Version 1.1
Let us start with the basics. After Hours and Hours of research, I have come with up with an Upgrade guide. It should help us all! (the other one was old, and didn’t help to much)
UPDATE: *added camshaft guide**added tune up guide and A/F tuning*
TUNEUP
The most basic, and one of the most important modifications that can be done to an Altima is the basic tune up. Its relatively inexpensive, and can Improve fuel economy, run smoother and cleaner, regain loss power, and in some cases, actual gain hp. Basics to look for would be, a routine oil change with filter and synthetic fluids, Distributor Cap and Rotor, new spark plug wires, fuel filter, new spark plugs with proper gap (you can gap up to .047in.though fuel economy might suffer a bit) Most of these parts can last a while, and have a fairly even spaced out service interval. Make sure you car is in tune to get the best of it.
Highs:
Keeps the car in running order
Improve fuel economy
Regain loss power
Inexpensive
Lows:
Some parts can be a little more costly depending on brand
Best Choice:
Mobile 1/ Royal Purple 5w-30 oil, NGK copper Plugs and wires.
CAI/WAI
From my personal Experience, and from several other recorded documents, CAI outperforms WAI. From low end, to top, and mid range too, CAI makes more power, and thickens up the power band. Though, through my experience, the WAI’s warmer intake temps actually improve Gas mileage over cooler temps of the CAI. Also, the WAI has slightly better throttle response. Also, with WAI, worrying about Hydro lock is not an Issue. WAI also cost a bit less than CAI (depending on the make), and CAI choices are limited. With a bypass valve, you can eliminate the risk of hydro lock on a CAI.
Highs:
Improved Throttle Response (wai)
Better Fuel economy (wai)
Lower end Torque/ Broader power band (cai)
Inexpensive (Wai)
Sound (cai, Lesser extent wai)
Lows:
Chance of Hydro lock (Cai)
Peaky power band (wai)
Cost (cai)
Best choices:
JWT (Wai)
Hotshot (Cai)
Example of CAI making more power than WAI
http://www.ka24development.com/file_...dyno_injen.jpg
http://www.se-r.net/about/200sx/scc/april98/april3.jpg
HEADER
The Header is most likely one of the Best Mods for the Altima. For bang for buck, look not further, because this is the mod wakes the Motor up. Altima drivers have two choices as far as Headers go. 4-2-1, and 4-1. 4-2-1 (street) is considered optimal for a nice low to mid range power; while 4-1 (race) is thought better for Top end power. Many members who have had both haven't felt, or seen, any difference in power between the two. Though part throttle power may be different.
Highs:
Great bang for buck (both)
Great power gain (both)
-High RPM (4-1)
-Low to mid RPM (4-2-1)
Lows:
Reduces refinement (more vibration)
More noise
Best Choices:
Hotshot (4-2-1)
Stillen (4-1)
EXHAUST
A hotly debated subject on the Altima Boards. It comes down to this, the bigger you go, the more power you can make. 3ich Cat backs have been shown to make Power at the upper Rpm range, and lose no low-end power, BUT they can reduce throttle response, and don’t make as much low/mid range power as smaller piping. Meaning, at part throttle daily Driving, you’ll feel like you lost a lot of power. Altima drivers have long used 2.25, but even that may be too small for optimal breathing. 2.5 seem like the Best compromise between 3.0 and 2.25. It offers superior low-end power, and excellent top end. Though, because of the bigger size, 2.5 might be louder than 2.25. In the end it comes down to preference. If you want maximum power, go 3inch, if you want to keep things quiet, go 2.25. If you want the best of both worlds, go 2.5. Of course, all piping should be mandrel bent for the best flow.
Highs:
Good power increase (all)
Large top end gains (3.0)
Good sound (all…varies)
Part throttle power (2.25 mostly. 2.5)
Lows:
Cost
Noise level (2.5 – 3.0 Mostly depends on setup)
Most Exhaust made for Altima only offer smaller size piping
Best Choices:
OBX (2.25)
Greddy (2.35)
VRS (2.5/3.0)
Custom (x.xx)
http://img.photobucket.com/albums/v1...ynoCompare.jpg
http://www.worldwidechang.com/Pics/C...keExhaust1.jpg
TB SPACER
A relatively new mod for Altima, the Idea Stemmed from a Current member (Ecco), and has been dyno tested to show merit. The TB spacer mod is actually two mods in one. The spacer, and the coolant line Bypass. The spacer actually adds a good amount of power for a low price. A good amount of low end power gained, is available right off idle, and carries some of the gains close to redline. Judging from the Dyno graph, some Top end Power might be lost due to running slightly richer, but for the power gained under the curve its worth it. The coolant bypass keeps the intake temperature cooler, and thus, you can gain back some lost power due to heat. Users have also reported better fuel economy.
Highs:
More low-end power
Better Fuel economy
Low to moderate cost
Good For FI use?
Lows:
Richer mixture can reduce top end power
Not as much power in higher RPM
Must reposition intake
Good for FI use?
