Turbo header design

Aaron Willis darkmonahue at awwwsome.com
Wed Jan 6 23:24:20 GMT 1999


Clarence Wood wrote:
> 
>   Several years ago I read an article on the design of a collector for V8's that produced a bolt-on 20 hp increase.  I thought the idea was very slick:  pair the tubes to their 180 out partner, baffle their exit into the collector.  In other words:  as tube #1 was pushing out exhaust the cylinder that tube #2 was servicing was on the power stroke;  as tube #2 started to extract it was helped by the vacuum created by the extraction of tube #1 which had just finished.
>   My question is: why can't this be applied to the header of a turbo'd engine: pre-turbo.  I know that the turbine is already turning and therefor creating a vacuum; but, at velocities reaching .75 mach, wouldn't any tuning, like using the 180 out exhaust arrangement help??  I don't think the header tubes would have to be lengthened to any great extent but, the baffling would have to be in place.  Also, wouldn't the pairing of 180 out tubes help to more efficiently direct the vacuum created by the turbine?
> 
> Just a thought....
> 
> IZCC #3426
>  1982 280ZX Turbo GL
>  1966 El Camino
>  1982 Yamaha Maxim XJ-1101J Motorcycle
>  1975 Honda CB750 SS (black engine)
>  1986 Snapper Comet lawn mower
> Clarence Wood
> Software&Such...
> clarencewood at centuryinter.net
> Savannah, TN.

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



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