[DeTomaso] 351 C Building Advice for Forced AIr and EFI

[Daniel C Jones]

> Should I get an aussie block for higher nickel content? Does that even
> matter?

I've not been able to independently verify the claim the standard Aussie
blocks have more nickel content than U.S. blocks.  In any event, extra
nickel doesn't make the block stronger, though it may improve surface
wear.  The standard Aussie blocks are 2 bolt main.  I'd certainly go
with a U.S. 4 bolt main block over a 2 bolt main Aussie block.  The
Aussie XE 4 bolt main race block (which is thicker all over the block)
would be the one to get but they are very rare and much more expensive.
In this case, 4 bolt mains are worth the extra cost assuming the block
passes sonic check.

For a given power level, a supercharger is generally easier on an engine
because you need to spin a normally aspirated engine to a higher RPM and
loads on the bottom end increase with square of RPM.  However, there are
places where a supercharger is not so easy on the engine.  With a crank
driven supercharger, loads at the crankshaft snout can be very high
and any typ of compressor increases thermal loads.

> If I am to use forced air induction should I use 4V heads?

The 4V iron heads would work well, particularly wioth some short side
radius work, offering little restriction to the supercharger.  The
bigger ports are beneficial for turbo/supercharged applications where
the impellor defines the flow rate.  Even better would be the Ford
Motorsport A3 aluminum high port heads.  The intake ports are better
than a 4V's and the exhaust ports are particularly well suited to a
turbocharger or nitrous.  Assuming you convert a tunnel ram to EFI
for the intake, the A3's will match on 3 sides, needing only the tunnel
ram port floor raised to match.  Assuming you want to run pump gas,
I'd run closed chamber heads with either a mirror image dish or D-dish
pistons.  You want to get your compression down in the 8 to 8.5:1 range
while preserving the quench effect (you want a flat part on the piston
to come near the flat part of the combustion chamber opposite the spark
plug).  You also want a blower specific forged piston design with a
thicker crown and lands.  Also, consider inconel valves (particularly
on the exhaust side), an ignition controller that pulls timing in
proportion to boost (e.g. MSD-6BTM) and/or water/alcohol injection.
Run a longer rod to reduce side wall loading under boost.  With a
standard stroke, you have plenty of room for 6" to 6.2" rod with
Chevy journal.  With the connecting rods, you'll be concerned with
buckling under pressure so you'd want something with a larger cross-
section like a forged steel H-beam design or even aluminum rods from
someone like BME.  You'll probably want a custom cam but Crower lists
a 351C hydraulic flat tappet blower cam with wide lobe separation angle.
Specs are 246 degrees @ 0.050", 0.548" lift, 114 degrees LSA with
power band between 2400 and 6700 RPM.  Makes a nice nitrous cam, as
well.  Compression means lots of heat so don't skimp on the cooling
system.  An Edelbrock water pump, larger radiator and better fans,
along with an increased capacity road race Pantera oil pan (Armondo
or Aviad), along with oil temperature and boost gauges.  Look at Victor
Rienz for the head gaksets.

> The more I read about different heads the more it is confusing on
> which ones to buy.

Ones like the CHI 3V's will limit your intake choices to a very tall
single plane or a dual plane, neither of hich will be well suited to
you application.  CHI will open the ports up on a 3V to match 4V intake
manifolds, however.  Don't even consider the 2V heads.  If doing a
positive displacement supercharger, the Offy 360 intake is often used
as a base, thouh there were 351C-4V blower manifold available at one
time.

A word about boost.  Boost isn't necessarily proportional to power.
You can make a bunch of boost on a restrictive induction system but
not that much power.  Install a less restrictive induction system
and you'll make less boost but more power.  B&M's supercharger catalog
used to have a strong warning against using stock 302/351W heads with
their Roots style superchargers because the OEM Windsor heads are too
restrictive.  They'd make lots of boost but not that much power and
would actually overheat.  Pick a power level and let the boost work
out to what it needs to be, not the other way around.

> It appears turbos are easier to position in the engine bay but I would
> prefer a supercharger although I cannot perform the maneuvers Dave has
> done myself.

By maneuvers, do you mean fabrication?  Either way, you are looking at
custom fabrication and the turbos will package better in a Pantera.
There isn't much room between the bulkhead and front of the motor for
crank driven superchargers.  It can be done, however.  Contact Fred
Terry on what he did for his crank driven supercharger.

Dick Koch, Dave Doddeck, and Pat Mical all have twin turbo Panteras.
Here's a picture of Dick's engine:

 http://www.panteraplace.com/ICD/2004/ICD%202004%2020.jpg

If considering turbos, you might want to contact Dave or Dick.  Dick
originally had a blow through carb set-up with larger twin turbos.
I think he is much happier with his smaller turbo EFI set-up.  His
basic engine isn't anything exotic, just open chamber 4V heads on a
standard 351C block with mild cam but under boost it makes plenty of
power.

If I were doing one for my own self, I'd pick Ford Motorsport A3 high
port heads and an XE.  Hmmm, come to think of it I have an XE block
fitted with an XH1 forged steel crank and Carrillo rods.  That would
make a very nice blower foundation.

> It seems like everyone else in the automotive community (outside
> the Pantera community) is doing really well with supercharged and
> turbocharged street/race engines.

I know the 5.0L Mustangs guys are doing really well at splitting
the 5.0L blocks right down the middle under boost :-)

> I'd definitely go with the aussie block which should have siamesed
> bores and much stronger main bearing mounts (not just the caps!).
> Be careful- not all blocks from australia are 'aussie-cast' blocks!

Exceedingly few of the Aussie blocks are the XE race blocks.  Ford
only made 2 batches of them with a few hundred blocks in each batch.
The guys selling Aussie blocks on the web are trying to fool people
into believing their blocks are the stronger XE blocks.  They are not.
The typical Aussie 2 bolt main block weighs and sonic checks no
different than U.S. 2 bolt main blocks.  The XE block is completely
different with thicker main webs, main caps, walls, deck and valley.

Dan Jones