[Stan Weiss]

First pull..OK so here’s the specs 455 .030 over with Iron d-port heads 114 cc chamber. Made 370 hp. 470 pounds torque.

Second pull, Edelbrock D-Port heads heart shape chamber . No other changes just bolt heads on right out of the box. 450 hp and 515 lbs torque

So 80 more hp 45 lbs torque!

Note that’s with cheap 3 tube header. Not bad for out of box heads.

Saw this on another web site. Has anyone seen this much HP increase from just a head swap? Yes I know it is not apples to apples as the Edelbrock heads had to have increased the CR

Stan

[25stevem]

I would like to see the details of the Cam used and the exact Iron D port casting used, but I could see it happen, especially if for instance the heads used where the 5C casting with there 2 CC on average smallee port size as compared to any other iron head with a 2.11" valve .

And in terms of port volume also due to the port air speed with 455 CID under the heads!

When go and look at this just by sheer numbers I find that producing 370 hp took 181 cfm@28" per cylinder out of a head that flowed 200 to 205 CFM.

To make 450 hp took only 228 CFM@28" per cylinder out of a head that out of the box flowed about 260, maybe a tad more.

Another major advantage to the aftermarket head is the Heart shaped combustion chamber over the D port head.
The better pressure recovery of the intake flow can stack on a easy 20 hp all on its own even in a non racing built motor!

Just to note 230 CFM@525" lift can be had out of a 670 casting with the right valve job and a very light bowl blend in the right places.

[Cliff R]

Yes, I've witnessed first hand TREMENDOUS improvements in power by changing just one part, cylinder heads included.

Back when I did the KRE head testing and resulting HPP and Popular Hot Rodding Engine Masters articles we replaced my 232cfm 6X-4 heads with out of the box KRE aluminum "D" ports and picked up over 40hp. The testing was backed up by track runs a few days later and we saw a nice improvement at the track as well.

https://www.motortrend.com/how-to/05...-dyno-results/

https://www.motortrend.com/how-to/05...track-results/

As for this head swap compression is your friend with these things, plus added air flow. For the test we did compression was increased less than half a point. When you do both plus a much more efficient combustion chamber one will be nicely rewarded with more power at every RPM (torque), plus a nice improvement in upper mid-range and top-end power........

[Formulajones]

Yep, and not just on Pontiacs. I've seen similar results upgrading to a nice cylinder head over an OEM piece on other engines as well.

[PAUL K]

We usually see 60-80 hp going from a standard port Edelbrock head to our off-set pushrod E-heads and the compression ratio isn't changing.

[Cliff R]

Take your average SBC 350 engine build. Remove the POS "882" casting heads your uneducated "builder" just ported the piss out of and dumped a bunch of money into and bolt on a set of World Products Sportsman heads. Toss the thick "builder" gasket they used and put in a .020" shim at the same time. Make no other changes. The increase in compression going from 76cc crappy chambers with a big thick head gasket to 64cc modern chambers plus 165cc intake runners to 200 will make a BUTT-LOAD more power at every RPM without any other changes. Now you woln't have to drop your vehicle off a floor jack at WOT to do a burnout.....it will ROAST the tires right off of it just stabbing the throttle pretty hard!........

[i82much]

Not to brag, but I have accomplished this simply by adjusting my throttle cable after realizing my secondaries were not opening ...

[PAUL K]

Originally Posted by i82much

Not to brag, but I have accomplished this simply by adjusting my throttle cable after realizing my secondaries were not opening ...

We did that at the track once and the car ran exactly the same!


So you need numbers to back that up

[PAUL K]

Hopefully the builder is a member here and he will chime in with the details.... And maybe share the dyno sheets

[Formulajones]

Originally Posted by PAUL K

We usually see 60-80 hp going from a standard port Edelbrock head to our off-set pushrod E-heads and the compression ratio isn't changing.

