Exhaust Primary Joins

[Carlitos]

Hey!!

Just a quick question, anyone ever seen these kind of collectors before?

If so, of what use are they?

Thank you very much in advance!

http://img73.imageshack.us/img73/1228/foto8jw7.jpg

[Michael Palaszynski]

I'm going to assume the two joints you are refering two are not there for fluid flow. They're merely there to support the primaries.

[Wesley]

They're for noise attenuation.

Did a big study regarding crossovers last year, to see if they impacted power, and our results found that only noise output levels were affected by the diameter and distance from valve head of the crossover placement.

[Michael Palaszynski]

any detrament to the power output?

[Wesley]

Negligible change. WAVE says maybe a tenth of a horsepower change, depending on the variables. Never tested them rigorously, but WAVE had generally been pretty accurate.

[Carlitos]

positive or negative power change?

Wesley do you know of any published work on this?

cheers!


Phisec Racing

[Peter7307]

Interesting arrangement.

Pete.

[Adambomb]

That is very interesting. In old school hot rods at least, it is widely known that an H-pipe (or X-pipe if you're less old school) will make it quieter, and generally boost low end torque without sacrificing top end. In fact, my '88 Ninja 600 has an H-pipe right after the collectors (it's running a stock pair of 4-2 headers...gotta love those Top-Gun style duals).

Of course with those setups the H or X is after the collectors. Would have never thought of putting it that far upstream...what effect does this have?

[Charlie]

It's the same configuration as the stock F4i header (maybe a bit closer to the head). So not anything extreme.

We tried it when Iw as doing the work, WAVE showed a good improvement but dyno tests showed a much smaller one. A difficult thing to test and implement, and with the F4i firing order, it's not theoretically the same effect on each cylinder so you have to deal with that as well.