Before Modifying your Z
By: Jeff Wisener
(Posted with the authors full knowledge and permission.)
So you want to modify your 350Z?Read this first!
1. Define your goal. Are you simply trying to make your car look nicer, building it for street racing, drag racing, autoX, track, or a show car. Maybe it is a combination of more than just one of these, if so, be sure which one is more important because they may conflict each other.
2. Set your budget. You could easily spend in excess of $25, 000 on mods if you went with upgraded suspension, wheels and tires, and a Twin Turbo alone. Someone recently asked himself why he was spending so much money on modifying his 350Z when he could have purchase a Z06 Vette that will out perform his Z and the Vette would still have the factory warranty. Know what you want to achieve and how much you are willing to spend before beginning to modify your car.
3. Determine if you are willing to void your warranty from Nissan. Many suspension mods void anything related to suspension so if you spend $2000 on coilover suspension, be ready to accept that Nissan will not fix your tire feathering problems found on many 350Z after 5000 miles with anything but stock or NISMO S suspension.
4. Determine how much of a risk taker you are. A lot of people would love to have 500hp but how concerned are you about reliability. Your car has been designed stock to provide good performance with reliability. Nissan told their engineers to design the 350Z motor to last 200,000 miles. As a general rule, the more hp, the less reliability although some would argue that fact.
5. How long will you keep your 350Z? In many cases, most modifications do not bring higher resale and in many situations depreciate the cars value. I have already seen several nice 350Z’s with modifications of over $10,000 and then be sold off for parts bringing penny’s on a dollar due to people selling their 350Z months after modifying it. Ask yourself how long you plan to keep a 2 seater sports car. For most young couples, when the baby comes, the 350Z goes.
Once you have considered items 1-5 above, now you are ready to begin modifying your car. The list I will make below is just a simple overview of each category. You should read up on each area using the search option and get a lot of good advice in many threads. There are many experienced members on line that have specific expertise in areas such as stereo or wheels and tires. Use their knowledge and leave your ego off line. All of us can learn from someone else. If you need my opinion on something, feel free to pm me and I will do what I can to help you. I suggest you begin modifying your Z in the following order:
1. Protecting your paint job: In case you did not know, the 350Z is known for paint chipping in the front bumper. It will happen within the first 1-2000 miles and I doubt you will get it covered under warranty. I strongly suggest you think about protecting your paint. I do not personally like black bras on the front. I like the clear bra type product which provides a clear film of protection to prevent chipping, just like provided in front of your rear wheel well by Nissan from the factory but this is a thinner material. There are different brands of course and I picked one and I am happy with it. Maybe you will pick another product and find it is excellent as well? My only suggestion is get it from a certified installer of this type of product. That does not mean a window tint installer. Just because you can tint windows does not mean you can apply a clear bra.
2. Tinting windows. Do a search on find out what percentage of tinting is legal in your state. This is another cheap modification that can be done right away.
3. Tires and wheels: This is a great place to start doing the bigger type of modifications. It will enhance the appearance and performance of your car and for the most part will not negatively affect reliability. If you are adding a body kit to your car, it would be wise to decide which one and how if any this affects your wheel and tire selection. You don’t need to know as much about wheels and tires to select them (as compared to designing a twin turbo for your car) although there are many issues to consider but even if you make a choice based on personal taste, you wont blow up your motor!
Wheels: If you are most interested in looks, 19” might be your best bet. Just remember the 2 negatives of 19” tires. Negative #1 is you will run a very low profile tire thus more likely to bend a wheel (and ride a little rougher). Negative #2: weight of wheel is greater and for every 6lbs you add to a wheel/tire, you lose 1 hp.
If you want a combination of looks and performance, then 18″ wheels might be a wise choice. You get a slightly lighter wheel thus a little more hp but it does not have as aggressive of a look as the 19” wheels.
If you want the maximum performance then 17” wheels put the most hp to the ground. For those that want optimal appearance for the street and optimal track performance go with 19” street wheels and tires and separate 17” track wheels and tires. Again, what is your goal and budget?
