this is a frequently asked question post about modifying your protege. these topics have been covered enough times here to require a post to outline them. i will cover the naturally aspirated and forced induction options here and go into the options of internal modifications (pistons, rods, oil systems, ect.). this will be divided into bolt-on, top-end, and bottom-end.

first things first, you need to choose whether you are going naturally aspirated or forced induction. in all honesty, naturally aspirated is way more expensive power for power, but much more unique. you can argue that a turbo kit is expensive, but with most cars, you can double the wheel horse power with just 7-10 psi and the right supporting mods. with natural aspiration, it would easily cost you the value of the car to come anywhere near that and odds are that you would never even reach double the wheel horsepower.

i have covered natural aspiration in great depth with info from a member from another forum, thread titled "N/A theory" ( https://www.mazdaforum.com/m_71331/tm.htm ) but i will go over the basics with you here. forced induction will be covered to it's full extent here. i will go into turbo selection briefly since all of the bolt-ons are basically the same after that.

TURBO KITS

your turbo selection depends on your power goals and uses for your car. a larger turbo is going to lag more, but put down more power. a smaller turbo is going to lag less, but run out of steam in high rpm's. the mazdaspeed protege uses a gt25, so that is usually a good place to start. a gt25 will spool quickly, but won't put down a ridiculous amount of power. remember, the harder you push a small turbo, the more problems you will have with it. a common upgrade for these is a gt28, which will support the motor over 220 whp. some people have tried gt30's and gt35's, but these are very large for this motor and there are not definite whp numbers. i, personally, have seen 1 car that has put down 400 whp with a gt35. that is a really ambitious goal and will cost a lot of money and tuning to do, but is possible. you also need to remember that the higher you get into hp, the less street driving abilities you will have.

BOLT-ONS;

intake, header, exhaust

these will be your biggest bolt-on gains whether you are forced induction or naturally aspirated.

for natural aspiration, you will want to get an exhaust that will reduce the back-pressure, but not too much. the exhaust needs a certain amount of restriction to operate since it uses exhaust pulses to pull more exhaust out of the engine, therein reducing the amount of energy the engine uses to expel exhaust. the N/A theory post goes further into naturally aspirated exhaust selection. with turbo, the hot-side holds all of the back-pressure that you will need, so you can use the same size exhaust that is coming off of the outlet (i.e., some turbos have a 3" outlet, you can continue that through the entire exhaust). i will go further into turbo exhaust mods later.

header selection is pretty much the same for either turbo or n/a. you want a header that will open up the exhaust and have equal length runners. this concept is covered in the n/a post, but i will go ahead and cover the basics of it. basically, what you are looking at doing is allowing the motor to exhale more easily and causing exhaust pulses to reach the collector at the same time that another pulse is expelled so that one spent exhaust pulse pulls the next one out at a certain power band. the longer the runners, the higher in the band that you will produce power. 4-1 is the best exhaust arrangement for this effect, but n/a also has 4-2-1 which will open the exhaust further out, but will not do what i described above.

intake selection is pretty cut-and-dry. there are two basic kinds of intakes; short ram and cool air. the selection is widely open to speculation and there are many facts, opinions, and exceptions. the main thing that you need to consider is that air has mass and pressure. like any other thing which has mass, it travels best in a straight line and in one direction. the more curves that an intake has, the more restricted the air flow will be, bottom line. a short ram pulls air from the engine compartment, which a lot of people say will reduce the horsepower. it does, however, use shorter tubing which allows less flow restriction. a cold air intake will pull air from outside of the compartment, but will be much longer intake tubing and require more bends to pull from outside of the compartment. my opinion is that a cold air intake is going to have too many bends and has to go through the engine compartment anyways, which will cause the air to heat up. it also tends to cause turbulent air to hit the MAF which can cause inaccurate readings. remember, this is only an opinion and even though i am a mod here, i am still entitled to it.

that is all for i/h/e. this is all open to speculation, but there it is take it or leave it.

ignition

this is kind of open to speculation whether or not these are bolt-ons, but my feeling is that you don't have to crack open the engine to get to it, it is a bolt-on. the basic elements of the ignition system are the spark plugs, coil packs/distributor, and plug wires.

spark plugs are the cheapest and easiest mod that you can do. there are a lot of different plugs to choose from and all of them make all kinds of claims. remember that they are all just advertising. no one in their right mind is going to push their product as inferior, so just keep that in mind. the only tests that i have seen on spark plugs have brought platinum 4 point plugs and e2 plugs to the top of the charts. these are all about minimizing the electrical resistance and making a quality spark. i am willing to bet that you will never notice a whole lot of difference between plugs, but the dyno will see some. don't be afraid to spend 30-40 on plugs if you feel like you need to compare. you will at least get it back in gas later.

there is a coil pack mod that you can do which is simple and frees up a few extra hp (if you have a 2.0l, that is). the 1.8L coil packs are different than the 2.0 and seem to add a couple of hp numbers to the 2.0. the steps that you have to go through are a little extensive, but pretty cheap (comparable to other mods you may do). you need a 1.8L valve cover, the coil packs, and the plug wires. all of them are direct fits, but you will have to find a place to mount the coils. most people mount them on the front of the valve cover. there are other coil pack mods, but they require custom plug wires and boots, so i recommend having a fabricator do that work. you can use pretty much whatever coils that you want, you just have to have wires made for them.

wires are pretty key here also. you just need to find a set of wires that will keep the resistance down. there isn't really a whole lot to say here, so that is about it.

i will be back with more posts, but that is all for now.

