Engine mapping

Hammyman

Ebe_Scrooge wrote: »

Call me an old cynic, but you don't get owt for nowt. If remapping is so wonderful, why isn't the engine mapped that way in the first place ?

OK...

Factory mapping is done to suit the widest possible range of criteria and done on a conservative "one size fits all" basis to provide good fuel economy for an average driver, length of life, longer service periods and provide the smoothest drive.

When performance mapped it is taken for granted that the user is going to be prepared for some losses in some areas for benefits in specific others.

As for getting owt for nowt - with modern fuel injection and ignition systems then yes you do. As you say, old skool involved fixed cam profiles, larger valves etc etc etc. Because a modern engine is at quite a good level of tune in this respect but has power limited by running weak mixtures, then there's a lot of free power to be had simply by altering how much fuel is fed to the engine. With injectors having pulse and duration controlled by computer, instead of being fixed as in old mechanical injection where you could only increase fuelling across the board or even worse with carbs, it means you can have them chuck gobs of fuel in when its wanted but still provide the same very low miserly amount the factory setting gives when you just want to cruise on light throttle. The more control you have over timing and fuelling, the more you can achieve.

I'll illustrate.

Firstly, the standard state of tune:

In 1985 when my Ford Capri 2L Laser rolled off the production line, it had 98BHP and averaged 32MPG
In 2009, VW released a 1.6L VW Polo which has 105BHP and averages 44MPG.
The VW Polo mechanically (cams/valves etc) is in a higher state of tune to get more power with a weaker fuel mixture. To give you an idea how much potential performance is in the modern car engine, if you take the 2L Ecotec engine out of a Vauxhall Cavalier which gives 140BHP as factory standard and do nothing to it other than strap on a set of throttle bodies and alter the ignition timing, it'll do over 230BHP on stock internals. A similar story exists for the Ford Zetec engine. A 2 litre Pinto engine needs a monumental amount of work including a complete altering of the shape of the inlet ports (not just smoothing and enlarging) to get over 200BHP, it'll run like a dog under 2500RPM and be pretty undriveable at low speeds around town.

Onto owt for nowt...
Lets take early mass market fuel injection such as the Bosch fitted to the Capri 2.8i V6.
In this system you had four injectors constantly delivering fuel. The pressure it was sent to the injectors at was controlled by a flap which raised and lowered depending on the amount of air being drawn past it into the engine.
The timing was done by a distributor with it altered by vacuum advance and manually set by hand. The only way to increase fuelling was to fit larger injectors which altered everything throughout the range so walloped fuel. The only way to alter timing was to alter the static advance which meant it was altered throughout the rev range and unsuitable or a poor compromise for certain engine speed/load/throttle combinations.

Modern system as fitted to a modern car.
The ECU is programmed with the specific information for each individual injector so it knows how each one will perform. The ECU controls the time the fuel is injected in the cycle and also the duration. To increase fuelling, you can simply alter those parameters. The ECU also is told the exact position of the throttle, the incoming air temperature and can alter fuelling accordingly to take these into account. The timing is done by a fixed crank sensor so the ECU knows at all times what the real timing of the engine is. It can control when every individual spark is sent to a far far more accurate level than the Capri system.

Now take into account the conservative settings applied by manufacturers, there's much more scope and ability to change the modern car than the older one with very little detriment in normal driving.

bigjl

The company you have linked to Gloomanddoom are the ones that i shall be getting my tune up box for my Mondeo from, he started out working on Rover 75's, under the name Roverron, he has a long standing good reputation and actually owns the a lot of vehicles that he does the tuning boxes for, and uses his own car as a test bed.

mikey72

Normal trade off is in emissions, most factory cars are tuned to be as clean as possible.

Jakg

Ebe_Scrooge wrote: »

Call me an old cynic, but you don't get owt for nowt. If remapping is so wonderful, why isn't the engine mapped that way in the first place ?

because a lot of VAG engines are (pretty much) the same engine, but detuned for cheaper models (and by that - i mean so they can charge more for the "original" tune).

It also means they can target emissions / insurance groups / MPG etc.

Usually MPG goes down from an off-the-shelf remap unless it was underpowered to start off with.

bigjl wrote: »

The company you have linked to Gloomanddoom are the ones that i shall be getting my tune up box for my Mondeo from, he started out working on Rover 75's, under the name Roverron, he has a long standing good reputation and actually owns the a lot of vehicles that he does the tuning boxes for, and uses his own car as a test bed.

Roverron is very *very* well respected amongst the 75 / ZT community.

Whilst im not 100% convinced by how it works (seems to only plug into the MAF and thus I assume simply overfuels?), loads of owners have it and have found significant performance improvements, dyno proven. Only downside is a little more smoke when enjoying that extra power.

A proper remap (i.e. one actually done with the car, rather than an off-the-shelf-map) will be better, though.




You dont get something for nothing, but you can get a lot for a small compromise. Example - a diesel doesn't need a cat to pass an MOT as the emissions aren't testable (although if the tester thinks it's been removed he can fail it - but if you said it's a sports cat theres nothing he can do to disprove it). Remove it, and you save weight, and get a bit more power thanks to reduced backpressure, and you'll get some £ back for the cat, at the expense of different (not neccesarily reduced) emissions.

Locknut

I have pretty much the same car as you an A4 140 bhp I had it mapped by motech and they put the 50-50 map in so under 50% accelatarion or 50% throttle its is on standard mapping but once you haev given it full beans it seamlessly ups the power to 185bhp as why would you need 185 bhp for driving to the shop's!!!!!

I would strongly advise against a tuning box on a PD engine they really dont like them and give a horrid flat spot at around 2k rpm and all they do is up the fuel pressure to give more power but in turn that kills the fuel pump.