Forum » General Tuning Discussion » Dynoing for the first time all by myself What do i need to know or be perpared for

Dynoing for the first time all by myself What do i need to know or be perpared for

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my friend is strapping my car down then he'll some me how to use the dyno then it's all on me! any tips advise things to do thingas not to do.

Are you tuning or just some power runs?

First thing which people often over look is the basic checks, oil, water etc.

If you're tuning, have you been through the efi fundamental course? Also I would check out the Practical dyno tuning course.

Both a great place to start!

Things to do:

Ask the owner lists of questions and if you're unsure midseason, stop and go ask.

Work in steady state as much as you can, up to 70% of the map can be done this way.

Take your time, it's better to have a good first half of a map than a totally wasted session, you can always book more time.

Keep an eye on your temperatures.

Stop periodically and check for leaks etc, this is usually a good time to let the car cool down.

Thing not to do:

Ignore any warning signs, steam and smoke etc

Go for a full throttle power run too early

Try to map around a fault, stop and fix it

Should be enough to get you going

I, personally, can't stress enough that the car needs to be in "good nic". Any leaks etc need to be fixed before you start, dynoing is a high pressure exercise and an engine, or drive train, that isn't up to the task because it is leaking or seen better days is a grenade waiting to go off.

In Australia if a drag car is failed at safety inspection its not allowed to race I would use the same common sense with regards to dynoing (and I know in many dyno championships if a car has a leak it isn't allowed on the dyno). After all you don't want a stream of oil (engine, g/box/transmission/diff, going all over the floor or worse still the dyno rollers.

The rest has already been said, do steady state and get it right, Chris has an excellent point on faults in that if one crops up fix it before you keep going.

First off thank you for the responses it help me feel confident and prepared as well as maximized my time on the dyno! Unfortunately tho I feel as I got no where with my tune, actually I know I didnt. Here are the reason first I have the hardest time getting the dyno to operate in steady state it is a dyno jet 250I something that my freind has built into the ground. I also found out the he did buy the live link for real time torque till I was strapped on, which is a huge disappointment becuase that makes it near impossible to find the minimum timing for best torque.

I need help, how do you manage the gas pedal during steady state is it always fully open? One thing I felt the dyno wasnt doing porperly was holdind the car under load first we trying using engine speed but I dont know if it was my wasted spark or my 10.9mm plug wire but it it seemed to nlt give the dyno a good signal and caused the load to skip around making near impossible to keep at the right rpm. Then we tried wheel speed loading and it was constantly better but to stay in a bin or to get the lower bins I had to change the pedal position and no matter what I did I couldnt seem to get above 100 kpa or so on my boosted car. The dyno would always get into the max load for the brake. Was I just not giving the dyno enough time to stabilize? Or was I using the wrong setting my friend who owns the dyno at this point probably knows less about using the dyno in this steady state way then I do so he is no help.

Then the other thing is the have over want theory, we started doing some sample runs since we weren't getting anywhere, data logging them as we did them. Then using have over want to try to get the fueling right it seems as it worked below 3500 pretty well over shooting a little bit but nothing I couldnt figure out, id love to have it perfect but I'm starting to think that might not help with my system. Anyway at 4000 I started fighting a either really rich misfire or a blowing out the spark my gap to start with were 38 thousands too big I know so we dropped them to 28 much better but it still did so we dropped it to 22 seemed better but still had way to much fuel 10.0 plus. What gap sould I set for 4000 plus feet and 20+ psi? At this point it was getting late and we called it but as you can see my map was all over the place not smooth at all and it seemed to call for far more fuel then my auto tuning ever has.

The dyno is a 250i dyno jet.

We use a Dynojet 424xlc2 to tune cars on a regular basis, so first things to check is, if your friends dyno has an eddy current load control.

You need this to tune the car in steady state, otherwise you're only able to use the dynojet in inertia mode.

Next thing check, if your the dynojet stack is equipped with the torque module, that way you have live torque feedback from the drum and can tune the timing.

If it's a 4x4 dynojet, make sure you disable the electronic linkage and speed control in the settings if your car is only FWD or RWD, otherwise the load control will sense a difference in the front and rear roller speed and the brake power goes all the way up to a 100% on both drums and car will stop.

Also, for the load control to work properly the dyno needs a stable RPM input. If it's jumping around you'll find that you can't hold the car at the specified RPM. So either you use the optical RPM input and sync the roller speed with the car's RPM in the gear you want to tune, or you simply have the dyno brake to a specific MPH/KPH of the drum.

Once you have all this working, take your car up to a moderate RPM and have the LC activate. Use slow and light throttle inputs to move up the load cells on your ECU while giving the dyno's PID algorithm enough time to hold the RPMs by applying the brakes of the drum.

PS: set the PID of the dynos load control values to the default settings ;)

Thank you for the response the 250i has a eddy brake on it I will check the pid figures. I'm using wasted spark and im thinking that was tripping the dyno out under engine speed so we switch to wheel speed but I also think we just were new to it and didn't know how to match rpm with wheel speed well enough and I was probably being to aggressive with my throttle contorl. Unfortunately my friend tune bikes and atvs on it I believe dyno jet widen it or sold him a diffrent roller setuo so he could use side by sides as well. Its good to tune up to 1000hp I think so none of that should be the issue but it does not of the torque link. So no MBT any tips to getting it close?

Oh, I just realized, that the 250i is a Motorcycle Dyno. In that case you might want to contact Dynojet directly and ask them for the correct settings, even moreso if the rollers have been changed or upgraded.

If you, or in that case your friend, is the original dyno purchaser, then they'll support you and they are really helpful.

Getting the timing to MBT without the feedback of a dynamometer is actually impossimble. You can get it close, but I suggest you purchase the road tuning course to get an idea.

Yes, Im thinking it was some kind of a custom setup since it was bought all at once from them, I'll ask if he feels good about me contacting them it shouldn't be a issue.. Sounds like maybe I just didn't control the throttle pedal well enough to give the dyno time to pid. Also it seems we were using the secondary input that connects to a plug wire instead of the smaller primary and I'm using some huge insulated Taylor 10.9 so maybe that's why engine speed rpm single loading was skipping around or back to the wasted spark being the issue.. I know that screws up some timing lights.

If you're plugs fire one at a time (direct fire), than the dynojet setting needs to be "spark plug fires every 720 degrees". With a waste spark setup, that degree setting has to be half the value, so 360.

It's really easy, if you see double the RPM on the dynojet display than what your tach says, you half the value to correct that. If the RPM is jumping around though, the dyno has trouble getting a clean RPM signal.

Sometimes it helps to put the inductive clamp to a different spark plug wire, and if that doesn't cure the problem, I usually just use the optical pickup device.

May I ask how you're dealing with intake air temp density. I set my curve like I'm told I'm the courses but I'm not sure if it was working since I had so much going on. Or do I zero it and record temp at start and then tune out the correction valves later

You set the fuel air temp correction map prior to the tuning. Depending on the ECU though, it may already be accounting for that, so your table might just be used for situation the car might get out on the road or race track, for engine protection strategy reasons