18 replies to this topic

[marcusmazza]

I just put my 1.6L SM on the dyno for a test/tune and wanted to share the results with everyone. I have a Sunbelt engine with roughly 30hrs on it. Compression is 204, 204, 203, 204, and leakdown was slightly less than 1% on all cylinders. Basline going into the tuning session was 12deg spark advance, stock (unopened) AFM, used iridium NGK plugs (normal heat range), pump gas 93 octane, Mobil1 10W30 High Mileage formula + 1qt. Mobil1 V-twin. I also just installed a 5X AFPR. The intake is home made, but looks very similar to the SPX straight intake.

 

I have to say, the biggest take away is how minor the changes to power and torque are when tuning. You need to be very consistent when making the runs. One of my goals was to see if the unopened AFM school of thought is better than the tuned AFM school of thought.

 

All numbers in the graphs are uncorrected. The day started around 65deg and ended at 69deg. The SAE correction factor stayed stable at 0.95, and the STD correction factor stayed stable at 0.98 (humidity went down as the temp. came up). I'll let you do the conversions if you want.

 

First thing I looked at was fuel pressure. The graph below shows three fuel pressures, each run is a 1.0psi adjustment in pressure.

 

 

 

[marcusmazza]

As you can see, leaning out the car definitely makes more power and torque. I wasn't willing to go much leaner. Next I played with the spark advance. I started at 12, then went to 14, 16, and 17. Don't look at the run numbers. 12 is the top run shown on the graph, and they go in order from there. You can see there is a slight dip at 14, 12 and 16 give similar results, and 17 is definitely past the sweet spot. I was curious why it dipped at 14, so I did a couple more runs at 12 and 14, similar results. The second graph shows those results, with the first two runs being at 14, and the second two at 12. Keep in mind, this may be slightly different for every engine.

 

 

 

[marcusmazza]

Next I went on to tune the AFM. I had the AFM open the whole time and was watching to see how far the flapper door opened during each run. I did this by marking the AFM when manually holding the flapper open 100%. With the stock tuning, the flapper door did not come close to opening fully. First on the list was to adjust the spring pre-tension. The next graph shows the results, loosening the door 2 clicks at a time. Definite power and torque increase, although it plateaus very quickly. Even with the flapper super loose (10 clicks), the door still never opened fully. The first run is stock AFM, followed by 2, 4, 6, 8, and 10 clicks looser.

 

 

[marcusmazza]

I didn't bother adjusting the AFM sweeper relative to the flapper door. I believe this adjustment is almost identical to adjusting the fuel pressure, just harder to do and less repeatable when trying to go back to a given setting. I did however try angling the board. The next graph shows the stock board vs. the board fully angled (should make the top end leaner, or in this case made the bottom end richer.) This adjustment was not as dramatic as I was hoping. I really wanted to tune out the 6,500 - 7,200 fuel enrichment. Didn't happen. I was also hoping to do something about the enrichment I was seeing between 4,000 and 4,500. Again, no deal.

 

[marcusmazza]

In the end, I feel that adjusting the AFM was a big deal. After seeing how much farther the flapper opens up when you loosen the clock spring, and seeing the numbers, I am convinced that this is the way to go. This graph pretty much shows it. Same fuel pressure, same timing, same everthing. The second run shown on the graph is with the spring 6 clicks looser.

 

[marcusmazza]

The last experiment was spark plugs. I tried a new set of NGK iridium (one heat range colder) and a new set of NGK standard copper (also one heat range colder). I was surprised to see that both plugs seemed to lose power and torque compared to the used plugs I had in. The graph below only shows the two new plugs. Did several runs on each plug. The copper plugs seemed to do a bit better.

 

 

[marcusmazza]

2hrs later and $200 poorer, but pretty happy with the results. Learned a lot. I wish I had my own dyno!

 

-Marc

[Alberto]

nice

[RussMcB]

Thank you for sharing.  It's always interesting to hear about testing and results.

[Todd Green]

+1, thanks for taking the time to share your results!

[Danny Steyn]

Marcus, thanks for the detailed writeup of the process and thinking behind it. I think you might have helped many with this write up.

