pcmhacking.net

I guess the following demonstrates the advantage of road/track tuning over dyno tuning when it comes to ramp rates.
https://www.youtube.com/watch?v=jTxdU-90Xi8

you do what you can with tools you have, if road tuning good knock monitoring tools are needed even more. Theres a few commercial ones out now, i used festys knockbox myself.

i tune on both. no matter how good the dyno is, you just can't simulate all load conditions, i find even boosted cars will pick up boost on the road vs the dyno due to different load conditions.

Tre-Cool wrote:i tune on both. no matter how good the dyno is, you just can't simulate all load conditions, i find even boosted cars will pick up boost on the road vs the dyno due to different load conditions.

Good point about boosted cars. Turbo especially, boost can end up any where as there is no physical mechanical connection with the crankshaft. Explains why some turbo dynod cars ping when true ramp rates are applied on the road or track. This is one area where spark tuning on road or track is vital.

Interesting on how most of the mapping is done on this car.
https://www.facebook.com/watch/?v=990196814405772

Could not help myself, this certainly reinforces my experience in road/track tuning.
https://www.youtube.com/watch?v=SXsuE2_JQnc

https://www.youtube.com/watch?v=MCJCvubxaaE

It has always interested me why there is a variation between a dyno tune vehicle and a road track tuned vehicle where a dyno tune is perceived as superior. With a dyno steady state tune where one would imagine if the load/rpm cell is done under dyno steady state tuning it should be the same on the road, however after data logging dyno tuned vehicles at the track there is a variation.

The problem as I see it is dyno steady state tuning where the load/rpm is held constant and tuned is an abnormal operating condition that never occurs in the real world at WOT. On the road/track at WOT the air speed through the engine is constantly accelerating influencing the cylinder filling and consequently the tune as compared to steady state condition.

The above youtube clip gives an insight into variations in road/track vs dyno tuning turbo vehicles.

Variations between the 2 aren't caused by different load conditions, that's the whole point of steady state tuning is to get to every load/speed possible that isn't on the road.

The differences are caused by parameters associated with dynamic conditions that weren't looked at when on the dyno becasue the "issues" never arose, examples is AE, transient spark conditions.

A good tuner will first calibrate the injector data, then work on the dyno to get all the load conditions for VE and spark and then finally tweak things like AE, spark transient parameters and possibly temp/fuel offset as air and coolant temps can vary dynamically on the road. One should not readjust via road tune the main tables once they are done on the dyno becasue that's not where the problems are if any discrepancies , rather adjust 2ndary parameters not touched on the dyno. Blaming the dyno for not producing the same results as the road is like using a hammer for a screwdriver and then blaming the tool for not doing what you expected.

That is the most sense you have ever made Vlad... ever...

I might add both methods are just as important to get a great tune and they work together to achieve that, but a dyno will get you far closer to a perfect tune than the road by itself ever can.

For example road might get you 50-60% of the way there to perfect and still be quite drivable. Dyno will get you 90% of the way there and much quicker too.