Aluminum heads $ per HP?

[abdywgn]

Out of the box,bolted on to existing short block,with any special pieces needed to work,what is the dollar amount spent per horsepower? And lets narrow that down to rocker shaft versions with standard rocker arms,not offset. Changing springs to match cam not part of dollar amount.
Thanks! Bob P.S. don't include the blow-out sales that pop up every once in awhile, just standard Summit/Jegs/CNC performance and such.

 

[RustyRatRod]

To do this honestly, you need to also level the playing field by including the costs to bring the iron heads back from the grave. Otherwise, it's a one sided comparison. The last official year for the big block was 1978. Possibly 1979 for trucks, so even those are slap worn out "by now".

 

[12many]

Gotta consider the weight savings and effect on mph and ET, as well as effort to port (even repairing) aluminum vs iron. Thats where its at

 

[PRH]

A lot will come down to how big the motor they’re going on is, and probably even more importantly...... how much power you’re trying to make.

If we are talking about something “ready to bolt on”, where the only involvement from the end user is paying for them........

If you’re trying to make under 400hp from a stroker, then pretty much whatever 340/360 sized heads with 2.02 valves you can buy cheapest will likely be the best bang for the buck.

However, if you’re looking to make 550+, then the higher flowing heads are going to end up being more cost effective.

Obviously, those who have the tools and skills to do some blending/porting themselves can buy cheaper heads and do their own work and save money that way.

As with almost all of it.......”it depends”.

 

[318willrun]

Out of the box,bolted on to existing short block,with any special pieces needed to work,what is the dollar amount spent per horsepower? And lets narrow that down to rocker shaft versions with standard rocker arms,not offset. Changing springs to match cam not part of dollar amount.
Thanks! Bob P.S. don't include the blow-out sales that pop up every once in awhile, just standard Summit/Jegs/CNC performance and such.

the rest of the build would determine that. In other words, if you have a well built 360, with 240 @ 050/.557 lift cam and have stock smog heads on top, your gain would be more than if you bolted them on a 100% complete stock 318. So, really not way to say "all engines gain 52 hp" or the such.

 

[PRH]

Using the current pricing.......
If I were looking for a decent bang for the buck set of new heads....... I’d get the Bare Speedmasters, their valves, and then use springs/retainers/locks/seals that suited whatever the cam was.

Depending on exactly what springs were used...... $1000-1100 in heads/parts.

If you paid a shop to check/hone the guides, recut the seats, mild bowl blend, clean and assemble....... add $300-400.

 

[ir3333]

stock small block j heads will support about 400 hp and can be had very cheap used in bolt on condition, so at that level the iron would win out.

 

[abdywgn]

let's say the short block is a flat top pistoned,leveled decks,509 hyd cam,basic 587 heads with2.02 intakes and clean up after the larger seat is cut,cast iron 1.5 adjustable rockers,air gap with a 3310. WITHOUT porting and matching ports,what would be the increase with each different brand of cylinder currently available? and to throw another monkey wrench in the works,which head would have the greatest potential?

 

[PRH]

To just throw some numbers out there......
Depending on how well the stock heads are done, and how good they flow, along with how well the particular set of new heads you end up flow.........and then there’s still the cubes of the build........I’ll say.......

Unported “RPM style” heads:
340/360 - 20-40hp
408/416 - 25-50hp

TF heads:
340/360 - 25-50hp
408/416 - 30-60hp

Assuming the stock heads were at least “pretty good”.........With the low-ish lift cam and VS carb, I think they’d all end up showing improvements nearer the lower end of the range....... and even that might be a bit optimistic.

The heads have to be what’s holding the combo back before you’ll see big gains(or any gains) from swapping them for something better.
It’s always about the complete package.

Two street pump gas 360’s on the dyno here last year.
The one that was the better overall combo made about 80hp more than the one that had the better flowing aluminum heads.

