Subject: Re: [Fot] Fot Digest, Vol 66, Issue 9-Stahl header

From: George Harmuth <[email-masked]>
Date: Fri, 4 May 2012 08:38:17 -0400

"the use of a Stahl in a Spitfire also requires some pretty
good changes to the frame and right-side suspension upright.

Thanks for the info everyone. My bell housing has a large notch in it and
the frame rail looks like the flange was beat into submission sometime in
the distant past. I'll bet there was a Stahl header installed by a PO. If
not, I have a good start on the mods to put one on now.
Follow up question, ceramic coating or not? My thinking is not to coat, let
the gas cool quickly and contract, reducing the volume and back pressure.
Less pressure == better flow?

thanks
mike h

G. Michael Harmuth
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From: [email-masked]
Date: Fri, 4 May 2012 15:40:41 +0000 (UTC)

Go with the ceramic coating, there is no justification other than budget to not coat it. 

They all claim to improve the flow. My experience with Stahl is mixed for the TR4/IRS. 

I had to mo dify my frame ( not so for the live axle car ) The general weld and bend quality 

was good but fit up to the head was poor. Mine is coated inside & out and engine bay 

temps were reduced. 

just my .02 

jim g 

----- Original Message -----

From: "George Harmuth" <[email-masked]> 
To: [email-masked] 
Sent: Friday, May 4, 2012 6:38:17 AM 
Subject: Re: [Fot] Fot Digest, Vol 66, Issue 9-Stahl header 

thanks 
mike h 

G. Michael Harmuth 

Unsubscribe: http://autox.team.net/mailman/options/fot/[email-masked]

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From: Bob Kramer <[email-masked]>
Date: Fri, 4 May 2012 12:40:39 -0500

I have a couple of equal tube length Hooker headers that seem to work really
well on my car but stick out the bottom too far. I've bounced them off the
floor and cracked them a few times. I switched what may be a Monza because I
had it floating around the garage. I noticed the power loss. Thankfully Road
Atlanta allowed a lot more momentum carrying than TX World. I should probably
source a new TR4A header rather than scrounge up used stuff.

Sent from my iPhone

On May 4, 2012, at 10:40 AM, [email-masked] wrote:

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From: [email-masked]
Date: Fri, 4 May 2012 17:47:52 +0000 (UTC)

We ( TR4 drivers ) really need a good header fabricator. My dealings with Stahl have been less than 

satisfactory. They don't normally build TR4 headers so you kind of have to catch them at the right moment 

to get it done. I'm quite certain the next set I need I'll build myself. 

jim g 

----- Original Message -----

From: "Bob Kramer" <[email-masked]> 
To: [email-masked] 
Cc: "George Harmuth" <[email-masked]>, [email-masked] 
Sent: Friday, May 4, 2012 11:40:39 AM 
Subject: Re: [Fot] Fot Digest, Vol 66, Issue 9-Stahl header 

I have a couple of equal tube length Hooker headers that seem to work really well on my car but stick out the bottom too far. I've bounced them off the floor and cracked them a few times. I switched what may be a Monza because I had it floating around the garage. I noticed the power loss. Thankfully Road Atlanta allowed a lot more momentum carrying than TX World. I should probably source a new TR4A header rather than scrounge up used stuff. 

Sent from my iPhone 

On May 4, 2012, at 10:40 AM, [email-masked] wrote: 

> Unsubscribe: http://autox.team.net/mailman/options/fot/[email-masked]

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From: Duncan Charlton <[email-masked]>
Date: Fri, 4 May 2012 16:01:05 -0500

Mike,

Several sources claim that keeping heat in the headers causes the gases to
exit the system faster due to decreased density.  I haven't pursued the
science behind this.  One header wrap vendor says hotter exhaust gases are
like hotter liquids that lose their viscosity as they heat up, creating less
resistance to flow.  I'm not sure I buy that explanation.  We would probably
all accept the claim that the velocity of gas flow is important on the intake
side of an engine, although we would also agree that higher density
(cooler=denser) of the incoming charge is good too.

Whatever the true cause, Cool Concepts Performance Coatings goes so far as to
cite dyno tests (but I didn't spot any graphs or explanation of test
conditions there).  From their website: "Dyno tests have revealed power gains
of 8-10 hp in a 550 hp engine. This is mainly due to the heat barriers
trapping heat inside the header pipes and increasing exhaust velocity. It was
also acknowledged that more gains could be had when installed in an engine
bay, where hot air robs power."  Presumably the latter refers to the heat from
the headers causing the intake air to be hotter and therefore less dense.

I'm using coated headers on both my race car and a street car.

Duncan
(Texas)
1952 Morgan Plus 4 red #6

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From: "Bob Kramer" <[email-masked]>
Date: Sat, 5 May 2012 09:25:28 -0500

Maybe I should look into modifying the Hookers. They sit about that much
below the frame and the current set tucks in nicely. I'd have to dyno
test them to be sure, but with equal length and big tubes they may be as
good as anything out there. My seat tells me they are worth some HP.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] 
Sent: Friday, May 04, 2012 12:48 PM
To: Bob Kramer
Cc: George Harmuth; [email-masked]
Subject: Re: [Fot] Fot Digest, Vol 66, Issue 9-Stahl header

We ( TR4 drivers ) really need a good header fabricator. My dealings
with Stahl have been less than

satisfactory. They don't normally build TR4 headers so you kind of have
to catch them at the right moment

jim g

  _____  

I have a couple of equal tube length Hooker headers that seem to work
really well on my car but stick out the bottom too far. I've bounced
them off the floor and cracked them a few times. I switched what may be
a Monza because I had it floating around the garage. I noticed the power
loss. Thankfully Road Atlanta allowed a lot more momentum carrying than
TX World. I should probably source a new TR4A header rather than
scrounge up used stuff.

Sent from my iPhone