Well I took a crack at the FE Head Comparo with the Gonkulator.
I chose 2 engines. Both are pretty well wrung out on the Gonkulator-vs-Dyno scale so I trust them.
Of course, swapping heads does introduce Gonkulator uncertainty, but most of these heads have some dyno data support too.
And the comparison is free!
1. Bone stock 428CJ
2. 492 Stroker from Jay’s TGFEIC series with port matched Vic Dominator intake.
These cover the range from 380hp to 650hp so you can see the effect of swapping heads on the range of engines most of us would build.
I’ll compare the common iron heads, the Edelbrock, and a modern average called the Goodhead:
• C4AE-G et al stock (C1AE-A, B9AE-B, C6AE-R similar) 352, 390, 390PI, 390GT, etc. 1959-1966
• C4AE-G with 2.09 and 1.66 and ported exhaust roof, aka “poor mans CJ” heads (C6AE-R similar)
• C8AE-H stock, D2TE-AA similar, 390GT, 410, 7-Litre, 390IP, trucks, etc. 1968-1976
• C8OE-N stock 428CJ 1968-1970
• And the “ultimate” head of not so long ago, the box-stock Edelbrock. I’m using the more recent 21st century version, though the late 1990s heads showed better flow numbers.
• Finally, I lump together 6 sets of modern good heads. Think of Dr Goodhead from James Bond’s Moonraker.
Goodhead is the 6-way average of:
• TFS head
• BBM head
• Survival head
• Survival CNC head
• Edelbrock Stage 3J (a little better than Stage 3, this was Jay’s prep for the TGFEIC 492 stroker)
• Blair’s Pro Port
Since these 6 heads are all pretty doggone good but are all being sold by some of the great vendors that now support the FE, I didn’t want to get into a pissing contest between them as it could be so easily misleading. So I’m just averaging all 6 and calling that average Dr Goodhead. Fair enough?
In each case, for brevity (as if!) I’ll just list
• Peak Torque
• Peak Horsepower
• Ponies, the metric I like, which is the average of the two. I find Ponies correlates quite well with performance of a street car and wide gear spreads of the old 3 and 4 speeds we used to be stuck with back in the day.
• Delta Ponies vs the Base Case 428CJ iron C8OE-N heads
Stock 428CJ engine including iron exhaust:
Torq Power Ponies Delta
459 346 398 -27 C8AE-H stock
458 360 406 -19 C4AE-G stock
472 377 422 -3 C4AE-G 2.09 x 1.66 & port roof “poor mans CJ”
476 380 425 xxx C8OE-N 428cj BASE CASE stock 428CJ as FoMoCo built them
484 387 433 +8 Edelbrock 21st century heads. At least they’re lighter.
512 421 464 +39 Dr Goodhead, average of 6 modern heads
Jay’s TGFEIC 492 stroker, port matched Vic Dominator
Torq Power Ponies Delta
516 504 510 -42 C8AE-H stock
521 522 521 -31 C4AE-G stock
538 563 550 -2 C4AE-G 2.09 x 1.66 & port roof “poor mans CJ”
542 563 552 xxx C8OE-N 428cj BASE CASE
552 594 572 +20 Edelbrock 21st century heads. Better but see below.
585 641 612 +60 Dr Goodhead, average of 6 modern heads
My conclusion is, if you have a good set of C4AE-G etc (or even C8AE-H) and can modify them cheap, and they don’t need serious machine shop money, a set of Poor Mans CJ heads is a good goal. Otherwise jump up to the 1990s-era Edelbrocks (at least).
If you have a decent set of 428CJ heads, don’t bother with the old-school Edelbrocks bos stock. Not much gain.
The real gains show up with any of the Dr Goodhead selections (that makes it easy to remember doesn’t it?)
This is a 9% gain in Ponies on a “mild” 380hp build, and an 11% gain on a 650hp build, vs 428CJ iron which is pretty good already.
A stroker kit picked up about 8% Ponies on a 428CJ level build, which, cost wise, is about in line with the Dr Goodhead average cylinder head gains.
Sure, cams or compression will add Ponies cheaper, but they can make the engine impractical too. Stroker kits or Heads are a good comparison because they don’t really affect streetability. Of course the tradeoff is they cost more than cams or compression or NOSS.
I hope this helps a little, at least food for thought.
The other problem with a dyno head comparo is, as mentioned, compression ratio and/or piston shape would change with each head swap. In the Gonkulator, all that stuff “magically” stays constant. Gonkulator gaskets can also be re-used multiple times – I don’t think I’ve ever changed gaskets in the Gonkulator, except for when Microsoft does an “automatic Windows 10 update”. Ugh.
For fun, I tried a few more different cylinder heads on the TGFEIC 492 stroker engine.
In the Gonkulator, with a few iffy assumptions such as imagining that the valves will somehow fit down the bore, and more trivial issues like bolt pattern and gasket seal, we can try heads from different engine families onto the FE. Here are a couple heads from the Lima Ford and the Rat Chevy, to compare to the FE offerings.
Torq Power Ponies Gain
560 557 558 +6 429SCJ Lima iron, very little gain vs 428CJ iron because exhausts are so bad.
618 684 650 +98 Kaase P-51 Lima heads. Box-stock Lima heads have come a long way since 1970.
568 617 592 +40 L72 Rat iron vintage 1966. It does help when the exhaust can get out.
620 677 648 +96 AFR305 Rat, among the best of newer box-stock Rat heads.
558 611 584 +32 FE HiRiser vintage 1964. The HiRiser was a good competitor to the Rat (and held together better).
Why was the 427 HiRiser head so good, and the 429SCJ head, 6 years later, so bad? Did Ford forget everything?
Notice I refuse to refer to the Lima as the “385 Series”. That name is about as silly as when FoMoCo was using those GM-style 5750062 part numbers back in 1959. Does anybody talk about the “335 Series” ever? What was THAT going to be, anyway?
Notice also that the Lima vs Rat battle looks about equal these days, except that the factory iron Lima block can be built to a lot more inches than the little Rat motor. If only I’d had todays Lima heads back in the disco era!
