Is there any difference in 4-2-1 and 4-1 headers, how are they going to perform differently?

 

Generally, 4-2-1 yields low to mid range gain, whereas 4-1 yields mid to high end gain.

 

you should note the stock tsx header is a 4-1, but after market 4-2-1 headers yield better low, mid and top end power.

 

how much low end we talkin about here? are they worth the money? im ordering a cai in the next few weeks could i just put the headr on and get gains without a catback? does it sound different? thanks

 

http://www.comptechusa.com/images/dyno/tsx_header.pdf
2 Pages

 

Header won't change the sound unless you have an after market exhaust. And even then its not too noticeable. Yes a header is worth the money except for the Comptech unit. Go with the DC. A few people have had a couple issues with it so to prevent it just tack weld the flex pipe to the flange with 4 tack welds. Make sure you use the lowest heat and slowest wire feed or you burn holes through the flex pipe. =) This way you don't need to worry about it breaking like some others have had. Just a precautionary thing to do.

 

How do headers help the low end, and do they in turn reduce high end power as a consequence? I'm looking for a technical explaination. Also, why does the 4-2-1 and 4-1 have different effects?

Slats

 

Ok are you being serious or is this one of your troll remarks??

 

Give him at least the benefit of the doubt... Not everyone knows the proper functions of a header..

 

I was just asking him because from what I have read in the past he is pretty sarcastic with his comments about the TSX.

 

I dont know either.. i only found out about header not long ago, one of the mopar guys was telling be that oem header are not smooth and air restriction etc, and aftermarket are better made for air flow but I only found out about the 4-1 ; 4-2-1 recently when i was shopping for it.. and i also like to know why 4-2-1 is better.. thanks..

 

 

In short air is lazy they wants to go out the easiest way.
With 4-1 header you'll be seeing an improvement at high RPMs since air is relatively fast enough so they want short and direct pipes. With a 4-2-1 you'll be gaining a lot of power down to mid RPMs where air speed is still some what slow and require a designe that will increase the speed of the air. The 4-2-1 is that design that i'm talking about.

 

Wow.

I think you meant to say something intelligent about how a 4-1 header isn't as efficient at passing air as a 4-2-1 header. I think you also meant to say that the 4-1 header is better for low end power because of the increased backpressure that it creates over a 4-2-1 header. Lastly, I think you meant to mention that the 4-2-1, being more efficient, improves top end power because it allows the engine to breathe more freely.

 

And you forgot to mention that your low end gains (if any) will be nominal even with a 4-1 header.

 

Ummm not sure where you got your info..but a 4-2-1 is better for low end power with some mid and high end gains where as a 4-1 header is mainly upper mid ranger and high end power. So no I don't think he said or meant to say anything you just said. I think you watches fast and the furious too many times man. Do some research and you will learn your way off...

 

I wasn't imply anything you said at all i_am_sandman. It was actually kinda the other way around.
I have already typed this up once about 4-2-1 and 4-1 long time ago and I'm not gonna do it again. Anyway, i'm not saying one is better than the other all i'm saying is the benefit you're getting from it is different. Simply put, 4-2-1 will improves your low to mid performance and 4-1 will improves your high RPMs performance.
If you need more indepth analysis about this just let me know.

 

Ahhh, yes. You're right. I must have had it backwards. Check this out:

http://www.comptechusa.com/images/dyno/tsx_header.pdf

That's the dyno sheet for a stock tsx, and one with the Comptech header (4-2-1). Look at the massive amounts of low end power that thing makes. Jesus, it's a low end monster.

Look at the graph, moron. The only place that it makes consistent noticeable power is at the UPPER END.

Wait, maybe it will help if I translate for some people here:

wazz it do man makes lotsa power go vroom in da low end cuz the high is where da air ain't lazy like it is in da low.

P.S. I have seen "The Fast and the Furious" too many times: once.

 

Is it getting a little warm in here ....

 

4-2-1 makes better low end...not the 4-1 thats what you were sayin originally if not mistaken...watch who you are callin moron...and btw comptech sucks for power...and if I am such a moron how come I have most power for a TSX on this board. Kiss my ass troll.

 

right there you are stating that 4-1 is making better low end which is not true. Do some research work on some cars and come back. Don't talk shit to people who know more than you. I'm done some one hit this fool with a before he starts more trouble..

 

Here's a great video for you to watch Sandman. It should help you out


http://eclipse.erichmoraga.com/AEM/posting.htm

 

 

Ok, you just can't judge something with ONE dyno graph from Comptech.
I'm not going to disagree with you that the Comptech header shows more improvement at high RPMs. You also have to consider how well the OEM on TSX performs, too. If Comptech had made a 4-1 header I bet you that you'll even see more gain up top and looses some low end grunt. In some cases you might get the best of both worlds with a well designed 4-1, means that you won't loose any low end power. Just go and take a look at Comptech's Integra race header and street header comparison.
And WTF are you trying to say in that last paragraph, I don't honestly understands.

