Project Nissan 300ZX: Part 6

You know how project cars can be, especially ones with goals that are as ambitious as the results we desire from Project 300ZX; stuff has to be made, things fail during testing, other things need to be redesigned. Days stretch out to become weeks, weeks become months and sometimes years go by before you know it. Thus it is with our car. Lots of trick, new parts make for long delays.

Despite the pressure to keep you fed with constant updates, we will not compromise our mission of bringing you a new level of beyond-bolt-on trickness for the sake of editorial speed. An offshoot of our project car program is to make a lot of new, previously unobtainable parts available to you fellow Z lovers, so please be patient and bear with us. As we left off in the last installment of Project Z, we are still prepping our chassis to make things ready for our Jim Wolf Technology super-motor which is currently under construction.

Engine Cooling: High-Capacity Radiator
It is a fact that the cooling on a 300ZX Twin Turbo performs marginally for track use. On hot days running more than stock boost level, the temperature gauge climbs steadily to the red zone if a track session is more than 20 minutes, usually forcing the driver to back off for a few laps to allow things to cool off. The Z is not explosively prone to overheat like its Japanese supercar cousin, the FD3S RX-7, but an aggressive driver can still reach the thermal overload threshold without a lot of effort. As our engine will be packing big gains in power, we will need to do something to improve cooling.

Looking through the Website of www.speedlab.com, the trick Japanese Internet parts brokers that supplied us with some hot Japan-only stuff in the last edition of Project Z, we found a Border large-capacity radiator. Border is a Japanese Z tuner that makes some really trick, specialized stuff, engine parts as well as aero components. Tak Nishida, the President of Speedlab informed us that the Border Radiator had twice the heat rejection capacity as the stock radiator and was a direct bolt in. Sounded great to us; we were originally going to use a big-buck, custom-made heat exchanger that was going to require that we modify the core support of the car. Naturally, since the Z is most likely going to end up being a valuable classic car someday, we were a little reluctant to do sheet metal cutting modifications.

After sending in our check, we received the radiator in short order from Speedlab. Even though the parts are custom ordered and must come across the ocean through customs, we have always been surprised with the good service that we received from Speedlab. Speedlab's thoroughness has always been evident, down to the expertly translated instructions that they include with your order, a great help if you can only comprehend sukoshi Nihongo like yours truly. Nishida has lived in the states for most of his life and speaks and reads English. This service is quite a plus, especially if your part is a complicated one and you're not an avid reader of technical Japanese.

Speedlab also packs the parts carefully, so they will most likely arrive at your door in good shape after their long voyage. At first, we were a bit apprehensive about wiring money across the ocean to a company that we had only heard of over the net, but so far, we are quite pleased with the level of service that we have received from Speedlab.

Upon opening the packaging and giving the radiator a close inspection, we noted that its core was more than twice as thick and the radiator itself and quite heavy compared with the stock Nissan unit. Fortunately, it bolted right in, with little effort on our part--typical of Japanese parts. We did have to slightly notch some of the mounting bolt holes in the Border-supplied upper radiator brackets. We found out the hard way that a U.S.-spec Z has a pesky wiring harness that required the radiator be set about 1/8-inch further back in order to clear it, but it was no big deal. We also had to shorten the upper radiator hose slightly to make up for the thicker core of the radiator.

To try a rough evaluation, we tested the stock radiator with a Nissan Consult diagnostic computer, checking the temperature range spread under a certain fixed driving loop with varied driving conditions. During our test loop, we saw a coolant temperature variation of 6 degrees Celsius with the stock radiator. With the Border radiator under the same conditions, the spread was only about 3 degrees Celsius, with the temp. hovering right around the thermostat opening point.

Hopefully this radiator will keep our monster motor cool on the track and for extended high-speed running. We are also considering running the car in the Silver State Classic, so cooling is going to be critical for that extended high-speed jaunt.

Silicone Hoses
One often-overlooked item that can do you in is the radiator hoses. If one of these babies leaks at an inopportune moment, your motor can be dust. To help insure against this and to dress up our engine compartment, we obtained some heavy-duty silicone radiator hoses from Courtesy Nissan. Courtesy Nissan is a dealership with a large discount mail-order parts business. Unlike most Nissan dealerships, Courtesy stocks a large number of parts in house, so you can expect minimal delay in getting your goods. Courtesy also supports the Nissan performance community by giving club discounts, hosting club events and making an extra effort to keep parts for popular performance Nissans in stock.

