Since we were changing heads, we
opted for aluminum. Not only is aluminum tremendously
easier to port, but we'd offset some weight we had added
in the way of a steel bellhousing and planned roll cage.
Even though the World Jr. comes out of the box with a
59cc combustion chamber, compared to the 64cc chamber
volume of the Sr. head, we'd actually see no gain in compression
ratio due to the material removed by TEA to reduce shrouding
and increase flow.
Total Engine Airflow performed their Stage 2 porting and
chamber reshaping on our World Jr. heads. The end-results
were phenomenal, with roughly an average gain in flow
of 30% all across the lift range.
 |
World Jr. combustion chamber, out of the box with
1.94" intake and 1.60" exhaust valves.
Note how close the edge of the chamber is to the
intake valve. Compare to the image above, where
TEA removed considerable material to reduce shrouding.
|
 |
This is the combustion chamber from the World Sr.
heads. Note here the intrusion of the valve guide
bosses and the ridge in the exhaust port just below
the valve seat. |
 |
The valve is the largest obstruction to flow in
any head. TEA not only increases flow past the valve
by reducing shrouding, but they also experimented
with different valves. They found considerable gains
in mid-lift flow on the intake side, by simply changing
to a different valve! (see graph 3 below) |
|
Results:
TEA's ability to increase flow on the intake side by over
30%, without compromising low lift flow or velocity shows
why they are the choice of top racers. Many inexperienced
"porters" will remove too much material in the
wrong places. Removing material will always increase flow
eventually, but typically at too high of a lift and at
the sacrifice of low end flow. A street car with a half-inch
lift cam gains nothing from 40 additional cfm at .600"
valve lift.
Graph
1: World Windsor
Jr. Intake flow before and after. |
Graph 2: World
Windsor Jr. Exhaust flow before and after. |
TEA likes to be very methodical when it comes to exhaust
side modifications. Brian believes that a little exhaust
work goes along way, but too much can quickly rob horsepower.
He tries to maintain exhaust flow at 70-80% of intake
flow, and felt the 1.60" valve on most aftermarket
Ford heads is too big. He is also quick to point out that
Winston Cup cars typically use a 1.58" exhaust valve.
Graph 3: World
Windsor Jr. 1.94" Intake valve comparison.
|
Graph 3 compares 1.94" intake
valves supplied by World (manufactured by Manley) to the
valves carried by TEA (Ferrea valves.) The TEA valves
improved flow from .100" all the way to .450"
lift, with a gain of over 23cfm at 0.200", due simply
to a different valve! The TEA valve did give up about
16 cfm at .600, however since our cam is in the .560"
lift range, there is no downside. The increased mid-lift
flow calculates to a greater average horsepower.
The end result is an astounding gain in flow of 30% average
across the lift range. Assuming the rest of the engine
is matched to take advantage of this flow (better intake,
cam, and carburation) this sort of airflow may yeild as
much of a gain in horsepower. Watch for future articles
where we bolt these heads to a project motor and get dyno
and track data.  |
|
| |
|
|
The as-cast Windsor Jr. exhaust
port is not only irregular in shape, but note the casting
flash and ridges on the walls. Gas exit would undoubtedly
be turbulent and obstructed with this port. |
| |
"The objective is to get
mid-lift airflow as big as possible. Peak flow numbers
are not important." -Brian Tooley, TEA |
|
Intake
Flow Results:
| valve
lift |
Before |
After |
gain |
| .100" |
66cfm |
61cfm |
-5 |
| .150" |
92.8 |
95.4 |
2.6 |
| .200" |
119.2 |
129.8 |
10.6 |
| .250" |
137.6 |
162.8 |
25.2 |
| .300" |
155.9 |
195.8 |
39.9 |
| .350" |
172.0 |
219.5 |
47.5 |
| .400" |
188.1 |
243.2 |
55.1 |
| .450" |
196.2 |
256.7 |
60.5 |
| .500" |
204.4 |
270.3 |
65.9 |
| .550" |
207.9 |
274.0 |
66.1 |
| .600" |
211.4 |
277.7 |
66.3 |
|
| |
Exhaust
Flow Results
| valve
lift |
Before |
After |
gain |
| .100" |
59.9 |
60.1 |
.2 |
| .150" |
88.3 |
95.7 |
7.4 |
| .200" |
116.7 |
131.2 |
14.5 |
| .250" |
128.0 |
150.8 |
22.8 |
| .300" |
139.3 |
170.4 |
31.1 |
| .350" |
147.4 |
186.1 |
38.7 |
| .400" |
155.6 |
201.8 |
46.2 |
| .450" |
160.9 |
210.3 |
49.4 |
| .500" |
166.1 |
218.7 |
52.6 |
| .550" |
171.4 |
225.1 |
53.7 |
| .600" |
176.6 |
231.5 |
54.9 |
|
| |
Intake
Valve Comparison Flow Results:
| valve
lift |
World
1.94" |
TEA
1.94" |
gain |
| .100" |
61cfm |
69.9
|
8.9 |
| .150" |
95.4 |
111.6 |
16.2 |
| .200" |
129.8 |
153.3 |
23.5 |
| .250" |
162.8 |
181.9 |
19.1 |
| .300" |
195.8 |
210.5 |
14.7 |
| .350" |
219.5 |
230.4 |
10.9 |
| .400" |
243.2 |
250.3 |
7.1 |
| .450" |
256.7 |
258.7 |
2 |
| .500" |
270.3 |
267.1 |
-3.2 |
| .550" |
274.0 |
264.5 |
-9.5 |
| .600" |
277.7 |
262.0 |
-15.7 |
|
| |
Sources:
Total Engine Airflow
915-A Lovers Lane
Bowling Green, Kentucky 42101
(270) 782-6397
World Castings
35330 Stanley
Sterling Heights, MI 48312
810-939-9628 |
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