It has come to my attention in a previous thread that has bought me to start this thread because a dyno sheet was posted of a 124 build with great numbers and someone posting that the shop who did the run was known for giving happy numbers.I myself can only assume they were implying that certain shops who do dyno testing on bikes fake the numbers to make them look better then what they are on the run of the test.

My question is if numbers don't mean anything as alot of you have said on here then those who believe that shops do this kind of thing why would it matter in the first place if numbers are higher then you think they should be?

 

I only view the numbers as a method to see what works and what doesn't but it does muddy the water with the bogus numbers you see on some builds.

 

What i don't understand is who knows what numbers are correct and what are not?I see some people on here post numbers of builds and people get all googly eyed over but when the numbers get posted their is no question of weather the numbers are false but if numbers are posted someplace else then that shop gives happy numbers.Now all of this and people on here claim that numbers aren't important.

 

Mark MPDC, I have read your posts 3 times and I'm still not sure what your question is. Jim.

 

its how they perform beside other bikes.. some will have it and some want to have it.... but if you dont ride hard or agressive, theres not much reason to have built motors... most things can be accomplished with a down shift

 

Well its been stated that some shops who dyno tune give better numbers then other shops and my question is how does one know this and why is it such a concern if people are not worried about what the numbers are on a dyno sheet.

 

Mark, if you go to a reputable shop, known for performing a good job Tuning your engine, you should be fine. The whole idea is getting a Dyno-Tune, emphasis on Tune. If you get your Bike Tuned well, then the numbers are'nt really important, that does not mean they are worthless, it just means the numbers on a Dyno sheet are not written in stone [ so to speak ] so are there shops that pump up the numbers, sure, but they are still fairly close. In other words, you can't take a stage 1, 96 c.i. and say the Dyno reads 140 H.P. and 140 T.Q. but it should be reasonably close. The main reason for the Dyno Tune is the Tune, let your seat of the pants Dyno numbers be your final test. People who race at the Bar with only their Dyno sheets as comparison are a joke. Jim.

 

Here is a little history lesson. Years ago when DynoJet was getting started and Motorcycle dynos were becoming popular, the owner of the company at that time decided to make the dynos (with software) read inflated numbers. It is a long story but Sales were important and lets face it large numbers seem to make everybody happy. Over the years dynos like anything else have gotten more accurate, more popular, and there are many dyno companies in the game. Any body who has a dyno and tunes knows how to inflate the numbers if they really want to. There are a set of Standards called SAE which is suppose to somewhat level the playing field or make the numbers correct for environment conditions at that moment in time. There are several sets of Standards, around the US SAE is the one most used.
I like to believe that most dyno owners want to produce as accurate as numbers as possible, maybe I am naive, but this is my belief. Dynos can all be calibrated (Torque cell)and this calibration will change the output of the numbers. For example my Dyno a couple of years ago had some software that was calculating the low RPM Torque too high. I told people the 2000-2750 Torque values were inflated. I worked with DynoStar to fix my software and they have, the numbers now are much more accurate and real. I have many customers who liked the old numbers as it added 5-10 ft-lbs to the Torque numbers. I want the numbers being put out as accurate as they can be. Calibration of a dyno and software driving the dyno can have a big effect on the numbers. DynaPro is another company who has added 16 RPM triggers to get the RPM as accurate as possible, my DynoStar has 4 triggers and I believe DynoJets have 1 trigger. RPM is a key element in the calculation of HP and TQ. As you can see there are many differences between dynos and the data collection and software manipulation is critical. How do we expect them to all read the same. It will never happen so this is why most tuners use the tool and data for tuning the bike. I use it to show customers the before as delivered WOT run verusus the final tune WOT run. These before and after numbers on the same dyno are the best way for people to see what they gained. As already mentioned the Dyno is a diagnostic tool to be used for a variety of things. The peak WOT HP/TQ values are not that important. What is important is the delta or gain from before and after the tune on the same dyno. The other factor that the dyno can not measure is rideability, this requires the "butt" dyno and miles on the road. Yes, you can feel the smoothness or accel/decel on the dyno and can feel the accel to decel transition but the real feeling is on the road. If the tuner gets the bike tuned accross the entire RPM/TPS/MAP range it will usually correlate to a very smooth bike on the rode.

 

Mark -

While some people get giddy over peak numbers (myself included... I'd love to grab a fist full of a 150 tq @ 2500 rpm motor sometime) it's really the shape of the curves and the area under them. My curve jumps up to almost peak tq at 2700 rpm and stays flat until right under 5k. My tuner warned me ahead of time that he has an accurate dyno compared to others in town and to spend time in the saddle before being disappointed. That statement is soooo true in my case at least.

Just for kicks, I went to a different dyno after my tune during a dyno day they were having. I have a new chart with the almost the exact shape of torque curve, but the numbers were 10% higher. Does the bike ride any different now? Nope. Still rides great, smooth running, good economy when I control my wrist, and I'm still just as pleased as when I took it for its first ride after the tune.

Bottom line... in the end, it's really not about a happy dyno or not, or what the peak numbers are as much as the shape of the line they make on the graph.

 

Mark, viewers of dyno sheets can decide for themselves what to make of them. For some, a dynos sheet on a particular cam, SE kit, indy's headwork, etc. is THE holy grail of comparison to other cams, kits, etc.

For others, a dyno sheet is a way to confirm that the engine has been correctly assembled. Since many of the builds are repeat builds (i.e. others have assembled identical or highly simlilar builds) the WOT sheet will validate that the engine has been assembled and tuned correctly. If there is a gross deviation (e.g. the engine puts out significantly less power), that probably indicates a problem such as sumping, misaligned cams, etc. If the dyno sheet shows numbers significantly higher than virtually identical builds (say, 10% higher) from a particular tuner, the numbers may be the result of a dyno that simply reads higher hp and torque (i.e. the tuner isn't manipulating the dyno to generate higher numbers) or the tuner may be manipulating the dyno to produce higher numbers to attract business for himself or the shop that uses him to tune their builds. In either case, looking at dyno sheets from other tuners for the same or nearly identical builds tends to identify the happy dyno.

As for your repeated question about posting dyno sheets by those who say the numbers don't mean anything, that's more an expression about the specific numbers resulting from a properly assembled engine and sharing with others that information for general comparative purposes. Said another way, PhilM isn't going to tear the engine apart because his hp/tq is 5 low from what he might have expected when he's making 130/150 or so.

Taking PhilM's 124 build as an example, Ed could have continued to advance timing and adding fuel in the WOT runs to the point of pinging in each rpm segment from 2K to 6500 rpm and backed off 3 degrees of timing when pingning was detected and had a maximum power tune with higher numbers than posted. However, in July and August when it's much hotter in Dallas, that max power tune would probably ping like crazy because the air would be less dense (less oxygen), and Phil would need to take out some timing to eliminate the tune. As Ed explained, they didn't do a max power tune.

As for folks being "googly eyed" about PhilM's peak dyno numbers, I wouldn't characterize the comments that way. In any event, there is no denying that PhilM's build is not what we usually see on HDF from one of our own. And I don't see many 130 hp/150 tq Road Glides around. So yes, I'm impressed to see someone take a twin cam motor and produce that kind of power in a streetable touring bike that can deliver 40+ mpg.

You're having a 117" engine built for you. I hope you will do as Phil did and post pictures of how the engine was assembled, what components you used, and how the bike behaves after the engine is installed and you've gotten some miles on it.

Carl