It's a good idea to use the standard head to work on. The Holbay ports are not
exactly "polished" but the sharp edge in the inlet close to the valve is taken
away and it is smother. The exhaust on the other hand, seems to have received
less interest.
Kristian J
----- Ursprungligt meddelande -----
Fren: "Tom Hill" <tom.hill@att.net>
Till: <alpines@autox.team.net>
Skickat: den 23 maj 2003 17:40
Dmne: RE: Torque or not more torque
> It is my understanding that Rootes contracted with Holbay to produce a
> performance version of the fastback Alpine. The prototype that was
> delivered to Rootes was very fast but had lousy low end performance. This
> was deemed not acceptable for a road car by the Rootes people. This was
> communicated back to the Holbay people and they reconfigured the engine with
> the smaller intake ports. The effect was that the velocity of the intake
> charge remained high at lower RPMs resulting in better low end performance,
> i.e. torque.
>
> Last year I built a Holbay engine for my SV Alpine complete with an NOS
> Holbay head, a Holbay replica camshaft from Sunbeam Specialties, and the
> correct Weber setup. The engine was tested on the dyno and made around 125
> peak hp but the torque curve was absolutely flat (about 120 ft/lbs, need to
> check notes) from 2500 RPM to redline. So I would imagine if a "stock" head
> was modified by reshaping the combustion chamber and polishing the intake
> and exhaust ports like the Holbay, then the result would be a high RPM
> (relative to Rootes) engine.
>
> The flowbench results comparing the Holbay head to stock can be found at
> http://www.tomhill.freeservers.com/custom.html. (sorry for the popups, its
> free)
>
> tom hill
>
> -----Original Message-----
> From: owner-alpines@autox.team.net
> [mailto:owner-alpines@autox.team.net]On Behalf Of
> Jay_Laifman@countrywide.com
> Sent: Monday, May 19, 2003 7:53 PM
> To: alpines@autox.team.net
> Subject: Torque or not more torque
>
>
> "Together with the Holbay camshaft and the correct Webers and right air
> filter (look up! the carb set-up is very sensitive to the air filter) you
> get a torque engine. Its not a high RPM engine! This suits the 3.77 rear
> end with overdrive gearbox."
>
> I do not think this is 100% accurate. In general, if you take two
> identical sized engines and try to increase power to one of them by better
> breathing and carberation, that brings on power at the higher rpms at the
> expense of the lower rpms. On the other hand, if you take otherwise
> identical engines and increase the size of one of the engines, you will
> gain that power and torque at the lower rpms. So, by going the Holbay
> route, you generally lose torque and power at the lower ends.
>
> Jay
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