DJ Dep

Hi Ratmen :D

Preliminary info: I am close to buying a set of aluminum heads for my 454. The main thing is they have to be rectangular port and have a larger intake valve than my stock round port heads. So from the beginning that eliminates the Edelbrock heads. Only benefit I would get from them is weight saving and a slightly better flow.

The two heads I am considering are either Brodix or the factory Chevy head part # 12363400.

The questions:
I heard that Brodix has the exhaust ports raised for better flow on ALL their heads. Does this mean the exhaust manifold/headers will be located higher than normal? If this is the case, doesn't that make header/exhaust manifold installation a real headache on a Vette? Or is the amont that is raised not enough to make a difference?

On the factory Chevy head...do they also raise the exhaust ports on that head too? I think probably not, but I'm not sure.

Thanks for any info you can give me on this!

Dep
(Where is Chuck Harmon when I need him ;)

69stingray

Have you looked at AFR heads? They do make ones for Big Blocks but not sure if they are rectangle or oval ports.

http://www.airflowresearch.com/

Flareside

Dep, you're right on about the raised ports and headers. If the ports are raised, the headers have to be cut and extended. It's up to each owner to decide whether or not the extra exhaust port flow is worth the expense.

The AFRs and Dart Pro-1s are raised .3", so they will be easier to fit. The Brodix, Canfield, etc., are raised .6" or more, so they're a tougher install. The GM heads are stock height, and as a result the exhaust port flow is lower. Some GM race heads have raised ports.

The ports are raised up from the head deck, so when a .6" raised head is installed on the engine (at a 45 or so degree angle) the header flange will be .3" higher than stock, and .3" out farther toward the fender.

Not that you want them, but Edelbrock does make square port, 2.25" valve heads :) The Victor Jr. heads flow great, but they're exhaust port is raised .75"! :eek:


[Modified by Flareside, 3:08 PM 1/5/2003]

73 LS-4

Hey Dep,

The edelbrocks are 2.19 intake, 1.88 exhaust, bigger then the stock 2.06,1.72 combination on the large oval ports.

Why the need for rectangular ports? are you going to be spinning this engine over 6k frequently? If you are then I see the need, if not then I don't since a good large oval port is much better under 6k rpm then the rectangular ports.

:cheers:
Pat Kunz

Steve Straus

I have Canfield's on mine and spent over $1K on header modifications to get them to work. The GM bowtie heads have the exhaust runners in the stock location.

I'm happy with my setup, but It'll be some time before I can tell you if it was worth it or not.

DJ Dep

Hi Pat,
A legitimate question. The answer is simple. The best part of the rat motor IS the heads. Why settle for tiny intakes and exhausts when I can get 2.30/1.88 with the breathing advantages of the rectangular port heads for about the same price? I will be $$$ ahead for future mods I plan on making.
Understand, this car is going to be more strip than street. So torque, fuel economy, and all the other street "benefits" that guys crave who are driving on the street aren't a major concern to me. I guess I should have said that in my initial post and I apologize for the confusion. I also appreciate your concern for my choice.
But in my case bigger really IS better ;) :thumbs: :thumbs: :thumbs:

Dep

ZL1powr

I went with the Eldebrock Vivtor Jr CNC heads on mine. They were the best flowing heads I could find with the exhaust ports in the stock location.

73 LS-4

Hi Pat,
A legitimate question. The answer is simple. The best part of the rat motor IS the heads. Why settle for tiny intakes and exhausts when I can get 2.30/1.88 with the breathing advantages of the rectangular port heads for about the same price? I will be $$$ ahead for future mods I plan on making.
Understand, this car is going to be more strip than street. So torque, fuel economy, and all the other street "benefits" that guys crave who are driving on the street aren't a major concern to me. I guess I should have said that in my initial post and I apologize for the confusion. I also appreciate your concern for my choice.
But in my case bigger really IS better ;) :thumbs: :thumbs: :thumbs:

Dep[/QUOTE]

I understand, just didn't know what you were going for :thumbs:

:cheers:
Pat Kunz

JoeC427

I have a set of Dart 320's fully CNC'd on my 427. Dart in my opinion is the best over all. Why, well I installed a set of Hooker Super Comps with no issues of the raised exhaust ports coming into play. All of the names such as Brodix,Canfield and GM are great products, but in talking with various pro-builders they seem to use Dart stuff on there OWN projects and sell the others. Don't flame me, it was just what I uncovered. Either way it's worth the extra bucks to have them CNC'D so you know exactly what you've got. I plan on building a 540+ motor someday soon and I should be able to use my same Dart 320's on that engine as well. That will save some flow, you know? :cool:

Flareside

Hey, thanks for the clarification ZL1powr. I never realized that Edelbrock had a Victor Jr. "Chapman" head with standard ports, and a Victor with .75" raised ports. Are there any flow or cc numbers around for the Jr. heads?

Dep, my previous post should have read "Victor", not "Victor Jr.".

