Unique Fiero 2.8 iron exh...

[ForcedFirebird]

We could make exhaust sound like this!

Getting ready to experiment on a little something with a unique primary routing. Let me know what you think...

[mickaz]

interesting but how???

[robertisaar]

maybe it's just my laptop speakers and approaching deafness, but that sounded likda ricey to me....

[ForcedFirebird]

maybe it's just my laptop speakers and approaching deafness, but that sounded likda ricey to me....

Actually, it's an exotic car sound. Since most exotic cars use a flat plane crank and same-bank headers, you hear pairing of cylinders that are both at TDC,one on the intake stroke, one on the exhaust stroke.

Here's an example of the same situation on a v8...

ls7

sbf

sbc

[robertisaar]

so THAT'S what 180* headers mean?

seems to work well with 8 cylinders, but on the fiero(after watching for like the 5th and 6th times), the transition from idle to heavy throttle has the "gasping" that ricers create before they start buzzing. otherwise, it does sound good.

[bszopi]

When you mentioned unique primary routing, pretty much figured you were talking about 180* headers. The sound is interesting, but not sure if its for me...

[CNCguy]

180° headers are very common on circle track cars. They are used to balance the exhaust pulses when the firing order doesn't go from bank to bank (common for a V. The SBC firing order is 1-8-4-3-6-5-7-2 so they group primaries 1-4-6-7 and 8-3-5-2. 60V6 exhaust pulses are naturally balanced since the firing order is 1-2-3-4-5-6.

I vote that the Fiero must have picked up an Oriental accent while living in Taiwan. I'd say it's all in the exhaust routing and muffler. Some people here said my 3900 sounded ricey with the first muffler that was on it.

Okay... enough fun and back to building headers.

[robertisaar]

see, the 1-6 firing order of the 660s makes me wonder why this would even be necessary? exhausts left bank then exhausts right bank alternately the same way the 180* headers dump out exhaust....

am i missing something?

[ForcedFirebird]

180° headers are very common on circle track cars. They are used to balance the exhaust pulses when the firing order doesn't go from bank to bank (common for a V. The SBC firing order is 1-8-4-3-6-5-7-2 so they group primaries 1-4-6-7 and 8-3-5-2. 60V6 exhaust pulses are naturally balanced since the firing order is 1-2-3-4-5-6.

I vote that the Fiero must have picked up an Oriental accent while living in Taiwan. I'd say it's all in the exhaust routing and muffler. Some people here said my 3900 sounded ricey with the first muffler that was on it.

Okay... enough fun and back to building headers.

Lol. Blades come in for the new band saw tomorrow, trust me the itch is killing me.

Well, these headers I am talking is a 6-3-1 system, like the first video. What the intended purpose is to pair two cyls at TDC to help evacuate the opposing cylinder, thus creating the sound of three flat planes on a crank.

If you look into the guy's build, you will see where the primaries cross over, just don't ask me what it says...

http://tw.myblog.yahoo.com/ferrari-owner/article?mid=9902

see, the 1-6 firing order of the 660s makes me wonder why this would even be necessary? exhausts left bank then exhausts right bank alternately the same way the 180* headers dump out exhaust....

am i missing something?

Well, kinda. If you think about it, there are 3 cyls grouped together, but they are not alternating truly since one cyl in the 3-1 collector is not at the opposing position to the other 2.

[robertisaar]

makes sense.... if only you had the ability to cast cranks john...

but i guess connecting the correct sets of cylinders together would work, as long as you want to deal with the more complex exhaust plumbing.

it does sound similar in conecpt to Tri-Ys.... but with 2 less cylinders, and i know those headers make some hellacious midrange power.

[neo71665]

I think I like the sound of my long tubes and flow 40

[Superdave]

an X pipe on a '660 is also a huge improvement, even though the pulses are balanced it still increases the scavenging and cleans up the exhaust note.. probably better than it does on a V8. I wish i had taken some videos of my Z24 after i put the latest X pipe on it.


Now if we only knew someone with an engine dyno we could test shorties vs longtubes vs 180's...

[ForcedFirebird]

makes sense.... if only you had the ability to cast cranks john...

but i guess connecting the correct sets of cylinders together would work, as long as you want to deal with the more complex exhaust plumbing.

it does sound similar in conecpt to Tri-Ys.... but with 2 less cylinders, and i know those headers make some hellacious midrange power.

But it IS tri-y's 6 primaries, paired to 360* of crank rotation, to one 3-1 collector. Only other way to get the same scavenging effect is to do a 6-1 collector. Search 6-1 headers and tell me what you think of them

I think I like the sound of my long tubes and flow 40

Still have rasp on decel/rev-down.

an X pipe on a '660 is also a huge improvement, even though the pulses are balanced it still increases the scavenging and cleans up the exhaust note.. probably better than it does on a V8. I wish i had taken some videos of my Z24 after i put the latest X pipe on it.


Now if we only knew someone with an engine dyno we could test shorties vs longtubes vs 180's...

Dynoes to back theories and prototypes is a must. Tru duals sound so nice on an even-fire v6 because of the way the primaries will "twist" the pulses to create a "toilet bowl" effect in scavenging. The x-pipe will increase performance and sound because the secondaries are joined so late in the exit.

OOPS! I realized when I said "first video" that the 6-3-1 video was never posted because the videographer wanted secrecy.

[robertisaar]

LOL, with a V8, i guess there's actually 6 Y's but i see the point.

i see 6-1 headers for straight 6 motors.... and they look fairly straightfoward.

i'm interested in results here.

i have a hard time seeing all of this fitting nicely in a FWD application though... but i imagine it is possible with enough tweaking and prototyping.

[robertisaar]

so i was thinking about it a bit more....

combine 1-4, 2-5 and 3-6 cylinders together for this 180* effect? then to a 3-1 collector? damn these are gonna be complicated...