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56-210Sedan
05-18-2014, 07:39 AM
I am trying to get some answers/opinion on something i am investigating on BBC Cylinder Heads. To start i can buy a set of cast iron 049 cylinder heads ( $350) that have been ported and polished, flow benched, CC'd, the 049 has 112CC combustion chamber 255 Intake and 119 exhaust ports

GM Performance oval port aluminum heads (12363392) have 110 CC combustion chambers 290 intake 110 exhaust ports price anywhere from $1,800 to $2,000 on average

AFR 290 aluminum heads 112 combustion chamber 290 intake ports, could not get exhaust info online i will call Monday $2,800 to $3,000 on average

So to the meat of my thread i am researching is to see if the cast iron head would work effectively with the ramjet setup for the 540 i am going to run in my 56, i know right off that the cast iron heads are around 60lbs heavier then the aluminum counter parts and intake runner numbers are up against the cast iron, but how do you think the cast iron 049 heads would work for a street driven car? i have no plans or racing this engine. The savings dollar wise is what really makes this interesting for me :) what are your thoughts bad or good i put my feelings on the shelf LOL

chevynut
05-18-2014, 07:53 AM
I thought the weight difference was around 85 pounds between aluminum and iron. One thing to keep in mind is the aluminum heads also allow you to run a little more compression ratio. $350 seems like a steal compared to the price of aluminum heads, but I'm not sure what your objective is. Obviously OEM heads work, just not as well. I'd try to do some comparisons of the performance the way you intend to use the engine and consider your budget.

Here's some articles:

http://www.superchevy.com/technical/engines_drivetrain/completebuilds_testing/sucp_1208_big_block_heads_shootout_the_o_vs_r/
http://www.carcraft.com/techarticles/ccrp_0803_big_block_cylinder_heads/
http://www.chevyhardcore.com/tech-stories/engine/ultimate-guide-to-budget-bbc-cylinder-heads-under-2000/

Maddog
05-18-2014, 11:21 AM
Even for a "street engine" those 049 heads are too small for a 540, so are the GM perf heads. I would use a slightly larger AFR head (305-310cc). The 049's would be OK if you were using a 454 cu in. Of course AFR is about the best out there and are costly but why bother with the cost of a 540 and ramjet to choke it with low budget heads.

56-210Sedan
05-18-2014, 11:53 AM
I found this part out of one the articles very interesting,

Budget Big Block Chevy Cylinder Heads For Entry Level Street
Looking for an entry level set of heads for street use goes beyond price. Given that GM factory production heads commonly had runner volumes of 230 to 270 cc. Larger volume runners were used in GM’s performance versions. Aftermarket cylinder heads have improved airflow but must be matched to the camshaft, intake and exhaust systems for the optimal results. The heads listed below are good choices for an application that is intended to be higher performing than stock and still used on the street for daily driving.
Smaller ports and runners will keep the mixture of air/fuel at a higher velocity making driving from stop light to stop light and idle quality a lot more steady. With too large of a runner volume, a basic stock type engine will lug at low RPMs until it gets to cruising speed. Entry level heads are designed for engine where there are not too many high performance upgrades already installed and the engine will be running on mid to high octane pump gas. Optimal runner volume for these conditions is somewhere in the range of 270 cc to 290 cc.

The 049 are at 255 so that is below what they have but they also have had some extensive work done to them and so there flow numbers should go up. Maddog i understand some of what you say but as far as to small in what direction due you mean? valve sizes are the same as the aluminum heads 2.25 in 1.88 ex on all that are listed

Rick_L
05-18-2014, 12:39 PM
On the valve size, it doesn't matter how big the faucet is if the pipe leading to it is small.

Maddog
05-18-2014, 12:54 PM
290 cc intake runner volume is too small for 540 cu in. 290cc is a good performance street size for a normal BB, up to about 460 cu in. An engine is an air pump, you limit it's ability by restricting the air flow, 290 cc heads will stop the 540 at about 4500-4800 rpm, it's like putting late model "peanut port" heads on a 454-stops making power at 4500RPM. You need 305-310 cc heads, if you were building a 540 with more of a high performance (race) type you would need 320cc heads. The low end will be very responsive with the smallish heads but will fall flat on it's face above 4500 RPM. Honestly, I can appreciate the "cost" factor but if you half ass the 540 you'd be better off building a 454. 305-310cc heads are small enough for a 540 to keep the low end peppy.

