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Re: [Fot] Exhaust header question

To: Mike Harmuth <ofracer@gmail.com>
Subject: Re: [Fot] Exhaust header question
From: David Cutter via Fot <fot@autox.team.net>
Date: Thu, 27 Jul 2023 13:01:46 -0400
Cc: FoTTriumph <fot@autox.team.net>
Delivered-to: mharc@autox.team.net
Delivered-to: fot@autox.team.net
References: <CAO0FjVY+8pu=KZzSYXB-HXsyH3LHv_oJruffyNOawkprh0vj5w@mail.gmail.com>
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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 <fot@autox.te=
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
> (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">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:fot@autox.team.net";>fot@autox.team.net</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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</blockquote></div>

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