DCI Motorsports Edelbrock D port article...
 

is in the new HPP magazine (July 2011). Their street/strip port heads flow at 324/225 @ .700 lift.

And look at what the port volumes were even out of the box, not small.

Good article and pictures of the head.

Thanks for the plug Johnny!! An important thing to note also, is that we achieved these numbers with the 2.11 intake valve. Obviously with a larger valve we will see even more cfm. The port volume is a little bigger than Edelbrock states in their advertising, but I don't think it will be detrimental. Another thing to note, is that these are the big chamber heads. If they are like the round port E-heads, the smaller chambers will even flow a little more cfm.

Don Johnston
DCI MOTORSPORTS INC.
330-628-3354 cell
330-850-5050 shop
Designer of the TIGER Heads and the NEW DCI Ram Air V heads coming soon!!!

"The port volume is a little bigger than Edelbrock states in their advertising, but I don't think it will be detrimental. "

Don we used to have some serious debates here on how anything bigger than 185cc would kill even a 455's low end-so I couldn't resist:) I would bet Edelbrock's casting is top notch also with little porosity. I know their Pontiac and 409 heads are.

Don,
I was reading you stating that the large chamber had a slight flow indifference???
So the smaller chamber heads won't have this minor problem???
What's the difference???
Thanks
Jeff

Jeff on the round ports, and I assume Don is alluding to the same potential on the D ports, the smaller chamber since it is shallower has a different short turn radius in the throat that gives a little better flow numbers even though the rest of the port is the same shape.

Combustion chamber shape will effect flow - if it is deep and steep the air will not flow out around the valve as well as a shallow chamber with a laid back wall in relation the the valve seat angle-- it was explained to me that the first inch on either side of the valve control the lions share of the flow potential of a head

Curious, what size opening for intake gasket?

You guy's are getting sharper and sharper. As skip fix and cgeise stated, port entry and chamber shrouding both effect air flow. On the round port E-heads they sunk the seat a little as well as make the combustion chamber deeper shrouding the valve a little more. I have not worked with the new D-port enough yet to know if the same thing is true with them or not. For this reason I tell my customers to buy the smallest chamber available and run a dished piston. Preferably with dish mirroring the combustion chambers as close as possible. The engine will require less timing and make more power. The guy's that want the big chamber heads are taking some power off the table as well as making the engine a littler harder to tune. In most instances they are buying pistons anyway, and dished pistons are only an additional $50.00 for the set. I don't know!! Call me crazy.


Curt I have not forgot about you!! I need to get a size for the decal from you to make sure it will fit.


Don Johnston
DCI MOTORSPORTS INC.
330-628-3354 cell
330-850-5050 shop
Designer of the TIGER Heads and the NEW DCI Ram Air V heads coming soon!!!

How much does the street/strip port add to the cost?

For those who do not have access to Don's very fine article in HPP magazine about his work and findings on these new Edelbrock d-port heads the intake runner volume on the production as cast head ended up at about 213.5 cc's. That is slightly less than the 215cc intake runner volume on the Edelbrock Performer round port head.

As noted here that is no big deal and in many applications it could be a asset.

Here was a comment made by Edelbrock on that subject:

"Many feel the 215cc intake port of our Performer RPM is too large for the street, but we've found that the long connecting rod and big crankshaft throw associated with the Pontiac V-8 tend to make them less sensitive to port volume. The RPM is a great head for street engines, and I pushed for a large intake port when developing the Performer D-port-one much like that used in our Performer RPM."
http://www.highperformancepontiac.co...ads/index.html


.

Don,

Will the readily available and affordable 1 3/4" headers be able to keep up with the intake side on your street/strip heads?

The intake port opening is the same as a 1233 Felpro. An 1-3/4" header will work just fine, although 1-7/8" would obviously be better. The additional street strip porting over an as cast head is $650.00 only if I do the heads from start to finish. If you have a set that have a valve job other than what we use. I would need to see them before I quote a price.


Don Johnston
DCI MOTORSPORTS INC.
330-628-3354 cell
330-850-5050 shop
Designer of the TIGER Heads and the NEW DCI Ram Air V heads coming soon!!!