 

[ir3333]

Aluminum dissipates heat and all things being equal will produce less hp than the iron pieces at .480 or .490 lift cams.So refreshing or bolting on useable stock iron heads will make more hp save hundreds.Now if those iron heads you bought need $1000 to refresh your probably still hundreds ahead of the game until you need extensive work to take advantage of a large cam...then it gets cloudy.Aluminum ring out $2000 plus in this area.

 

[PRH]

Aluminum dissipates heat and all things being equal will produce less hp than the iron

One of the magazines did a pretty good test of this on a SBC where they used two sets of the same model Dart heads.
One set aluminum, one set iron.
They made the same power.
I don’t know that there is any other platform besides a SBC where there are truely equivalent heads available in iron and aluminum.

Whatever difference there might be between equivalent heads that are iron or aluminum....... is minimal enough to where it shouldn’t be part of the decision making process for which to buy.

However...... that Chevy test was done with two equal heads.
Stock LA heads are not the equivalent head to something like an RPM head.
As much bad press as the genuine LA RPM gets, it would still require a set of pretty decent reworked stock heads to be as good.
So, on a combo as described above, unless the stock heads were done to where they were more reworked than just a little blending under the valve....... I’d expect the unmodified RPM’s to make more power.

When the BB RPM heads were pretty new there were all kinds of tests in magazines between them vs ported iron heads........ with the RPM’s usually beating the ported iron by 20-50hp.
The variables being how high an effort the motor was(hp per ci)and how good the ported iron heads really were.

My feeling is that if you’re “trying to make some power”, in other words not building an 8:1 318/360 for your DD, the only place the stock iron LA heads might be better than new aftermarket aluminum heads is....... cost.
And that’s a “maybe”.

I’m not saying reworked iron can’t be made to work well(as it has for many years)..... but depending on what the goals are....... an aftermarket aluminum head is likely a more cost effective option for many performance oriented builds these days.

To me........ for a new build it’s a no brainer.
If you’re “upgrading”........ then you’re back to “it depends”.

 

[ir3333]

That was a bad example..especially coming from me.I quoted info from a test i saw that also paired identical small block chev heads in both aluminum and iron and test results in the one i read the iron made 8 hp more.I had no first hand experience and passed along info i read.This is thing i always complain about from responders...My Bad!
but aluminum does allow you run higher cylinder pressure.Yes above the .480 more .490 cam you would be comparing apples to oranges.In HP output ( above 400) you would need a big cam to justify the expense.But when it's a hobby does it matter?

 

[abdywgn]

Thank-you PRH! that was the basic info I was looking for. the choice of parts was a general idea for a start.IF aluminum heads were installed,after being run,then parts would be changed to optimize the combo. more of a just wanted to know question.Thanks to all who took time to answer and educate. Bob

 

[rumblefish360]

but aluminum does allow you run higher cylinder pressure.Yes above the .480 more .490 cam you would be comparing apples to oranges.

I have found this to largely incorrect because the thing that allows you to run pump gas is a multi fold issue with the cylinder head material being a nine issue. For starters, The bottom line is dynamic cylinder pressure. Followed by timing of the ignition and cam timing events.

Someone mentioned above the lighter weight is a big deal on the 1/4 mile times. Semi true. But if you gain a 1/10th due to a 50lbs. reduction, I’d say it is more of the better flowing ports of the head helping the combo rather than the weight. Like PRH was saying earlier.

A lot is how much power your making, car weight, how well it hooks, etc.... that article you read between the iron and aluminum heads would be a good measuring tool and even better yet on various HP levels on a well sorted out car.

If a 100lbs. is a 1/10th......

For a street machine or even a bracket racer, it doesn’t matter. Run your time as close to the break out as possible consistently and you should be the winner all the time. If your running in a bracket that stops at 10.00, then that’s your target to run as close as possible. It only matters to run the time. What your running just doesn’t matter. Iron heads, a convertible, a extended van, a John Deer ... etc ...

 

[nm9stheham]

FWIW.. where folks get mislead on the temperature matter of the head material is that they think of the peak temperatures and pressures... but that only applies to the tendency to detonate.

