Question for Engine Builders with Dynos

[304065]

Can you describe for the forum the Dyno process?

I was wondering how you determine the optimum fuel/air ratio and ignition tables.

Do you set up the engine at a constant RPM and wide-open-throttle, with the dyno brake holding the revs at a particular point, and then alter the fuel settings and alter the ignition settings? Such that when more power is achieved against the brake, the revs climb?

Or do you make changes and do WOT pulls from low to high RPM and then compare the results?

As much practical detail as can be shared would be helpful to demystify the process.

Bonus question: when you build a new engine, do you break it in on the dyno? Can you describe this process? I have to take my almost-complete engine to Peter Dawe and would be interested in knowing what this entails.

Thanks! In advance. . .

[Steve@Rennsport]

Originally Posted by 304065

Can you describe for the forum the Dyno process?

I was wondering how you determine the optimum fuel/air ratio and ignition tables.

Do you set up the engine at a constant RPM and wide-open-throttle, with the dyno brake holding the revs at a particular point, and then alter the fuel settings and alter the ignition settings? Such that when more power is achieved against the brake, the revs climb?

Or do you make changes and do WOT pulls from low to high RPM and then compare the results?

As much practical detail as can be shared would be helpful to demystify the process.

Bonus question: when you build a new engine, do you break it in on the dyno? Can you describe this process? I have to take my almost-complete engine to Peter Dawe and would be interested in knowing what this entails.

Thanks! In advance. . .

Hi John,

Call me during business hours and I'll tell you what you need to know,....

Stay well, pal.

[304065]

With you five by five Steve. . .

[ShinySideDown]

And post a summary for the rest of us!

[PFM]

304065,

Saying "dyno" is a little like saying engine, a broad statement. Twenty odd years ago the dyno shop I worked with had a manual control dyno with "state of the art" data acquisition. This dyno made sweep pulls period and the experience of the operator was what made the day.



Today with fully computer controlled dynos all kinds of tests are possible, we still do sweep pulls at WOT but can also do mapping pulls where the dyno holds the motor at X RPM and allows you to make adjustments looking for best power.

You asked about air fuel ratio, at one time we did this with EGT's then narrow band O2 sensors one per bank today we can do a wide band sensor per cylinder if desired. "THE" ratio is not a set number each motor makes best power at some air fuel ratio but it can and does vary motor to motor and even in some cases RPM to RPM usually favoring a little richer mixture at PK TQ than any where else.

Timing is another story, with a distributor individual cylinder timing changes are hard to do, COP ignition allows each cylinder to be trimmed for best power. Some dyno systems can measure cylinder pressure to best optimize each cylinder. Some EMS systems allow a true timing curve that can be optimized on the dyno for both max output at WOT and best economy at part throttle light load settings.

So the long answer as to what to expect depends a lot on the dyno facility, type of dyno and operator experience.

[Flieger]

[PFM]

And then there is an Uber Dyno!!!!

[Schwarzeritter]

Want that dyno want that dyno! Right now! oh well guess will have to do it the ole usual way! I like the video. Still even with modern dyno's you are at the mercy of the operator / engineer. Also a lot of times the rigs or pulls etc will not experience a road going conditions however these are hopefully factored in. Then again you are limited to the points / parameters available to adjust or monitor. I love tech / test equipment.