Dodge 360 Grooves Testing, 2-17-06.

Reference and credit;


Combustion chamber quench pad grooves were dyno tested on this Dodge 360.

The engine specs are;

The average correction factor varied between 1.056 to 1.066 during the day of this testing, all the tests were started with oil and water tempteratures of about 175F 5F. This testing involved six before and after dyno tests with the only change being the grooving of the combustion chamber quench pads;

Before grooving;

  • Two 6200-4000 wide open throttle sweep tests.
  • Two 4000-2000 wide open throttle sweep tests.
  • Two 4500-2000 throttle stop sweep tests (average CTQ 200 ft. lbs.).

After grooving;

  • Two 6200-4000 wide open throttle sweep tests.
  • Two 4000-2000 wide open throttle sweep tests.
  • Two 4500-2000 throttle stop sweep tests (average CTQ 200 ft. lbs.).

Here are pictures of a head before and after the grooving.

The combustion chambers had carbon over the whole chamber, the picture is deceiving, there is oil on the head making it look like that quench pad was clean.


The grooves did not make much difference in the 6200-4000 wide open throttle sweep tests.

It is interesting that the EGT delta went down with the grooves, EGT delta is how much the EGTs are different from each other.

Comparing the worst after groove test to the best before groove test shows an average loss of about 1 ft. lb. torque over the 6200-4000 rpm band.



The grooving made basically no power difference in the throttle stop tests. It does look like they slightly lowered the part throttle EGTs. (The throttle stop testing was intended to test part throttle cruising type conditions, like passing someone on a highway.)



The 4000-2000 wide open throttle sweep tests proved to be more interesting. In the best case scenario there was a 6.5 ft. lb. average torque gain in the 2200-3500 RPM band.


Comparing the best before groove 4000-2000 wide open throttle test to the worst after groove test still shows a 2.68 ft. lb. average torque gain in the 2200-3500 RPM band.



A wide band O2 meter (LM-1) was used during all the testing but it did not show much difference in A/F ratios before and after the grooving. Here are LM-1 logs of tests 1047 and 1058.

Test 1047 LM-1 log.

Test 1054 LM-1 log.


The dyno DAQ does output BSFC numbers but again the differences are very small. There was a slight decrease in BSFC in the 4000-2000 WOT tests after the grooving. A better test of combustion efficiency might be in using a exhaust gas analyzer.


Here are 350K MP3 files of the engine idling. The grooves had no apparent effect but these sound clips are when the engine is warmed up. The grooves may make more difference in cold engine idling.


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