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MG MGF Technical - Rolling Road

Whats that all about?

Does it just tell you how much power car the is producing or do they tune it to produce more?




Here is an explanation of rolling roads extracted from the Emerald homepage:
"A rolling road is a set of rollers on which a vehicle can simulate driving. The rollers are attached to a ‘brake’ that can measure the turning force applied to them and the roller speed. Using these two pieces of information the power applied to the rollers by the cars driven wheels can be measured. Generally an engine will produce maximum torque for any given speed and load when the fuelling and timing are at their optimum."
Special MEMS units (or engine management computers) can be fitted to most electronic fuel injected engines that allow for user programming whilst the engine is subjected to varying loads at varying speeds on a rolling road. The process involves varying the ignition and fuel injection timing look-up tables (or maps) within the computer in real time to optimise torque and power over the rev range.

Try the Emerald page for some good gen: ""
Steve Jones

Thanks Steve,

Do you reacon its worth doing?

Do Superchips make any difference to performance?


Superchips claim a power increase of around 6% (about 8 bhp for an otherwise unmodified VVC) and a torque increase of 7.5% (about 9 lb ft). With a superchip retailing at about 300 quid (+ about 50 quid for a rolling road tune), its up to you, but in terms of pounds for bhp/torque, I personally don't think a chip upgrade alone represents the best value for money when compared to a decent head porting/cam job. But replacement MEMS units do become very worthwhile (and sometimes neccessary)when carrying out other engine modifications such as forced induction, porting, filters, exhausts. cams etc.
Steve Jones

I just re-read what I wrote above and thought I should clarify one thing: Superchips, Racelogic etc. provide upgrades to the existing original computer (which means that they can only work within the constraints of the original computer), whereas MEMS units such as the Emerald, Lumenition, DTA etc. completely replace the original computer. The latter are more expensive but offer more flexibility for increased performance.
Steve Jones

Ian, I think Steve has put it very nicely. Superchips are so called 'piggy back' ones where it goes 'with' the original MEMS.

I had it on my car for about a month. I returned the chip since I couldn't justify the power output for the price (even though I could get one for 210 pounds brand new).

I got a sport exhaust instead, and the power increase was around the same (with my feel.. not on rolling road), that means Superchips don't produce 8hp, but rather close to 4hp. Oh the noise.. you can't forget.

Hanah Kim


I have the motobuild chip on my VVC and really noticed the diference when i had it fitted.. if you want a comparison I'm probably not far away if you want to meet one evening over a beer..


A rolling road tune after installing a chip - be it a piggy back such as the Superchips ICON or the complete replacement such as Emerald's M3D is an absolute PREREQUISTE.

Failing to tune an ECU will lead to a Dirk-style engine failure (for those who don't know - that was a complete engine and exhaust manifold melt down...) Best avoided IMO ;o)
Rob Bell

Stu, dont mind meeting up...

but you do realse my mpi with its K&N wont even keep up with yours : (



This thread was discussed between 14/09/2002 and 15/09/2002

MG MGF Technical index

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