Had the opportunity to run the ported aluminum Mummert heads on the 312 dyno mule.  I was already in the process or running a variety of iron heads in a single day on the mule engine in preparation of the ‘Exhaust test to end all tests’ and did manage to sneak the ported aluminum heads into this test session. The ported aluminum heads were conveniently off of the EMC engine to make molds of the combustion chambers for a new domed piston design so it was just a matter of bolting them onto the mule for a quick three pull test.  Thanks to Randy Gummelt for spending the day in helping change out several sets of heads while doing the dyno testing.

 

The mule engine is the +060 over 312 with cast pistons that reside 0.025” in the hole and still retains the same Crower camshaft that’s been used in a multitude of other tests.  1.6:1 roller rockers are being used with Best Gasket head gaskets.  A stock Mummert intake with 750cfm Holley carb atop a 1” spacer is also being used.  377HP with the EMC headers and 368HP with the Sanderson headers.  Here’s the graph showing the ported Mummert aluminum heads on the dyno mule with both the Sanderson 1½” tube headers w/22” of 2½” collector extension/no mufflers and the EMC 1¾” stepped headers with mufflers.

 

Lorena, Texas (South of Waco)

Ted, thats exceptionally impressive torqe figure improvement: with the EMC headers, 1 3/4" stepped headers? how is that configuration. regards bill.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

Ted

what do you think the compression ratio is of the mule with the aluminum heads?

Gary Ryan San Antonio.TX.

Just goes to show the heads really work!!!!! on both ends. Great job Ted.

-Gary Burnette-

Ted,

Thanks for doing this test. I'd hinted before about using the EMC heads on the dyno mule and as John had said that the labor and therefore the cost, would be restrictive for a street engine. It's great to see how well the ported aluminium heads have done over the raw ones. I assume an increase in volumetric efficiency and interesting to see how well they work at lower RPM, as Bill pointed out, the torque figures. It would be interesting to see how well they drove. 

36.4 hp increase at about 1.2 hp per cube is impressive for a run of the mill engine.

Your and John's work with these heads have certainly opened up options in engine upgrades. 

I think I read earlier that John had made changes to the castings and ports of the aluminium heads. the EMC heads being one of the first cast runs. Are there flow figures for raw and street ported and street ported (later casts) for comparison?

Regards

Warren Adams

Grizzly (Aussie Mainline)

Bill.  The EMC headers are 1¾“ coming off of the heads for 8”, go to 1 7/8” for 24”, and then into a 3½” diameter 12” long collector.  Within the collector is a merge collector that necks down to 3”.  All this then connects to a 3½” inlet and outlet Magnaflow muffler.  Here’s a pair of links to past threads showing pictures of the EMC headers.

http://forums.y-blocksforever.com/FindPost51824.aspx 

http://forums.y-blocksforever.com/FindPost51872.aspx 

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Gary.  The compression ratio on the mule engine using the 60cc aluminum heads is 9.8:1.

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Warren.  John may have some more exact numbers but I’m using 235cfm intake flow for the stock aluminum heads and 270 cfm intake flow for the ported aluminum.

Lorena, Texas (South of Waco)

I'm impressed with the Sanderson Headers. They are far better than I would have thought by looking at them.

I'll be on the fence about the aluminum heads when used with small displacement and naturally aspirated, on the street until I hear some real world reviews. While the torque is excellent above 2500rpm, it looks like it drops of considerably below that, where a street engine will spend most of it's time. However, that's sorta what happens with performance heads, so in that regard, it is a huge success!


Lawrenceville, GA

Charlie, probably an unported set would work great with your setup where the torque figures would be stronger on the lowend and cheaper to purchase as well. With a mild build that's what I'll do anyway and they'll still beat a good ported set of iron heads.

-Gary Burnette-

That is very likely. Actually, I think I spoke too quickly, with the Sanderson headers, it might be alright. It is only with the EMC headers that it appears to have a significant dip below 2500rpm. I won't be in the market for a set for at least another year so I'll have plenty of time to find out how their street manners are but when I do get some, it will not be for a NA motor so they will be getting some additional "help" to enhance the low end.


Lawrenceville, GA

It is really impressive that an almost 40 horsepower increase was added and that the engine was able to make 370 horsepower through 1 1/2 inch headers.