Difference Between 4-2-1 and 4-1 Headers

[Flagship]

Is there ANY difference between 4-2-1 and 4-1 headers? I really dig the way the 4-2-1 header looks, but I don't know if it yields the same results. It actually might be better. I'm doing the math on it later tonight... that'll take a couple of hours. In the meantime, does anyone know the answer?

Thanks Men,
Frank

 

[evilmonkeyMSP]

one goes from 4 pipes, to two pipes into one pipe...the other goes from 4 pipes into one pipe....duh....

lol

 

[Flagship]

you're shittin' me (jerkit) ... but seriously.

 

[Speed_Racer]

I've always assumed (general knowledge) that 4-2-1 header have better cylinder scavenging properties than 4-1.

basically Im trying to say the exhaust pulse order (firing order) on a 4-2-1 helps to evacuate left over exhaust gases from the previous cylinder.

 

[Flagship]

I'm doing the math on scavenging as we speak. I'm looking at the pics and trying to find approximate lengths and widths (and s***).

 

[Speed_Racer]

bro thats sick, I dont even want to try. I haven't taken fluid dynamics yet lol. im a noob.

 

[03.5MSP]

I also read somewhere that the 4-2-1 designs are better and will yeal more power. But that was in high hp NA cars.

 

[Speed_Racer]

so manybe 4-2-1 would yeild more power in high rpm aplications, whereas 4-1 would be enough for your average N/A applications. that still doesnt answer what the advantage is of having 4-1 tho, or what the drawback is with the 4-2-1 design.

 

[Lord_Zath]

Yeah unless going crazy, a 4-1 vs 4-2-1 won't be very different. 4-2-1's are also usually more expensive, too.

 

[Flagship]

bro thats sick, I dont even want to try. I haven't taken fluid dynamics yet lol. im a noob.

You can learn it yourself. That's kind of what I did. College Fluid Dynamics is near the end of a Physics major's stint, but you can ask for help from your professors. Pain in the ass, but VERY functional math. Applying it to automobiles is a b**** though. High variation in temps, avg unburned fuel, angles, and approximating the effects bad welds... a b****. My nose bleeds constantly.

 

[Speed_Racer]

believe me, i know, i helped a friend with a project once. so many f******* variables to be accounted for, and that with equasions being provided by the teacher..

 

[Flagship]

OKAY! 4-2-1 comes out on top. It looks like the point at which the four pipes merge on a 4-1 could create a point of restriction due to stagnancy. Not a MASSIVE difference though. 1-2 more hp and a little more focus on the low-end side of things. No exact numbers. I'm just seeing some patterns here and making an educated guess.

 

[zoomin MP3]

Numbers are very close, but rule of thumb is: 4-2-1 is better for low end torque, 4-1, better for higher rpm power. It depends on where you want to focus your power. Low-mid range, go with 4-2-1, mid-high, go 4-1.

 

[Action Jackson]

One of my buddies had/has both OBX and Vibrant headers on his P5.

I am assuming that the Vibrant is 4-2-1 and OBX a 4-1 (but I could be wrong).

The Vibrant gave better high end power, whereas the OBX gave better low to mid range power.

The peculiar thing about this is that their designs went against the normal convention that I was accustomed to. i.e. 4-1 gives better high end and 4-2-1 gives better low to mid end (which was true on most Honda engines).

Go figure.

 

[i12drivemyMP5]

Go figure.

Is that a fluid dynamics joke?

 

[Lord_Zath]

One of my buddies had/has both OBX and Vibrant headers on his P5.

I am assuming that the Vibrant is 4-2-1 and OBX a 4-1 (but I could be wrong).

The Vibrant gave better high end power, whereas the OBX gave better low to mid range power.

The peculiar thing about this is that their designs went against the normal convention that I was accustomed to. i.e. 4-1 gives better high end and 4-2-1 gives better low to mid end (which was true on most Honda engines).

Go figure.

Probably because going from 4-1 creates more backpressure?

 

[Flagship]

Numbers are very close, but rule of thumb is: 4-2-1 is better for low end torque, 4-1, better for higher rpm power. It depends on where you want to focus your power. Low-mid range, go with 4-2-1, mid-high, go 4-1.

thats what my calculations showed

 

[Flagship]

Probably because going from 4-1 creates more backpressure?

also what I figured out. the point at which the four ports combine is a possible source of back pressure.

 

[thrasher]

Remember, the exhaust flows are not constant. They pulse.

The firing order is important in determining which exhaust paths to match up. a 4-2-1 can either relieve some back pressure, or be the cause of it.

 

[Flagship]

Remember, the exhaust flows are not constant. They pulse.

The firing order is important in determining which exhaust paths to match up. a 4-2-1 can either relieve some back pressure, or be the cause of it.

Yup. I checked that too. The ports on both are almost completely in phase. Again, the only problem presented was the joining of the ports on the 4-1 and the standing wave problem.