Is dyno tuning really any good ??

I finally got my engine back into the Road King. After I but on an easy 500 miles on it I brought it back to my engine rebuilder to do the dyno tuning work. This was something I have been dying to watch. I have always had my doubts about how effective an inertia dyno can be for a complete map adjustment.

My doubts where confirmed. I watched as they made about 6 WOT runs from 2000 rpm to 5500 rpm. They produced some pretty power and torque curves, but the only changes they did between each run was download 6 different pre-made curves from the Power Commander map list. They picked the best one and called it good. I never saw their AFR meter go below 22. I new it was going to be up to me to get the bike to run right and I was going to have to do it with out an AFR meter.

I want to go to another “dyno expert” and find if there is someone who can really calibrate a complete RPM vs. Throttle position fuel and spark map on a dyno. These are the things that I think you would need;
1. An electric dynamometer – An electric dyno can hold a speed as you check all of the throttle positions on the map, such as 20%, 40%, 60%, etc. at one speed then change to another speed on the map. I am sure this type of dyno is too expensive for most shops. Has anyone ever seen one of these?
2. An air fuel ratio (AFR) meter that actually works. Perfect AFR for gasoline is 14.7 to 1, but at WOT it should be richer, like 11 or 12 to 1, not 22 to 1 like I mentioned above.

With proper equipment I believe you could actually do this in a couple of hours. In my engine rebuilder’s defense I will have to admit that his claim to fame is drag racing. So the WOT runs make some sense cause they don’t care about anything else. But, most of us on this forum are not drag racers, we’re cruisers. We need crisp throttle response, no pinging on hot days, no coughing thru the air cleaner when you are trying to pull out in traffic, etc.

Now I got a beef about these “pre-made” maps that are on the Power Commander disk. Why is there no uniformity to any of these maps? How can they go from adding 11% fuel at one point and then subtracting -8% in the cell right next to it? This does not make an sense. I am sure that from the multitude of ours spent on an engine dyno at Harley-Davidson Engineering Department that they came up with a smoother base map than that to work from. I have to believe that when we make changes like changing exhaust pipes or camshafts that these things affect the whole engine map in a uniform manner. I am not saying that it is the same everywhere on the map. I am sure air flow will be better at some points then others due to these changes but the air flow can’t be as erratic as I see in these maps supplied by Power Commander. Has anyone else come up with a smoother looking map for their bike? I am just curious how other people are doing with mapping their own engines.

On a carbureted bike and inertia dyno helps for tuning because you can simulate WOT plug chops and read the plugs. On EFI bikes, an inertia dyno is about useless for anything more than giving you WOT max HP and Torque values.

EFI bikes require a load cell dyno such as the Dynojet 250I.

http://www.dynojet.com/motorcycle_dyno/250i_dyno/index.aspx

Using a load cell dyno and a tuning device like the Power Commander USB allows the technician to create a custom map with AF Ratios as close to optimum as possible. The caveat to that is that a really good tuner knows where to add or remove fuel and or timing to insure the mixture is not too lean to prevent proper cooling.

These load cell dyno's aren't cheap at over 25k and to be an authorized tuning center you must have six months experience on the 250I and attend a class at Dynojet.

There are several tuning centers in CA
http://www.powercommander.com/centers_ca.shtml

"Now I got a beef about these “pre-made” maps that are on the Power Commander disk. Why is there no uniformity to any of these maps? How can they go from adding 11% fuel at one point and then subtracting -8% in the cell right next to it? This does not make an sense. I am sure that from the multitude of ours spent on an engine dyno at Harley-Davidson Engineering Department that they came up with a smoother base map than that to work from. I have to believe that when we make changes like changing exhaust pipes or camshafts that these things affect the whole engine map in a uniform manner. I am not saying that it is the same everywhere on the map. I am sure air flow will be better at some points then others due to these changes but the air flow can’t be as erratic as I see in these maps supplied by Power Commander. Has anyone else come up with a smoother looking map for their bike? I am just curious how other people are doing with mapping their own engines."

These "pre-made" or "canned" maps are the result of testing with that configuration at Dynojet and are not just something an engineer puts together. Why do the cells vary so much? Because an exhaust does not flow the same CFM at every throttle and RPM setting. If you were to look at the flow test charts of an exhaust it will look not have a uniform flow across the RPM range. At some point every exhaust has some reversion characteristics. Every system will flow better at one RPM than another. In order to get the tuning right you have to vary the AFR and sometimes the timing. Another thing to consider is that you are not seeing the HD map in the ECU so you have no idea what it's cell is reading. If you have 10 cells the ECU map may be up and down cell to cell. The Power Commander cells use that cell as a reference and using it's parameters will add or reduce fuel as needed. The maps are developed on the 250I that performs the functions you describe.

My dyno tune included an AF ratio across the rpm ranges. It is pretty flat at somewhere between 13 & 14. I only have the stage 1 with a stock ECM and the bike (2002 Heritage Softail Classic) has a really good torque curve and max numbers of 77HP and 83 ft/lb torque. I am in Richmond, Va and I used the Dyno tune shop listed on the website. It was $200 and I was well pleased with the results. I have over 8K miles on the tune and the bike runs great with only a blurby blurb gurgle gurgle under rapid de-acceleration. No real popping or backfiring. I don't have my print out in front of me or I would give the exact numbers. I have the BSS and Ness Big Sucker that I purchased here and installed them myself.

Well CD, I stand corrected. I am glad to see that Power Commander spent some time on these. I was under the impression that they came from different sources.

I see the 250i load control dyno is the ticket. Thanks for the links. That is a very nice web site w/quick access to road map locations of test sites. I should have done a little more research.

I am used to doing calibration on V8’s so the exhaust reverb problem must be a lot more pronounced with the V2’s. This makes sense now that I think about it.

They other thing I was dealing with was the area around 2000/3000rpm and 40/70% throttle. My bike was pinking like crazy and I added a lot of fuel in this area (as much as 22%) and took out 5 degrees in a couple of cells and I may have to take out more.

This may be due to the fact that we shaved the heads and I don’t see any maps for higher compression EVO’s. I had the a Power Commander before and didn’t need that much fuel change. Now, after the rebuild, it definitely needs the PC.

Then I blended the map in to the 2000rpm and above and 0/10% throttle area to get rid of back fire and induction cough. The bike runs nice but who really knows what the AFR is. So with all the changes I did - I basically through out the M801-320.djm map I started with.

I may have to break down and go to one of the dyno centers. I'll call Pomona tomorrow.

Thanks,

98 EVO, Red injectors, Andrews 27 cam, K&N, Stage 2 ECM burn, Shaved heads.