John_Z

Very interesting design. I'd like to see the the dyno hp/tq curves moreso than the numbers.

MINES13

Much worse is the decrease in exhaust gas velocity from improperly sized (see to big) of a merge collector, maintaining exhaust gas velocity will make or break a header design.


That Skunk piece and the Hytech look to be the only properly designed off the shelf options for the F20C. All of the theory they discuss is pretty much dead on for the most part (Tri Y, sequential pairng, etc.) Be aware that a proper header like this could likely effect your fuel curves significantly enough to require tuning to take full advantage of this piece, and there is nothing wrong with this in my eyes. The only thing I didnt see menitoned is anti-reversion chambers...

Luke530

How much of a difference between the f20c and f22c is there?
How would this header work on an f20c?

I agree that anyone with a header/test pipe/exhaust should buy a vafc or emanage and definately hop on a dyno for a tune to make the best of those mods.

I don't think exhaust gas velocity will make a difference as long as the merge collector is smaller or the same size as the text pipe/exhaust.

the tri-y theory or whatever they call it is not really a theory. scavanging effect does exist. and if this header works like it's supposed to, it will definately do it's job and make plenty more power than others.

I don't think there should be much worry about scraping either... unless you like going off-road.

MINES13

Scavenging absolutely exists, no question.

Exhaust gas velocity is absolutely the most important factor when desgining a proper header, period. This is why they use scavenging in the first place, the scavenging effect generates a vaccum in the cylinder which draws in more air (which, ofcourse demands more fuel to effectively burn) then a non scavenged setup. Naturally, the exhaust gases themselves are generaiting this vacuum do to the velocity at which they are moving. the merge collector is a major factor in this aswell, as I stated earlier if you go to big on the collector the exhaust gasses slow dramatically. The purpose of properly engineering a header is so that your engine does not have to work as hard to generate power, thus increasing your engines volumetric efficiency.

Slows2k

I can tell you a stock height S2k will scrape a Toda header collector over rises/speedbumps. I've done it.

trinydex

[QUOTE=MINES13,Aug 31 2006, 02:37 PM] Much worse is the decrease in exhaust gas velocity from improperly sized (see to big) of a merge collector, maintaining exhaust gas velocity will make or break a header design.

MINES13

Right, but you can not quantify what is happening in the exhaust manifold at those hypersonic speeds, a point at which Bernoulli's principle begins to work inversely. There are no look up tables to even begin to calculate this stuff, there is no formula, and it is not simply a matter of flow. It is simply a matter of trial and error.

A header CAN be optimized for a set point in the power band, this is true. However, it can also be optimized for its true intended purpose. To compliment and enhance the maximum effiency of the engine, not simply where it makes its peak energy and force.

There is simply one answer, because a proper header that will take full advantage of an engine

HvRRZ

looks almost identical to my old hytech header

MINES13

Your Hy-Tech was a 4-2-1 design though right? I have never seen John do a 4-1.

HvRRZ

no my hytech was a 4-1 design. I bought it off another member and when I saw the pics it looked like a 4-2-1, but when I went to pick it up it wasn't. I was very excited because I know 4-1's are known to make better power, especially top end.

I was lucky to find it though, and almost didn't. I was originally going to have a custom one built by burnsstainless, and I may do that this time around.