Reply to "aluminum heads"

> The 3V port is 2V in size, but it is raised approx. 3/8" so that the roof
> of the port is the same height as the roof of a 4V port. If it were raised
> another 3/8", it would approximate the location of the ports in the C302 Ford
> Motorsport heads.

A bit of a nit but the 3V port is larger than a 2V. It's also larger than
an (unported) C302 port (and of considerably different shape). It's close
to the size of a ported 2V outline of the turkey pan. The unported 3V is
approximately the same size as my ported C302B (218 vs 217 cc's). I've got
a CHI 3V intake here. I should take some pictures with gasket overlays to
show the differences.

> John Kaase won the 2004 Engine Masters competition with CHI 3V heads.

Remember that a number of heads were excluded from the competition.
A3's, C302B's, Yates, Brodix BF300's and Blue Thunder to name a few.

> Realistically, a 2V head that supports 600 bhp is about all anybody needs!

Saying that an AFD 2V head can support over 600 HP out-of-the-box is
somewhat misleading. What you really care about is how will a given head
work on your engine relative to other cylinder heads. You can have 4 or 5
different heads all of which can support 600 HP but on a given engine
there can be 150 HP between the best and the worst. When I was designing
my engine, I ran a series of detailed simulations using Dynomation for
2V, 4V, CHI 3V, A3, C302, C302B, and Brodix BF300 heads. Except for the
CHI 3V all the head flow and dimensional data were from heads that I or
someone I know had personally flow tested. For the CHI 3V, I had to rely
on CHI provided data which I've not independently verified. Except for
the 2V heads, all of these heads are capable of supporting over 600 HP on
the right engine. That includes the stock 4V heads. I know of a dyno
verified stock displacement 351C with unported (NHRA legal valve job only)
open chamber 4V heads that made 630+ HP.

Though both could support 600 HP, on my particular engine, the difference
between the 4V heads and the C302B was huge. Over 100 HP difference at the
peak and the C302B's were better across the RPM range. The C302B's, C302,
and A3 heads were all fairly close with the Brodix and CHI 3V around 40 HP
less at peak. While the C302B's were ported they were near identical in
port volume to the CHI 3V heads (217 vs 218 cc's). By looking at the claimed
flow numbers for the AFD, CHI and Edelbrock 2V heads, I can see they will
all make less power than the CHI 3V's.

I guess this is a long-winded way saying that I disagree with your statement
that "a 2V head that supports 600 bhp is about all anybody needs". If I can
60 or 70 HP through heads alone, it's worth it to me. Increasing RPM and cam
timing come at a durability cost but better airflow does not.

On a milder engine the gap between the heads will close and may well be
influenced by what headers and intake are available. For instance, a
CHI 3V head coupled with Scott Parker's intake may not make any more
power than a 4V head and a Blue Thunder intake if the better intake of
one combination is enough to offset the better heads of another.

The CHI 3V's are excellent heads but in terms of all out power production
the raised exhaust port heads have an advantage. I believe both AFD and
CHI are working on race heads with raised exhaust ports to address this.

> the alloy 2V heads from CHI & AFD, which sell for around $1800 to your door
> in the US

Have you verified this is true, Goerge? I tried following up on the rumor
that CHI was going to price match the Edelbrock 2V head price but found it
wasn't true. Assembled and delivered cost was still several hundered dollars
more than the Edelbrocks from the vendors I contacted. Anyone know if this
has changed or what AFD's current pricing is?

Dan Jones