The engine is a D15B block with a Y8 head and manifold.
The cam is a stage 2 crower cam.
Application is Street so emphasis on low and mid more than on peak power.


If you could pick one header design from this list of options.
Which one would it be and why ?

Thanks

 

wow, are you looking to fab a custom manifold?

well here are some basics, a 4-1 is usually best for a small powerband(more peak power, but in a smaller band), and equal length is key.

4-2-1 "tri-y" is usually best for a broader powerband(not at much peak power but more across a broader range as compared to 4-1). tri-ys i think are always companion cylinders together, so 1-4, and then 2-3.

 

i personally like tri-ys, broader range of torque, which alot of honda engines are low on to begin with.

so for me, 4-2-1, 1-4 and 2-3

 

4-1 would maybe be easier to design as far as finding tubing size/length, collector size and so on. there are design calculators on the web that will give you some ball park specs on primary length with the given engine size and desired RPM for peak torque.

do a google search for "exhaust setup site: one cam only . com" great read, a little long, but worth it!

 

if you want good midrange, think long tubes. I like a 4-2-1 setup with VERY short secondaries. think 26-30" primaries, 4-2 merge collectors, 6" secondaries, 2-1 merge collector. Should give a total overall length of around 40-44" I made a header like this only with 22" primaries and it turned out great. No dyno though sorry.
The 4-2-1 headers with short primaries, under 16" don't actually support great mid-range like they often claim to.

 

Thanks guys. Im aware of the fact that 4x1 is good for peak power and 4x2x1 for a broader power range.

The screen shot is from a s/w that allows you to design various exhausts. Its called dat4t.
Im surprised that none of you guys are recommending the interconnect options.

Yes I believe in long headers and decent sized secondaries.
The exact lengths and dia's will depend on the cam profile and application.

Nobody has discused the options in 4x2x1. i.e. why a 1&4 with 2&3 is better or worse than the 1&2 with 3&4.
Looks like I will have to try each one and figure out what works the best.

 

1&4 and 2&3 is is because of the exhaust timing, it spaces the exhaust pulses out to provide maximum scavenging. 1&2 and 3&4 dont provide the right spacing between exhaust pulses to scavenge properly on a 4 cylinder. those options are most likely for a v8.

 

Thanks.
The interconnect option is normally used on most modern super bikes.