z31.com | Modifications
There are many opinions on how and what to modify to make your car
faster, hopefully the information here will answer any questions
If you want performance nearing the license suspension and "obscene"
ranges a turbo is a must unless you have very deep pockets.
If you have a turbo, the turbo faq
is required reading.
- Intake &
Exhaust: Ask anyone who knows, and
they'll tell you that this is the first thing you should do.
With a lower restriction intake and/or exhaust much less power is consumed
in moving air around. Also, if you intend to do further engine
modifications, then improved intake and exhaust are a must, espically
on a turbo. These are also relatively cheap modifications and the
replace things that are usually worn out anyway on a 10+ year old car.
The type and kind of upgrades you desire is up to each
individual. The main upgrades available are shocks, springs, roll
bars(sway bars), brakes, and wheels.
The ever present strut braces are also available - Courtesy Nissan
sells a rear brace for all years and a front brace for 87-89 models.
A front brace for 84-86 models is in the works and will be available in
the near future.
- Springs and shocks:
A good pair of springs and shocks(struts) is the probably the single
best suspension upgrade for the money. There are a huge variety of
springs and struts from many different manufacturers which range
in price, performance, and quality. Performance-wise, the best
springs available are SS or Suspension Techniques(if you fix your camber)
with bilstein shocks. Eibach springs are garbage performance-wise.
You could also go with a ghetto "coil over"
setup and get your choice of spring rates.
- Sway bars:
There are a few companies that make sway bars for early 300ZXs,
Suspension Techniques, Eibach, Tokico, Addco and 1 or 2 others.
Sway bars aren't a very
common modification because they are a little on the expensive side
and not nearly the same value as a set of springs and shocks,
I would reccomend the Suspension Techniques however, even though they
are hideously expensive($450).
They are well worth the
money if you can afford a set, in my opinion. Expect to pay
about $200-$250 per set.
- Suspension bushings: Made by prothane and available from
MotorSport Auto for around $140
and has all the bushings needed for any year Z31. Polyurethane rear
crossmember bushings are also available from
MSA for $40.
The stock 300ZX brakes are as good or better than any other car with similar
performance as the first generation 300ZX.
Options include everything from better pads to going all out and
buying monster rotors and calipers.
The best for the money is to buy quality pads and completely
clean the hydraulics.
Consider braided teflon lines and rebuilding the calipers also.
Motorsport sells their set of 6 teflon brake lines for $120(2 rear, 1 front
per side), many other places also have them for comparable prices.
The 87-89 rear vented brakes retrofit to 84-86 by simply swapping the
entire rear control arm, rotor, and caliper as an assembly.
87-89 front hubs, rotors, and calipers bolt right on to any 84-86 strut.
By choosing the correct wheel, you can increase acceleration, and
improve handling. Choosing a lighter wheel reduces the unsprung weight
and inertia. Really, if you get wheels that are significantly lighter,
you can actually feel it. Be ready to empty your wallet
if you desire to get a wheel that is substantially lighter.
Cheapie wheels can be had for $100 each from western auto or somewhere
like that, but good, lightweight, quality wheels will run you anywhere
from $150-$400 each, depending on size and quality.
Be careful with the sizes you choose. Too far off the stock wheel and tire
diameter, and your speedo will become inaccurate(If this matters to you)
diameter will increase acceleration though(lowers effictive gearing)
- Camber stuff:
Camber plates can be had for the front(they require cutting up the strut
towers, not a big deal) for around $200/pair from Ground Control.
Rear camber can be adjusted by re-locating either pivot point for each
rear control arm(ie. outer points down or inner points up). Any competent
speed shop could do this for you if you can't(requires cutting and welding).
Basic bolt-ons? No-holds-barred buildup? The sky and your credit card
are the only limits. Best bang for the buck is to start with a low
mile vg33 engine - 10% more displacement means 10% more power for free.
If you have unlimited money start with the NisMo heads.
- Underdrive pulley:
Unorthodox Racing used to make some.
No longer available.
Camshafts are what open and close the valves in your engne.
By opening the valves further and/or for a longer time, engine breathing can be
greatly increased. Cams are a PITA to install, but thankfully fairly cheap.
All cam makers will tell you to install new lifters with a new cam, however
lifters are incredibly expensive($30 or more each, and you need 12)....
A quality machine shop can lightly grind a new surface on lifters so that
they can be reused with a new cam, or you can do it yourself with a
perfectly flat surface and some very fine wet-dry sandpaper
in your kitchen sink. Simply lightly sand until a fresh surface
is visible on the face of the lifters.
Avoid getting water into the insides of your lifters, they might rust
- Turbo and intercooler stuff:
If you need a new one, talk with a
reputable turbocharger vendor and you can get any type of turbo
made that you can imagine. Hybrids with larger compressor turbines
and larger bearings
are fairly common, enabling you to use more boost than the stock
unit was designed to produce.
A quality intercooler is mandatory on any heavily turbocharged engine. It
is very difficult to go overboard on an intercooler. But they're not worth
the money or effort on a basically stock car.
- Intake manifold upgrades:
The two most common choices are a gutted stock plenum and a stock
pathfinder plenum. Dyno results on heavily modified cars have shown
an increase of 8% in hp and 12% in torque for a gutted stock manifold
and 1% gain in hp with a 8% gain in torque with the pathfinder manifold.
Which is better depends on your use - these peak numbers are just that,
peak numbers. Any engine spends 99% of it's time at speeds other than
peak power/torque, so take into account the shape of the curve. A gutted
stock plenum is likely better for high rpm performance while the pathfinder
plenum with it's long runners provides larger increases in low-rpm power.
Gutting the stock plenum entails cutting it open, machining out the insides,
and welding it back up.
Installing the pathfinder manifold is very
straight forward with basic tools and a visit to the junkyard.
- Spark plugs:
Any street driven car can use the stock plugs without any problems at all.
If your engine is heavily modified(at least 400rwhp) you can consider using
colder plugs. If you know what you're doing you can also chase down an
extra percent or two power by using some trick plugs.
- Drivetrain: Strength is not an issue
with any z31 drivetrain part until you can cut 1.6 or better 60' times
with a manual transmission.
At this power level with a manual transmission you will find the axle
stubs to be the weak link. Not much you can do except pick the nicest
axles you can find and go easy on them. Drivetrain upgrades are done
basically for performance reasons, not reliability.
You can buy a new LSD in a variety of ratios from Nissan Motorsports
at about $700 each. Or you can buy one from a wrecked 87-89 turbo
and bolt it right into yours.
You could also get a 3.9 open differential from a 88-89
non-turbo, see the differential page for which ratios are
The stock unit is plenty strong, but aluminum driveshafts are available
to reduce rotational intertia. The driveshaft is so short that weight
reduction is minimal and the cost is high, so this should be well down
at the bottom of your upgrade list. MSA sells
aluminum driveshafts and they are readily available custom made from any
competent driveshaft shop.
- Ignition: The stock ignition is pretty good unless you have some
serious modifications. The best dollar-wise investment would be good
plugs and a good set of wires(NGK) along with a new cap and rotor.
I'd say Bosch platinum, Nissan cap and rotor, and the thickest
wires you can find. NGK plugs are the stock plug specified by Nissan,
I use Bosch with no problems as do others. Many people say that your
car will run like crap if you use anything other than NGK plugs, but this
Speaks for itsself. Very entertaining.
- Fuel/ignition system:
Many options. Stock injectors are 160cc/min on non turbo and 259cc/min on
turbos - in other words tiny.
Yes, some people want to do cosmetic modifications to their car. We have
information on some.
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