Inconsistant dyno readings
 

Any of you guys ever seen 3 pulls on a dyno with no adjustments to the engine and seen different numbers. About a 50hp fluctuation on a couple pulls.

This is my first experience with a dyno so all info will be good.

We did make carb and timing adjustments and power increases did occur and the inconsistancies were pretty consistant even when making more power.

Thaks.

Something is wrong for sure. Without being there or having a LOT more details, I couldn't say for sure, but you should be within a couple of ftlb's pull to pull

Yes, the outer ring on the damper was slipping and timing was all over the place. Take a punch or chisel and witness mark the hub/ring.

He is using an old style dyno with the lever on the water brake, If it is engaged at slightly different rpms and at a different pace while working the throttle, would that change the output readings.

Also, on the graph when calculating the chart. When you set the in and out points on the graph. It will change the readings. I don't know what that is about either. I monkyed with it myself for a little while, but I didn't want to mess up someones elses tools.

No that should not matter. If it is maintained well it should be pretty consistant

Do you mean after the run the graph changes depending on how you set it up? If so then there's something wrong with his calculations.

If you mean that the results vary if you change the starting and ending points of the sweep, then that's different. In that case there could be any number of things going on.

Give me some more details.

he graph changes depending on the starting and ending pints after the run.

You set the starting point at 4000 and end at 6000 it says one thing. If you start it at 3000 and end it at 6000 it says something different.

Then you've got computer problems, not dyno problems

I kind of thought that alos, but I didn't want to offend the guy. He was a big help in final tuning and running the motor on the dyno stand alone was worth the cash because of finding the little gremlins that were in one engine.

Computer software is early 90's running on windows 3.1

I couldn't believe it when I saw it start up the first time.