Tires: The most common tire size upgrade is to a 245 ft tire and 275 rears. Notice the rears are larger than the front to maintain the understeer/oversteer issue. Your stock wheels will not accommodate this big of a tire thus read up on what size wheel works for the tires you want to put on your car. I strongly suggest you use this website http://www.miata.net/garage/tirecalc.html This site will tell you how much difference there is between your stock tire and tire you desire. If you increase or decrease your tire size over 3% of stock size (in outsize rolling diameter) it will affect your ABS braking system and VDC. Simply put, your car will sense the back wheels are rotating too quickly for example and the ECU will think you are spinning your tires/losing traction which will possibly cause your car to brake or cut off the throttle. I recommend you keep the margin within 1.5%. I went with larger tires, 265 fronts and 295 rears. This is not as wise a choice for performance if you plan on maintaining the stock motor however if you plan on adding at least 100 hp, it might be something to consider. You need to be careful going with this large a tire combination. Your wheel offset must be just right or your tires will rub against the fenders. Mine don’t but I did my homework.
4. Suspension: Now that you got your wheels and tires, you might think that gap between your fender and wheel is too big! In addition, most of these suspension upgrades tend to get rid of that annoying freeway hop found on stock 350Z’s. For many, the biggest added bonus is improved handling. If handling is important to you, add stiffer sway bars while you are adding suspension. Again just as with Wheels and tires, suspension options are on the market now so why not start here before adding hp. Here are your options:
Springs: Companies like Eibach and B&G have springs that will lower your car and make it look great. Costs on these springs are about $200-$250. There are strings attached. Eibachs lower your car 1.2” in the rear and .8” in the front and remember, anything over .8” drop will make your camber impossible to be within factory camber specifications. You can drive it with springs only and lose up to 20% tire life (inside edge of tire will wear out first) or get camber kits. These kits will cost you in excess of $400 for just rears or fronts. If you add these camber kits to the cost of the springs, this option is not as cheap as you might first think. Another negative of lowering beyond .8” is going over speed bumps and bottoming out. This option is good for those whose priority is looks. Make sure to get a 4 wheel alignment after installing springs.
Spring/shock combo: Right now, the number one option in this group is NISMO S suspension. Cost about $1300-$1800 depending on the vendor and most will ship them to you. The suspension lowers the Z about .8” thus no camber issues, no need to get alignment after install either. This gets rid of fwy bounce as well. NISMO maintains factory warranty and handles very well on street as well as track. The negative of this option compared to Coil-over springs is lack of adjustment in height, ride hardness, etc.
Coilovers: Cost varies from about $1600 to over $2000. You can control ht and ride. Teins even have a feature called EDFC which allows you to adjust ride hardness within the car as you are driving. You can preset it to 3 levels too such as casual driving, aggressive street, and track. JIC’s seem to be the choice of those with track being their number one priority but remember it is stiff so if you don’t want to feel the road, consider something else besides JIC’s. These are just two options, every month new coil-overs are being introduced to the market. Maybe SportZ magazine will have a shoot out on different suspension systems later like they did on exhausts and it might make the choice of selecting a suspension system an easier task then it is right now.
5. Stereo: The stock stereo is weak, many are not happy with the Bose as well. Many good options on stereos are available right now so you can’t go wrong. This might be your first choice to modify your car. After all, what is better than listening to good tunes in your new Z?
There too many speakers, amps, and head units to list and compare in a brief overview. Again, read up on the options you have, and ask questions. Many people have upgraded their stereo already including me and would be more than willing to advise you. I had a sub woofer enclosure made that I feel is one of the best modifications I have done to date. Again, do your homework to get the desired effect.
6. Brakes: Before adding a lot of hp, you might want to consider being able to stop your car better. Both the stock brakes and the brembo’s found on the Track model are excellent brakes. If all you are planning on doing is driving on the street and braking hard only during emergencies, than your stock brakes are as good as you need. With that being said, then why should you consider upgrading your brakes? Two reasons; the most important being if you do repeated hard braking on mountain roads or on a track, you might experience brake fade which simply means that as the brakes heat up, they take longer to stop. The more they heat up, the less they stop.
