Remapping question

[anonymous-user]

This may be a stupid question but here goes:

If a car has been remapped my understanding is you would have your laptop plugged into the car and would cycle the car through gears and or revs on either a rolling road or out on the real road with someone else driving? If it was done on the road (if this is possible) would you be able to measure power and torque levels or can that only be done on a rolling road?

If it can't be measured am I right in saying a car could be mapped out on a drive but the power and torque levels would be unknown?

Thanks

TB

[rev-erend]

Power and torque are measured on a rolling road only.

It is possible to fine tune a car on the public road that has already been mapped on a rolling road but finding a quiet road and not causing police and public attention are not really advised.

[xRIEx]

I can't imagine it would be possible to do out on the road, I've never heard of that being done. I'm not aware that they actually map the car while under load, they just measure what is going in and what is coming out to determine the optimum air-fuel ratio, ignition advance (or whatever they change). They make changes then test it under load again.

You can't measure torque and power without a dyno, but if you've got enough output data from a remap you could approximately calculate it based on revs and throttle position.

[crossy67]

You can find the torque and power at the wheels on the road if you know the weight accurately and have an accelerometer. We used to try a few years back when I had a car worth knowing the power of.

We all found a quiet straight and flat road, a friend had a box/program (too old to remember or care now what it was called) and stuck it to the dashes of our cars. We all did a run from 0-60 (may have been a bit more or less) and it worked out your power outputs based on speed/time. It was surprisingly accurate on all the cars that managed to to a full speed run. We were on a quiet public road on an industrial estate round the corner from Demon Tweaks and after a few attempts caught the attention of the local police so had to tone it down a bit.

Personally I would have a map on a rolling road then tweaked on the road. I know a lot of people that have road made maps and they never seem to get as smoother power delivery or peal power/torque outputs. After all, you are relying on the feeling of someone's butt/pant interaction aren't you

[anonymous-user]

So if your car was remapped you would expect it to be done on a rolling road?

[rev-erend]

Yes.

[Monty Python]

rev-erend said:

Yes.

Makes you wonder how the mobile ones manage then....

[SturdyHSV]

Monty Python said:

Makes you wonder how the mobile ones manage then....

Just a generic flash not tailored to the individual car but to the model of engine I'd imagine...

You can tune on the road provided you have something to log the data coming out. You can install a wideband O2 sensor, log air fuel ratio etc, log the parameters around whatever property you're looking at changing at the time etc. etc. then make your changes, and repeat.

Getting absolute peak power you're not going to know, as you won't be able to tell the difference between a few bhp here and there, but you can certainly dial it in so that it's running at the right AFR when cruising about and at WOT, advance the timing until you start to see knock, dial it back a couple of degrees, that sort of thing.

You'd want a dyno to tune it for absolute best figures, but if you've made changes to how the air flows through your engine, you can certainly dial things in a bit without going on a dyno (assuming you have the necessary software...)

[blindswelledrat]

Surely teh only purpose of the rolling road is to test the results of the remap?
It's not actually part of the remapping process as is being suggested is it?

[Lazadude]

Having had a couple cars remapped, on Dyno / Road and Dyno + Road, its easily possible to do either.

Dyno maps will show you Power made in a nice shiny graph, but from experience, I'd say the road maps were nicer to drive daily.

If you get a specialised mapper, who only does one set of cars, VAG / Mitsi / Subaru / Nissan etc, chances are they have seen it all before, and know what an expected base would be based on specific spec of car.

This "base" map, would then be loaded, and you can then go on the road to fine tune any areas, exactly the same as running the car up on a dyno.

However, as road driving would be more keyed to how you drive, compared to a Dyno where someone either throttles on or off in a select gear. (Normally all mapped on a single gear, 3rd for example, to get a base and then extrapolated). Road mapping is the better refinement, and results in a smoother drive.

All except you don't get a number on a piece of paper...

[s p a c e m a n]

Topbox said:

So if your car was remapped you would expect it to be done on a rolling road?

No, not if it was just flash copied from a previous ecu that the tuner had done, like most vag/diesel £300ish versions are. I would expect a RR tune if I was paying proper money for a custom tune to my steup, not if I was just having say a standard audi s4 mapped.

[SturdyHSV]

blindswelledrat said:

Surely teh only purpose of the rolling road is to test the results of the remap?
It's not actually part of the remapping process as is being suggested is it?

It is used to test the results yes, but if you want maximum power, it is useful to be able to test it in reasonably similar conditions.

You can tune the car based on what it 'should' do, and how everything 'should' work, what AFR is meant to be best, and what degree of timing advance is meant to be best, but there will always be a little bit of tweaking for each individual engine to get the most out of it, which is where a dyno is useful.

As mentioned above, generic £300 engine remap is just a standard flash of the OS with a few values changed to give a bit more performance job done. Could be any example of the engine it's being flashed to. It won't be the best the engine could do, but it'll be better, and it's cheap.

[spitfire4v8]

Any good mapper will use a dyno AND the road. You can't see small hp changes without a dyno, but likewise you can't accurately gauge smoothness etc without going on the road. Those people who come to your house are just putting in a relatively safe generic map, they often have no idea if it's right for your car or not. To be fair it's normally diesel remapping that's done on your doorstep and that's relatively difficult to cock up.

[crossy67]

spitfire4v8 said:

Any good mapper will use a dyno AND the road. You can't see small hp changes without a dyno, but likewise you can't accurately gauge smoothness etc without going on the road. Those people who come to your house are just putting in a relatively safe generic map, they often have no idea if it's right for your car or not. To be fair it's normally diesel remapping that's done on your doorstep and that's relatively difficult to cock up.

Agree 100%.

I have had a car mapped on a dyno, it took about 7 hours then the mapper took it out and drove it round for a further hour or so. The result was a very smooth running car with great power out put. I have driven other cars mapped by this mapper and they're all the same. I have friends that had cars mapped by someone that used to install a generic map then fettle it on the road. Their cars always seemed to have odd issues, smoothly, holes in the torque etc.

[Crafty_]

crossy67 said:

spitfire4v8 said:

Any good mapper will use a dyno AND the road. You can't see small hp changes without a dyno, but likewise you can't accurately gauge smoothness etc without going on the road. Those people who come to your house are just putting in a relatively safe generic map, they often have no idea if it's right for your car or not. To be fair it's normally diesel remapping that's done on your doorstep and that's relatively difficult to cock up.

Agree 100%.

I have had a car mapped on a dyno, it took about 7 hours then the mapper took it out and drove it round for a further hour or so. The result was a very smooth running car with great power out put. I have driven other cars mapped by this mapper and they're all the same. I have friends that had cars mapped by someone that used to install a generic map then fettle it on the road. Their cars always seemed to have odd issues, smoothly, holes in the torque etc.

+1
Its never a "one fits all" deal. Every car is different.

For what its worth when looking at dyno graphs I'm not too concerned with the figures, I pay more attention to the plotted lines and the space underneath them.