Courtesy also sells high-performance parts and has a line of its own performance parts. Courtesy saw a need for heavy-duty colored silicone radiator hoses a few years back and now makes them for most of the popular performance Nissans. Silicone hoses have long been popular with the long-haul truck and racecar industry, where their resistance to heat and chemicals makes them the hose of choice for these extreme applications. Silicone rubber can withstand temperatures of more than 400 degrees without deteriorating. The Courtesy hoses are multi-ply reinforced and are much thicker and stiffer than factory hoses. This should help prevent the lower hose from collapsing at high rpm--a situation that has caused a few Zs to meet an early demise. These hoses should also last the life of the car. The cool thing is that they are also available in various colors, just the thing to dress up the engine compartment. Currently the hoses are available in red, blue and yellow. Remember, there is function as well as style to these, so learn to like these colors!

Heavy Duty Hose Clamps
Hose Techniques supplied us with some of their heavy-duty T-Bolt hose clamps to secure the hoses. T-Bolt clamps are aircraft-type clamps that apply a positive and even clamping pressure all around the hose without crimping the hose, cutting into it or binding. This greatly reduces the chance of intercooler and radiator hose blow-off or weakening the end of the hose by inadvertently cutting it while over-tightening the clamp.

T-Bolt clamps come from the aerospace, heavy-duty industrial and racecar industry and are used wherever an ultra-reliable hose clamp is needed. Hose Techniques T-Bolt Clamps are made of polished 100 percent stainless steel and look awesome as well. They are just the thing you need for a race car, or a show car, as a finishing touch to such a detailed engine compartment. This is another small detail part that adds functionality and looks good.

Carbon Radiator Baffle
We also ordered a Border carbon-fiber radiator baffle from Speedlab. The carbon is purely for snob appeal; any stiff, thin material like sheet aluminum would work here. The baffle prevents air ingested into the front of the car from blowing over the cowl and it makes more air flow through the radiator instead. Although this will help high-speed cooling, we also think it looks trick.

Other Stuff: ACPT Carbon Fiber Driveshaft
Driveshaft failure scares us. The thought of the car pole-vaulting at high speeds on a severed driveshaft gives us chills, as does the thought of a flailing broken driveshaft sawing through the car's thin sheet metal floor, and then through our legs. As Project Z has big, sticky tires and lots of power, the strain on the drivetrain is several times greater than that of a stock car. Although the Z has a very strong and robust powertrain, we would still like to eliminate some risk.

Although an NHRA-approved driveshaft loop would help prevent the bad side effects of some of these accidents, the way in which the driveshaft is buried under the exhaust system, deep inside the Z's transmission tunnel, makes such a driveshaft loop impossible to mount in the car.

On the advice of our friend, Adam Saruwatari, we looked up ACPT to make a custom carbon fiber driveshaft for us. The carbon driveshaft has many advantages over the stock steel shaft. First, carbon fiber is eight times stronger, in tensile strength, than steel. It is also much stiffer. This gives carbon composites the potential to be stronger, lighter and stiffer than stock. Our driveshaft weighs 13 lbs., which is more than 14 lbs. lighter than the stock driveshaft. We became well aware of the shaft's weight difference when we dropped the stock driveshaft on our chests and foreheads while removing it from the car: Ouch!

Second, carbon fiber has a soft failure mode. That means, when a carbon driveshaft breaks, it breaks up into a soft, broom-like mass of carbon fibers that merely brush the underside of the car, rather than ripping it-along with your legs-in half, like an enraged buzz saw. This mass of straws is not able to support the car in pole-vaulting maneuvers either--another big gain for safety. Audi recently went to a carbon rear drive shaft in some of its Quattro models for these very reasons.

Third, a carbon driveshaft has give in it. This give can cushion the transmission, clutch and differential, lessening the chance of these parts failing. With the huge amounts of power that we anticipate from our new motor, we need all the help we can get to improve drivetrain durability.

Forth, the woven carbon laminate with its cross plies is virtually non-resonant. Driveshaft resonance is a bad problem with modern cars. If the driveshaft is spun at an speed close to its natural frequency, vibrations can build up to the point where it can shake the whole car, even destroying the driveshaft. Because of resonance, all driveshafts have a critical speed that should not be exceeded. The non-resonant, very stiff carbon shaft is not bothered by resonance-related problems to the same extent as a metal driveshaft. Because of this, staying away from the shaft's critical speed is not as important for a carbon driveshaft.

