Rocker arm and intake manifold testing on the new heads.


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By Ted - 14 Years Ago

These graphs are specifically for Geoff but others can feel free to comment.  These show the results of some dyno testing with the aluminum heads where both the rocker arm ratios and the intake manifold was being experimented with.  All this took place on the EMC engine combination using last years 824cfm carburetor.  This years carb of choice is making more power but was not included in this round of testing due to waiting for another pair of metering blocks to show up for it.

 

Looking at the scores for each combination that was tested, the 1.6/1.6 rocker assemblies with the modified plenum intake is 19 points better than the next best combination that was tested.  Each manifold was tested with both rocker arm combinations so there was a total of four different combinations in which to evaluate.  The scoring was only figured based on the 2500-6500 rpm range and does not take into account any activity that’s taking place above 6500 rpms.

 

 

 

 

By Ted - 14 Years Ago
And these graphs compare to the two intake manifolds using the same 1.6/1.6 rocker arm assemblies.

 

 

By charliemccraney - 14 Years Ago
What is the modified plenum? It looks better for the street.
By Ted - 14 Years Ago
For the time being, I’ll let John or Geoff comment on the changes and/or modifications performed to the plenum.  Geoff was good enough to do quite a bit of work on it and then send it to me to try out on the EMC engine.  The height of the manifold as sent to me is already at the limit by the EMC rules so I didn't take the opportunity to do any additional spacer testing on it.  But when I get my good carb back together, I may just put a spacer or two under it just to see what the manifold is really capable of.
By pegleg - 14 Years Ago
Geoff's pretty good with the grinder. I've watched him work. He has done some amazing work on Yamaha 4 wheeler heads too.
By Ted - 14 Years Ago

Finally got in some more metering blocks for the carb I plan on using on the EMC engine and the changes in the metering blocks netted some nice gains both in peak numbers and averages.  Also experiemented with the ignition curves as the aluminum heads were preferring something different in this area as compared to the iron heads.   The carb and ignition changes now has the engine peaking at 540+ HP at 6200 rpms.  And the current combination is now 313.1 points ahead of its 2009 EMC score which now has it slowly moving up in last years rankings.  At this point the engine has now overtaken the Ford 427 SOHC and the two Chrysler Hemis that were immediately ahead of the Y in the 2009 EMC rankings.  Here’s a graph showing the current horsepower and torque curves.  Keep in mind that this is still a pump gas engine and all testing is being performed through a set of mufflers.  Next on the list is getting back to the exhaust and doing some more work in that area with Geoff Mummert’s help but that will take place sometime after Columbus.

 

By John Mummert - 14 Years Ago
Ted, looks like you're making some good progress. I'm guessing that 540 is near the HP limit. Most of the gains from here on in will probably be in the 2500 to 4500 RPM range.

Your score is up from last year and other contestants scores this year should be lower due to the dual plane intake requirement and 6500 RPM test limit. All in all should be better than last time.

Keep up the great work!

By aussiebill - 14 Years Ago
Great improvements! john, did you get my PM i sent the other day?  regards bill.Smile