headers:what difference

[2oodoor]

http://static.summitracing.com/global/images/prod/large/psm-70-1250.jpg
http://static.summitracing.com/global/images/prod/large/hed-36024.jpg
Both seem to have the same specs, same brand, same name, yes they look a lot different. Both are supposed to fit the same car. So what gives? what is the difference? which one would best fit an Accord with a b20a?
EDIT , it must be summits mistake, one is for an A20 but they say it fits b20-21...

[2oodoor]

so it looks like you can still buy new Hedman headers for your A20, as well as pacesetter.

[evil88accordLX]

possibly one is a race header and the other isnt? the top pic looks as though its meant to run a catless custom exhaust. im thinking the extra piece is a straight pipe, and you just run your exhaust setup from there. also, the runner patterns are different. wonder what that does?

[evil88accordLX]

i just noticed the flanges are way different also. no way these are for the same application.

[2drSE-i]

i didnt even know they offered hedman headers for the a20...

[2oodoor]

Yes the flange that is O OO O is A series
the one that is O O O O is B series

[evil88accordLX]

even the flange at the collector is different. wonder if you might have to have the top half for the B20 and the downpipe for the A20 to make it fit properly? does the distance from the head flange to the front crossmember change after swapping in a B20? if so you may want to take that into consideration before purchasing something that doesnt fit correctly.

[2oodoor]

Yes the b20 is a lot further forward, but a prelude b20a5 is SAID to fit in there with slight mod to the downpipe and rat tail file in one of the bolt holes.

[evil88accordLX]

possibly be easier to mod the crossmember than the downpipe? ive read about others notching the crossmember to make headers fit. or custom headers might be a consideration.

[2oodoor]

http://i4.photobucket.com/albums/y110/scneonchic501/miscelaneous/4to1Header_3.jpg
http://i4.photobucket.com/albums/y110/scneonchic501/miscelaneous/4to1Header_1.jpg

This sure looks like it would fit, flange.. is the distance between ports different? I can fix the bolt holes. This is supposed to fit all b series...
signed, confused:D

[2oodoor]

I tried a search but ran out of time, anybody know why B18 usdm exhaust do not fit b20 87=90 models?

[fogged]

I have the top one, and I run a magniflow hi flow cat and spoon rezzie and a DC can all laced together with 2 1/4 pipe. I cut the ball off so that I can run a real flex pipe. The lil pipe is suppost to do away with the flex pipe. IMO it blew balls big time.

The bottom looks like a B20b

[Hauntd ca3]

Yes the b20 is a lot further forward, but a prelude b20a5 is SAID to fit in there with slight mod to the downpipe and rat tail file in one of the bolt holes.

my headers are for a poolude and apart from losing my air con, they fit straight on.
is a minor cut and reweld of the pipe that goes unger the motor since the poolude b20a leans backwards and the accord doesnt.
i'd try find outif there is a 4-1 header myself( better for top end) over 4-2-1(beter for midrange) but depends what you want from your exhaust

[AccordB20A]

awesome. im going with the modded h22 OEM headers. cause they were free lightweight and look better and should improve my powers yaaaahhuuhss

[2oodoor]

awesome. im going with the modded h22 OEM headers. cause they were free lightweight and look better and should improve my powers yaaaahhuuhss

somebody needs to do instructions for that with pics. I can find plenty of those. The soonest I can get a hedman or pacesetter is two to three weeks, I cant stand to wait any longer!!

[2oodoor]

Also how much different are B16, B18 headers... could they be made to fit B20a??
I have not found this question answered directly upon searching.

[AccordB20A]

i would also like to know. the b series intake is nearly the same i wonder if the exhaust is too lol whos tried this.. ??

[2oodoor]

Looks like it could be cut in the middle and metal added, everything would be A ok...
http://www.ottawaprelude.ca/members/setups/994_IMGP1417.JPG

[A20A1]

You're looking for a stepped header or just the fitment?