The best way to determine if you need brakes upgraded is to track it. I drove my Z at the track for 30 minutes on, 30 minutes off all day long. Even after that, it took all day for them to begin to fade. In other words, who might need better brakes but unless you brake hard frequently, you most likely don’t.
Another reason to upgrade brakes has nothing to do with stopping, it is for looks. Many of the people that upgrade to 15” brake kits are doing so for looks. As I stated before, 17” wheels are optimal for tracking your car. 17” wheels can only accommodate 13” rotors thus adding 14” or 15” brake kits force you to track your Z with less than optimal tires and wheels. 13” rotors on most after market brake kits will meet all your stopping needs on the street and track. If you are never going to run 17” wheels, knock yourself out and get those bigger kits if you like, they look awesome.
Brembo, Stoptech, AP, and others all have kits starting at about $1700 for front brakes. You can get a 4 wheel brake set but the front brakes are the most critical. You might want to consider changing your brake lines and fluid as a cheaper alternative than an entire brake kit.
7. Drive train/Engine modifications: I listed this category towards the end for good reason. The first reason you should be getting use to your car in stock form and learning its limits before adding hp. I felt I need to add hp to my Z the very first day I drove it off the dealer lot. Not until I took it to a track did I realize the full capabilities of my 350Z. I found that while I was driving it, the main performance modification needed to be modified was me, being the driver learning how to drive it to its full potential. Honestly, if you care anything about performance, you should take your Z to the track. No matter how aggressive you drive on the street, driving it on a track allows you to push it much harder and in a safe environment. Besides that, it is a blast to do.
There are new options in this group being released almost daily. Just in this month alone (November 2003), the Vortec SC is being released; the Greddy TT is now taking new orders. Several other SC and TT kits are scheduled to be released within 1-2 months. Waiting a little bit to add other modifications is not a bad idea. Let’s go over the options:
NOS: Do you want cheap HP and your desire is to beat that Mustang next to you? NOS is an option you should consider. Some people dislike it but no one can disagree that it adds hp for short bursts and does it cheaply.
NA: Some people think real engines are Naturally Aspired (NA). For those people, NOS is just flat cheating and SC and TT cars are better but have limitations. Every one of these options has pros and cons or there would only be one option. Here are the pros/cons of NA: SC and TT may have a tendency to run hotter. There is a question of reliability when you FI a motor. The 350Z VQ motor was designed as a high compression motor yet FI motors run optimally as low compression. With a NA motor, you do not have the “turbo lag” often found on TT. This turbo lag can be an enemy on the track. Most people that decide to add hp by NA often state it as being more dependable and predictable on a track. The negative is cost. Expect to spend approximately $5000 to add 50-60 hp. In addition, as soon you you add cams, your motor warranty is void, even if it is a NISMO cam because the NISMO cams are type R which is for racing thus no warranty as compared to type S which are for street and maintain the factory warranty. Typical NA mods include exhaust and headers, cams, pulleys, air intakes, and plenum. Remember, don’t add a plenum and then decide to get a Dream Workes or Stillen supercharger because you will simply be taking off the plenum you just purchased. You got to make up your mind if you are going NA, SC, or TT before you begin modifying your motor unless you like wasting money.
Superchargers: There are two types of FI, Superchargers (SC) and turbos which are most often twin turbos (TT) on 350Z’s. A lot of debate is covered on various threads concerning advantages and disadvantages of SC vs. TT. Some people tend to be very pro – supercharger and others are pro TT. I will try to be as objective as possible but I am sure my opinion will differ from others.
Supercharger kits typically run about $4800-$6000 + installation takes anywhere from 8-20 hours labor depending on the kit thus figure at least another $1000 in labor to install. All of the kits either come with an intercooler (IC) or can be added as an option to the base kit. I strongly suggest you get the IC since it keeps the motor running cooler and cooling is a major issue for any FI motor.
