Frank:
Thanks for the update. I'm looking forward to your pictures of the
installation. I have the right-angle adapter/oil filter set-up and if
these new CAT headers clear the obstruction, I'll be able to upgrade
from the original exhaust manifolds (placing them carefully in a box on
the shelf, of course) :-)
Regards
David Sosna
Frank Marrone wrote:
> Got my CAT headers today. They look pretty nice.
>
> The primary tube diameters vary from ~29" to ~33" and the average length
> is ~31". This is a bit longer than Ricks headers that vary from ~26.5"
> to 31.5" with an average length of 28.5".
>
> The primary diameters of the CAT headers are 1 5/8" OD Vs. 1 1/2" OD for
> Ricks.
>
> The CAT headers have a merged tube type collector with a relatively
> steep taper of ~12 degrees. Ricks headers terminate in a baffle type
> header with no real taper other than for a short distance just past
> where the primaries merge into the collector.
>
> The CAT headers have a collector diameter of ~2 1/4", Ricks are ~2 1/2".
>
> I can see that the CAT headers are designed to give more clearance near
> the oil filter area and I am hopeful that I will indeed be able to run a
> shorty filter directly on the block or at least be able to use the Ford
> Racing/Econoline 90 degree filter adaptor.
>
> I'll post some pictures of the two header types for comparison tomorrow.
>
> Warning! Editorial comments to follow!
>
> The collector design of the CAT headers is superior to the collectors on
> Ricks headers. The merged tube design used on the CAT headers has
> inherent advantages over the baffle type collector used on Rick's
> headers. The fact that Ricks headers have no real collector taper makes
> matters worse. I noted that the taper of the CAT collector is fairly
> steep and I have read that a less steep taper (10 degrees) would be more
> effective for lower broader RPM ranges relative to steeper tapers.
>
> The merged collector promotes less flow turbulence because of the smooth
> transition into the collector. The merged collector design relies
> primarily on inertia effects for scavenging and the flow enhancements
> of this design are conducive to this.
>
> The merged collector design reduces the effects of resonance tuning.
> This is good and bad. Resonance tuning can both help and hinder
> scavenging depending on the RPM range of operation (and cam timing and
> gazillions of other effects). A merged tube collector won't exhibit as
> many bumps in the torque curve compared to a baffle type collector
> because of the reduced effects of resonance tuning.
>
> The primary tube diameter of the CAT headers is also better suited to
> larger displacement and higher revving motors as compared to Ricks
> headers. The converse of this is that Ricks headers may be a better
> choice for a stock or mild 260.
>
> The effects cited are normally pretty subtle and probably do not matter
> much for the daily driven non-competitive Tiger. Header science is
> non-exact (except for those with lifetimes of knowledge and big
> computers) and the comments here are general and made by someone without
> a lot of practical experience with a wide variety of header designs so
> caveat emptor. I have read that the best practical way to decide what
> is right for your combination is to spend a lot of time on the dyno with
> a lot of different types of headers. Like that is going to happen for
> most of us! Just passing on some things I have learned.
>
> Frank
|