h22 firing order is 1 - 3 - 2 - 4 , piston 1 on driverside, correct?
so a sequencial paired primary header would pair 1-3 and 2-4, and a non-seqencial (oem, mugen, everybody) pairs 1-4 and
2-3. Im a little confused after seeing picks of an smsp
4-2-1 "sequencial" that paired 1-2 and 3-4...
set me straight please, thanks
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Last edited by leptolude : 02-10-2003 at 03:37 PM.
heres a link to the smsp post (i geuss he moved from 1-2 3-4 to he conventional 1-4 2-3), id just go ahead and ask dave, but (understandably) he wont say ANYTHING about his headers, wouldnt even let me know what type of welding he is using (i know its probably MIG.. but details are everything).
Firing order on every 4-banger I've ever worked on is 1-3-4-2 with the piston closest to the belts as #1. On Hondas that spin the "wrong" way this is the driver's side (newer F and K motors and V6's spin the other way). #1 fires at TDC (according to timing marks).
duh, just like the valve adjustment order, i need a 2nd helms here at work.
so smsp's 4-2-1 header with 1-2 and 3-4 paired was a NON-seq. design, just a funky one. But hey, it works nicely... anyone ever seen a 1-3 and 2-4 paired header on a honda?
No, but I think it is more a logistical thing (routing primaries). Can you share with us what you have read that would indicate this to be ideal? Everything I have read states that header staging doesn't matter as much power-wise as thought, and even says that the primary length isn't as much of an issue.
When it comes to scavenging I would think that staging them 1-4 and 3-2 would be best to spread out the exhaust pulses so that they are evenly distributed. Meaning, with an order of 1 - 3 - 4 - 2 you would have 1 flowing and 4 flowing with the same length of time across the firing order. If you ganged 1 and 2, 1 would flow... then a long dead time, then 2, then 1 again real quick... dead time... follow my logic?
ive been reading everything i can get my paws on regarding exhaust design (which unfortunately isnt much). seems that most research that has gone on since the sixtys has been by the manufactures and they keap it to themselfs. My father in law worked at Ford, he says thier fluid dynamics guys have lots of well developed math and general theory, but they keap it under lock and key (not that thier bean counters let them do anything cool anyway). Burns stainless also has X-design, which im geussing is an exhaust focused, time step modeling applications similar to the stuff in desk-top dyno (which concentrates on head/block simulation), or maybe they just have alot of data and a chart....
works' realy busy today, but ill post what ive been thinking about/trying to figure out in one minute. Ill start a new thread in a minute.
Then again, sometimes reality goes against all theory. See the first volume of the Honda Building (Tuning?) Manual, or whatever it's called. Look at the header test. The header that should have done the best in theory was not the best!
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Billy - 98 Prelude
#27 H2 NASA TX HondaChallenge
#27 PTB NASA TX Performance Touring Racing makes heroin addiction seem like a vague wish for something salty. -- Peter Egan
All auto manufacturers and prob the good aftermarket designers are all using CFD (computational fluid dynamics) software such as STAR-CD and FLUENT to do any modeling of intakes or exhuasts. They then back up the modeling with real world testing. Also of good use is "WAVE" simulation which is a way to model gas flow as 1-d compresable simulations. Check out Optimim Power's Virtual 4-stroke for an application of this.
For some really serious reading, try some SAE tech papers. You have to pay for them, but alot of these papers are written by detroit, japan, and germany's best engineers.
1&4, 3&2: pulses evenly distributed across time in secondaries
1&2, 3&4: pulses unevenly distributed across time but sequential
1&3, 4&2: pulses unevenly distributed across time but sequential
I'm not sure if evening the pulses over time provides more gain with "continuous" scavenging, or if sequencing them right after one another (but then a dead time between the next) provides better scavenging in a system where the secondaries meet soon (better overall scavenging). In that case, I would think a 1&3 + 4&2 arrangement would be best as the pulse from 1 would scavenge 3, then 4 scavenge 2, and 2, 1, and so on.
lets take it to the other thread, big reply other there and ill copy yours todd. wish i oculd make it to the po.com meet, itd be great just to shoot the **** over a beer or two with the whole po.com smarty group. oh well BBS is the next best thing.
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