Finally, a carbon driveshaft can absorb vibrations. The Z is sensitive to driveshaft vibrations. The carbon shaft goes a long way to dampen out these vibrations. For safety and other reasons, carbon driveshafts are making big inroads in both race cars and all-out street cars.

The ACPT driveshaft is a one-piece driveshaft, unlike the Z's stock two-piece driveshaft with its sometimes-troublesome center bearing. The center bearing is known to cause vibrations in higher mileage Zs. The driveshaft has two Spicer U-Joints mounted to an aluminum yoke for further weight savings. If you are into domestic performance, Spicer U-Joints are know for their strength and durability, as well as the ability to be rebuilt.

Border Downpipes
As we intend to make some serious power-basically doubling our stock output-for track use and when running race gas, we will have to temporarily remove our catalytic converters to get peak power. Very high octane racing fuel contains lead by nature and we do not want to risk spoiling our catalysts with the lead. We placed yet another order with Speedlab and they delivered a set of Border downpipes straight from Japan to our door.

The downpipes are nearly 3-inches in diameter to better match our 3-inch B&B fabrication exhaust system. They are made of polished 304 stainless steel and are so pretty, it's a pity they are underneath the car where no one will ever see them. The border pipes will not bolt onto a typical U.S.-spec Z. You must run the HKS Z car O2 sensor housings for them to fit.

This part is sold separately from HKS and they are supposed to go with HKS sport turbos. They also fit on JWT Sport 650 turbochargers with the five-bolt exhaust housing flange. If you are running U.S.-spec pre-cats, you can run B&B fabrication downpipes or downpipes from SPG Racing. We happened to be using the HKS O2 sensor housings, so the Border downpipes were an easy bolt-on. The Border downpipes also have a welded-in bung for an EGT probe conveniently in place.

The Border downpipes changed the way Project Z sounds. The car suddenly sounds very deep and the note is quieter. The exhaust note went from a musical high-pitched scream to a throaty roar, much like a well-tuned V8, but higher revving. We like this deeper and quieter sound. The car feels faster, but we have not done a back-to-back dyno comparison, as we will swap engines soon. The Border downpipes also fit perfectly with a minimum of banging and bad language on our part.

Autopower Rollbar
Recent events have changed our minds on the subject of squeezing a roll bar into our 300ZX. Although Project Z will soon be capable of approaching hyper velocities, we were reluctant to cut panels and drill holes in the body of a car that would most likely end up being a collector classic one day. Having recently lost a friend and a business associate in separate high-speed crashes, safety is suddenly on the top of the priority list, classic car or no classic car. So we set upon Project Z with air drills and hole saws, punching holes in her untouched chassis, all in the name of safety.

We have never been fans of T-tops because they weaken the roof structure of the car and add weight. Unfortunately, nearly all of the twin turbo Z's that Nissan imported were saddled with the T-tops, ours included. This further convinced us that some roll-over protection was needed beyond the frame of the stock roof structure. We really wish the car was available without the damn things.

We contacted Autopower, perhaps the country's leading supplier of SCCA-approved roll bars and cages. Autopower has applications for nearly every popular raceable performance car made. Autopower supplied an SCCA-approved (for Solo 1 type events) roll bar. The bar had a cross bar for harness mounting and an SCCA-required diagonal reinforcing bar for additional strength.

After talking in detail with Rick White-the owner of Autopower-it was decided that since a twin turbo Z is so heavy, the bar should be made of thick wall 0.120-inch DOM mild steel. DOM stands for Drawn Over Mandrel, which means that the steel for the bar is made into tubing by extruding it into a tube over a mandrel. This is much stronger than typical rollbar ERW seamed steel, which is rolled into a tube from a sheet of metal and welded. Mild steel is a better choice here than the higher tensile strength and lighter 4130 chrome moly, because mild steel can take repeated impacts, simply deforming whereas chrome moly tends to shatter. Although the Autopower bar fit the car very well, it was not easy to install it in the unobtrusive way we like. This is almost always the case in doing a clean installation of any rollbar in an upholstered street car.

We carefully removed Project Z's interior and grunted the bar into place without causing too much damage. Cutting the carpet and interior panels was done only after checking, re-checking, measuring, masking and praying. With patience, care and a lot of help, the bar was in place with even the panels and carpeting fitted well around the new bar where the tubes pierced them.