-Joe


[Modified by Flareside, 9:22 PM 1/5/2003]

467-Ratman

Dep, Here is my 2 cents worth, I went with Merlin rectangular raised port heads. I wish now I would have spent the extra money for the aluminum ones. As for the specs on the heads they have 2.25 intake and 1.88 exhaust, 310cc intake runners and 119cc combustion chambers. They are a raised port design, and Bill Grumpy Jenkins redesigned them a few years ago. All I know is that they are awesome, the performance is un-real!!! I think for the money they are one of the best heads on the market. I got mine from Jegs, the bare ones cost about $475 each. Check them out and also talk to a few people about them, the engine experts I talked to said you cant beat them, enough said.... Good luck and If you have more questions just ask! 467-Ratman

ZL1powr

Flareside

The flow numbers for the Victor Jr CNC heads are 341 cfm intake and 276 cfm exhaust. They have 2.25" intakes and 1.9" exhausts with a 320 cc intake runner and a fully machined 112 cc combustion chamber.

DJ Dep

Hi All,
Can't tell you how much I appreciate the feedback on this head question. I found out all kinds of stuff I needed to know.
Okay...first off...as a public service to all of us I went around and found the
different head websites for big blocks. Here they are:
http://www.edelbrock.com/automotive/raceheadbbchev.html
http://www.dartheads.com/
(Lots of Java...need to be patient)
http://www.brodix.com/
http://www.worldcastings.com/
(Need Adobe Acrobat to read info and takes a LONG time to load)

After reading ZL1's post about Edelbrock heads, it really caught my attention.
Those valve sizes and flow numbers are tough to beat and the exhaust ports are in the stock location. Looks like they are what I will go with.

Thanks again for all the input!

Dep



[Modified by Dep, 11:42 PM 1/5/2003]

mapman

Dep,

The GM Performance Parts catalog shows 12363400 as the same as 12363410 except for the valves .....

The 12363410 description says intake and exhaust ports are in stock locations. (Page 107 of 2002 catalog)

DJ Dep

Yep...got the catalog right in front of me. The 410 head is a bare head with no valves, springs, retainers, etc. The 400 is the complete head with all parts ready to bolt in.

The Edelbrock head comes with valves, but that's all. Not a big problem to supply the rest. The Edelbrock heads have the exhaust ports in the stock location and have BIGGER exhaust valves. Nice! :D

Dep


[Modified by Dep, 12:48 AM 1/6/2003]

Steve Straus

I didn't see this one on your list. These are my heads, and I must say the power out of my engine feels unreal. I have to get it on a wheel dyno..
http://www.canfieldheads.com/bbc_990.html

DJ Dep

Steve: Oops...sorry. Missed that site. Also couldn't locate the AFR site.

Dep



[Modified by Dep, 1:25 AM 1/6/2003]

Flareside

Dep, http://www.airflowresearch.com

If you call AFR, they will put you on the phone with Tony, the product manager and designer of the heads. He's a very friendly and knowledgable guy. Give them a call. I had a set of their heads on order for months last year (before they were available), but finally got sick of waiting and went with the Dart CNC heads.

The big advantage of the Victor Jrs over the GM heads is the CNC option ("Chapman" heads). That will make a BIG difference in flow potential for the right combo.

mapman

Dep,

Question - Have you seen any info on how the size of Intake/Exhaust valves effects engine performance?

I know that intake manifolds, designed to provide better low/mid range power, use restrictive runners to keep fuel air velocity up at lower RPM. For applications at sustained high RPM, less restrictive manifolds are appropriate as the fuel droplets remain in suspension because of the high speed air flow.

Likewise exhaust systems can be tuned for particular RPM ranges.

Do you know of a resource that discusses (charts & graphs) this topic?

DJ Dep

mapman: Only in very general terms. I know that bigger valves are mainly more useful at high RPM and are not a lot of help at low RPM. I think big valves may actually hurt "street" performance in some cases. Sorta like big header tubes. They found that on smallblocks they can't really effectively use humongous header tubes like on the big blocks. I think the velocity subject you mention affects a lot of these same components. I also think that these problems are much less noticeable on big block engines because of the amount of brute power that is available even at idle. An example that comes to mind is the high rise manifold found on the hotter big blocks. The one with the center section cut away. I think the L-88 and ZL-1 came with this modification. It aids airflow at high RPMs but negatively affects it at low RPMs. But since those two engines put out such massive power to start with, it's not really all that noticeable at low RPM. It's definitely something you DON'T want to do for a street engine or a smallblock.

A lot of us are also handicapped, sometimes by choice, to what we can use.
I know Wes (Wa 2 fst) has a low rise LS-6 manifold on his 454 and doesn't want to swtich to a high rise because he would have to lose the hood or cut a hole in it. I can understand that and I sympathize with him. I have that same LS-6 manifold but haven't decided for absolutely sure I will run it. I may go with the factory high rise. I WON'T cut a hole in the hood, but an L-88 hood isn't an impossibility in my case. The same applies with my cylinder head exhaust port thing. I DON'T want to make extensive header/body/frame mods just to use a head that has raised exhaust ports. I know they perform better but it's just something I don't think I want to get into.

Another thing I remember is that many guys used to polish the heck out of the internal parts of their intake manifols. Then they discovered that this was NOT a good thing because the fuel teneded to "atomize" more and burned better with a rough surface than a smotth shiney surface.

I can't help you with a location for graphs on that stuff though.

Dep