SB iron vs edlb. alum heads question

[DAVE JONES]

Hey guys, I need to get smarter here on why the edl. alum heads run so much better than ported cast iron ones. What I'm using as a comparision is info from Hughes. From his data charts, he claims that his stage 1 porting on sb iron heads are actually better than the alum Edlb. ones out of the box. Example:
I have the 587 castings now. If I go with his 725.00 stage 1 pkg which includes opening up my iron ones on the intake to 2.02 and exhaust to 1.62, they out flow the alum ones big time untill they hit a lift of .450 which is the same at 246.3 cfm and .500 which is 7 cfm higher. According to my 587 castings, the intake port volume is 170 cc and Ex is 75 cc. The alum ones have a intake port volume of 174 cc and ex of 80 cc. I would think that If I can get more flow while keeping the port volumes down , I would increase my velosity which I know is critical. I do know that the chamber size of mine is an open 73 cc and the alum ones is 65 cc but I would think that I could mill mine down to achieve the same chamber size to get the same compression. I'm sure that there are great differences in these heads and I should get alot more performance from them but I'd like to know why. I know that they will be lighter.....I know that there is a difference of 30 yrs of improved technology here (possibly port configuration)?, but why are these alum ones going to give me that much more HP and overall performance like everyone says. I'd appreciate you guys educating me.....thanks........DAVE

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[Streetwize]

Dave,

Your low and mid lift flow numbers are even more important than peak flow CFM on a street motor. Think about the fact that your valve passes twice through the low-mid numbers but only once through the peak lift. Also, visualize airflow in terms of say duration at .200" lift, .300" lift etc.
In the valve event, how long is the valve at (at least).200 lift compared to .500 lift.
Do you see why and how this is critical?
The cylinder fills and empties through the entire valve event.

As for combustion chamber size an aluminum head loses/dissipates more heat through the better thermal transfer properties of aluminum. What this means is you can usually (in fact, need to) run anywhere fron 1/2 point to over a full point of compression higher with an aluminum head to get the same effective compression (i.e., energy driving the piston down)as with an equivalent Iron head. The smaller CC of the aluminum head evens the score to some extent.

Of course, the later heads incorporate more efficient crescent shaped chambers that optimize burn rates within the cylinder. But the latest A engine magnum iron heads (as opposed to those designed 30+ yrs ago) have these features as well.

That ought to get the ball rolling!!!

Wize 1

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Streetwize

[montrose ram]

Aliuminum offers 3 advantges --(1)They are lighter(2) Allow you to run more compression(on pump gas) hence a bigger cam and (3)Have raised intake and exhaust ports and closed chamber/high swirl--these last cause the alluminum head to make more horse power--But thats on a dyno! As Wize says, on the street(cruising, etc.,)you would probably like the cast iron Hughes better! just my .02

[This message has been edited by montrose ram (edited December 09, 2000).]

[rumblefish360]

See if you can get a flow chart from Hughes. Then you could compare it against the Edel. heads. Bigger #'s aren't allways better.
Also the , the design of the chamber will help/hurt power levels as well. Depends on how well the gas is mixed from carb to cyl.
The heads have the air & fuel last and it could have a critical effect when looking for a specific.

[DAVE JONES]

The numbers that I mentioned before are from the Hughes comparison charts which I printed and compared Iron stage 1&2 and Edlb alum stock and stage 1&2. He has a nice setup at his site and for any iron or edlb. head, you can call up the flow numbers which is how I got my info. I would recommend that you guys look there if you're ever interested. So far, from what you guys and some hardcore locals are saying, based on my engine and my personal needs..(99% street) , it looks like the "re-done" iron may be the way to go. You may or may not remember my engine setup but I'm in the middle of it right now. The motor will be in a 69 barracuda. Its a 70(non TA) 340 bored +.04 with forged flat tops (mfg to be determinded). Cam is a Hughes Hyd .515/.535 with .237/.245 at .05. Stock refurbished rods. Forged crank ground -.02. Induction is
a 70 AAR 6 pack setup. Mopar el. stock but recurved dist(no vaccum, 16/36 totally in at 1850 rpm) with a MSD 6A box. Elec fuel pump. 727 with reverse manual valve body and 2800 stall, TTI headers and 3.91 gears (soon to purchase). Thats basically my setup which you can see is not wild by any stretch. It seems that If I was really going to go wild with my motor then the alum ones would offer better potential after modifiations but with my setup it doesnt seem that the extra
1,000 for the alum at stage 1 are warranted due to the fact that it doesnt sound like my motor would really be able to utilize what they could potentially do. Based on my additional info, do you guys agree that redone ported iron is the way I should go?. Thanks for your input and help again....DAVE


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[Leigh]

Dave,
Please don't be offended. That setup can use a stock 360 or 340 head, in my opinion. Those parts add up to off idle to 5500. Let us know how it goes. Take it easy.