The two most common types of SC used on the Z are the centrifugal SC and the Root type SC.
The ATI Procharger and Vortec SC are the most popular centrifugal SC available currently. Both of these kits put out approximately 350-370 rear wheel hp (RWHP) at 7 psi of boost. Adding the approximate 17% loss from the crank to the wheels, that would equal about 409 to 432 rwhp. This is a significant jump over the 287 crank hp (approximately 230-245 rwhp found on a stock 350Z). Both of these kits void the engine warranty by Nissan unless you can find a dealer that will sell you them installed on the car when it is new. The significant difference between the centrifugal SC and the root is the centrifugal SC does not have full boost until you reach higher rpm’s. To be simplistic, a centrifugal SC has 1 psi of boost per 1000rpm being the peak boost is 7 psi. Boost increases hp thus a centrifugal SC really kicks in when it is above 4500 rpm since it is then approaching full boost/ peak hp.
The other type of SC is the root. The only current root SC available is made by Stillen. Dream Workes (DW) is scheduled to release a root type SC in January of 2004. The root blower is position on top of the motor as compared to the centrifugal SC that is located off to the side of the motor. The Stillen SC sets so high on top of the motor that to install it, the strut brace has to be removed reducing handling and the hood has to be cut out and a scoop added or an entire hood has to be installed. The soon to be released DW SC is designed to use the stock hood and maintain the strut. Both of these root type SC have full boost at low to high rpm thus more low end grunt. These SC kits tend to put out less peak hp by approximately 20-30hp but advocates of the root type blower will say that the root SC provides you with more power where you need it rather than a little more hp right before you shift. The Stillen SC will provide you with an engine warranty if you do not boost it over 5.5 psi but then you will be putting out approximately the same hp as a built NA motor. DW plans on offering their SC with 400 crank hp (approximately 330 rwhp) with a full drive train warranty and be the first to offer CARB legal installation which means that owners in California can pass smog with their SC Z’s. In addition, they plan on having upgrades to further increase hp but the warranty will be voided. Stillen has just released an IC for their Sc kit which creates more hp. the warranty would be void with this set up so it comes down to hp vs risk level. that is a choice you must make based on your needs and comfort level.
With all of these FI kits, tuning and boost seem to be critical issues related to reliability. I cannot stress enough that you should get an experienced tuner to install these kits. Before doing that, you should read hours and hours of posts and anything else you can get your hands on before selecting a kit and an installer. Do your research and ask a lot of questions before you decide on a kit. If you raise the boost, most of these SC kits have the capability to exceed 500hp. The other side of the coin is if you raise the boost, are you keeping within the specifications of the kit your purchased? Even adding a simple addtional modification might cause problems with a FI kit. Be sure to talk in detail to the manufacture and installer before doing anything. Something you might think is ok to do might not be ok and cost you thousands of dollars to repair. As with turbos, I strong suggest that if you exceed 7psi of boost, you consider modifying your pistons, rods etc to maintain durability.
Twin Turbos: for the person that wishes to build the ultimate hp capable in the VQ, the TT is their most likely choice. Boost can be modified on a SC by changing the pulley but it is simpler and quicker in the TT. You simply dial it in sitting in the driver seat. The two most commonly discussed TT kits currently are the Greddy TT and Power Enterprise TT (PE). Both of these kits cost approximately $7-8000 and then installation needs to be added to that cost. The TT has the potential to exceed 800hp. Before you dream of just turning up the boost to get those numbers, strongly consider building the internal portion of your motor to accommodate that power output. You better know what you are doing if you are putting out this much hp. An improperly tuned motor putting out this much hp is a time bomb waiting to explode.
Since all of these SC and TT kits have either been just out a couple of months or not even out yet, the reliability of these kits are not proven to MY personal satisfaction. Large debates over how much boost can be given to each kit goes on daily. To be blunt, everyone has their opinion but the fact is no one knows what is a safe level of boost yet. Motors will be blown up defining those limits. Some argue the VQ is extremely limited in the amount of boost it can take, others feel it is a question of proper tuning and once tuners get a better handle on the ECU (car computer) and can control the fuel management, they will be able to safely increase boost to higher levels.