JT56
05-18-2014, 12:57 PM
If your going with a 540, finish the deal and put some good heads on it. I believe you will be kicking yourself later! Now if you had a 454 or 496 then that is an option.

56-210Sedan
05-18-2014, 04:01 PM
well then getting back to the drawing board then :D this is the biggest set i could find out on the market that comes close to those volumes. Remember i have to stay with oval port to make the ramjet intake work. http://www.race-mart.com/product.asp?itemid=513888&gclid=CJLCwKLJtr4CFciGfgodlA0A9g#

Maddog
05-18-2014, 04:46 PM
Or consider the AFR 300, a little more money but AFR quality is hard to beat. Either will work well.

56-210Sedan
05-18-2014, 05:40 PM
Yikes!!! by almost another grand :( LOL :) i understand you on the AFR being a better quality head, problem is i am to old to sell myself to make that kind of coin :eek: LOL. Well then how about them ore-ida tater tots.

Maddog
05-18-2014, 06:17 PM
I would also be concerned if that Ramjet will function well with a 540. Hopefully you've looked into this. I would call AFR and talk to their tech dept about what you're doing and want and see what they have to say. AFR is probably the leading expert in head flow.

chevynut
05-18-2014, 09:46 PM
On the valve size, it doesn't matter how big the faucet is if the pipe leading to it is small.

Conversely, it doesn't matter how big the pipe is if the faucet is too small. ;)

At some point the port size is bigger than the valves can flow with a given camshaft. Most performance BBC heads have 2.25" intakes and 1.88" exhaust valves. How big of a port can those valves support, with a cam designed for the street?

I really think you can over-do the port sizes to the point that they don't help anymore, and may actually hurt. Bigger isn't always better.

"While intake port volumes are a valuable guide in cylinder head selection, remember that port volume is not necessarily proportional to port flow, and that just because one design has 340-cc runners and another has 320s, that doesn’t mean that the larger head flows more air or makes more power, although that is usually the case. In fact, if two heads with different- size runners have the same flowbench numbers, you are generally better off with the smaller runner head, especially if low-RPM throttle response and drivability are important. Also, when comparing port volume of spread port cylinder heads, remember that because these heads have raised runner locations, they are longer than conventional cylinder head intake ports, and the port volume is greater due to the extra length. A 400-cc raised-runner intake port may actually be smaller in cross-sectional area than a 380-cc conventional intake port. Be careful when comparing apples to oranges.
There are aftermarket oval port heads with about 290-cc intake runners, and small rectangular port heads with around 300-cc ports. I’ll bet you a year’s supply of donuts that the power difference on the dyno is minimal, and you could never tell the difference from the driver’s seat."

http://www.cartechbooks.com/techtips/killerbigblockchevy/


If I were you Marty, I'd select a camshaft that you think will work well on the street and see what heads work well with that camshaft. Whatever you do, don't try to use the GM Ramjet twin 48mm throttle body or everything else is worthless. It only flows 635 CFM and was designed for a 350.

chevynut
05-18-2014, 09:54 PM
Yikes!!! by almost another grand :( LOL :) i understand you on the AFR being a better quality head, problem is i am to old to sell myself to make that kind of coin :eek: LOL. Well then how about them ore-ida tater tots.


Some guys just like to spend other guys' money. :)

Keep your objectives in mind, and don't try to build an engine with as much horsepower as you can get, or it won't be streetable. On the street, torque is king. IMO you should try to maximize torque in the 4000-6000 RPM range and don't try to push over 6000RPM with a BBC. Think about how you drive the car on the street. I would look for a head with ports and valves that don't restrict flow with the cam that you choose. Trying to maximize airflow when you don't need the horsepower will just cost you more money.

chevynut
05-18-2014, 10:12 PM
I see all sorts of aluminum BBC heads on eBay from under $1000 to $2000 a pair.

