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

> But you go on picking nits! I wouldn't have you change a bit, I love your
> engineer's eye for detail.

If I'm coming across argumentative, I don't mean to. I appreciate your
posts. I'm just trying to add a different perspective. I hate to see
guys give up power they don't have to.

> all the head the majority of enthusiasts will ever need.

What were we talking about again? :-)

> You were making a point by citing the 4V motor's bhp,
> the same way I'm making a point by saying the 2Vs will support 600 bhp.

I meant to imply both were misleading to the point of being useless.

> Other head characteristics are equally important to power production however,
> such as port velocity, port contour and combustion chamber design. The new
> heads have advantages over the Motorsport heads in that respect,

As far as port velocity and port contour go, the C302B still has the edge.
The higher location of the ports, especially the exhaust port, allow a
better port contour. Based upon my testing, the heads flow more for the same
cross-sectional area and at a lower lift so velocity is higher. The CHI/AFD
heads may have a chamber design advantage but I'm not convinced of that.
The C302B and Brodix BF300 series already have a very good quench chamber.

> computerized dyno software does not do well in factoring those things into
> the equation.

Agreed.

> The gap between heads closes because on a milder motor, the race heads are
> overkill, at lower lifts they don't flow any better than the non-race heads.

That's not been my experience with A3 and C302B heads. They flow better
than the non-race heads at all lifts. Better than 4V, Aussie 2V, CHI 3V,
and EM-185, etc. Some race heads do indeed trade low lift flow for higher
lift flow but not the Motorsport high ports. That's one of the reasons I
like them so much. They make a great street head.

> Or to put it differently, the mild motor can't use the race heads to their
> potential.

That's one way of looking at it but they can often still benefit. On an
otherwise identical motor (377C with Isky 280 flat tappet hydraulic street
cam), switching from iron 4V heads and Strip Dominator intake to C302B
heads with matching Motorsport intake brought the powerband in 1000 RPM
sooner due to the higher velocity ports of the head/intake combo.

> Your comment about headers & intake brings to my mind a good point. The
> combination of parts is what needs to be considered, not just the heads
> alone.

Very true.

> The Motorsport stuff is more difficult to locate than the parts available
> brand new.

You forget the C302B's (in the form of the Brodix BF300) and matching intakes
(Edelbrock Victor AHII and Kelly Coffield IR EFI) are still avalable new.

> One price I remember is that of the 4V head; it was priced at $2050 in street
> performance set-up. I don't remember the other prices.

I highly recommend anyone considering those heads get the upgraded valves.
I know of two guys (one a friend, the other a Pantera owner who contacted me)
who have had the 5000 series valves they use fail on them.

> However, I'm still on the hunt for the A331 intake, if I find one, I may
> spring for the A3 heads. In fact, if you hear of an A331 for sale, I would
> appreciate you keeping me in mind.

Will do but Dennis at PPC seems to buy everyone he can get his hands on.

> They don't mention at what pressures the flow numbers are obtained.
> The Motorsport numbers were at 25in-mg. Everyone else seems to use 28in-mg.

The Ford Motorsport catalog data was indeed taken at 25 in Hg and even
then is conservative. The heads I've flowed have all been at 28 in Hg.

> If one can extrapalate the A3 to 28 then they outflow them out of the
> box.

My unported A3's were quite good on the flow bench, better than the
CHI 3V heads in terms of raw flow numbers but that's not an apples
to apples comparison because of the A3's larger ports. My C302B
heads were essentially the same port volumes and were better than
the A3's or the CHI 3V's.

> Who said the A3's were being run out of the box, stock? The C3's certainly
> aren't.

A3's flow quite well out of the box so some people run them as is.
C302B's were desiged to permit custom porting so most of those are
ported. That said, Kelly Coffield's Brodix BF300 C302B clones did
pretty well unported (and with small valves). IIRC, they were about
equal to the CHI 3V's in flow but had smaller ports (196 cc's).
I've still got a set of new-in-box A3's (and matching A331). If and
when I get around to using them, I will have a conservative bowl port
job done on them. Not much metal needs to be removed, just a subtle
reshaping, to make a big improvement. I'll probably have the guy
that did my Buick heads have a go at them. He did an amazing job
on those small port heads.

> The highport "advantage" is line of sight. Exactly what that is worth
> on a street engine is contraversial at best.

Not controversial at all in my book.

Dan Jones