I'm not saying they are a waste of time... probably will depend on your cam profile and rpm.



i'd try find outif there is a 4-1 header myself( better for top end) over 4-2-1(beter for midrange) but depends what you want from your exhaust

Don't forget 4-2-1 come in sequential and non-sequential pairing, as well as having long, short or equal Primary/Secondary lengths.

And pay attention to 4-1's collector; the merge, collector diameter, reverse cones (usually used on 2-cycle engines), megaphones, venturies, chokes, length, and taper. Especially if it's run open header.

[Hauntd ca3]

i realise that there are many diff lengths and diameters of primary but just sayin i prefer 4/1 with short fat primaries.
sure they dont work properly until you have 5k rpm on the clock but thats dont bother me. i dont see many members running 4/1 headers so have to assume they are hard to get in the states in which case i'd go for a combo of the two bottom headers if the middle flanges are similar or yu able to make the two work.
the primaries of the top set and the secondaries of the bottom simply because the collectors look better designed
i think reversion cones etc are only worth worrying bout if you building something that will only live in a narrow part of the top end
but end of day is about whats available to you or what you prepared to make or buy from overseas

[2oodoor]

i would also like to know. the b series intake is nearly the same i wonder if the exhaust is too lol whos tried this.. ??

I was getting frustrated in my search but I finally gathered up enough info. It seems that either the B series or H22 flange CAN be made to fit b20a (ours) but it takes some port matching, filling and redrilling of the bolt holes, and cutting the flange to space the two inner pipes (then reweld redrill bolt holes. Some brands you will need to 180 flip the downpipe flange, some you need to adjust the angle of the downpipe (3rd gen prelude style) There is a lot of negative writing about adapting these other headers because people are trying to make them fit lean back b20's which presents a whole other set of fitament woes.
None of this is that difficult if you have the tools , time and pateince. So considering headers for our cars are scarce, it is worth the effort IMO especially if you can land a header cheap since the B18 and H22 parts are falling out of the sky.
A20A1 I am with you on the styles, I certainly would like to have the most effiecient style for low end torque tuning but that aside, those shiny flowing tubes would really look good under the hood. speaking of the pics in previous post. :wave:

[A20A1]

A 2 piece 4-2-1 will be easier to modify the downpipe

http://www.3geez.com/forum/showpost.php?p=626343&postcount=29

pardon the poor flux cored mig welding :)


i realise that there are many diff lengths and diameters of primary but just sayin i prefer 4/1 with short fat primaries.
sure they dont work properly until you have 5k rpm on the clock but thats dont bother me. i dont see many members running 4/1 headers so have to assume they are hard to get in the states in which case i'd go for a combo of the two bottom headers if the middle flanges are similar or yu able to make the two work.
the primaries of the top set and the secondaries of the bottom simply because the collectors look better designed
i think reversion cones etc are only worth worrying bout if you building something that will only live in a narrow part of the top end
but end of day is about whats available to you or what you prepared to make or buy from overseas

I like 4-1's too and built one myself a while back.
The end result was that my 4-1 length was not 61" long, the pipes did not run smoothly to the collector, and the fit was not perfect. Also since I was using a 1-5/8" / 1.625" diameter primary, I had a smaller selection to choose from when buying a pre-built 4-1 collector. What I ended up with was a 3" collector outlet, because a custom collector was out of my price range at the time. I'd prefer a custom one because I decided later to try a merge collector with a 1.75" choke tapering back up to a 2" diameter megaphone outlet.

[Hauntd ca3]

i think a 2 inch outlet is prob to small unless you are joining back into the factory exhaust.
my headers have 1 5/8 or 1 3/4 primaries that collect at the same place those 4/2/1 items you have a link to and modded to fit in the same way aswell
but have a 2 1/4 inch collector with room to mod to 2 1/2 if desired.
would post pics but for some reason the post pic option is now missing from my reply screen.

[A20A1]

i think a 2 inch outlet is prob to small unless you are joining back into the factory exhaust.

