I was researching heads to use on my 400 stroker combo and after researching the Mopar Performance Stage VI (6) Cylinder heads here is what I have learned. I am by no means an expert on Mopar engines just thought I’d share what I’ve “dug up” Enjoy!
1st thing! DO NOT USE the first “generation of these castings. ( Early 1990’s)They are junk! From what I have read Mopar quickly changed the casting process as the first “generation” almost always had cracking problems and leaked water and oil!
These heads can be identified by the casting logo. The new heads have an “M” with a circle around them about 1/2- 5/8 diameter. The junk heads have a larger logo about ¾ “. This is my description looking at a picture in the book by HP books titled Big Block Mopar Performance.
The “Chapman” head (part # P4876383) is a totally different casting than the Mopar Stage 6 head (part# P4529335)
Mopar Performance parts Stage VI part #’s P4529335 and (P5249579 is the Max wedge/big port version)
“Chapman” Mopar part # is P4876383 and (P4876386 Max Wedge design)
The Chapman heads use longer Valves than the Mopar stage 6 heads. (11/32 stem Dia.).The spring pockets then are higher. The intake valve is bigger on the Chapman heads .The combustion chamber shape is different too. I’m not totally sure but, when looking at the Chapman combustion chamber it looks like they are of the angle plug design. Here is a link to the Chapman site.
http://www.chapmanracingheads.com/products/prodDetails.asp?pID=42The Mopar Stage 6 head uses stock valves (3/8 stem Dia.), springs and stock rocker gear. It is also a straight plug design. Uses stock header flanges too. Both the intake and exhaust ports are raised. The amount they are raised is the same amount between a low deck block and a raised block.( about just under .750”) These heads are advertised to flow 40% more than stock due to their raised ports. If using these heads on a low deck block (eg. 383,400) then you must use a RB intake (eg. 440). From what I’ve read this is a good thing as it gives a little bit bigger intake volume. A modification that looks wise is to mill a small slot from one spring pocket to the next to let oil escape as it builds up as the spring pockets are so deep. Doing this helps the valve seals do their job. I have heard that HUGE spring pressures on these heads is not wise as the spring pockets are close to the ports and cracking may be a problem From what I’ve read these heads work great on 475 CID or less. Perfect for a street 451” stroker! I wonder what the raised port design does for header/sparkplug clearances. Looks like it would help?
If using these heads on a 440 then you must use intake spacers.
When reading different articles about this head it gets confusing. Depending on when the article was written it’s hard to distinguish what stage 6 head is being talked about. Chapman of Mopar performance? Also I have read that seven different versions of these heads were at one time available. Now (2009) only 4 part #’s are available from Mopar they are the Chapman regular port and the max wedge ports and the regular Mopar part #’s for regular and Max wedge ports.
If building an “All out” drag racing engine these are most likely not the head for you. There are probably better choices. But for a street engine or a street strip engine these might be the ticket for you! Again these heads were designed to work best up to 475CID .The DO flow better and give more performance than any stock cast iron head. From what I have read and with talking to engine builders I respect huge ports are great for a drag engine but not so good for the street.
The following is taken from web site listed below:
http://www.allpar.com/history/mopar/performance/heads-for-dodge.htmlThe last in the saga of MP heads is, in reality, also not quite new: the Stage VI aluminum big-block piece. We covered this head in intimately in the February, 1993 issue, so we won't go into macrodetail here. Suffice to say that the Stage 6 is a thoroughly modern head, penned in-house by Chrysler Engineering. The bare head, P4529335, is designed to use as many stock parts as possible, including valves, rockers, headers; etc., while attaining big numbers. The six's rely on what has to be the cylinder head trick of the decade: since it's well known that raising the intake ports gives the mix a straighter shot at the bowl, the Chrysler crew raised the intake a whole bunch. Uh, special intake manifold required, right? Wrong! Just bolt the heads on your 383/400 low-deck block, then bolt up a stock 440 ("RB") manifold. Trick! (Usage on a 440 requires that set of P5249189 spacers be utilized.)
The real news about the Stage VI is just how much horsepower can be made with them. The limiting factor would seem to be the stock port window, but looks can be deceiving. The crew at Muscle Motors in Lansing, Michigan ((517] 482-4900) has built a Daytona Super Pro car as a rolling test bed for their Stage VI development work. Using a single four barrel carb, the 2200-pound car has gone a best of 8.45 secs. at 161 MPH, without ever seeing the high side of 7,000 RPM. This takes some serious power (over 700 ponies, in fact), which, in turn, takes some equally serious airflow through the heads. While MP offers ported 6s (P5249113), these guys wanted more-much more. How much is much? Well, take a look at this chart (intake).
Valve Lift 0.20 0.30 0.40 0.50 0.60 0.70 0.80
As Cast 81.2 109.6 127.1 134.1 138.2 140.1 142.1
Bowl Ported 85.2 114.6 139.1 150.0 157.9 161.8 166.8
Max Ported 86.9 123.5 151,7 186.7 194.5 199.4 201.7
There is one last version of the Stage 6 head available, and it's for the hardest of hard-core racers only. P4349600 will bring you a bare unmachined (for guides) casting, allowing the daring, creative types to experiment with almost unlimited freedom.
The Following is from the web site link below:
http://www.moparmusclemagazine.com/images/mopp_0608_mopar_cylinder_heads/brodix_cylinder_heads.htmlStage VI Heads
With no less than seven versions of the Stage VI aluminum head displayed in their catalog, Mopar Performance shows they are dedicated to providing engine builders with a head that will meet their needs. These heads are available in bare form, allowing the engine builder to custom port the heads, or in several states of machining all the way up to fully CNC ported units. Port size as cast is either standard or Max Wedge size. The Stage VI heads will work on a healthy street motor, but really come into their own when utilized on high-compression, large ci race engines. They are a 78cc closed chamber design that incorporates 2.18-inch intake and 1.81-inch exhaust valves. The spark plug location is canted toward the exhaust valve to promote efficient combustion. Using these heads does come at a price, however, as offset rockers must be purchased to make them work. Certain Stage VI heads are designed to use an RB intake on a B block. Using a B intake on a B block or an RB intake on an RB block will require intake manifold spacers.
We've used aluminum Stage VI heads on bracket engines with some success, but have found them to perform better with port and bowl work. This bare casting shows a lot of casting flashing that needed to be cleaned up before the head could be installed. Also notice the deep spring pockets unique to the Stage VI casting. These pockets cause the top of the guide to be submerged in oil, necessitating valve seals be used even on race applications.
