Dyno Stuff

[koko64]

The dyno I regularly use has changed from a fair to middling dyno to a stingier dyno as far as readouts from local dynos are concerned. After conversations with my dyno guy it appears that upgrades to the same dyno (software, etc) have made his dyno read more conservatively. He is a good guy and we talk about stuff. It got me thinking.

I was aware of different makes of dynos reading differently, Dynojet Vs Factory Pro being very clear examples, and also aware of different models from the same dyno manufacturer reading differently over the years, but what threw me was the same actual dyno reading differently due to programme upgrades. Now my old data is useless. I'm not the only person to have mentioned this after discussion with different people. It seems the later version Dynojet model dynos read more conservative (up to over 10%), and that's leaving out any dyno shenanigans (another issue again). On that note it seems that if you own the whole set up you may be able to play with temp, barometric and correction factors to pump things up to look good. One guy I know who leases the dyno computer is locked out of those parameters and couldn't cheat if he wanted to. His customers have complained of his dyno stealing hp!

The dyno I have taken bikes to for years has become more conservative so now I can go anywhere as corrected comparisons are now useless. Shame. The only comparison I can rely on now are the before and after readouts on the same day.

Some guys own the whole set up, some lease the whole set up and some might own the machine and lease the computer hardware. With that comes upgrades to software and firmware that could recalibrate the same machine to read differently. Bugger.

I now have easy access to three dynos and I know for sure they read differently. One is a Dynojet that is owned outright and reads much higher than most around here, one is part owned and part leased that was a midrange dyno among the local ones here but which has recently become stingy, and one is owned outright that is a custom built amalgam of different dynos to meet the operator's particular requirements (brilliant professor type guy in the hills). None of these guys would cheat as they are good blokes, just the machines say it different. One bloke had customers complaining that their bike made less hp than before when run on another dyno, but he was able to point to the big hp increase between his dyno runs after the work. It's just that the improved power after the work was done was still less than the dyno reading from the other side of town!

I am interested in any thoughts from experienced dyno users on this topic.

For those of you that get their bikes dyno tuned, I believe this is the best way if you have access to an accomplished dyno tuner (in conjunction with road testing). Don't feel sad if your bike makes 10hp less than your mate's identical bike with the same mods if it's on a different dyno. Even if the dyno is the same model by the same manufacturer, that means nothing. Just look at the before and after graphs and ignore the hp numbers.
I road tested a bike recently after a dyno tune and took it straight back to have some adjustments made. The configuration of the motor (big air cooled single) had different fuel requirements above what which was theoretically required for a water cooled in line 4 cylinder.While dynos are great tools, that's just what they are and not the whole picture.

Good to know I can easily add ten ponies via choice of dyno.

[Dirty Duc]

Not an experienced user yet, but this is the main reason I ended up rolling my own (of yet to be determined consistency)... In the end the house numbers are basically bragging rights. What's really important is percent change and maximizing that result.

I'll know more as I gain experience with the homebuilt job.

[koko64]

You did a pretty cool job too .

[Dirty Duc]

Thanks for the kudos... Now I just have to figure the data to log and how to do it.

Lots of racers install o2 sensors for running and remove them for the salt... I'm thinking that plus a single cylinder egt will tell me something useful.

[Speeddog]

@koko
Are all of the dynos 'inertia' style?

[koko64]

DD. What you are doing is interesting for sure and understandable because you have requirements related to your particular goals. I just it's so cool how you did it .
A bloke I know built his dyno out of a few different types available to get what he wanted. It seemed he was able to get features from each dyno manufacturer to meet his own very strict requirements. He tunes everything from modern superbikes to Formula One side cars to old classic and vintage racers.

SD.
I'm told two are the same Dynojet models but with a big hp variance, might be generations of computer software as one is owned outright (reads high around here) and one is leased with periodic updates (becoming more conservative over time). The third custom one does everything. The guy wants to measure everything everywhere in every way. It probably has a Flux Capacitor.

PM sent.

[clubhousemotorsports]

Dynos are best used to compare before and after runs and used for diagnoses /setup. What they truly get used for is bragging rights and bench racing. I have seen people lose their minds trying to chase a silly number that made little to no difference but .... because it was there.

