DeTomaso Mailing List: May 99, Message #110

Anyone see the 351C versus 351W article in the May issue of Mustang 
Monthly?  It held some promise but they managed to muck it up by not
knowing how to build a Cleveland.  While the 351W engine tested is a 
reasonable selection of parts (essentially an Edelbrock Performer RPM 
package with a bigger hydraulic roller cam), the Cleveland engine is 
not.  They saddled the 351C with a low rise Edelbrock Performer intake 
manifold but allowed the 351W to use a high rise Performer RPM.  A 
Weiand Xcelerator would have been a much better comparison.  They chose 
Aussie closed chamber 2V heads but use dished pistons (from what I can 
gather from the pictures - no compression ratio is given), ruining 
the quench effect which is the whole reason for using the Aussie heads.  
Then they cam it all wrong.  The hydraulic roller cam specs out at 246/256 
degrees duration @ 0.050" lift, 0.560"/0.585" lift and an LSA of 108 
degrees.  That's way more cam than the intake and compression can 
support.  Furthermore, the big lift is wasted on the 2V Aussie heads, 
which start leveling off after 0.500" or so.  The cam also has a wide 
dual pattern meant to crutch up a 4V head's poor intake-to-exhaust 
flow ratio.  With an excellent exhaust port, 2V heads have a good flow 
ratio and don't need a wide dual pattern.  Given that they chose to 
install 4V valves, the heavy hydraulic roller lifters will probably 
limit rpm to 6200 rpm or so.  I also question whether or not the 4V 
valves do anything for flow without extensive porting.  No dimensions
are given but they state the the headers are different.  No information
is given on carb calibration or ignition curve but they do state an 
Edelbrock 700 cfm carb was used.  I assume they meant 750 cfm, since 
Edelbrock doesn't make a 700 cfm version.  They also only made one 
pull per engine.  No tuning whatsoever but they claim they will make
more runs in a later issue.

Even with all the mismatch, the Cleveland was able to make within 6 hp 
of the Windsor if the numbers are to be believed.  However, if you look 
at numbers printed:

             351C     351W
   RPM      HP  TQ   HP  TQ
   4500     348 410  373 409 
   5000     380 389  390 369
   5500     384 357  386 320
   6000     376 319  366 266

they show the Cleveland making more torque at every point above 4000
rpm but making less power.  Last time I checked that was impossible
since horsepower is a direct function of torque and rpm.  Damn magazines.  
FWIW, the relationship between torque and horsepowe can be expressed as:

   HP = (TQ*2.0*PI*RPM)/33000.0
or
   TQ = (33000.0*HP)/(2.0*PI*RPM)
 
where:
 
   TQ  = torque in ft-lbs
   HP  = power in horsepower
   RPM = engine speed in revolutions per minute
   PI  = the mathematical constant PI (approximately 3.141592654)
   Note: 33000 = conversion factor (550 ft-lbs/sec * 60 sec/min)

They also instruct the reader to use a "copious line of of RTV" instead 
of the rubber end seals.  While I don't like the rubber seals either,
loading it up with RTV is bad too.  When you torque down the manifold,
the RTV has to go someplace, most likely into the oil supply so it can
stop up the lifters or pickup.  Cork gaskets, a peened surface, and some 
contact cement or gasket sealer is the way to go. 

I question their selection of parts as well.  The Windsor was totally
aftermarket - SVO crank and block, custom pistons and rods, etc.  All
for a motor that peaks at 5000 rpm.  There's a bunch of other stuff 
wrong with the article but the above will do for starters. 

Dan Jones