The 2" outlet is on purpose. I planned to make a well under the car to fit in a 2.50" Hooker Aerochamber muffler right after the collector outlet so that the exhaust exits into the muffler with about .5" overlap and can expand and cool with a little bit of a exhaust reversion dam created from the difference in pipe diameter. The exhaust velocity will drop so I will just run 2.5" back to a 2.5" straight through style muffler... preferably a Buddy Club ProSpec, since I've installed them on another car and it sounded quite nice. Problem is all packed mufflers will tend to deteriorate and the sound quality will drop over time, unless it's packing some serious packing. :D Also with the Hooker Aerochamber muffler installed under the car might increase interior noise.

I also would have considered a 2" SMSP Catalytic Converter overlapping into the Hooker or the 2" collector overlapping into a 2.5" SMSP Cat.
The concern between those two options is that having a proper sized cat may help it flow better past the screen/mesh... where as the wrong size can just screw up everything I'm trying to do. The placement of the cat closer to the engine is partly because I remember reading that hotter gases help the cat work better... not sure if that's true or not.

Note that the large increase in exhaust pipe diameter after the header goes against the view that the exhaust and header should be tuned together to reach a Optimal Exhaust Velocity of 240-260 FPS at a given rpm. I'm settling on the idea that I can get away with just getting the velocity I need from the header and everything else after the header should flow enough CFM to not cause any back pressure.



my headers have 1 5/8 or 1 3/4 primaries that collect at the same place those 4/2/1 items you have a link to and modded to fit in the same way aswell
but have a 2 1/4 inch collector with room to mod to 2 1/2 if desired.

A word of caution when following the lengths of aftermarket headers IE: DC SPORTS, PACESETTER, LIGHTSPEED, is that they have to be built to fit the stock mounting points or risk losing customers, they are not built with a specific engine build in mind. It's not to say that the stock header lengths are not a good place to start, but it's a fair bet that production cost will mean they are shorter then they should be.



would post pics but for some reason the post pic option is now missing from my reply screen.

just do a photobucket account and post the links they generate for you.

[A20A1]

Looks like it could be cut in the middle and metal added, everything would be A ok...
http://www.ottawaprelude.ca/members/setups/994_IMGP1417.JPG

once you start spreading those pipes apart the flange will be angled wrong the ports will no longer be horizontal to each other, the inner pipes will be taller... but probably not by much.

I will end up with almost the same problem on the Megan Racing header but It's not really a problem since I'm welding it to an A20 flange.

You might want to consider getting a flange made for your engine then you can spread the pipes out with a little less worry, reshape the ports as needed, and have a solid flange.

[Hauntd ca3]

The 2" outlet is on purpose. I planned to make a well under the car to fit in a 2.50" Hooker Aerochamber muffler right after the collector outlet so that the exhaust exits into the muffler with about .5" overlap and can expand and cool with a little bit of a exhaust reversion dam created from the difference in pipe diameter. The exhaust velocity will drop so I will just run 2.5" back to a 2.5" straight through style muffler... preferably a Buddy Club ProSpec, since I've installed them on another car and it sounded quite nice. Problem is all packed mufflers will tend to deteriorate and the sound quality will drop over time, unless it's packing some serious packing. :D Also with the Hooker Aerochamber muffler installed under the car might increase interior noise.

I also would have considered a 2" SMSP Catalytic Converter overlapping into the Hooker or the 2" collector overlapping into a 2.5" SMSP Cat.
The concern between those two options is that having a proper sized cat may help it flow better past the screen/mesh... where as the wrong size can just screw up everything I'm trying to do. The placement of the cat closer to the engine is partly because I remember reading that hotter gases help the cat work better... not sure if that's true or not.

Note that the large increase in exhaust pipe diameter after the header goes against the view that the exhaust and header should be tuned together to reach a Optimal Exhaust Velocity of 240-260 FPS at a given rpm. I'm settling on the idea that I can get away with just getting the velocity I need from the header and everything else after the header should flow enough CFM to not cause any back pressure.



