I had the same discussion with Smitty when I bought my Holbay setup. When I
talked to my engine builder about the port differences, he smiled and said,
"its right the opposite of what we always thought". His point was in many
cases bigger ports are not always better. Flow is not just a funtion of the
capacity of the port. The shape of the port and the velocity of the flow
are also very important factors. This guy has been in business forever and
has a great deal of drag and circle track engine experience.
We will have flow numbers on both heads in a few weeks.
Tom Hill
-----Original Message-----
From: owner-alpines@autox.team.net
[mailto:owner-alpines@autox.team.net]On Behalf Of
sosnaenergyconsulting@home.com
Sent: Friday, March 09, 2001 8:44 AM
To: Greg Locke
Cc: Jarrid Gross; Tom Hill; Christopher Albers; alpines@autox.team.net
Subject: Re: More Power from the 1725
Y'know, Smitty has a Holbay head and we were puzzling over the smaller
intake ports recently. He thought that going from a large carb opening
to a small intake port would increase the velocity of the air/fuel mix.
Wouldn't that contribute to better torque?
I think that somebody else (apologies for not remembering who) wrote
yesterday that the intent of the Holbay head was to make better low-end
torque rather than high-end horsepower.
Regards
David Sosna
56 S4 GT V6
Greg Locke wrote:
>
> I heard that holbay originally delivered the H120 powered rapier (or
> hunter?) with decent sized ports and rootes said... "No way. this is too
> fast, make it slower". The reduction in port size was holbays answer. I
> thought they only reduced the size of the intake manifold runners, and the
> head ports were standard, but I may be wrong here. Would take a lot of
work
> to weld up the ports and re bore them.
>
> more information form vague sources.... The original engine did put out
> 120hp, but the port mods reduced it to about 107.
>
> Kindof defeats the purpose of the webers in the first place, but it was
more
> of a sales gimmic anyway, as a result of the london-sydney win.
>
> Greg
>
> ----- Original Message -----
> From: Jarrid Gross <JGross@econolite.com>
> To: Tom Hill <tom.hill@att.net>; Christopher Albers
> <Christopher.Albers@bubbs.biola.edu>
> Cc: <alpines@autox.team.net>
> Sent: Friday, 9 March 2001 09:02
> Subject: RE: RE: More Power from the 1725
>
> > tom wrote,
> >
> > >I am referring to the port diameter at the intake manifold not the
valve
> > >size. I think the valves are the same on the standard and Holbay
heads.
> >
> > >tom
> >
> > CNA wrote,
> >
> > >Huh? That doesn't seem right. How does the head breath with an intake
> > >only, what, 1.2"? I can't recall the stock size, I seem to recall
> > >about 1.4" for the intake & 1.2" for the exaust.
> >
> >
> >
> > This is correct, the ports on the holbay are about 1.25.
> >
> > The valves are 1.30 and 1.52, the same and SV alpines.
> >
> >
> > Jarrid Gross
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