Ditto on what both Frank and Don says in regards to aluminum versus cast iron in cylinder head construction.  To reitterate, all else being equal, iron heads will typically make more power than aluminum.  But most newer aluminum castings incorporate advances in flow technology as well as improved combustion chamber designs that more than makes up for any inefficiencies of the aluminum being used.  Many of the newer heads are now increasing the horsepower outputs significantly without measurable flow increases on a flow bench so there’s obviously more to this than meets the eye.

I didn’t get to talk in detail but to a few of  the competitors about their choice of cams but roller camshafts were definitely in the majority.  The Y was clearly in a minority group if not by itself with its flat tappet camshaft.  Once the magazine articles come out with the details of each engine, that aspect should be more clear.

Lorena, Texas (South of Waco)

Don,

        Absolutely, Mummert's aluminum head has a significantly different chamber from the Y-block heads. Of course they're not all the same either. Just looking at them with an uneducated eye, the 113's look to me to be the best. But i don't have a set of G's to compare. Be interesting to see a back to back between 471's 113's and G's on a dyno. The compression differences would definitely favor the G's But I wouldn't be surprised to find the 471 & 113 flowed as well. Shrouding of the valves by the chamber walls has a major effect of flow into the cylinder. That's one of the reasons big valves often show no real improvement.

.

Frank/Rebop

Bristol, In ( by Elkhart) 

Ted,

    824 cfm!!? I thought Y's didn't like big carbs!!

Frank/Rebop

Bristol, In ( by Elkhart) 

Be interesting to see a back to back between 471's 113's and G's on a dyno. The compression differences would definitely favor the G's But I wouldn't be surprised to find the 471 & 113 flowed as well. Shrouding of the valves by the chamber walls has a major effect of flow into the cylinder. That's one of the reasons big valves often show no real improvement.



Ted,



Previously covered by John's YBM porting articles. If I had known in advance I would end up with domed pistons that had to be cut down, I likely wouldn't have started with "G" heads. Most all material I am now removing to CC match them is coming from around the intake valves.



P.S. One other disadvantage (though minor) of aluminum heads might be slower cranking due to the resultant static CR increase?

6 VOLTS/POS. GRD. NW INDIANA

OOps, again I addressed Ted when I meant Frank! (brain short-circuiting)

6 VOLTS/POS. GRD. NW INDIANA

Actually this particular Y liked a 1050 cfm Holley Dominator carb.  Just didn’t have time to make a carb/spacer adapter that fit the rules before taking the engine to the competition.  Here’s a pic of the Y on the dyno with the Dominator carb.

Lorena, Texas (South of Waco)

Those headers are more than 1 1/2 too. Of course that's a big inch Y.

Frank/Rebop

Bristol, In ( by Elkhart) 

The -471's definitely flow the best of the big valve castings but never done a back to back dyno test. As I recall G heads flow 169cfm, -113's 173cfm and -471's 180cfm.

Don't forget how important the exhaust port is. The most surprising engine I ever dyno'ed had the small letter ECZ-G heads, which in my opinion have the best exhaust port of any Y-Block head. The most disappointing engine had some heads that someone had hogged out the exhaust ports in all the wrong places.

Unfortunately that engine was the only one I've ever tested with the small letter Dearborn ECZ-G heads. No back-up to confirm the heads were the real difference.

With regards to heat disappation, an aluminum head has a lot less water in it to help reduce the amount of heat that is carried away. I studied alot of aftermarket alum heads to try to get an idea of how much to leave out. The stock Y heads have water all the way to the intake gasket surface. Aluminum heads have just enough to cool the exhaust ports, valve guides and combustion chamber.

Crash test aluminum head is in the CNC machine and spent last weekend and Monday on program. Might not have much chance to work on it again before Friday. Hope to have it pretty well complete by Sunday PM.

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

EMC follow up. When will Popular Hot Rodding publish the results?..

Paul

Based on what I was told at the competition, The Popular Hot Rodding issue with the indepth article listing all the competitors and a description of the engines is expected to be the February issue.  I just received the January issue so its maybe only a month away.

The Engine Masters magazine itself will be out in early spring at the stores.  The EMC magazine is only published quarterly so there is no subscription available for it, newstand availability only for that one.

Lorena, Texas (South of Waco)