Because of the introduction of new kits monthly and the issues of safe boost and tuning, I again caution you to modify your wheels, tires, stereo, and suspension first until these issues are resolved. If you know more than me and feel comfortable doing it now, then that is fine as long as you know enough to make an educated choice with your money. A lot of people will tell you to go for it, that is easy to do when it is you taking the risk with your money. In my opinion, if you want only 400 – 435 crank hp and you are on a budget, the SC kit might be a wise choice. If you are desiring the ability to exceed 500hp with unlimited options in tuning, the TT kit may be a better choice for you assuming you can afford it.
8. ECU: Several companies are working on improving the ECU. It is set from Nissan at safe levels for availability of gas (91 octane or higher) and different climates and altitudes. Nissan sets the ECU to safe limits for all of its owner’s not maximum hp output for car enthusiasts like many of us on this site. People that modify their cars for maximum hp tend to want to push those margins of safety closer to the limits of what are considered safe for most consumers. You can expect modest hp gains from an ECU being reprogrammed on a stock Z. An ECU preprogrammed for a FI or built NA motor will most likely result in higher hp gains than stock. Companies such as Techno Square (TS) are currently reprogramming ECU’s now. I am sure other companies will enter this market soon.
9. Other drive train modifications: After adding 100hp by FI to your motor, you will most likely be forced to replace the clutch to be able to accommodate that power. In addition, some like a lighter flywheel instead of stock. The bottom line is your 350Z was designed to accommodate 287 crank hp. The more hp you add, the greater strain you are adding to your entire drive train. The fact is, the weakest link breaks thus if you are putting out additional 100 hp and rev your motor to 3000rpm and drop the clutch, something might break since it was not designed to handle that power.
I hope this helps you. I tried to be specific enough to give you a basic idea of options you have in modifying your 350Z. Of course, I did not get too specific assuming you need to do some research on your own.
I know there are many experienced individuals that have more experience in modifying cars on this website than myself. They can add suggestions to this post and even disagree if they like with portions of what I have written. The intent was to provide a new 350Z owner with a basic understanding of what can be done to modify their 350Z with the hope of doing so without regret in their decisions. This thread was not written to debate with experienced 350Z owners over fine details of modifications.
The best answer I have read regarding why you should modify your 350Z is because you are enjoying doing so. There will always be a faster car than a 350Z be it a M3, Vette, Viper, or a number of supercars on the market. I always wanted a 300TT Z but could not afford it at the time. Now, I can afford a Z so I am doing what I dreamed of doing years ago. Z06 Vettes and 911TT are awesome but that is not my dream. Maybe the cost of those cars new is just more than I want to expend? If I can build a 350Z and it performs close to the performance of those cars, I will be happy. The more I modify my Z, the more it reflects my personality and tastes. Some guys like blonds, others redheads. I guess some guys are muscle car types and me, I am a Z type guy. It is all personal taste. That is why some of us have CS, SS, while others have brickyards. Is one better than the other? To me no, but one is better for someones personal taste.
I have been recently been hired by SportZ magazine (months after I first posted this thread). With this new postion come the opportunity to provide articles that will give Z owners another source for information in selecting aftermarket products through comparing products in tests that measure their performance. I am sure these comparisions will not show clear “winners” all the time since selecting a product must be defined by what you personallly want it to do. When selecting an exhaust, are you looking for sound quality, hp gains, torque gains, warranty, or appearance? If warranty is your top objective, a certain exhaust might be the winner in your opinion as compared to hp gain or even weight of the exhaust.
The brief overview I gave on this thread cannot replace your own research. If I am able, I will do my best to influence SportZ magazine to create more comparsions much like the exhaust shoot out they wrote.
Good luck and enjoy your 350Z be it stock or modded.