 

Nice lol. I am in the process of modding my protege.
2003 Mazda Protege ES 2.0 Man Trans

Catback Exhaust
Cold Air Intake
E3 Spark Plugs

Never thought about coil packs...... hmmm. Oh and i also heard you may lose torque with headers

 

with a tuned length header you will move the torque and hp band a little higher in the rpm range. you won't really lose it, just move it. i have some things coming up on internals, cams, clutches, and flywheels. i will also do a full write-up on lightening the drivetrain a bit later on. too much stuff to write, not enough time.

 

now that i have covered the basic bolt-ons, i will now cover top-end. the top-end is basically anything that sits on top of the engine block. the most modified of the top-end is either the intake manifold or the cams, but we will go into other work also. here we go

TOP-END

intake manifold

the intake manifold has several mods that can be made to it. they are cheap for the most part, but they take up a lot of time since the manifold is pretty hard to remove and reinstall. with the right tools, the right amount of time, and just a little bit of money, you can do all of these mods at once.

the first is the most common, porting and polishing. basically, this means that you are cleaning up the intake runners and smoothing them out. for this, you need some kind of rotary tool like a dremel or an air powered rotary tool set to a low speed. with this, you can end up digging too deep and getting into coolant lines if you aren't careful. i recommend going into minimum work here and just smooth out what is there rather than trying to wallow the runners out too much. polishing is simple and it doesn't take too much work to polish out a port job if you keep the work clean, especially on aluminum.

the next is also a common mod for our cars. you can remove the butterflys from either the secondary intake ports or both the primary and secondary ports. this adds a little bit of power and will help the other mods to be more effective. it is pretty self-explanatory here. you just pull the butterflys and put it all back together.

finally, you can modify the throttle body. there are larger throttle bodies available and the housing can be slightly ported and polished. you can also space the throttle body, but this has very little effect. it is another one of those mods that only does a little, but adds to the effect of other mods.

cams

these are often modified for forced induction, but they have a lot of effect on natural aspiration also. the cams are basically what make the engine breathe. they open and close the intake and exhaust valves. along with modifying the cams, you can modify the cam gears to either advance or retard the timing. this is another mod that is covered heavily in the n/a theory post ( https://www.mazdaforum.com/m_71331/tm.htm ), but i will cover it here a little also. cams are basically categorized by lift and duration. lift is how far the cam will open the valve and duration is how long it will stay opened. i strongly urge you to look at the n/a theory thread to get an idea on this. the guy who wrote that is an n/a god and it has tons of useful info on cams and valves. there are quite a few options here. you can go with jdm cams, which will add a little power but are very cost effective; there are twiggy sticks, which are more expensive, but will give you many more gains; there are integral cams, which are basically the same as twiggy sticks and about the same price. all that i can say is that "stage1, stage2, stage3, etc." are all useless terms unless you know the lift and duration. once again, i strongly urge you to look into the n/a theory post about cams whether you are going forced or natural. there is a lot of info that will help you there.

cam gears are covered in the n/a theory post and i am not going into them here. you will have to go there.

valvetrain

when you modify the cams, it is important to do the springs and retainers also. if you plan on going into high hp applications, i recommend doing valves while you are at it. when you modify here, you are just replacing the valvetrain with parts that have a higher tensile strength. this means that the valves will be more solidly responsive with the cam and will stand up to the higher hp. you don't want the valves to float during the compression or combustion cycles or else you will lose compression and power. you may also pollute the next combustion cycle and not allow all of the fuel to burn due to inadequate oxygen in the chamber. these are also covered in the n/a theory post, so this is all that i really have to say about these.

machine work

there is a little bit of machining that you can do to the head itself. the main work is to mill the head in order to raise the compression. this will make the clearances tighter in the engine, which will bring the compression a little higher. you can also intake match the intake runners in the head with the intake runners on the manifold. this creates less resistance which allows the motor to breathe a little better. finally, you can do some porting and polishing to the intake and exhaust runners on the head. this is done the same way that the intake manifold is done and has about the same effect.

still more work to come.