[451Mopar]

I haven't seen flow numbers on the Hughes heads, but I suspect the Edelbrock heads flow way better on the exhaust side.

The stock iron small block heads flow really good at lifts below 0.450" on the intake side, even in stock form.
The draw-back to the stock iron heads is that intake flow stalls out around 0.480" lift, but porting can help a bit to where the head will continue to flow up to about the 0.520" to 0.550" range depending on the amount of porting.
The exhaust side of the stock head is the real weak spot. The port moves back from the valve seat right away and causes alot of turblance. Porting has a small effect, but installing a slightly larger "Tulip" head exhaust valve seems to work pretty good to help the problem (short of welding the port, and re-shaping it.) This is one reason I like Hughes, because they use an exhaust valve like the one described.

On the other hand, the Edelbrock head fixed the exhaust port flow problem in the casting and the flow numbers are very good.
Without the exact numbers, I suspect the Edelbrock head probbly flows 15% better on the exhaust side than the modified Hughes head.

Also, the aluminum head weighs less, and has better cylinder chamber design. This will allow more compression (and power) on the same octane fuel.
The Edelbrock head may have one draw-back in cold weather driving, there is no exhaust heat crossover. This is good for power, but in cold weather it may take longer for the intake manifold to warm-up. I don't see it as a big deal since aluminum transmits heat pretty fast, and with the aluminum head and intake manifold (with the bottom in contact with hot oil on the small block), the manifold should warm up fairly quick.

[J D]

[This message has been edited by J D (edited December 10, 2000).]

[montrose ram]

Originally posted by Leigh:
Dave,
Please don't be offended. That setup can use a stock 360 or 340 head, in my opinion. Those parts add up to off idle to 5500. Let us know how it goes. Take it easy.

Leigh--He may not be offended but I AM!! Just kiddin'! But why would'nt a non-stock set-up benefit from a non-stock up-grade? I think I see what you are saying in the RPM range he will be working in, but are'nt we also talking lift, i.e., the lift and flow will be greater even tho the rpm range is with-in stock parameters. Am I understanding you, correctly?

[Leigh]

Hey Ram,
First off, let me reinforce, I am NOT a head expert. I felt that the aplication will benfit from high velocity rates rather than larger than can be used gross flow. His combo is leaning towards more torque than hp. Streetwize's response makes alot of sense, the valve events hang out at low to mid lifts a greater % of the time and thus will benefit from increase velocity more than raw flow #'s incerase. Maybe if a quick opening, fast cyl. pressure rising cam is installed (much like a stock eliminater cheater grind), the combo can be "tricked" into using the extra flow. Heres the perfect place to insert this: "If the results don't mach your theories, always believe the results and invent some new theories." One of my favorites!

[DAVE JONES]

Great info so far guys. Leigh.....I take no offense to your reply at all. Thats why I'm asking questions and hearing opinions based on theory and actual application. I was playing with switching to a solid or roller setup. If I did, would this help if I went with the ported stage 1 iron or am I just adding some more crap to confuse the issue. I know that by using a mechanical I can build more power and I've heard that If I went with a roller setup that besides an increase in power, It is easier on the cam also. Is this true or Hype. The cam and heads are still an open issue that can be changed on a moments notice. Like I said earlier. I drive this on nice days only and its going to be 99% street. I'd like to make it a little "street hotter" if going to the different cam and iron ported heads would do the trick. The only reason I'm saying ported iron is that is sounds for my application that extra bucks for the alum wouldn't really be utilized. Give me some of your wisedom regarding me possibly changing my cam to a mechanical or roller....thanks again......DAVE

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[DAVE JONES]

Got some more info on the Alum heads. Per Dave at Hughes, after doing some more flow testing they are finding that the Edlb. alum out of the box are many times not flowing as per the specs listed and there is as much as a 20 cmf drop from 1 port to the next. He now is offering 3 levels of porting for these now including highly recommending to redust the seats. I just got this from him today and I wanted to pass this along.......DAVE

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[Nightri1]

Having to do a valve job on a new set of heads? Yes, sadly the one problem that Edelbrock heads suffer from is that they are cast fairly light. These heads could benefit from additional aluminum in the deck surface. I guess they are OK if you don't mind having them reworked more often than some of the heavier aluminum heads.