Unfortunately, we did not like the easily scratched paint finish that came on the bar, so out came everything again, and the bar was shipped off to Worco powder coating for a more durable finish. Worco is a local shop that does high-quality, custom one-off powder coating jobs for hot rodders and racecar constructors. We powder coated the bar gloss black to better match the vehicle's interior. The bar came back from Worco in short order, the job flawless. If you are picky about your bar's appearance, do yourself a favor and order it from Autopower unpainted. Then you won't have to pay extra like we did to have the bar powder blasted to remove the old paint before powder coating!

For the second, and final installation, we double nutted the bolts holding the main hoop in place--an important detail needed to pass SCCA tech inspections. Stepping back, the fully installed bar looks beautiful, hardly noticeable.

Unfortunately, there are a few unavoidable drawbacks in having a rollbar in a tight two seater like a Z. Even though the bar fits in the car pretty tightly, the top of the hoop partially obscures the view in the rearview mirror. Also, the passenger seat cannot be pushed back all the way because of interference with the crossbar. This is not Autopower's fault; it is the only way the SCCA-mandated crossbar could be fitted into the car. This will pretty much assure that tall guys will not want to ride with you. This also means that Swedish supermodels might not dig your ride either, creating major problems for suave guys like us. There is also slight interference with one of the decorative side finishers on the driver's seat and the roll bar's main hoop when the seat is pushed back all the way. If the seat has to be back all the way, it can simply be removed and you will have to look at the seat's main hinge--big deal. I am a short-and-stocky 5'8" so this is not much of an issue, although it might be bad for anyone more than 6 feet tall.

We sometimes have mixed feelings about driving a rollbar-equipped car on the street. We feel that sometimes when driving on the street with no helmet, it is possible for your unprotected head to strike the bar in certain types of accidents, perhaps making for worse injuries than you might have suffered with no bar. Fortunately, the Autopower bar is positioned pretty far away from your head, making injury unlikely in almost any foreseeable accident.

The bar, along with the structural foam injection done during our last installment with the Stillen rear and the Speedlab AB-Flug front strut tower bars all made a huge difference in chassis stiffness. This made our nearly full-race suspension tolerable for ride comfort as well as eliminating many minor noises and vibrations. The car now has a solid bank vault feeling and we are sure that the added rigidity will make the car much more responsive to suspension tuning as weight can be transferred from corner to corner with adjustments to a greater extent.

MOMO Harnesses
To further improve our safety, we obtained a set of cam lock five-point racing harnesses from Momo for Project Z. Since Project Z is a 1992 model, it was equipped with the stupid government-mandated, door-mounted seatbelts. We had to do something to improve this situation. The door-mounted seatbelt was a fine example of our government's misguided logic, where cars that did not have dual front airbags had to have passive seatbelts. Since the motorized mouse belts most manufacturers used were both annoying and unsafe, Nissan simply mounted its seatbelts on the door, claiming that you could leave them belted and shuffle in and out of the car with the belts in place. The reality is that the belts could be used conventionally, unlike most passive belts, and natural selection could continue unabated. The one downside to these door-mounted belts, however, is that if you are unfortunate enough to be in an accident where the door is torn off, the seatbelts will allow you to be conveniently ejected. Mind you, this was not Nissan's fault, it had to comply with the law, as the car has a driver's side airbag only.

Because of this flawed design, we felt compelled to install some 3-inch belts for safety while on the track. We chose the MOMO wrap-around style mounts for the shoulder harnesses. This allows us to attach the shoulder harnesses directly to the sturdy crossbar of the Autopower rollbar. For the lap belt we used MOMO's supplied anchor bolts, which handily threaded into the stock seat belt anchor position on the seat. For the door-side mount, we found a perforated circle in the carpet and after punching it out, we found the mounting point for the much better Canadian and European lap belt! The MOMO anchor bolt screwed in, giving us sano mounts with no drilling. We did end up drilling a single hole in the floor for the anti-submarine belt, but that was a minor and simple operation.

With the harnesses and the rollbar in place, once we add a fire extinguisher, we will be ready to pass tech for time trial events and open road events like the Silver State Challenge. At this point, we are strongly considering getting a racing type on-board fire extinguishing system, where the main stickler was finding a place to put the bottle in the tight confines of the car.

