Subject: [Fot] Exhaust header question

From: Mike Harmuth via Fot <[email-masked]>
Date: Thu, 27 Jul 2023 10:09:00 -0400

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Hi folks, I've been looking over my setup (1296, billet crank, head work, 2
SUs etc) and I'm wondering about a header change. I currently have one of
the Stahl headers from Joe Siam but I was wondering if I'd gain some power
(high end) with a 2 into 1 style, taking advantage of the scavenging.  I
have one now in the parts bin, 1 5/8" diameter that I only need to weld a
bung on for the AFR probe. I've used it in the past with an engine (SCCA
legal) without this level of prep so I'm not sure it's up to the task.

My Stahl header needs the engine out (current condition) to be removed so
it seems like a good time to try it but I'd hate to take a step backwards
and have to pull the engine to put the Stahl back in.

Any thoughts on this?

thanks
mike h

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<div dir=3D"ltr">Hi folks, I&#39;ve been looking over my setup (1296, bille=
t crank, head work, 2 SUs etc) and I&#39;m wondering about a header change.=
 I currently have one of the Stahl headers from Joe Siam but I was wonderin=
g if I&#39;d gain some power (high end) with a 2 into 1 style, taking advan=
tage of the scavenging.=C2=A0 I have one now in the parts bin, 1 5/8&quot; =
diameter that I only need to weld a bung on for the AFR probe. I&#39;ve use=
d it in the past with an engine (SCCA legal) without this level of prep so =
I&#39;m not sure it&#39;s up to the task.<div><br></div><div>My Stahl heade=
r needs the engine out (current condition) to be removed so it seems like a=
 good time to try it but I&#39;d hate to take a step=C2=A0backwards and hav=
e to pull the engine to put the Stahl back in.</div><div><br></div><div>Any=
 thoughts on this?</div><div><br></div><div>thanks</div><div>mike h</div><d=
iv><br></div><div><br></div></div><div id=3D"DAB4FAD8-2DD7-40BB-A1B8-4E2AA1=
F9FDF2"><br><table style=3D"border-top:1px solid #d3d4de"><tr><td style=3D"=
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From: David Cutter via Fot <[email-masked]>
Date: Thu, 27 Jul 2023 13:01:46 -0400

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Mike,

Jon Wolfe in his Spitfire racing guide says: "UK aftermarket exhaust are
available...on the Spitfire they are of the 4 into 2 into 1 design which is
often considered best for tuned road use whereas the 4 into 1 configuration
is generally preferred for high revving race and rally cars...I have
experimented with both designs and the 4-2-1 does have a significant
mid-torque range advantage, whereas the 4-1 gives better top end power."

Nothing explicit in the Kastner material, but seems to imply 4-1, i.e. the
Chuck Gee collector pictured p.235.

Cheers, Dave

On Thu, Jul 27, 2023 at 11:38=E2=80=AFAM Mike Harmuth via Fot <[email-masked]=
am.net>
wrote:

> Hi folks, I've been looking over my setup (1296, billet crank, head work,
> 2 SUs etc) and I'm wondering about a header change. I currently have one =
of
> the Stahl headers from Joe Siam but I was wondering if I'd gain some powe=
r
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<div dir=3D"ltr">Mike,=C2=A0<div><br></div><div>Jon Wolfe in his Spitfire r=
acing guide says: &quot;UK aftermarket exhaust are available...on the Spitf=
ire they are of the 4 into 2 into 1 design=C2=A0which is often considered b=
est for tuned road use whereas the 4 into 1 configuration is generally pref=
erred for high revving=C2=A0race and rally cars...I have experimented with =
both designs and the 4-2-1 does have a significant mid-torque range advanta=
ge, whereas=C2=A0the 4-1 gives better top end power.&quot;</div><div><br></=
div><div>Nothing explicit in the Kastner material, but seems to imply 4-1, =
i.e. the Chuck Gee collector pictured p.235.</div><div><br></div><div>Cheer=
s, Dave</div><div><br></div><div><br><div><br></div><div><br></div></div></=
div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On=
 Thu, Jul 27, 2023 at 11:38=E2=80=AFAM Mike Harmuth via Fot &lt;<a href=3D"=
mailto:[email-masked]">[email-masked]</a>&gt; wrote:<br></div><bloc=
kquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:=
1px solid rgb(204,204,204);padding-left:1ex"><div dir=3D"ltr">Hi folks, I&#=
39;ve been looking over my setup (1296, billet crank, head work, 2 SUs etc)=
 and I&#39;m wondering about a header change. I currently have one of the S=
tahl headers from Joe Siam but I was wondering if I&#39;d gain some power (=
high end) with a 2 into 1 style, taking advantage of the scavenging.=C2=A0 =
I have one now in the parts bin, 1 5/8&quot; diameter that I only need to w=
eld a bung on for the AFR probe. I&#39;ve used it in the past with an engin=
e (SCCA legal) without this level of prep so I&#39;m not sure it&#39;s up t=
o the task.<div><br></div><div>My Stahl header needs the engine out (curren=
t condition) to be removed so it seems like a good time to try it but I&#39=
;d hate to take a step=C2=A0backwards and have to pull the engine to put th=
e Stahl back in.</div><div><br></div><div>Any thoughts on this?</div><div><=
br></div><div>thanks</div><div>mike h</div><div><br></div><div><br></div></=
div><div id=3D"m_3201267496559648606DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><=
br><table style=3D"border-top:1px solid rgb(211,212,222)"><tbody><tr><td st=
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