I have used a number of dynos all Dynojets, mine is a 100 converted to 150 spec running winpep-8. The 250i we had at the dealership was great with the eddycurrent brake, I do want that upgrade but for now mine does the job just fine. The one we had prior to that was a 150 , similar to what I have now but both at the dealership were running winpep-7. The winpap-7 dynos have a single pickup on the drum where the winpep-8 has about 12 pickups so the resolution is better. This helps with diagnosing issues some times as little things show up more.

I can tell you they all were off a little between then our first one at the dealership we had to measure humidity and enter all data before running ourselves. #2 did that for us and being brand new at the time the HP was just a little higher than #1. #2 being used also had worn knurling on the drum which allowed some tire slip, strapping the bike down did help equalize this. My Dyno #3 is obviously old and the knurling is good but not new, most bikes do not need to be strapped down but high HP bikes I do tie down. Your dyno that has lost power may simply be losing traction on the drum.

My Dyno is about 5hp lower than the dealership dynos I used, again as long as you are comparing before and after it is no big deal but I have to caution customers about dynos so they are not too disappointed when they see the numbers. I am not sure but have a hunch that winpep-8 lowered the numbers to be more in line with other brands because of the claim of "dynojet-dyno numbers". It may be more accurate but customers still read magazines and sales brochures with bogus hp numbers (engine vs rear wheel hp and dry weights are about as useful), and expect to see advertised numbers because they are sure that their buddys bike is faster.

Can you manipulate the hp numbers? yes by choosing different conversion factors you can fish for the highest number but this is no good if you are comparing your run in DIN and your buddys in  SAE one will have a advantage but the bikes are no different. If you are using a DYNO room and the room is pressurized so the room does not run out of oxygen then you are also pressurising the intake charge of the bike and just like any forced induction system they tend to make more HP. A dyno in a small room with no reserve of oxygen will use up whats there and after too many runs the power starts to suffer.

[koko64]

Appreciate you chipping in. Seems Instruments  can be used for diagnosis and measurement Vs marketing and propaganda, and like any tools can wear or change calibration. . Cheers.

[koko64]

Over the last few weeks I have had interesting conversations with three blokes who operate or use dynos and build/tune race engines. All three said it wasn't worth using the dyno correction factors anymore, as they no longer believed that one can compare data over time by using them. All agreed that all that mattered were the before and after runs on the same day, and that one should just ignore the actual hp/torque (except the AFR) numbers and look at the curves. Each bloke just ran the dyno uncorrected and accepted that the power displayed was for that day.

When discussing how the local dynos varied so much in their power readings, one bloke said that one dyno known to him displays so much horsepower that there's a hayshed behind the dyno room .

[Speeddog]

I can understand where they're coming from, for sure.

Buuuuut......

How would they then realistically compare before/after engine mods that can't be done in one day?

[koko64]

I have no idea mate. A big job might take days or weeks.
I guess they would have to make do.

[clubhousemotorsports]

I also see where they are coming from but like nick said pick a correction factor and stay with it. In the US SAE is the most common so I use it, In Au I am not sure what you use commonly but I am sure there is a standard.

It may also be in their benefit to use whatever the others do not because then they can point to that as the reason the powers "off" make everything apples to oranges and it is some times easier than educating your customers.

[koko64]

They have no choice on long running jobs I'm sure. One guy is getting complaints about his stingy dyno.

I see SAE, PS and STD used , both corrected and uncorrected on Dynojet dynos here.

I 'd be ecstatic just to have my own, but would probably be bankrupt by now from testing every question I've ever wondered about.

[clubhousemotorsports]

Once you buy one you will need to have one after that because it becomes one of the most valuable tools you will own and I do not mean for handing out runs and making money. I have used mine for everything for injection and carb set up to test riding race bikes or non road legal bikes. Diagnosing running issues from final drive to ignition systems.

Yes you will waste tons of time using the BS detector to come to your own conclusions instead of trusting manufacturers specs or some jerk on the internet who is making claims.

I will at some point have a inexpensive modernized dynojet for sale if you feel the need, I think that shipping would kill you but I would consider selling only to buy a eddy current model. Keep an eye open in your are as they can pop up and I would have tried any brand model to start. Keep in mind the spending does not stop after buying as I have spent 3x the money spent buying the dyno on upgrading.

[koko64]

Yeah, thats what JD Hord calls dynos,.. "bullshit meters".