NuTech Speed-Link adjustable anti-roll bar end link
NuTech Suspension's Ken Nord noticed several problems with traditional aftermarket anti-roll bar end links. Many of the popular aftermarket bars have end links that are not even at the ends, causing the bar to pre-load the car in one direction or the other. To prevent jacking weight on the car, which can interfere with corner weighting and other set-up operations, you must shim the end links to assure that the bar is not twisted and pre-loading any of the wheels.

Also, the end links are often kinked at acute angles on lowered cars. This is because most aftermarket bars are designed on cars at stock height. The stock rubber or urethane bushings can also contribute to play in the bar, binding of the bar and limiting its effectiveness by taking up body motion in mushing the soft material.

The rear end links on Project Z displayed some of these negative attributes. Our bar was bent slightly off so we had to shim the end links on one side during our original installation. Since the car was lowered, the end links were bent at an acute angle, and the end link bushings took up some of the bar's effectiveness, especially when the rear bar was set, like ours, to full stiff.

To cure this, we installed some NuTech adjustable Speed-Link end links. The NuTech end links replace all of the stock rubber or aftermarket polyurethane with zero play, inflexible spherical bearing Heim joints. Now every bit of body roll gets transferred into the sway bar, greatly increasing its effectiveness. The NuTech end links are also shorter and adjustable so they can be set as close to 90 degrees to the bar as possible. This ensures that all of the body motion gets transferred into the bar right away, rather than being wasted on straightening out the end link. The smooth-acting Heim joints also eliminate any bind that is present in the bushings. Finally, the individual length of the links can be adjusted to eliminate wheel preloading caused by a slightly mis-bent anti-roll bar. This also helps keep the end link angle close to 90 degrees because the overall length of the link can be adjusted when the link is moved to different stiffness settings.

Although the NuTech end links seem like a small detail, we could actually feel the difference. The new links helped the car rotate better in lift-throttle conditions. In fact, the bar works so much better, we may have to re-adjust it one-step softer as the car is a bit too tail-happy now. By the time you read this, NuTech should have adjustable endlinks for the Z, the SE-R Sentra and 200SX, as well as some Honda models.

Energy Steering Rack Bushings
The big, heavy 300ZXTT is known to eat steering rack bushings, especially when driven by autocrossers using big, fat front tires. Some autocrossers report going through one set of the soft, gushy rubber stock bushings every autocross season. We replaced our rack bushings with hard polyurethane bushings from Energy Suspension. These bushings are several times harder than the stock bushings and should last for several years, if not the entire life of the car.

The bushings gave the car a very precise feel, like every tiny movement of the steering wheel made the car respond. Surprisingly, this was the most apparent on the freeway, where the car was very responsive. Feel was also improved in back-and-forth, slalom-like maneuvers. Our stock bushings were in good shape so the new bushings were a subtle, but nice, difference. The polyurethane bushings on a higher-mileage Z or one with worn bushings would make a night-and-day difference.

Alignment
All of the changes we made threw our alignment way out of whack. Once again, we had the chassis set-up wizards at Johnson's Alignment readjust the car's chassis and re-cornerweight the suspension. Johnson's set the car at some new specs to reflect the added rear camber adjustability we now flexed.

At the front, we further reduced our positive caster to 8.5 degrees from the factory setting of 10 degrees. Excess positive caster can cause the camber to go excessively negative under extreme steering lock conditions with wide tires. As our 265 meats qualify, in our minds, as very wide tires, we decided to experiment with reduced caster; 8.5 is still quite a bit compared with typical settings being around 4 degrees, which many rear-drive cars use. We kept the front camber at 1.75 degrees negative and the total toe-in at about 1/16-inch.

On the rear, our wonderful Stillen adjustable rear arms allowed us to reduce our rear camber from a tread-eating, wheel-spinning 2.75 degrees negative to a more livable 1.5 degrees negative. This should vastly help our acceleration and braking traction, as well as greatly increase tire life. With the HICAS eliminator in place, we set toe at 1/16 total toe-in.

All of the suspension and chassis mods we have done during these last two installments have transformed Project 300XZ. The car feels like it's shrunken down to SE-R Sentra size. It feels nimble and tossable, much different from the ponderous, heavy feel it used to have. The big Z now feels much like the revered Skyline GT-R--a monstrous car that feels small and light at speed. Surprisingly, with the removal of the four-wheel steering HICAS system, the car turns even better than before. We are at loss to explain why, but it does.

Stay tuned for the next installment of Project 300ZX. We should be able to start providing you with details on the long awaited super engine.