 

Ahhh here's a metaphore that might help you out.
You understand that 4-1 is less restrictive than 4-2-1 right? Lets say that you're drinking a lemonade with two types of straw. first is an ordinary size one, another with a size twice as big. Your mouth is an engine. So you start drinking your lemonade right after your football game. It's hard to drink from small straw at a very fast pace because it won't give you enough flow, it's restrictive. Now you switch you bigger ones, voila! you get more lemonade with the same amount of work. Now lets say that you just woke up in the morning and want to drink some lemonade. It's easier to drink with smaller straw at a lower work you're mouth is doind; however, given the same amount of work with the bigger straw it's hard to drink that lemonade now so the amount of lemonade you're getting is less than smaller ones.
Hope you get it this time.
And it's rude to start call'in someone a moron.

 

We should adopt it for our forum.

 

Yes Johnny we should. HAHA

 

OK, question from a total If the inside diameter of the 4 is the same on the 4-1 and the 4-2-1 and the inside diameter of the 1 is the same also, how is either of them better than the other when you compare air flow?

jlukja, who remembers just enough from his enginnering classes to be dangerous.

 

Out of top of my head without being too detailed. The 4-1 will be a better header because 4-2-1 has a bottle neck at 2, assume that the diameter is smaller. If for any reason the 2 has a larger diameter then you will not only have a restrictive 4-2-1 but a header with a volumetric flow that is higher than you need. Result is no back pressrure to draw out the exhaust.

 

I think you've got things mixed up a bit:
- 4-2-1 is less restrictive than having 4 pipes leading into a single collector.
-the diameters get bigger as they merge, not smaller
-backpressure does not "draw out exhaust" gasses, it opposes the flow of the gasses. Backpressure does not create horsepower, exhaust velocity does.

The faster your exhaust gasses flow, the better the scavenging effect. Given the same volume of gas, a smaller tube will flow faster than a bigger one. The problem is, the smaller the tube, the more restriction you have. When designing an ehaust, you need to use a size of tube that provides the highest exhaust velocity while maintaining the least positive backpressure.

A 4-1 header will produce more power on the low end because the ehaust velocity is higher. The problem is once you get into the mid to high RPM range, it can't handle the exhaust flow rate of engine and becomes too restrictive. The 4-2-1 has a lower resistance which means it will have lower exhaust velocities at low RPM but it flows better so it won't be as restrictive as a 4-1 on the mid to high end.

 

Thanks Dan for that very good explanation.

 

Too bad I can't find my Sport Compact Car header shootout article... but here are some general info below...

I have done my own personal testing of 4-1 and 4-2-1 headers from the same company on the same car. The 4-1 was clearly lacking low end based on dyno results but it was not a real problem due the my SC setup. However, I ended up with the 4-2-1 due to better ground clearance for a lowered car.


http://www.racingbeat.com/4_1%20Head...headertest.htm

http://www.racingbeat.com/2001header/headertest.htm

http://www.dcsports.com/product_headers.asp

 

An added benefit of using a 4-2-1 design is that you can pipe the 4-2 merges in such a way that the firing order of the cylinders alternates between pairs. This results in reduced contention between the exhaust cycles of different cylinders. If you look at any 4-2-1 header you will see that the 4-2 merges do not use adjacent cylinders. This is why.

 

So Johnny what you are saying is that 4-2-1 has better low and mid range than 4-1. That is what I have been taught since day one. And that the 4-1 has better high end peak power. If I am wrong I would really like someone to show me otherwise...

 

Will someone simplify this for me...

According to JTso's post, he said that the 4-2-1 will yield low to mid range power gain, where as a 4-1 will yield high end gain....

But in Dan Martin's post above, the 4-1 will produce more power down low, where as a 4-2-1 has a lower resistance so it flows better at mid to high end.

So, which one is which???

 

That's why I said "generally". Just look at the Comptech header dyno and it only has high end. But if you look at my DC dyno, gains are across the entire rpm range.

I think it's time for a TSX header shootout!

 

LOL everything I've been tought about headers is reversed in that article. I agree JT, we need a 4-1 vs 4-2-1 shootout on the TSX.

 

The problem is people making generalizations based on the results from some very non-generalized replacement parts.

Dan - summed it up best - ALL ELSE BEING EQUAL. Just because that ONE Comptech dyno seems to show otherwise is not an indication that he was wrong.

Of course the Comptech 4-2-1 is going to perform differently (better) than the stock 4-1 - it's a replacement part. This in no way leads to any specific conclusion about the merits of 4-2-1 vs. 4-1 technologies. Also important are pipe sizes and tapers, etc etc etc.

 

But if the same company designs both types of headers for the same car and has specific design and target goal, why wouldn't there be conclusion?

 

and Dan will donate a nice shift knob to the winner!