For the matter of power, that is due to the change in pressure/temperature of the gases in the chamber from start to finish of the expansion cycle (power stroke). If you start the power stroke with a higher chamber pressure/temp, then you will end with higher pressure/temp too, but the pressure/temperature change is from start to finish is going to be the same.... or at least close enough to not see any measurable difference in the energy extracted. (This assumes equal compression ratios, which is what was done in the tests cited by PRH.)

 

[K.O. SWINGER]

I ran 340 x heads for decades and love them they were always an overachiever with a little bit of work and a good set of Springs they're great head as is the Jays and the 308 Etc, but there is no doubt my Pro Comp aluminum's are a upgrade I can run more timingwith the smaller combustion chamber without detonation something that I had to watch on my iron heads, all new, much lighter, and better flowing. It was hard for me to move away from my X heads it would just cost too much money to bring them back and make them competitive to an RPM or a pro comp head. Plus it just gets harder and harder and more expensive to find someone who can really do justice to a set of iron heads

 

[MOPAROFFICIAL]

I can run more timing with the smaller combustion chamber without detonation

Let's think about that statement, or should I say rethink it.

 

[K.O. SWINGER]

Let's think about that statement, or should I say rethink it.

okay I will speak so I'm not misunderstood. With a pro comp closed chamber aluminum head both the design and product material both combat against detonation allowing you to run more timing with a smaller combustion chamber providing more compression or and power

 

[MOPAROFFICIAL]

okay I will speak so I'm not misunderstood. With a pro comp closed chamber aluminum head both the design and product material both combat against detonation allowing you to run more timing with a smaller combustion chamber providing more compression or and power

I know what you mean. It's just looking at it from the taillights.lol
A smaller compact chamber, plug in the right spot, will burn faster shorter flame travel. That means youll need less timing..add quench and its helpful re mix effect will speed that too with a more complete burn.Also with the faster burn...one would think there is lesser time for end gas or hotspots to light up an opposing flame front.. as well as dead spots from fuel fall out etc. The cooler faster dissipation of heat through the chambers counters the hotspot issue. Really.. more heat causes greater molecule expansion ..and they expand so much before heat induced self ignition. It gets much deeper and goes into all sorts of pitfalls of traditional chamber designs of the 60s
But it mostly revolves around pump gas, or maximization of its resistance. Run everything at 99% its capacity/tolerance and you'll make thee absolute most power, right .
When you look at a piston or a chamber and you see dark areas vs clean spotless areas...that's showing you where good mix is and burning vs fuel fall out/lean...however tight quench area show lean/clean too. There are some really good circle track articles and engine builder online I highly recommend people search and read, read, and read some more.
Really the smaller compact chamber design lends the bigger hand though.

 

[abdywgn]

Thanks all for your input! If/when I spend that kind of money,I want it to be an educated purchase not a "guess this will work".

There are some really good circle track articles and engine builder online I highly recommend people search and read, read, and read some more.

I miss reading those magazines(my wife would bring them home from work for me when she worked at TEN). Which of those are still being printed? And which articles do you recommend reading?

 

[MOPAROFFICIAL]

Thanks all for your input! If/when I spend that kind of money,I want it to be an educated purchase not a "guess this will work".


I miss reading those magazines(my wife would bring them home from work for me when she worked at TEN). Which of those are still being printed? And which articles do you recommend reading?

Here's a few I had bookmarked.
Search their site, it's there in an article titled something related.
Wet Flow Testing - Engine Builder Magazine Wet Flow Testing

Recommended Valve Spring Pressures - Engine Builder Magazine
Recommended Valve Spring Pressures
Under Pressure: The Importance of Getting the Right Amount of Spring Pressure - Engine Builder Magazine
Under Pressure: The Importance of Getting the Right Amount of Spring Pressure
Valves and Valve Seats - There’s More than Meets the Eye - Engine Builder Magazine
Valves and Valve Seats – There’s More than Meets the Eye
Cylinder Head Design and Modification - Getting Started - Engine Builder Magazine
Cylinder Head Design and Modification – Getting Started
Flow Bench Testing is More Than CFM Numbers - What You Need to Know - Engine Builder Magazine
Flow Bench Testing is More Than CFM Numbers – What You Need to Know
Cracking Down on Block Fillers - Engine Builder Magazine
Cracking Down on Block Fillers

Check your own thinking, know what you're looking at..it's good practice.

