Few questions

[BigTDawg]

anyone know where i can get headers for an 03 i4?
can i use the headers for any year i4? if i can i dont really need to know where to look
what is MAF and MAP?
the 03 i4 is beta right?
what are the pluses for 4-1 and 4-2-1 headers? or you could tell me which one is better and why

[Prowler87]

I read somewhere that the 4-2-1 headers were better for an automatic, and the 4-1 were better for the manual

[Mister_Sinister]

4-2-1 headers give you more power in lower-mid RPM band, and 4-1 headers give you more power in the upper RPM band. Neither is better, it just depends on where you want more power at.

MAF and MAP are two different types of air sensors. They're part of the air intake system. Your car has an MAP sensor.

[BigTDawg]

thanks guys
will the material an exhaust system is made out of effect the performence of it?

[Rickna]

I have Hotshots for the V6. Comes with a high flow cat. If you're gonna DIY, you need 8-12 hrs. THEY ROCK! But, it's gonna be loud!

[nisco]

gettin headers on a v6 is a pain in the ass.... especially if the car isnt brand new

[Rickna]

Originally Posted by nisco

gettin headers on a v6 is a pain in the ass.... especially if the car isnt brand new

Yeah, did mine with @12,000 mi. no frozen nutz or boltz, just a PITA.

[BigTDawg]

nothing is worse then getting the first o2 sensor off a plymoth voyager there was hardly enough room the get a socket on there and it was stuck and on top of all that you couldnt see it.
i really dont know what kind to get i'm not sure weather i want 4-1 or 4-2-1 then when i decided that i dont really know what company to get it from and i was wondering if anyone knows if i can use headers for earlier 4 cyl. tibs? i have an 03 i4

[tibby01]

pretty sure you cannot use headers of a rd(97-01) tib for your car, sorry.

MAF=mass air flow
MAP= manifold absolute pressure

a MAF detects how much air is entering the engine by how much the "hot wire" film is cooled. as the amount of air increases, the temp of the film decreases. this makes the film, which acts a resistor have a lower impedance, allowing more current to flow through while it tries to keep its programmed temp. up. the amount of current allowed to flow through is changed into a voltage, and that is passed back to the ecu.

a MAP works on something we all learned in chemistry. PV=nRT. pressure x volume= (number of moles of gas) x gas constant x temp. the ecu finds the number of moles of O2 it needs with the MAP sensor(which determines pressure in the manifold, equal to the pressure that the gas will be at when it enters the cylinder), and the temp. sensor located on the intake. volume will just be the amount of space in the cylinder, and the gas constant is a constant(never changes).

a 4-2-1 header is of better design for automatics because the gears are more spaced out(autos usually only have 4 gears to a manual's 5). the 4-2-1 header keeps the power band a little lower in the rpms, helping to alleviate the poor acceleration autos 'can' have in the lower range of rpms. a 4-1 header gives power higher in the rpm, which is perfect for manuals because the extra gear already gives a manual pretty good acceleration. write back if you want to know exactly why they give better power at certain rpms.

03 i4 is MAP, but i think the new I4 betas with CVVT are MAF -based.

[BigTDawg]

thanks tibby
didnt think i would be getting a chemistry lesson here
if you wouldnt mind explaining that more that would be great always looking to learn more

[tibby01]

it has to do with the length of the runners in the header. when the exhaust comes rushing out, it creates a vaccum by the closed valve. as we all know, hp doesnt just depend on how much exhaust you get out, but how fast you get it out too. the negative pressure area helps "pull" the exhaust gasses out of the combustion chamber once the valve opens.

this is why for torque, you want long runners(works the same on the intake side except, it has to do with the air bouncing off the intake valves). the longer runners help create a huge vaccum when the exhaust comes rushing out, which yanks the next wave of exhaust gasses out.

for hp in the high rpms, you want almost no runner at all, because the exhaust is already coming out REALLY fast.

[BigTDawg]

thanks tibby

[Prowler87]

Has anyone ever heard of OBX? I found some headers for my 04 i4... and was wonderin if they are any good?

[ImANewb]

another dumb question....whats a header?

[twospirits]

Dictionary of Automotive Terms will give you a description.
Its a good source material. You should bookmark it.

TS out