EGcivic_95

okay H-T. i need some advice i got some very good numbers so far but im not sure if its the right numbers so please if its wrong point me to the right direction, now i got to the volume of each cylinder which i divided 111.9 cu. in. by 4 so i got 27.957 cu. in per cylinder. so now what i did is multiplied 3.14*.5^2*36=28.27433388. which would round to 28 cu. in. which also equals 1 in. diameter and 36 in. long.....does this sound right at all if not please tell me what i did wrong or what else is needed.

EGcivic_95

any one lol?

EGcivic_95

bump?

EGcivic_95

out of every one on H-T no one has suggestions or ideas lol dang.

evo951

Sounds like a bunch of numbers i dont understand,lol

EGcivic_95

lol yeah it can be but if you know how to find the volume of crap then you will end up with weird numbers lol i guess i dont know how to put it but i did alot of work to just get these numbers.

ddd4114

Sorry, what are you trying to do here?

BlueIntegraBoy

iTrader: (5)

Are you trying to fabricate your own header? Perhaps the welding/fabrication forum will be better to answer your question.

Chiovnidca

I dont think many members here build their headers from scratch. 1" primary tubes seems a little small from what i've seen, but i'm no expert. Figure for a given cylinder volume, exhaust gasses expand making a need for a larger tube to properly vent them, correct? Engines that run at higher rpms usually have larger tubes also.

ddd4114

Cylinder volume is related to primary sizing, but the relationship isn't that straight-forward.

Primary sizing is mostly based off of exhaust velocity/inertia and acoustic resonance for your target powerband.

If you're hardcore, you can figure it out with math, but if you're at that level, you're probably not going to be asking questions about it on Honda-tech. Copy other people's designs for now, and read a lot if you're serious about this.

And yes, 1" is TINY.

EGcivic_95

yeah oka well thanks for the advice guys

NotAJDMFanBoy

You could buy the flanges and some bends and experiment.

EGcivic_95

i could but i have been doing some research and some people need to know bore, stroke, compression ratio, cam lift and duration, exhaust valve diameter, and target RPM range which i have all this information, now this is what determines the diameter of the pipe. now what is need to put all this into a diameter of a pipe? any useful info will be appreciated thank you

ddd4114

I'm sorry to say it, but you're in way over your head right now.

Continue reading... a lot.

EGcivic_95

tell me what you know about this. im sure ur advice will help mine. and i may not know what im doing but like they say practice makes perfact. and im trying to learn but lol no one has any advice to give me and i have been reading about this for about 2 months and getting a little advice from my grandfather who builds his own but he said for me to come up with my own way as he did because if he told me id get confused easily lol.

ddd4114

The easy option is to either copy what other people have done or use rules of thumb that are floating around online and in some books. "Four-Stroke Performance Tuning" is a good one to read there.

If you really want to understand how your engine parameters and target powerband affect primary sizing, you'll really have to start reading a lot about engine theory. Try "Advanced Engine Technology" for starters. Alternatively, spend a lot of time and money in flanges, tubing, and dyno time, and see what works best. A little of both is even better.

EGcivic_95

oka thank you ill start looking some more things up and read even more lol like i said thanks.