I dug up the Super Ford article mentioned earlier. It appeared in the
July 1988 issue and was titled "Small Block Intake Manifold Survey".
In the article they flow bench and dyno test 10 different intake
manifolds on a mild 5.0. The engine was a 1985 1/2 5.0 crate motor
fitted with factory shorty headers, factory Holley 600 cfm carb, stock
heads, and an SVO M-6250-A311 flat tappet camshaft. No clean-up was
performed on the intakes. The carb and ignition were also left alone.
The intakes tested were:
Intake Peak Flow Flow
HP Center End
Port Port
Offenhauser Tunnel Ram 213.1 196 196
Stock Ford 215.1 160 176
FPP Tiger 215.5 184 172
FPP Cobra 231.0 192 190
Edelbrock Performer 233.7 201 180
Holley Street Dominator 233.9 191 183
Edelbrock Torker II 234.7 211 207
Weiand Tunnel Ram 236.7 196 196
Weiand 7515 X-Celerator 240.9 203 188
Offenhauser Port-o-Sonic 241.6 207 201
The Offy Port-O-Sonic pulled the highest peak horsepower but the
Weiand X-Celerator had more area under the curve, generating more
power at each test point from 3000 to 5500 rpm, except at 5000 rpm.
The Port-O-Sonic apears to be slightly taller than the X-Celerator
but it's hard to tell fronm the pictures. The Torquer II and Street
Dominator were down across rev range, compared to the Offy and
Weiand single planes. Note that the plenums on single plane intakes
are intentionally under-sized on the assumption it's easier to add a carb
spacer than it is to mill a manifold. The tunnel rams were run with a
single carb plenum adapter.
The FPP Cobra was the only high rise dual plane tested. The Weiand
Stealth and Edelbrock Performer RPM were not yet introduced when
the article was published. Surprisingly, the Performer did slightly
better than the Cobra. I'd expect the RPM and Stealth to turn in a
better showing. If you're considering the Stealth and RPM, I've heard
the Stealth has larger volume runners and plenum and is somewhat
better at higher rpms than the RPM.
I would have liked to have seen this test with a more highly tuned
engine. I believe the differences between the manifolds would have
been more clearly established that way.
Dan Jones
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