I've been doing a fair amount of research, on forums with quite a few top racers/builders that like the single cam Honda's, particularly the d-series. (Don/SOHCinWA, Rushi, Big Tuna, occasionally Bisi, Luke/Live for Physics, DocHudson, Acid Beave, etc). A few of the previously mentioned people have said that ~40" long runners with a GOOD 4-1 collector (with good choke, a good taper back up to ~2.5", etc) will make good power through the entire rshared_pm range.
Good thread:
exhaust setup - onecamonly.com
I've seen more than one good source say that the programs/formulas for calculating manifold sizes aren't good. The exhuast is way too dynamic and nothing short of experimentation will get you the best results. I'm too poor to do that, so my header will be based on research and the design of a few other high-power builds.
From my build plans (PM me if you want to see all of it), I had the fallowing laid out for the header design. No idea on shape/design of the actual pipes, but this is just rough notes from my research. Not sure on a few numbers and I won't be until the engine is assembled.
D16 Stroked to 1.7L, 12:1+ comp, tuned on 93 oct, shooting for 170whp+
CAI, Edelbrock Performer X IM, Custom Header, 2.5" exhaust
D16Y8 VTEC Head (Good quench, Swirl Ports. Good low-mid range, porting will improve high end)
Bisimoto L3 Cam (2000-8000rshared_pm power range), Springs/Retainers/Cam Gear
Custom 4-1 Header, 40" primaries. Choke at collector same size or smaller than primary ID, transisition up to 2.5" exhaust, custom skid plate. Maybe do first 1/3 (~13") in twists (bent tubing) to similuate smaller ID pipe for stepped header (Bisi style)?
Aim to have pipe CSA 108% of exhaust valve diameter's area?
****Don't know exhuast port area! Need to figure that into calculations!
EV Dia = 26mm, 1061.32mm^2; 108% = 1146.2256mm^2, 38.2mm/1.5" pipe ID?
Then widen pipe CSA 25% to 42.7mm/1.68"? 1.68" = 1-11/16"
Collector Choke needs to be +5% CSA compared to primary pipe CSA.
Header Design:
40" Primaries, 4-1.
Steady 1.5" Pipe DIA.
Constant mandrel bends for first 13"
Straightest pipe possible after 13" for rest of 27"
Merge Collector Choke = a few % larger CSA than primary's CSA
V-slits as steps/anti-reversion here and there?
Originally Posted by
Evol-Eagle-96
Ultimately, the best design to evacuate exhaust gasses would probably be to have straight pipes angled squarely away from the engine at a 40 to 45 degrees upward angle...but I doubt seriously you want your car to look like the dragula car from the rob zombie video lol.
Something like this lol.
Packaging has alot to do with header design/I'll be running the header/exhaust under the engine/car, through a high flow cat, a muffler or two, and dump out of the rear bumper. So the above idea wouldn't work. And I've read that good exhuast scavenging really helps pull the last bit of power out, and working with a small displacement engine, I really need that last bit of power.
But idk. I'm mostly talking out of my ass. I'm no expert at anything, just trying to plan out a good build/header. My design would be something like this one (first pic), but I'm thinking about doing doing something more radicical like in the second pic (although with longer primaries)... Third picture is a Bisi header for a D16, fourth is a Bisi header for a F22 (both Bisi headers are Honda engines).
Hondanickx's Custom D16 header from OneCamOnly:
Random Race Header Remoer on OneCamOnly Found:
Bisimoto Version 2 Header for D15/D16's:
Bisimoto F20 Header (on BigMike's Prelude):
