I have the choice for my car to either have it mapped engine out on a dyno or take to car and have it mapped on the rollers,

What would people rather do? Is one better than the other etc......

Thanks

 

Everyone has that choice. But it would depend on the engine as to whether it's worth spending extra money on a dyno before installation into the car. IMO it would need to be something mega special to warrant that extra cost.

 

>Is one better than the other

Dyno is far better. It's next to impossible to hear high speed detonation on a rolling dyno. If you only want to pull a few power runs to make a nice chart, rollers are fine but that's about it.

If the engine needs to be mapped from scratch and you really want to make the most of it for a given fuel, i.e. properly map the ignition, fueling and wastegate, then a proper dyno is mandatory. What needs to be factored in is the huge amount of work required to install the engine on the dyno.

 

Have you ever tried ?

It's actually pretty easy to hear on any engine with the correct equipment in almost any environment

Regardless of where you decide to map it, it will still need finalised on the road.

 

Yes, I did, and it was horrible. Have you ever tried a fully soundproofed dyno cell, with vacuum double-door? I did, too, and it was perfect

Proper mapping implies getting within ONE degree of the onset of knock, at all possible load/speed operating points of the engine. You need to stay 10-20s steady on every cell on the map to set the base fuel, ignition and wastegate duty. At some point - when mapping mid and high loads - the engine stays near or at WOT for 2-3min uninterrupted (the time it takes to map an entire row - a certain load level - over the useable RPM range), while the oil, coolant, EGT and most importantly intake air temp must be kept in check at all time.

It takes two to three people to do this properly, one driving the bench (engine throttle and hydraulic brake), one on the laptop - mapping - and the third with his eyes on the dyno gauges - blow-by pressure, oil pressure and temp, per-cylinder EGT's - and one hand on the Big Red Stop Button. It gets very tense when the turbo is glowing yellow-orange behind the double bullet-proof window, in perfect silence. This is very remote from a rolling dyno power pull.

What correct equipment have you in mind? NGK gasket-type pressure sensors? Kistler cylinder pressure sensors? I'm all ears but nothing beats a good old copper pipe strategically bolted to the head and crossing the soundproofed wall, ending in a funnel - believe it or not this is still how base maps are made on every engine, including F1 - in addition to piezo sensors.

Rolling dynos are maybe OK to make small brush-ups (like make minor adjustments to the fueling on an otherwise well-sorted and safe map) but for engine development access to a proper dyno is a must.

 

Fortunately you will never be mapping my engine.

Proper mapping implies getting to the lowest timing level that achieves optimum power/torque for any given load site. It most certainly does not mean trying to achieve as close to detonation as possible.
In some or many cases that may not be achievable and detonation may prevent further timing. But that still doesnt mean you run right at the borderline with detonation at all times.

Although I would agree with this statement. But I certainly dont need a soundproofed cell to be able to hear. Good quality ear defenders eliminate pretty much all exterior noise anyway...so wherever I am using them, I have my own private soundproof room....even if it's sitting in a car.