Reply to "B. Goyaniuk's motor questions"

Jack,

I think I may have been the guy that provided the Blue Thunder intake
for your test. If you're the guy I'm thinking of, you ran an Offy
360 intake that had the lower portion of the ports filled with epoxy.
A piece broke off, destroying the engine which led to your new (at the
time) 377. IIRC, your compression was in the 10.5:1 range, the cam
was a solid lifter flat tappet of around 0.6" lift with 108 lobe centers.
I forget the duration. Was it in the 240 degree range? I recall you
testing one a 650 Holley and a Willy's modified 950 HP carb, along with
Blue Thunder, Offy 360 and Edelbrock Performer intakes. What was the
other intake?

Correct me if I'm wrong but I think you ran all the tests with the MPG
intake port plates in place. The smaller ports of the Edelbrock Performer
intake match up better with the port plates than the other intakes with 4V
sized ports so that probably affected the results. As I recall the Offy
did quite poorly, down maybe 40 or 50 HP to the Blue Thunder. The Edelbrock
was surprisingly close to the Blue Thunder. The Blue Thunder did best but
the margin between it and the Performer wasn't as large as expected. My
guess at the time was this was mainly due to the presence of port plates
which helped the Edelbrock but hurt the Blue Thunder, relatively speaking.
The 650 carb was too small for the engine and switching the Willys 950HP
was worth a bunch of power (as much as or more than the difference between
the worst and best intake manifolds).

We just finished up a dyno test of a 408 cubic inch Cleveland using that
very same Blue Thunder intake. Surprisingly it faired poorly and was the
worst intake tested. Going into the test, I would have guessed it would
have been the best match of the three intakes we tested. The engine is
a street motor with a mild hydraulic roller cam (232/236 deg @ 0.050",
0.609"/0.621", 108 LSA). Glen wanted to retain the Ford low rise dual
plane intake which we suspected would hurt power. The flow bench backed
up our suspicions as the heads alone peaked at 322 CFM @ 0.6" but with
the intake in place, some of the runners were down in the 258 CFM range.
The engine builder spent some time bringing up the worst flowing runners
to match the best (in the 275 CFM range) and that seemed to help a bunch.
Surprisingly, the ported Ford intake (with 1" spacer) bested the Blue
Thunder by a bunch. Running through mufflers, on Mobil 93 octane premium,
the best pulls came with 28 degrees timing. With a 1" spacer, the reworked
Ford aluminum intake and dyno carb (950 Holley HP) made 468 horsepower at
5500 rpm and 486 lbs/ft at 4500. It was a cool day and the air density
ratio was very good, 98.17% for a 1.0238 correction factor. Air temp was
56 Degrees F, humidity 36% and abs baro 29.26 in Hg. Very good conditions
for the 1100 ft altitude. BTW, Dave's dyno was tested against a DTS and
is about 4% conservative. Our dyno pulls were from 3000 to 6000 RPM and
the engine made 440 or more lbs/ft from 3100 to about 5600rpm. After that,
the engine drops off (probably needs more cam duration). The unported
Blue Thunder made 437 horsepower and 463 ft-lbs torque, at 5500 and 3900
rpm respectively. Adding a 1" open spacer to the Blue Thunder helped the
torque about 6 ft-lbs but horsepower stayed the same. The builder thought
the Blue Thunder would do better if it was ported like he did with the
Ford but we tried a Holley Strip Dominator single plane, instead. It
picked up about 15 HP with similar torque. The HP peak rpm moved up only
slightly, maybe 100 RPM and the torque curve with the Strip Dominator was
smoother, likely due to the Boss dual plane going into and out of tune.
The engine builder eyeballed the Strip Dominator and thought it would
benefit from some plenum entry work. Cammed for more RPM, the Strip
Dominator would likely do even better. We also tested a Torker and it
did pretty well, giving up only a few HP to the Strip Dominator. A 750
DP carb lost about 10 HP to the dyno carb.

We baselined the engine using a borrowed set of Hooker Competition headers
(probably part number HOK-6920HKR) with 1 3/4" diameter by 27" long
primaries, 3" diameter by 8" long collector with 12 inch long collector
extensions and 3" inlet/outler Magnaflow stainless steel mufflers.
They were tested against a set of Euro GTS mufflers and matching GTS
headers from the Pantera Performance Center in olorado. The GTS headers
are often refered to as tri-y's but are, in fact, 4-into-1 headers with
short tri-y collectors. Like most under-car Pantera headers, the primaries
are very short. The collector is also quite short and relatively small in
diameter, though the primaries are large (2" diameter) and matched the port
better than the Mustang headers. They also don't bend down at the head
port exit like the Mustang headers. The GTS headers did pretty well.
Compared to the Mustang long tubes, the GTS headers with a collector
extension was a near match. Without the extension, they gave up some
torque but were close on HP. The GTS mufflers, on the other hand, were
terrible and lost something like 50 HP compared to the 3" inlet/outlet
MagnaFlows. Though the body of the GTS mufflers is short the tips are
very long so the overall length was a bit more than the much less
restrictive MagnaFlows. It looks like the MagnaFlow muffler will fit
under a Pantera and they make a version with 3" inlet and dual 2.5" outlets
which would retain the quad tip Pantera look. Given that the diameter of
GTS collector outlet (looked like 2 1/4" or 2 1/2" ID, I forget to measure
it) is much less than the 3" pipes we used, it's possible a set of 2 1/2"
pipes might not lose any power compared to the 3" pipes. Something to
test on a future dyno session, perhaps. Glen likes the look of the GTS
mufflers and plans to gut them to get backsome of the lost power.

Dan Jones