How will a Power Chip effect the MPG

[Saab9-5]

Hi Guys,
I am interested to know how a chip will effect my Saab Diesel in terms of Mpg. My problem is i am torn between Power and MPG. I drive Motorways with some town and cross country as a taxi driver but i still like to give it a rareburst on the banjo when not in work mode. I do sometimes travel Five up plus luggage and have found my self having to shift down a gear compared to when i am on my own. Pls help. Regards Chris

[frv]

You should see an improvement in MPG as well as power but not by as big a percentage as the power uplift. I have been tempted in the past to chip my Honda but I don't do the miles to warrant it really especially as I am getting 60+mpg already.
You may be tempted to drop back into lead-foot mode if you have the power available which would ultimately hurt your fuel economy (FE).

[Karl]

That man is right.

Chipping turbo diesel will give a nice torque boost however this can cause clutch and gearbox issues later down the line. On VW engines it can destroy dual mass flywheels too - they are very expensive to fit.

I'd steer clear tbh. Engines and components are designed to certain tolerances. You start playing about with power levels you can end up spending much more than you could ever even think of saving as things start to break.

Back in the day I chipped my Fiesta RS Turbo up to 170BHP with 160 TQ... 4 gearboxes later I was poor and broke the car up for spares. Was a h00t to drive though.

[Saab9-5]

Hi Guys,
Thank you for your good advice and deep down i know i should stick with my engine as standard. I have put on 20000 miles in five months and the engine has hardly missed a beat. I dont want to compromise this engine that will easily do 250000. I am now getting 56-57 mpg which is way
beyond any expectations anyway. Thank you for a great site. Cheers Chris.
Ps My Kit Car does 15mpg and 100 miles on a tank. I reckon i could get 20mpg with hypermiling techniques.

[frv]

Found this interesting article about re-mapping:

Can you improve economy by chipping your car's engine?

http://www.telegraph.co.uk/motoring/new ... ngine.html

"The law of physics says you won't get something for nothing. In this case you might get improved economy but you might also find that your car doesn't drive as it once did. So for example you might find a flat spot in the power band or you may lose bottom-end acceleration." Quote from AA

[greenman]

Yes that's very interesting.I bought a chip thing soon after I bought the car (on ebay) and read around and decided maybe it was not a good idea. I like the idea of "something for nothing" but I agree with the article that things are not always what they seem to be. It is sitting in my basement - every now and then I come across it and think I must do something with it; maybe sell it??

[MikeMarsUK]

"The law of physics says you won't get something for nothing. In this case you might get improved economy but you might also find that your car doesn't drive as it once did. So for example you might find a flat spot in the power band or you may lose bottom-end acceleration." Quote from AA

On a diesel, the most efficient combustion point is 'TDC' (top-dead-centre). Typically the ignition has to be delayed a bit to pass NOx regulations. So one of the effects of a proper* remap is to move ignition back to this point.

Plus points:
* Better fuel consumption
* More torque
* Less particulate emissions

Negative points:
* Higher NOx emissions
* More strain on the clutch/gearbox


But claiming 20/30/40% improvement in fuel consumption is crazy, it's going to be a few % at best. If you see anything advertised with that sort of wild claim, steer well clear.



* By 'proper' I mean a remap which is unique to that individual car, since every engine is slightly different in terms of wear etc. If you have a 'chip', it is not tuned to that vehicle, and may smoke etc.

[Karl]

I've seen a lot of this. I remember being at Truck Fest a couple of years ago and they were hammering advertising for chipping trucks.

Most places want at least £300 a pop for this so I'll take a while to cover the cost!