Turbo header design

[Gary Derian]

A reasonably close approximation to true 180 deg. headers can be made with
the old tri-Y approach.  As Aaron wrote, true 180 would require merging 1-6,
8-5, 4-7, 3-2 which is difficult to make.  Merging 1-5, 3-7, 4-6, 2-8
enables cylinder pairs to share an exhaust pipe without interfering and is
relatively easy to build.  This is common in high output European and
Japanese V-8 engines.  Ferrari, on the other hand, uses a flat crank to make
a true 180 header easy.  Formula 1 and CART V-8 engines also use flat
cranks.

Flat crank V-8's vibrate like 2 4cyl engines.  A 90 degree crank V-8 has
complete primary and secondary balance with only weights on the crank.

Gary Derian <gderian at cybergate.net>

-----Original Message-----
From: Aaron Willis <darkmonahue at awwwsome.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Wednesday, January 06, 1999 6:29 PM
Subject: Re: Turbo header design


>
>Clarence,
>  This is easily done with an inline four having a 1-3-4-2 firing order,
>as you just pair cyl's 1-4 and 2-3 together.  Commonly done in NA
>headers and OEM manifolds too.  However, true 180 degree headers on a V8
>typically take up a lot of space.
>   The only firing order i am familiar with is for a GM engine, which is
>1-8-4-3-6-5-7-2.  Picture the cyliders as two rows (which they are):
>
>     1     2        you can see that #1's 180 degree partner is #6, #8's
>     3     4        is #5, #4's is #7 and #3's is #2.
>     5     6
>     7     8        Obviously these are all on opposite banks, so the
>pipes need to travel around the engine some distance to collect in a 180
>degree fashion. I really don't know much about whether the benifits
>would outweigh the extra bulk and length of the exhaust system, but I
>suspect not.
>   HOWEVER it must be said that this arrangement does offer a killer
>sound in NA form!  A gentleman in town has a '53 (?) Studebaker with a
>406 Chevy in it, using standard NASCAR 180-degree headers collected into
>a single exhaust, and it will raise the hair on the back of your neck.
>Almost sounds like an exotic foreign supercar (or a flat-crank V8, come
>to think of it)
>
>HTH
>
>Aaron
>
>ICQ # 27386985