[Andrew Warren]

Interesting finds. With essentially the exact same setup, a Torsen, and a different dyno I was able to make 120whp / 97wtq with a ~20hr RE motor on my 1.6L.

[Steve Scheifler]

Reviving an old thread.

Marcus, good stuff. I take it that all runs were with the hood up. A few questions.

From where was the dyno picking up temperature?

Did you have a fan blowing through the radiator? Did it also blow ambient air over the engine compartment?

Were the runs you displayed "singles" with adjustments between each, or taken from a set of several quick in succession with no changes?

[pat slattery]

Thanks for sharing

[marcusmazza]

Steve,

 

Just saw your questions. Hood was up and there was a fan blowing over the entire engine bay. By temperature, I assume you mean where was it picking up the ambient air temp? I assume somewhere near the computer, but not sure exactly where the sensor was. The runs I show are single runs. I did do multiple runs on certain configurations, but usually not back to back.

 

I recently rolled my 1.6 and am now building a '99, but I really felt that there was some more power to be gained with my 1.6. I never adjusted the wiper position on the AFM. I relied on the adjustable fuel pressure regulator to tune the A/F ratio. My theory now is that by using both the AFM wiper position and the adjustable fuel pressure regulator, that you are able to tune the A/F ratio and the spark map independently. Never had a chance to prove it out though.

 

Marc

[SaulSpeedwell]

My theory now is that by using both the AFM wiper position and the adjustable fuel pressure regulator, that you are able to tune the A/F ratio and the spark map independently. Never had a chance to prove it out though.

 

Marc

 

Ding ding ding! 

 

Although, I would frame it this way:  Once you have a "tuned" AFM, the fuel pressure is the easiest, most repeatable, most easily reversible way of adjusting for large environmental and fuel (% oxygen) changes.  This is why I advocated for allowing the AFPR for the 1.6 cars, but have always maintained that you still NEED a tuned AFM.  If you are only going to have one, you would still want the tuned AFM ... because fuel pressure alone can never address the "restrictor plate" effect of the a stock AFM at >116HP and >6500-6800 rpm.

 

The timing map issue matters, but the "restrictor plate" effect matters more, esp for peak HP. 

 

If I had a nickel for every "perfect A/F ratio" 1.6 I've seen that made 2-5 HP more on the dyno with "less perfect A/F ratio" and a "tuned" AFM ... I'd have .... $1.15, at least?

[Steve Scheifler]

I've spent hours on the dyno with our 1.6s recently. Unfortunately a lot of the time was spent chasing various issues, some real and some not, but hopefully I now have a solid baseline for the future tuning and testing.

I will try to post anything of potential use or interest as we go along, but should I continue this old topic or start a new one with a slightly different subject inviting participation and sharing? 1.6 drivers unite!

[OctaneNation]

 

The timing map issue matters, but the "restrictor plate" effect matters more, esp for peak HP. 

 

If I had a nickel for every "perfect A/F ratio" 1.6 I've seen that made 2-5 HP more on the dyno with "less perfect A/F ratio" and a "tuned" AFM ... I'd have .... $1.15, at least?

What exactly is the timing map issue you refer to? I've been thinking it would be nice to have a brake-type dyno for holding a steady state RPM and tricking the AFM voltage and other temp sensor inputs to see what the ECU does to ignition timing.

 

How loose can you go on the AFM spring? I started this past weekend with the AFM rotated 45 degrees and 5 or 7 clicks plus a moved wiper. Stock FPR. It was leaner than I like so I unrotated it a bit (to 30*?). And went 2 more clicks.

Still was a bit lean so I did 3 more clicks (10 or 12 total) and AFR was good (12.5 at redline, maybe 13.5 at 5k RPM).

[OctaneNation]

I've spent hours on the dyno with our 1.6s recently. Unfortunately a lot of the time was spent chasing various issues, some real and some not, but hopefully I now have a solid baseline for the future tuning and testing.

I will try to post anything of potential use or interest as we go along, but should I continue this old topic or start a new one with a slightly different subject inviting participation and sharing? 1.6 drivers unite!

I'm definitely interested. I even started a thread: http://mazdaracers.c...-tuning-advice/

I think either place is fine for sharing tuning tips...

I'll have more to share in the next week or two.