I figure this question from Daniel deserves a new thread which in turn will help to keep this topic separated from the 3X2 testing thread.

I recently tested the new Mummert manifold against the stock ECZ-B intake on the dyno mule prior to the 3X2 testing but the testing was performed with Reds (or Hedmans?) headers going into 4’ long 2” diameter lead pipes with no mufflers.  That exhaust system was later found to be too restrictive and in the ECZ-B vs Mummert test, a dip in the torque curve became obvious with the Mummert intake.  When the Mummert intake was later reinstalled on the engine with the better exhaust system, that dip in the torque curve cleaned up nicely.  At this point the stock intake hasn’t been rerun with the improved exhaust system yet so there isn’t a good direct comparison of the two manifolds with the improved exhaust system.

But I do have a comparison of both manifolds with the ‘poor’ exhaust system.  Both 4V manifold tests did use a L1850 600 cfm Holley that has had the air horn milled off and a K&N shorty stub stack on its top and the engine was using a set of replacement 1.40:1 rockers at the time.  Using the same scoring format as used in the 3X2 intake testing, the results with the ‘poor’ exhaust system are as follows:

1590.4 pts – Mummert aluminum intake with a HVH 1” ‘Performer’ dual slotted spacer

1572.7 pts – Stock ECZ-B iron intake with a Wilson 1” four hole spacer

Translated to peak torque and HP numbers, the results look like this:

314.4 Tq / 260.9 HP – Mummert aluminum 4V intake

313.9 Tq / 249.9 HP – Stock ECZ-B 4V intake

In looking at the raw data, the stock manifold is a better performer up to 3700 rpms at which point the Mummert intake takes over.  Overall score does fall to the Mummert manifold though if you have your foot into the throttle heavily.  If you’re simply just driving around, then the tip of the hat goes to the stock ECZ-B intake when using a restrictive exhaust system.

It was after that particular round of 4V intake testing that the four tube headers with mufflers from the EMC project were tried while sorting out the Stromberg carbs on the Edelbrock 573 and a clean 22 HP was found just in changing out the exhaust from one to the other.  After that one change the engine started responding nicely to the other changes including the rocker arm ratios.  With the Reds/Hedmans headers, the engine seemed to be stalemated at the 250 HP mark even with many of the changes that were being made and using the ECZ-B intake.  The Mummert intake was worth another eleven horsepower over the stock intake but it was eventually found that the exhaust system was holding back the potential for more.  That same engine is now sitting at 292 HP with the Mummert manifold with the improved exhaust system and 1.6:1 rocker arms.  The stock unported G heads are still on the engine at this point and there are plans to retest the stock intake on the stock heads with the better exhaust system at this point after looking at the data.

Obviously the very next round of testing will be going back and testing the stock ECZ-B 4V intake, the Blue Thunder intake, and the Mummert intake with the current exhaust system.

Lorena, Texas (South of Waco)