Best Choices:
Altimas.net member Ecco
Ace Precision
http://i13.photobucket.com/albums/a2...ynosheet-1.gif
http://i13.photobucket.com/albums/a2...ynosheet-2.gif
UNDERDRIVE PULLEY
Without getting into the subject of weather or not the KA is internally balanced or not, or if under driving damages other parts, many members (including myself) have run these pulleys, and have had no issues. Under drive pulleys don’t actually make power, instead, the “free up” lost drive train power. Automatic Altima seem to experience the biggest gain from the Pulley, compared to manual cars, which the difference isn’t as noticeable. The gains spread through the rpm band, both low through high. Most of the power “gains” comes from saved weight instead of actual under driving. Regardless, most don’t notice any change in accessory performance due to the pulley change.
Highs:
Gain throughout the power band
Can be inexpensive (check ebay)
Nice gains on automatics
Lows:
Scary history
No full pulley set
No big gains on manual cars
‘Off’ timing marks on (some) pulleys
Best Choices:
Unorthodox Racing
SWA
ECU/COMPUTER
At this time, there are not that many options on ECU upgrades on Altimas. Altimas.net member steeliz promises a tune soon, but as of right now, Altima Drivers have two choices. Standalone (and piggyback) or JWT’s ECU. JWT’s ecu adds these enchantments over the stock ecu
· Fuel and spark maps for optimal performance while maintaining OBD-II compatibility
· Removes the MPH top-speed-limit fuel cut function
· Raises the stock rev limit (7000rpm)
· Significantly improves transient throttle response (no tip-in retard)
· Leans out the A/F ratio at WOT for optimal performance
· Compensates for larger fuel injectors across the entire operating range
Gains on the ECU are said to be about a much as the header through the RPM range, though peak numbers are not as high. Also, the ECU’s cost means this should be a mod done later on. Fuel Economy can improve, though Premium fuel is required. So far, without going standalone, nothing offers what JWT does.
Highs:
More power all around, and good gains
Better fuel economy
Bigger power band
Re-programmable
Lows:
Cost
Premium fuel required
Best Choices:
JWT ECU
Sentra.net - Kojima's Garage - Engine Modifications
SCC Project Nissan 200SX 1.6 - February 2001
CAMSHAFTS
It’s no Secret that the Altima has generous low-end power, but dies at top end. Even after all the bolt ons, which perform more like a band-aid to problem, the upper RPM range remains weak. Because of the Set up of the motor, the Altima isn’t as flexible with cam swaps as the 240sx. Choosing the right cams is important, because cams as a whole have a big impact on your power curve. If you plan on using Factory camshafts as an upgrade, the best combo would be 248intake and a 232 Exhaust cam, though it would be harder to obtain in an Altima. Also Altimas can only use another Altima cam as the Exhaust cam! While cheaper, factory Cam Swapping can be a big hassle, and doesn’t really give the gains Aftermarket cams will.
As far as Aftermarket Cams go, if you are N/A, your best bet, auto or manual, is to look at JWT camshafts. PDM’s are said to make more peak power, but lose more down low, and Crowers camshafts aren’t as Aggressive as JWT’s until you get to Stage 3. Also, Crower cams are cheaper, offering a nice bang for buck
Cams are a difficult subject because there is no right or wrong answer. If you want max power, low-end power, or a nice broad power band, there is a cam set up for you.
Highs:
More Power at top end (all)
Low price (factory cams)
Proven 8+whp gain (PDM, JWT)
Better overall Power band
Lows:
Difficult install for those less Experienced (all)
Slight low-end loss
Cost (PDM, JWT)
Best Choice:
JWT, Crower
my comments on 248/240 s13 cam swap: Nissan Infiniti Forums - NICOclub
KA24DE Cams Specifications: Nissan Infiniti Forums - NICOclub
http://www.nissanclub.com/forums/eng...highlight=cams
http://www.ka24development.com/file_...x_dyno_JWT.jpg
A/F CONTROLLER
One of the character traits on the Altimas (and this is true of other Nissans, down to the 350Z) is that on higher RPM’s, the ECU dumps massive amounts of Fuel into the car, making it run rich up top, and killing power overall. A relatively cheap way of fixing this would be to get an A/F controller. An A/F controller does exactly what its name says, by controlling (or tricking the ECU) to richen, or lean out an A/F ratio. For F/I cars, running slightly rich would be ideal, and for N/A you’ll want a slightly leaner mixture. For the Altima in particular, you will want one with a knock Sensor Reading. The Downside to A/F controllers is you’ll also need a wideband to tune, or a Dyno. And for the cost of the unit and a Tune can rise in cost. Also, if tuned incorrectly, you run the risk of severe damage to your motor. Because of the nature of this mod, it is recommended that it is done last.
Highs:
Nice gains on a Tuned unit
Relatively inexpensive to buy
Lows:
If unfamiliar, it requires professional tune (recommended anyhow)
If tuned incorrectly, can cause serious motor damage
Should not be used with Aftermarket ECUs (JWT)
Best Choice:
SAFC/II
New Upgrade guide
Linear Mode
