Good "thowdown" thread on 428cj-C 428cj-A and 428pi intakes

[WerbyFord]

This started out as a thread on intake weights but evolved into the old "428cj vs 428pi" intake battle.
I learned a lot in terms of reconciling what all folks have seen over the years. TGFEIC was mentioned a lot of course as well as Muscle Parts, which has less data than TGFEIC but makes up for it with way more groovy colors. And that book is only $1.00. Oh wait.

Does anybody really know how the tests were done in Muscle Parts, which data are real and which are ballparked?

http://www.network54.com/Forum/74182/thread/1518317635/last-1518584028/View+Thread

[Katz427]

The only thing I can tell you is supposedly at the time much of the testing was done on one of the Autolite division dynos.   I can't verify that now, Probably  John V is one of the few left with us with any insight.

[Joe-JDC]

I know that when I was finishing up my Automotive degree back in '70s I used my '66 Fairlane as the chassis dyno test vehicle, and I swapped Ford carburetors just like the Muscle parts book said, and got exactly the same horsepower increase they said the change would net.  That is also where I got the information to swap the PI for a 6 hp increase over the CJ iron intake.  In spite of what everybody has said on the FE forum, I did see an improvement, and I have seen ported intakes pick up 35lb/ft torque with the PI over race prepped iron CJ.  It all comes down to how, and who does the work.  Stock Eliminator racers have been using the PI vs the CJ iron for years with great success.  Joe-JDC

[jayb]

The testing done for my book shows that in nearly every case, the cast iron CJ intake was better than the PI intake.  Even when both intakes were ported, the CJ intake came out on top in most cases.  However, in a lot of cases the difference was fairly small.  For example, on my +/-500 HP 390 stroker engine, the unported PI intake made 478.4 peak HP, 498.9 peak torque, 400.6 average HP (3000-6000 RPM), and 470.7 average torque.  The unported CJ intake on the same engine made 480.0 peak HP, 503.3 peak torque, 402.9 average HP, and 473.4 average torque.  So, a few HP and foot pounds of torque advantage goes to the CJ manifold.  Compare that with the 50+ pounds of weight savings that the PI intake offers, and its clear why Ford recommended going to the PI intake for racing use.  On the other hand, on the +/-375 HP Thunderbird engine, the CJ intake was up 12 HP over the PI, which would certainly be a noticeable difference.  On the 428CJ engine, the CJ manifold's advantage dropped to about 5 HP.  It seems that in unported form, the CJ intake's advantage got smaller with more horsepower, again making Ford's recommendation sensible for a racing engine - Jay

[manofmerc]

My 2 cents for what it is worth .I owned a 69 cylone 428 cj for 36 years .3.00 rear very mild convertor ex manifolds .In the 80s I found a nice pi manifold .Swapped it on there and was happy .My iron cj manifold sat around until I realized my car would be worth more with it instead of the pi. Well again another intake swap thinking I was going backward .NOT you could feel the additional torque and even in the midrange it felt stronger . But like Jay said the cj intake probably works better with a milder combo like mine .I did a freshen up in 2012 hyd. cam 218@.050 527 lift new eagle rods and most Importantly zero decked the block .With my cj intake and 735 carb with the yellow secondary spring it was really strong from low up into second (c6) .And got reasonable gas mileage .I sold my cyclone last year I miss it and that 428 taught me so much about FEs .One thing being that iron pig of an intake isn't so bad after all .Doug