[DeTomaso] CHI 3v 225

[Daniel C Jones]

> What is the best and still available dual plane and what
> is the best single plane for the chi 3v 225 heads?  I read
> Dan J say that Scott Cooks single and duals are good.
> Does the CHI brand dual and single intakes work as well?

I think you misread what I wrote.  CHI does not make a dual
plane for their 3V heads.  They used to carry the first
version of Scott Cook's dual plane which matched the 3V ports
but Scott Cook has introduced his own line of cylinder heads
and no longer has a business arrangement with CHI. That leaves
with only the single plane intakes shown here:

 http://www.chiheads.com.au/3v_manifolds.php

These are all very tall (a couple of inches taller than a
Holley Strip Dominator) single plane intake manifolds that
basically differ in the deck heights they are designed to
fit (8.2" SBF, 9.2" 351C, 9.5" 351W, 10.2" 351M/400) and
the carb pad (4150/4160 or Dominator).  9.2" deck CHI single
plane is perhaps the best I've seen and tested so far. On
the dyno 351C, it made 20 HP and 20 ft-lbs more than Scott's
dual plane.

Scott Cook now makes a revised low rise dual plane that looks
much like a Ford cast iron DOAE-9424-L dual plane but is cast
in aluminum, slightly taller (around 10 mm or a bit more than
3/8", still fits under a stock Pantera engine screen) with
smaller ports than an OEM Ford intake.  Scott also makes a new
medium rise single plane. Both of these fit his new heads which
have the intake port center line wall moved over around 0.030"
and I think the port roof may be revised as well. I've not
verified it but you should be able to port match the CHI 3V
heads to Scott's revised intake.

Scott's intakes also fit the Ford Motorsport A3 high port heads
as the A3 heads have a larger port.  In testing on my 10:1 403C
street hydraulic roller engine, the Scott Cook intake made 569 HP
and 512 ft-lbs beating a modified Ford Motorsport A331.

For compatibility with OEM and aftermarket intakes, CHI makes
2V and 4V versions of their heads.  The 4V version is essentially
a 3V port that has machined larger to fit a 4V port.

A lot of guys have it their mind that CHI 3V heads are the best
because of their success in the Engine Masters Competition but
keep in mind that better cylinder heads like C302B or D3 were
not legal in that competition.  If you look at this link you'll
see the reason why.

 http://i1127.photobucket.com/albums/l621/danielcjones2/351%20Cleveland%20Stuff/CHI-4VuniexhaustportversusC302-1.jpg

a shot comparing the CHI exhaust port (left) versus one of my
Ford Motorsport C3/C302/C302B high ports (right). Given the
much higher port location, the Ford Motorsport heads obviously
have greater potential but also requires compatible headers.
Luckily those are readily available for Panteras and compatible
intakes are still out there.

One mistake I see is guys buying heads like the CHI but using
the wrong exhaust or intake manifold which loses far more
horsepower than they might have gained from the cylinder head
swap.

Dan Jones