I remember Tony talking about moving the pushrods on Dad's E-heads for more flow. I don't recall what he said the gains would be but at that point in the process I think the cost was a factor. l like all that sneaky stuff

[25stevem]

I have found that in terms of a race only 14.5 comp motor that to limit power enough to keep a car from dropping into a faster class that the carb ( in this case a Dominator) had to be closed down by 25%!

[ta man]

I picked up 150hp to 175 hp with a head cam swap. mild ported 6x heads 041 cam to SD KRE 290 cfm heads and OF cam...

[grandam1979]

He didn’t say what cc of aluminum heads are but it probably jumped at least 2 points of compression with the head swap so not surprising at all it picked up that much.

[scott70]

Originally Posted by ta man

I picked up 150hp to 175 hp with a head cam swap. mild ported 6x heads 041 cam to SD KRE 290 cfm heads and OF cam...

Dports? Same intake and which one? Compression difference? Mild ported 6x,,,,like 220-230?Ive read some of your threads but dont remember the details.

[tom s]

I think it was 117 cc irons and 72 Es so big CR increase along with flo.Tom

[25stevem]

I don't understand why this is so hard to believe?

Just take for example the 1967 290 hp 400 motor with a 4 bbl and the 061 heads, now look at the 1968 RAII motor .
This was rated at 360 hp, yes it had a bigger Cam, but the 096 heads still used standard D port sized Intake ports !
Even if you know like I do that Pontiac may have exaggerated the hp number, I say ok, so let's say the RAII is 350 hp for the sake of discussion.
That's still 60 hp more then the 290 hp 400!

[ta man]

Originally Posted by scott70

Dports? Same intake and which one? Compression difference? Mild ported 6x,,,,like 220-230?Ive read some of your threads but dont remember the details.

I don't think I have this swap on any threads...I did have my last head cam swap on a thread a few years back.

Same intake carb headers went from 9 to 1 to 10.25 to 1.

Cam made huge difference to compliment the heads

went from .517 lift with mild heads 230cfm ? to approx .650 lift with 290cfm head flow

[Stan Weiss]

Originally Posted by 25stevem

I don't understand why this is so hard to believe?

Just take for example the 1967 290 hp 400 motor with a 4 bbl and the 061 heads, now look at the 1968 RAII motor .
This was rated at 360 hp, yes it had a bigger Cam, but the 096 heads still used standard D port sized Intake ports !
Even if you know like I do that Pontiac may have exaggerated the hp number, I say ok, so let's say the RAII is 350 hp for the sake of discussion.
That's still 60 hp more then the 290 hp 400!

Steve,
If you could only make 1 change to the '67 290HP 400. Would it be the '68 RAII heads or '68 RAII cam?

Stan

[25stevem]

The Cam.

[Gach]

It’s a build for friend, I talked him out of going with LS motor he wanted to make 500 hp. Here’s some information

His heads 114 cc chamber heads.. compression was 8.2 if I calculated it correctly. With E-Heads it’s now closer to 11.1. #96 heads. Didn’t know they made them with 114 cc chamber, I checked them with Borat (sp)

So your talking close to .3 more compression I’m guessing those iron heads flow 190 cfm and E-heads are say 260-270. So 60-70 more cfm. So it actually made 73 more hp he posted number wrong.

That was with his Lunati 1051072 cam. Don’t laugh And 3 tube headers
The latest change went with Comp cam BP6014SP and 4 tube headers 1-7-8”
Cam pick up 16 hp, and 1# torque. Headers pick up whopping 25 hp for total of 491 hp. The intake is a Edelbrock dual plane with the divider cut down, and it’s a Holley 850. With 1” spacer that fits under the hood.

After messing with timing and jetting it it end up making 502 hp at 4900 rpms

I’m blown away, says you can easily make 500 hp with nice stock block and bolt on out box heads. He’s super happy. My cam choice would’ve been Crower 60919 cam