Headers?

[Bolestuff]

I did a search, but came up with very little. What kind of performance gains would I get from a set of headers? I have a magnaflow on the rear and a chip.

[idanity]

depends on the headers.
long or short tube

i think simply port matching and polishing the exhaust side will yield 1-3hp..much higher than a sticker.

[nando]

On a mostly stock motor you want 1 3/8" - 1 1/2" primaries, 30-48" long. You will gain torque pretty much everywhere. Its better to err on smaller diameter primaries rather than larger.

[hooken m]

what kind of chip do u have? i personally prefer long tube headers, but i feel as if using shorties on a slightly modified engine is best.

[nando]

A chip doesn't really count as "modified" imo (in the context of headers). Neither does the muffler.

Short tubes would be best on an engine that makes its power at 8000+ rpm, exactly the opposite of what a stock engine needs.

[supernaughtIX]

I just got my set of "Bavauto" style headers in the mail today. Long tubes and they look sexy. They will be going on a 3.0L stroker though

[Bolestuff]

The motor is not modified, but the ecu and rear muffler have been. Just by the definition of the word. I have 180k on it now, and will probably do a build in a couple of years. For now I'm just looking at the small changes that can make a slight increase in power. I have an e46 M3 and a Honda vfr 800, so believe me I'm not try to make the 325 fast, just a little quicker with a better tone.

I put the cheap ass Pefformance chip off ebay. From my research it seemed to fit what in the cheap but effective zone. Was thinking header would do the same, as I have had great experiences with other cars. Sounds like I should just leave it be until I put a motor in it. Any idea how much you will spend total on the 3L stroker?

[supernaughtIX]

the 3.0L stroker is not cheap.
To get good gains I'm doing more than the stroked lower end. a lot of port massaging, 3 angle valve regrind, some intake work, moderate cam, beefy rockers, MS2 standalone management, lightened flywheel, new bearings and rings, etc, etc.

The stroker guts are composed of a M54 crank(89.6mm), M54 rods(135mm), and custom machined M54 pistons(84mm, 31mm CH, machined for clearance with valve reliefs). Will also need a oil seal spacer on the crank.

All of this will add up. An alternative is to buy one of the 3.0L or 3.1L kits for sale that basically use a lot of the same parts, but often with "custom" pistons and require overbore in the cylinders. My cylinders will be cleaned up for the new rings but I won't enlarge them.
the kits are usually between 2k-3k, and thats without any supporting headwork, assembly, etc. And engine like mine should respond well to addition of bavauto style headers.

[nando]

The motor is not modified, but the ecu and rear muffler have been. Just by the definition of the word. I have 180k on it now, and will probably do a build in a couple of years. For now I'm just looking at the small changes that can make a slight increase in power. I have an e46 M3 and a Honda vfr 800, so believe me I'm not try to make the 325 fast, just a little quicker with a better tone.

I put the cheap ass Pefformance chip off ebay. From my research it seemed to fit what in the cheap but effective zone. Was thinking header would do the same, as I have had great experiences with other cars. Sounds like I should just leave it be until I put a motor in it. Any idea how much you will spend total on the 3L stroker?

not at all - it depends on what you do. if you go with 1 1/2" diameter primaries with long tubes, you'd see a difference on the stock motor and it would work well on a stroker too. I have 1 5/8" primaries on my 2.8 and to be honest, I think it's too big.

the stock manifolds are basically just an exit path for the exhaust gasses. they do nothing at all to aide in exhaust extraction. pretty much any good quality header is going to be an improvement. the stock exhaust isn't especially restrictive or anything, but the exhaust manifolds are just that - manifolds. not headers.

[Bullet Ride]

Any idea how much you will spend total on the 3L stroker?

I just built a 2.8L stroker. It ended up costing me around $3500, but that was without any fancy head work, valves and seats weren't touched and the intake side was left alone. Check out my build thread for details. This is what it put down on the dyno as a baseline...

[nando]

the head is where big power gains will be had though, and it's also one of the more expensive peices to do, which is why so many skip it entirely.

[Bullet Ride]

the head is where big power gains will be had though, and it's also one of the more expensive peices to do, which is why so many skip it entirely.

Yeah, that'll come later when I have more money to play with :up:

[Bolestuff]

not at all - it depends on what you do. if you go with 1 1/2" diameter primaries with long tubes, you'd see a difference on the stock motor and it would work well on a stroker too. I have 1 5/8" primaries on my 2.8 and to be honest, I think it's too big.

the stock manifolds are basically just an exit path for the exhaust gasses. they do nothing at all to aide in exhaust extraction. pretty much any good quality header is going to be an improvement. the stock exhaust isn't especially restrictive or anything, but the exhaust manifolds are just that - manifolds. not headers.

Ding, ding, ding, this is the advice I was looking for.

Thanks