 

BOTTOM END

here is where the real work starts. if you are serious about building a high-performance, high-horsepower car, you will definitely be going into this work. there are options for n/a and forced induction and i will cover all of them.

pistons

these are essentially the heart of the motor. between the pistons and rods, which i will cover next, this is where the bulk of the engine stress is produced and taken. the compression of the engine can be controlled the most here, also. choosing high, low, or stock compression depends on what direction you want to take the motor and how much power you want to put down. choosing cast or forged also depends on your power goals.

forged pistons can handle a lot more power and abuse than cast, but they are also much more expensive. if you plan on putting down a lot of power, these are a complete necessity. if you are planning on staying low power, i wouldn't worry about going forged. stock would be just as good.

compression ratios depend on power and induction goals. if you are staying low power, stock compression is fine. if you want high power, you really need to change the ratio one way or another. naturally aspirated applications do best with high compression. you can also benefit more from higher octane gas if you raise the compression with natural aspiration. a turbo application benefits way more from lower compression. low compression allows the motor to breathe deeper with the turbo, which realizes more gains.

rods

rods, as i said earlier, take about the same amount of stress as the pistons, if not more. they are important to modify if you plan on doing any serious work since a failing rod can destroy your engine block and crankshaft. stock rods can bend and break under high hp conditions and take other parts with them. the stock rods are cast in an H shape and the design is a pretty weak point along with the production method. aftermarket rods are more solid design and forged for strength. the length of the rods can be changed slightly along with the specs of the crankshaft. that is a stroker package, but i will go into that in a later post. for now, i am just going into the basics.

crankshaft

on our engines, there aren't a whole lot of modifications that you can do to the crank most engine sizes have forged cranks anyways, so you really don't need to swap them out unless you are changing the specs of it. like i said, i will go into that in a later post. the crank can also be lightened, but i will also go into this in a later post.

more posts later including engine package options, oil systems, and lightening the drivetrain.

 

since my last post was about internals, i have decided to make this post about stroking, destroking, and boring. these things are about changing the displacement and stroke of the engine.

stroking requires a crankshaft that has a longer stroke (moves the pistons farther up and down) and longer rods. this brings the displacement up and raises the compression. this adds more torque and low end hp. once again, this is a mod that is best done in n/a applications.

de-stroking is basically the opposite of stroking and is best for turbo apps.

cylinder boring is just making the cylinders bigger which requires larger pistons. this also brings up the displacement.

i didn't cover these very in-depth here because it is covered in great depth in the n/a thread here https://www.mazdaforum.com/m_71331/tm.htm

 

lightening the drivetrain.

this is a mod that is reserved for the serious. you can do minor lightening and still keep it daily drivable, but if you lighten all of the way, you will be learning how to drive the car all over again. a lightened drivetrain means that there is less rotational mass, which means that the engine doesn't have all of the momentum that it used to have. if you take away all of that weight you will have to work to keep the motor from dying when you let off the clutch. picture it like this, if you throw a styrofoam ball, it isn't going to go very far because of resistance and lack of momentum. on the other hand, if you throw a football, the weight will keep the ball moving and it would fly farther. what that means to you is this; the engine is going to die if you launch at low RPM's and it will hook-up quickly at higher RPM's. basically, there will be a very small range between where you can let off the clutch and kill it and where you will let off the clutch and chirp the tires. that range being so small, the car will be really hard to keep running without launching crazy. that is the disclaimer that i am putting forth for lightened drivetrains.

clutch/flywheel

there are all kinds of clutches out now for all cars. to be really straightforward, clutch technology has come a really long way in the last 15-20 years. a lightened clutch can help have quicker hook-ups, faster response, and squeeze a little extra hp out of the motor since the motor won't have to work as hard to push everything. clutches are available in many weights and compositions with kevlar and ceramic being the top in both weight loss and compostition. once again, if you don't know anything about the clutch, stages mean nothing (stage 1, stage 2, etc.)

a lighter flywheeel has the same basic effect that a clutch does. it uses lighter material and sometimes shaves off excess, unneeded material to create less rotational mass. this squeezes a little bit more power out of the drivetrain and clutch/flywheel packages are pretty common and fairly cheap if bought together. if you do a clutch and no flywheel, you are taking a risk. light clutches are only meant to deal with a certain amount of rotational mass and can be destroyed if they have to deal with a heavier mass.

crank

to lighten a crank, knifing is the way to go. knifing not only takes off some material for weight loss, it also sharpens the leading edge of the crank to make it "cut through" crank fluids and gases. this will make the crank spin more freely and also add a little more power.

there is the bottom end lightening. this is best reserved for natural aspiration applications since you will be removing rotational mass which is important to build boost. turbos use engine load to build pressure and if you have less load, you have less pressure.

 

what's a good setup for moderate gains in hp and tourque for a 2002 lx 2.0? I would only be looking to get into the 180-200 range as it is going to remain my daily driver.

 

180-200 at the crank (120-ish at the wheels) could be hit with a good intake/header/exhaust combo with a mazda mp3 ecu. to use an mp3 ecu, you have to have a manual tranny though.

 

i do have manual woo! ive driven an auto protege once and it was like a totally different car. what's the wheel horse right now? the listed bhp is 132 i think.