Starting Mods for a 240SX

[DWF Engineering]

So you just got yourself a 240SX and you're looking for a good place to start modifying. The first thing to do is take your catalytic converter off and remove the catalyst. If you can find a steel tube with the correct diameter, drive it through the center of the cat housing so it's like a straight pipe. This allows you to run a richer mixture without the risk of overheating the cat. The next thing to do is remove the fan from the front of the engine; it weighs about 4 lbs so the gains equal about 1/2 of the gains experienced with an UR pully. You'll gain more top end too because you don't have the friction of the fan blades against the air. Advancing the ignition timing 2-3 degrees is good for a few extra ponies and the muffler can be removed quite easily as well. At this stage of the game you should invest in a fuel programmer (S-AFC etc.) and advance the ignition timing another 2 degrees or so. Advance the timing until slight detonation is heard over part of the rpm band at full throttle. Then use the fuel programmer to richen the mixture and surpress the detonation. This will yield substantial gains. This is where I'm at with my 240SX at the moment and I can easily outrun the 181 bhp Tiburon and 200 bhp Eclipse. The late model V8 pickups are also fun to shoot down.

I'm well aware that there are a lot of mods that are cheaper than the S-AFC but this is a good place to learn about tuning; the hotter your setup, the easier it will be for you to burn your engine down with improper tuning.

Follow-up mods for N/A setups should go as follows:
intake
header
ignition kit
cams

Turbo apps. should follow this sequence:
intake
complete big trim/big AR T3 setup (5 psi)
FMIC
7 psi

You may get away with as much as 12 psi boost but I wouldn't go much past 10 on my own car.

[Ace$nyper]

ummm thats great write up but was this meant as a reply it looks it? maybe it could be stickyed? or added to FAQ cause you got some good info.

[thelinja]

I totally disagree with you. The first thing I would do with any newly purchased used car would be to replace filters, fluids, plugs, wires, other ignition components, brake pads, rotors, and fluid. I would make sure the car is in top running condition before I started making it "faster."

[J SPEC SilEighty]

"This allows you to run a richer mixture"

Why would you want to run more rich, other than it being more safe? The motor will make the most power right at the point of detonation. So if you have the tools to tune your motor then you would want to run it more lean to achieve more power.

"The next thing to do is remove the fan from the front of the engine"

Do you mean remove the mechanical fan and replace it with an electrical fan? If so, then yeah that's a good idea to free up some of the power losses. On the other hand, if you live in hot, sunny, california or florida or even if you just commute long distances at times then your going to want that fan....

"You'll gain more top end too because you don't have the friction of the fan blades against the air."

It won't be anything noticeable at all...

"Advancing the ignition timing 2-3 degrees is good for a few extra ponies"

Your completely right about this statement. Advancing the timing will cause it to run a little more lean, which in turn will add power. What I don't understand though is why you said to advance the timing here (cause it to run more lean), but earlier you said something about "allowing you to run a more rich mixture."

[DWF Engineering]

Originally Posted by J SPEC SilEighty

"This allows you to run a richer mixture"

Why would you want to run more rich, other than it being more safe? The motor will make the most power right at the point of detonation. So if you have the tools to tune your motor then you would want to run it more lean to achieve more power.

"The next thing to do is remove the fan from the front of the engine"

Do you mean remove the mechanical fan and replace it with an electrical fan? If so, then yeah that's a good idea to free up some of the power losses. On the other hand, if you live in hot, sunny, california or florida or even if you just commute long distances at times then your going to want that fan....

"You'll gain more top end too because you don't have the friction of the fan blades against the air."

It won't be anything noticeable at all...

"Advancing the ignition timing 2-3 degrees is good for a few extra ponies"

Your completely right about this statement. Advancing the timing will cause it to run a little more lean, which in turn will add power. What I don't understand though is why you said to advance the timing here (cause it to run more lean), but earlier you said something about "allowing you to run a more rich mixture."

There are as many tuning theories as there are tuned up cars. I believe that ignition timing and a/f ratio are optimum when combustion takes place throughout the powerstroke. A lean mixture is hotter but it burns more rapidly, leaving the piston to coast for the last 20%, or so, of the powerstroke. The goal is to have even force against the crown of the piston throughout the powerstroke. The fan mod was gave the car fantastic throttle response. I live in Central Texas; it gets blazing hot outside. Even in this environment the engine did not overheat while driving, the only problem was running the AC while parked or in heavy traffic it would try to overheat. All I had to do was turn off the AC and the temp dropped.

[Soyo]

yea a good electric fan will cool just as good as the factory one as long as you don't have the AC on, but you can have the AC on when your say, driving down the highway and such but not if your stoping and accelerating over and over.

still kind of an out of the blue post, but as long as its not another RB or front end conversion post I'll be happy

[raven_240]

Ahh who needs A/C anyway get rid of the fan get an electric, even in texas where town is 6 hrs apart the electric fan keeps my sr20 cool enouph with the stock radiator. But again i have no A/C.