260 hp?
granted you will get alot bigger boost in horsepower with that much larger an engine, 15, maybe even 20 is believeable, but sorry, not 32.
assuming you have charts, there are most likely other factors than just headers, such as temperature, etc.

 

You sure that you didn't run it on 87 octane gas before and 91/92/93 octane on the other dyno? I truely have never heard such a thing. 32WHP increase from a header is crazy unless there was something wrong with the other one. I mean 32WHP gain from an intake for a car with 400hp is still pretty amazing let alone headers.

 

delete me plz....
(comment, not ME, lol)

 

wtf, i thought that was only 4-1 headers
and 4-2-1 would be good for the low-mid end of the power band.

 

nope,
and to tell you the truth im not really 100% sure why.
I think its because the backpressure from the exhaust puts a little more air (exhaust, really) into the cylinders thus leading to an increased amount psi inside the cyl, and the improved flow from high-flow headers eliminates this, and the improved exhaust flow only really increases output in the high-rpms.

Although really, I have no clue, so all thats prolly totally not true at all. I just kinda figured that was why.

 

you can go to acura-cl.com and get dyno there right now comptech's site is under construction so the dyno charts are not posted yet on the new side (there is a tab for them though) and i meant to say crank HP not wheel HP

headers gets you from peak of 208WHP @ 6200 to about 226WHP@ 6400 rpm where stock HP hasalreadyfallen to about 194. The HP peak goes from 260 to 290 ad moves further up into the rpm range.

If you have ever seen the exhaust collectors for a type S motor you will immediately understand WHY you get such a massive increase in power...............

 

The backpressure isn't really the reason. Imagine this analogy. You blow a breath of air into the end of a sewer pipe. It does nothing to the velocity of the air in the pipe. This is like an NA engine exhausting into a turbo exhaust (3"). Now you blow through a snorkel. It is easy to move the mass of air and the flow doesn't feel restricted. This compares to the exhaust that is about the right size. Now try blowing through a straw. Velocity is high, but flow is limited and you can't breathe fast at all. This is the stock exhaust.

This idea can be applied to every part of the intake, valving and exhaust. The flow rate and pattern are the important parts to maximizing power and performance.

 

Falk, you're an engineer so I figure you'll get this.

Itreally IS about backpressure. Or more accurately it's about exhaust scavenging. Better scavenging is always better. Trouble is, everyone wants to think about continuous steadyflow.

Exhaust flow isn't steady,it's pulsating. You get reflected pulses that are reflected back from branches in the tube. This reflected pulse gives an unsteady, momentary low pressure that can't be duplicated with continuous steady flow. So you invent some catch-phrase like "4-cylinder engines need backpressure", for folks who don't want to treat this like the acoustics problem that it really is.

 

Ok Jim, let me rephrase that ..... backpressure is not the key element to try to determine the correct system sizing and design. When the correct flowrate, velocity and flow-pattern are achieved, proper backpressure will result.

The thing most people are looking at is how to reduce or eleminate backpressure. Proper scavenging SHOULD be the goal. The ideal backpressure is where there is negligible increase in flow caused by increasing the tubing size. At this tube size, a slight decrease would have a noticable effect.

 

Yeah. But if you flow-test a header with steady flow, you don't see the reflected pulses that put a momentary vacuum at the exhaust port. So a steady-flow test, or a simplecalculation basedon sum(K)+f*l/d would be misleading.