[DeTomaso] 4.6 update

[Dave Doddek]

4.6 Update

I finally got the 4.6 project done.  It is tuned and headed back home with
its owner.  Tuning went very well.  The SCT software to program the 4.6 was
easy to use and even allowed me to datalog the wide band O2 sensor along
with other data.  We took it to the dyno shop this weekend for a couple of
pulls.  We wanted to check for any odd spikes or dips in the hp curve and
test our muffler modifications.

The horsepower results were pretty good.  We started with a 285hp engine
stock.  No internal modifications.  We added long tube headers for the
Pantera, a home made blower manifold and an Eaton supercharger with a 5.5
lb pulley.  It made 284 hp at the wheels with 321 lbs torque at 3400 rpm.
Really good torque and at a nice low value.  Torque was above 275 lbs from
2000 to 5000 rpm.  The curves were very smooth with no areas to worry
about.  But what was most interesting was the horsepower curve.  Instead of
running up to peak and then dropping off like most engines, it went to 284
hp at 5000 rpm and just stayed flat till 7000 rpm.  I expect we could of
easily turned 7500 or 8000 rpm with the stock cams.  It would be neat to
see what would happen with a better bottom end and more boost.  I bet this
engine could easily make 400 at the wheels and turn 8000 rpm.  The engine
sounded great with no pops or cutouts.  

The computer was adjusted conservative with only 14 degrees of timing and a
12.5:1 fuel ratio.  Next summer we will see if we can bump it up and get
another 40 hp.  That will be over 300hp at the wheels and 400hp at the
crank assuming 25% loss.  Pretty good for a little engine.  Based on what I
have learned about these engines, They can make big power with a new
calibration and a good intake.  Factory intakes seem to cost more power
than exhaust especially when you can add long tube headers to a Mustang and
gain only 12 hp.

Since the HP curve did not drop off, we believe we fixed the mysterious
power loss with stock GTS mufflers.  It would be interesting to try this
same muffler modification on a Cleveland powered car and compare before and
after dyno results.  We also experimented with a plug in one of the exhaust
tips.  We inserted a tube about 8 inches long with a 1/2 inch washer welded
to the end into one tip on each side.  This makes the car just a little
quieter but greatly reduces the rumble at idle and certain rpms.  The dyno
showed we lost only 6 hp peak with the loss starting at 3000 rpm.

As a final note on comparison, the stock Cleveland made 194 hp at 5200 and
212 lbs torque at 4500.  This 4.6 actually makes more torque at lower rpm.
The Cleveland got 19mpg best at 60mph.  The new 4.6 today got 24.5mpg at
70mph.

But best of all, ITS NOT IN MY GARAGE ANY MORE!!!!!!!

Here is the dyno chart and a video of the pull.

http://members.aol.com/ddoddek/alandyno.jpg
http://members.aol.com/ddoddek/alandyno.mpg



Dave "wow, what a project" D