[DeTomaso] Dyno Testing Update - unported iron 4V head testing

Mike Thomas mbefthomas at comcast.net
Fri Jul 24 22:23:02 EDT 2009


Dan

Too bad you don't have a set of Mind Trains to add to your testing.  If we
didn't have a bunch of driving yet to do this summer or I'd pull and ship to
you.

Mike Thomas
Panteras Northwest 

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of Daniel C Jones
Sent: Tuesday, July 21, 2009 3:50 PM
To: Pantera REALBIG forum
Subject: [DeTomaso] Dyno Testing Update - unported iron 4V head testing

An update on the dyno testing.  We're currently testing the unported iron 4V
heads.  As a quick re-cap, we previously tested the CHI 3V aluminum heads
along with the Pro Comp copies.  Fitted with the Scott Cook dual plane
intake, the CHI 3V heads made right at 400 HP and 400 ft-lbs of torque (420
HP and 420 ft-lbs when corrected for the dyno absorber) through the
mufflers.  We had some trace detonation so backed off the timing a few
degrees which dropped the uncorrected HP to 395 (415 HP corrected).
Switching to the single plane CHI 3V intake manifold picked up 20 HP (436 HP
corrected).  The stock ANSA Pantera mufflers cost a whopping 50 HP compared
to the 3" inlet/outlet Magnaflows.

For the second round of testing, we replaced the CHI 3V aluminum cylinder
heads from Australia to the Pro Comp knock-offs from China.  We tested the
same intakes (Scott Cook dual plane and CHI 3V 4150 pattern single plane).
On the flow bench the Pro Comps were down considerably to the CHI heads and
this was backed up on the dyno.  The best pull with the Pro Comps was 378 HP
and 381 lbs-ft of torque (397 HP and 400 ft-lbs corrected).  What worked on
the CHI as far as timing (32 degrees) and carburetor spacer (4 hole 1 inch)
also worked the best on the Pro Comp heads.

For our third round of testing we switched to unported iron 4V closed
chamber heads.  Interestingly, the unported iron 4V's made better power than
the Pro Comps.  Fitted with a Holley Strip Dominator single plane and a 1"
HVH spacer, the 351C made 397 HP and around 380 ft-lbs (417 HP and 399
ft-lbs corrected).  The Parker Funnelweb was tested next.  It picked up
around 10 ft-lbs in the mid-range but was down about 6 HP at the peak.  An
Edelbrock Torker was tried next which performed about as well as the Parker
for HP and the Strip Dominator for torque.  The Parker worked best with a 4
hole 1 inch spacer, while the Strip Dominator and Torker prefered the HVH.
The final test for the evening was with the Torker intake manifold but with
the 1 3/4" diamter long tube headers and Magnaflow mufflers replaced by the
OEM 351C-4V cast iron exhaust manifolds and a short elbow of pipe (no
mufflers).  The result was 366 horsepower and 351 ft-lbs of torque
(uncorrected), a nearly 30 HP/30 ft-lbs drop!
The engine also sounded rather odd and the increased back pressure upset the
idle quality noticeably.  Combine this test with the muffler test, and it's
easy to see you can throw away a bunch of HP on a 351C with a poor exhaust.

Dave noted the 3.5" stroke 351C with iron closed chamber 4V heads required
more timing than the 4" stroke 408C strokers he's tested with the same type
iron heads.

Rather than mill and drill the unported iron heads for studs and guide
plates, we used the bolt-down roller rockers from Randy Malik at R.M.
Competition.  These are fully adjustable aluminum roller rockers
manufactured by Harland Sharp to Randy's specs whichare dedicated Ford
351C/351M/400/429/460 rocker dimensions.  Randy says they will withstand
spring pressures in excess of 475 pounds open and over 625 pounds open when
using the option Jesel bolts.  These rockers are not the old style flat top
Harland Sharp rockers and are shaped more like the Crane Gold units.

We've got a bunch more intakes to test with the unported iron 4V heads but I
thought it was time for a quick update.

Thanks,
Dan Jones
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