybody here use one for this that can tell me more about it? I appreciate any advice you guys can give me. Thanks!

Welcome!
I can help get you started some as my first Z was a dark gray Z31 NA AT.
It was a cheap buy at the time and had some electrical issues as most Nissans do, and curiously no one except the mechanic of the place I bought it could tune it to run decently or at all, myself included...the only car I've EVER had this way but it wasn't a problem as the guy was easy to deal with and cheap, usually it cost me nothing to have him get it running perfectly. This would last 3-6 months and then back again. It had been broken into previously and that was where my time with it ended, as it then got stolen one weekend and when returned was stripped of many parts and I had to scrap it.
Overall I really liked the car as it handled very well stock and with performance tires, and was peppy enough to pass whenever needed and would spin the tires even with the AT. It wasn't in the greatest shape, prob a 7 of 10, but still looked good and got compliments often. It never broke down on me with the only problems the tune thing I mentioned and the fact the heater controls and such were a mess until one day I lucked into fixing it all, which lasted until it was stolen. The AT hit hard and as I said would easily handle aggressive driving, and the brakes were decent but not great.
As for upgrading the NA I doubt it's much different than the Z32 NA I had compared to my Z32 TT...night and day. Turbo-ing an NA anything is never advisable as the gains are minimal for a very high price, and include probable ruining of that motor very soon.
Quite possibly the classic guys here will mimic our Z32 call of "Buy a TT if you want turbo, period." I'm not sure of availability of turbo vs. NA in your area, but around here (Washington State) there are plenty of both to be had by anyone wanting one...so do yourself a favor and just get the turbo model if that's where you want to be.
As for autocross well, probably not going to be a great ride stock, but the car does handle pretty damn well if suspension is in good shape and with sticky tires although the brakes will prob not be up to the task of hard work for long periods.
I'm sure there are others here who can answer more accurately regarding autocross.
Good Luck!

Welcome to NICO!
I've owned a couple of Z31's and still have one of them, look in my sig for details on it. The Z31 is actually a very dependable car especially considering it's now 30 years old! The timing belt is the weak spot just like the Z32's you don't change it and the engine could be gone in an instant, whenever buying one if you don't know when the last timing belt was put on, replace it, and low miles isn't the only belt killer, time alone will rot a belt so the fact that the belt was done 5 years and 5k miles ago means plan on doing the timing belt. They aren't terribly difficult to service, the radiator being the only job I can think of being more difficult on a Z31 than a Z32. The drive belts brackets and tensioners are a bit tedious and add to the difficulty of replacing the timing belt. Often people will develop a slow power steering leak and refill using regular power steering fluid and make a small leak worse (These as many newer cars use Dexron type ATF which is still hydraulic fluid but thicker and with a higher operating temp).

As for power, the cone air filter and cat back exhaust will add a few hp and improve sound. If you want power the turbo swap is the answer, the most difficult part of the swap is you need a turbo front crossmember or a turbo relocation pipe. Yes you can add the turbo bits to the n/a you just have to tune for it. The potential power is limited by your budget, With just an intercooler and boost controller you can see well north of 250 whp, injectors and tuning can add another 100 whp, then you get into the range of upgrading head gaskets, head studs and pistons.

I actually started out autocrossing my 85 n/a in DS. It was later moved to GS nto sure it's still listed in stock class, might be eligible for the new heritage classes. The rear suspension is terrible, the semi trailing arm setup has terrible geometry, the lower the car is the more toe and camber you gain, unless you land an 87.8-89 turbo car you'll have an open diff. There is a nationally competitive Z31 running SSM. That thing is amazing, custom coil overs, custom big brakes, custom CCW wheels.

Buy the best chassis you can find, rust is the number one killer of all Z cars, the mechanical bits are all pretty well built but boy do they like to rust, the Z31 seems to rust in the rear lower quarters,behind the rear wheels, the floor pans behind the seats where the rear crossmember bolts to the body, lower A pillars, hatch floor under the tool tray and anywhere that it's seen an impact.