 

[abdywgn]

MOPAROFFICAL, thank-you for taking the time and posting this info. I have no doubt some of this is over my head but after reading a few times,it'll start to sink in. Thanks again! Bob

 

[ir3333]

Maybe we should have asked is this a street brawler or a quarter mile build? They are very different.
Better flowing heads might only be at there best at high rpm or at the strip.

 

[rumblefish360]

Maybe we should have asked is this a street brawler or a quarter mile build? They are very different.
Better flowing heads might only be at there best at high rpm or at the strip.

Very true and build dependent. Though, so far, the have t had a ported head so larger in the runner and flow super high as not to show an improvement on any Sb I have built. I think I’d have to go to the extreme for that. Like a fully ported W-7-8-9? IDK

Engine master did a show on that with a SBF. While the largest head did t really loose power per sai, it did t do as well as the mid level head.

 

[AJ/FormS]

I don't know about the science of this, but I can tell you what I run and how it works;
About a zero-deck 367cuber with flat-top KB107s, and topped by OOTB eddies.
This combo has run with;
the DC-292/292/108 cam,([email protected]),at 11.30 and .040Q
A Hughes... 270/276/110 ([email protected]),at 10.72 and .039Q
Hughes ..... 276/286/110 ([email protected]),at 10.95 and .034Q
With each cam I adjusted the Compression ratio (mostly deck height) to maintain a cylinder pressure in the 178 to 188 zone, cuz I knew it worked.
It has always run 87E10, with full timing, fresh cold air,and minimum coolant temp set to 205*F.
This engine first hit the road in 1999, and currently has over 125,000 miles on it.
The heads payed for themselves years and years ago in the cost of fuel grade savings alone.
In 2004, I attended a local club event held on an old airport runway. Out of 4 EighthMile trials, the only successful run got me; 7.92@93and change. At 3467pounds and 930 feet elevation, the Wallace calculator says that is a tic over 430 hp.

What absolute hp doesn't tell you is how it drives with a stick , 3.55s, and a 750DP carb; as a DailyDriver.
I can't tell you if it's;
the 178/183psi cranking cylinder pressure, or
the hot heads, or
the cold fresh air, or
what it might be;
But as a streeter,since ~2004 I have made no changes; I haven't wanted for more.
Another thing I can tell you is this;
When leaving the house on a summers morning, the engine might be at 70/80*. This engine has no choke. Instead I have a dash-mounted, dial-back, timing delay- box with a range of 15*. I have it set to be able to advance up to 6* or retard up to 9*. So when the engine is cold, I just add the 6 to the 14 and drive away. I travel about a mile to the hiway, then head 'er out about 15/20 minutes to work. I set my foot to 100kph/62mph and hold it there. About 2 miles out , the car starts to gain speed. Another mile and she may be doing 70 mph; enough that I have to reduce the throttle opening.
Now, the curious part; the coolant was up to normal about the time I hit 100kph. What happened between the 2 and 3 mile mark?
IDK, but I think the heads finally warmed up, lol.

Oh I forgot to tell you; this 68 Barracuda is geared 65=2240 in GVoverdrive, and is, at 2240, running ~51* timing advance; Which is 14 idle plus 10 distributor, plus 22 Vcan, plus 5 in the dial-back. She likes a lil more, but I need the 9retard for something else, and I got lazy and just left it there.

Bottom-line
if a streeter, absolute power means almost nothing, cuz over 300/350 your chassis and tires can't keep up anymore.
I say almost, cuz spinning the tires to any speed-limit in Canada is kindof fun, as long as it keeps going straight.