Reply to "Got a Blue Thunder Intake Laying Around?"

> The Blue Thunder and the Holley Strip Dominator are hands down the two
> favorite street intakes amongst Clevo enthusiasts, and have been since
> the '70s.

Out-of-the-box, the Holley Strip Dominator out-performed the Blue Thunder
by a wide margin during our last dyno test. We tested a ported Ford
aluminum dual plane (the over-the-counter version of the Boss 351 intake
with Holley carb pattern), Edelbrock Torker, Blue Thunder and a Holley
Strip Dominator. Unexpectedly, The Blue Thunder performed worst and was
down 45+ HP to the Strip Dominator.

The engine was a street 408C (10:1 compression, hydraulic roller cam
peaking around 5500 RPM) and tests were conducted through the GTS headers
and Magnafow mufflers on 93 octane). With the unported Blue Thunder dual
plane, it made 437 horsepower and 463 ft-lbs torque, at 5500 and 3900 rpm
respectively. Adding a 1 inch open spacer to the Blue Thunder helped the
torque about 6 ft-lbs but horsepower stayed the same. The ported Boss 351
intake made 468 horsepower at 5500 rpm and 486 lbs-ft at 4500 rpm. The
Holley Strip Dominator with a one inch spacer made abother 15 HP, peaking
at 5600 RPM. The torque curve with the Strip Dominator was smoother,
likely due to the long runners of the Boss dual plane going into and out
of tune. On a subsequent test, Dave found the Strip Dominator intake
liked a 4 hole 1 inch spacer better than an open or fancy HVH spacer,
at least with his dyno carb. That engine was identical to the 408C we
tested except it had more cam (best pull so far has been 510 HP at 6300
rpm and 481 lbs-ft at 4600 rpm).

Like the Ford Boss 351 dual plane intake, the Blue Thunder responded
with a big improvement on the flow bench with just plenum area work.
As with the Ford intake, Dave concentrated on bringing up the worst
runners to match the best. However, the pattern of the Blue Thunder
good versus bad runners was completely different than the stock Boss
intake. On the Blue Thunder intake, the good and bad runners were on
both the top and bottom planes. On the Ford intake, the top runners
were all much worse than the bottom ones. After porting, the worst
Blue Thunder runners are the top front ones, number 2 and number 5 but
they both out flowed the best runners of the unported intake. A typical
runner went from 250cfm to 276cfm. The resultant numbers are a fair bit
better than the ported Ford intake so we'd expect better dyno numbers
but did not get a chance to dyno the engine with that intake (it's
on a 393C in Mike McDougal's 1972 grabber blue Pantera). The flat pad
Blue Thunder did not fit under Mike's early style flat engine screen
with a drop base air cleaner but might clear with a later style screen.

Though it performed best, Dave also thought the Strip Dominator would
benefit from some plenum entry work.

Dan Jones