A word of caution when following the lengths of aftermarket headers IE: DC SPORTS, PACESETTER, LIGHTSPEED, is that they have to be built to fit the stock mounting points or risk losing customers, they are not built with a specific engine build in mind. It's not to say that the stock header lengths are not a good place to start, but it's a fair bet that production cost will mean they are shorter then they should be.



just do a photobucket account and post the links they generate for you.

havnt heard of those aerochamber thingees before.
are they a hollow resonator of some sort?
i think 2 1/2 is bout as big as you'd want without having to go to bigger cams and head work, you'd prob lose hp on a stock motor with an exhaust that size.
i fyou can pull the muffler to bits, repack it with stainless steel wool.
lasts for years but is a touch louder than fiberglass packed ones.
the cat will work better if its closer to the motor but only if you dont cane the crap out the motor.
you do that and the mesh in the cat will melt from getting to hot.
talk to the manufacturer of the cat to find out optimal posi.
i fyou run to big an exhaust, you can go back wards and actually create backpressure.
if you let the gas expand to quickly, it cools to fast and becomes more dense creating a sort of moving gas plug.
get some of that exhaust wrap tape and wrap it right back to the collector or a bit past it.
if you can keep the gas as hot as poss for as long as poss the gas moves faster and reduces bp.
my headers are none of those brands you mentioned.
the company that makes them duz quite a bit of research on he headers it produces so are prob a comprmise between power and torque.
and i had to lose my a/c to get them in
i found they work brilliantly, no drop off in power right to the limiter.
it just keeps pulling then limiter
so i think i have it spot on wit the combo i have

[A20A1]

I agree that the exhaust systems should maintain exhaust velocity till it's out the tail pipe and that 2.00"-2.25" is pretty much optimal for most people on the site without major mods, but I'm trying something different.

I'm testing:
1) Collector venturies
2) (Engine / Engine Exhaust CFM to Exhaust System CFM) based "0" Back Pressure System post I read a while back
3) Interior noise and exhaust sound differences with chambered muffler installed under mid section of the car rather then at the back.

Usually you would test those things individually against a baseline but it's too much work at the moment.

I need the jump in pipe cross section size to allow for a relatively strong and long suction wave A.K.A Scavenging Wave a few inches after 61". This way the header collector is the starting point of that negative wave, where as having the collector connect to a regular exhaust system with no cross sectional change till the muffler or tailpipe, will IMO ruin the tuning I put into the header. I also don't want there to be too little a change in cross section after the header from connecting the collector to a 2" or 2.25" exhaust, because I will end up with a long but weaker return pulse/suction wave. The 2.5" muffler inlet is plenty big, where as running an open header is too big and I risk losing the benefits of a longer return pulse/suction wave even if a shorter suction wave is stronger... and since 2.5" is the inlet size I might as well maintain that and run 2.5" outlet.

[Hauntd ca3]

from what i understand bout tuning lengths, just working on the speed of sound at which the pressure waves travel at i think, could be wrong
the pressure waves change direction at every change in pipe diameter.
so you'd get a pressure wave travelling backwards and forwards up the primary pipe, the idea from what i pick up is to have the length so that at the desired revs the reversion wave thats come back up from the collector gets to the exhaust port just as the valve is opening, that way the pressure wave is just turning to head backout the primary towards the collector as the new one is meeting it helping it drag the exhaust gas out. if am right , you'd try and match all the pressure waves up so that they do that same thing all the way along the whole exhaust.
but i dont know the science behind the gaseous side of the equation .

[A20A1]

Yup, the positive pressure wave starts at the valves and pushes gasses in the same direction, while gas will flow in the opposite direction of a negative suction wave created when the positive wave reaches the first change in diameter and travels up the pipe towards the valves.

[Hauntd ca3]

http://i441.photobucket.com/albums/qq140/h4untdca3/honda004.jpg
heres a quick pic of my headers.
nice, simple design that works well

[b20a86lude]

so wat or who makes headers and does the h22 fit gud