Maddog
05-19-2014, 07:09 AM
Yup, other peoples money, the best kind to spend and freely

56-210Sedan
05-19-2014, 10:52 AM
I have done my home work here quite some time ago or so i thought, anyway the tech at AFR recommended the AFR 290 series based on my build, and Mark Campbell at Street & Performance recommended a Brodix 206100, Mark made no bones about it that the reason he liked Brodix is because he used to work for them but did say that the head in mention would work great for my application based on the build i was doing and said the ramjet would perform great, although like Laszlo mentioned i will have to alter some things injector size, throttle body size, camshaft size, and CPU upgrade as well, all have been done except the last one (CPU)

Wanted to add this in as it really is a good read on upgrading the 502 ramjet http://www.superchevy.com/technical/engines_drivetrain/induction_poweradders/sucp_0408_502_big_block_addition/

Rick_L
05-19-2014, 02:33 PM
From the link:

*Cam changed from .527/.544 lift and 224/234 duration to .566/.566 lift and 296/302 duration, with a 110-degree centerline.

Surely that's a typo or out of context. That's a HUGE change.

What are the specs on the 502 Ram Jet heads?

Maddog
05-19-2014, 03:42 PM
I have done my home work here quite some time ago or so i thought, anyway the tech at AFR recommended the AFR 290 series based on my build, and Mark Campbell at Street & Performance recommended a Brodix 206100, Mark made no bones about it that the reason he liked Brodix is because he used to work for them but did say that the head in mention would work great for my application based on the build i was doing and said the ramjet would perform great, although like Laszlo mentioned i will have to alter some things injector size, throttle body size, camshaft size, and CPU upgrade as well, all have been done except the last one (CPU)

Wanted to add this in as it really is a good read on upgrading the 502 ramjet http://www.superchevy.com/technical/engines_drivetrain/induction_poweradders/sucp_0408_502_big_block_addition/

I'd still use the AFR 300.
Sounds like you've done and are doing your homework, good luck and listen to those experts

Maddog
05-19-2014, 03:44 PM
From the link:


Surely that's a typo or out of context. That's a HUGE change.

What are the specs on the 502 Ram Jet heads?

Night and day difference

chevynut
05-19-2014, 06:04 PM
What are the specs on the 502 Ram Jet heads?

Cylinder Heads (P/N 12363390): Aluminum oval port; 110cc chambers
Valve Size (in): 2.250 intake / 1.880 exhaust; stainless steel
290cc Intake Port
110cc Exhaust Port

Rick_L
05-19-2014, 06:42 PM
On using the Ram Jet 502 EFI on a 540, that shouldn't be that big a deal. I assume that the same tuning s/w that you can buy for the Ram Jet 350 controller can be used on the 502 setup. The engine is less than 10% bigger, it may not even need bigger injectors unless you're going to step on it quite a bit. And if that's not enough, you can always use an aftermarket controller.

chevynut
05-20-2014, 08:03 AM
Rick, I went with bigger injectors because I also went to a 1000 CFM Holley Throttle body. I didn't have injectors so I didn't replace mine, I just got the bigger ones....I think they're 42 lb/hr vs the stock 36 lb/hr. I recall looking at the required fuel flow at max power and the duty cycle for the injectors when I chose them.

Here's an interesting article I found.....some guys were smirking when I said I thought my car might hit close to 20 mpg highway with the 502 and Viper T56 (0.50 OD) :):


" Not that it Matters... Just MPG data for 502 Ram Jet Ok so I put a new set of nitto 555R's last fall and I started a millage log to see what I was getting out of them.. the last set had a dozen 1/8 mile dragstrip passes, 4 auto cross events and a half dozen laps of WGI.. they lasted 4700 miles. this year I am only street driving... and keeping track of fuel consumption...

the car weighs 3195 with me in it and 16 gallons of gas on the local scrap yard scales..

502 Ramjet 38 pph injectors 3:08 rear, 3:27 1st and 0.80 6th gear, rear tires are 28" tall...

13.7 MPG in the city, 18.9 with a mix of city and highway and I'm gonna estimate 22-23 with all highway... I will get more highway data as I will take a weekend trip in September..."


"I think you are not far off. For what is worth, My RamJet 502 has the Tremec 500 in it with 5th gear at ~.68. Tires are 245x45xr x17's also turning 3.08 diff. I turn right around 2100 rpm at 70mph. I have very little data with highway driving....seems I'm easily goated by Mustangs and Zo6's http://www.vettemod.com/forum/images/smilies/biggrin.gif I do remember 25-26 mph on an economy run down in Eureka Springs a number of years back, but that was after I pitched the MEFI, installed a larger throttle body and re-mapped the Gen 7 for economy. Even then It was tough keeping my foot out of it. Like you said though "not that it really matters". "

http://www.vettemod.com/forum/showthread.php?p=112911