[chetanhanda]

Originally Posted by ScarySkulls

No Manufacturer is happy honouring more and more warranty claims just because they wanted to give the "Real Deal" to the public.
A detuned engine is cheap insurance.

very very well said ..
detuned engines with mild fuel and timing maps is the safest choice..considering the margin for long service intervals, bad fuel,indian dusty conditions etc

[HPP]

Good thread.

I think the very simple answer to the OP question is: Conservative timing maps, stricter knock tables, lower boost levels, more conservative air/fuel ratios, stricter intake air temp tables, etc.

However, I'd probably say they run them richer rather then leaner. The fluctuation in fuel would make it a scary proposition in a leaner condition. And leaner A/F's have higher EGT's. But tuning via EGT is a huge mistake, you need a wideband O2 reading if you want to properly tune the fuel maps.

[sudhirlp]

Can't make head or tail of this !

But coming to what can be practically interesting for majority laymen like me - Sumo Grande has come out with the same 2.2 VTT engine that Safari has, except that Grande belts out 120bhp while Safari belts out 140bhp, thanks to detuning.

Will it be possible (outside of factory and in moderate economic terms to) reverse this "detuning" and bring Grande to 140bhp ? I'm for the moment excluding warranty considerations, just thinking out aloud.

[HPP]

Originally Posted by sudhirlp

Can't make head or tail of this !

But coming to what can be practically interesting for majority laymen like me - Sumo Grande has come out with the same 2.2 VTT engine that Safari has, except that Grande belts out 120bhp while Safari belts out 140bhp, thanks to detuning.

Will it be possible (outside of factory and in moderate economic terms to) reverse this "detuning" and bring Grande to 140bhp ? I'm for the moment excluding warranty considerations, just thinking out aloud.

That would be tough. I'm assuming the ECU's are not interchangeable? If they were, you may have a solution. If not, then you would need to be able to retune the ECU. But you would also need to know the factory parameters when doing so. So, like I said, not that easy a task.

I know when the same motor goes into different cars, it's not always just a detune of the ECU. There are actually mechanical differences as well. Different throttle bodies, different cams, different just about anything really. You have to know if it is merely just a detune of the ECU, or if it is also a mechanical difference.

[amitpunjani]

Originally Posted by ananthkamath

I will give you a gist of what came out of a lengthy discussion (more like argument) with a friend of mine who works for Ford Powertrain. We were talking about the finer points of electronic boost control. Some of this has also been confirmed by my room-mate who used to work for Holset (yes, the same jokers who manufacture turbochargers). And yet another who calibrates MY2010 Chrysler engines all day long sitting somewhere in some hick town in the midwest:

In case of turbocharged engines which use solenoid-actuated boost control, the boost map is modified to open the wastegate so that manifold absolute pressure (MAP) is kept to a safe limit with a very wide margin before knock onset. If a traditional wastegate actuator is used, the boost is calibrated by changing the spring tension of the actuator.

Usually OEM's do not exceed 1.75 bar MAP on gasoline vehicles for lack of a wide enough margin before knock onset. Even then, the use of 93 RON fuel is mandatory. Testing is also done with 87 RON fuel whereby the ECU retards the timing based on closed-loop operation (knock sensor and PPP detection via ion sensing).

When a recalibration is done for lower octane fuel, a more conservative spark advance map is used. The engine is also run leaner (yes, leaner) to keep the EGT within the operating limits of the turbine impeller material, specially when the spark is retarded by large amounts to control knock.

This is the complex answer to your question. The simple answer is, the spark advance and MAP are the main controlled parameters for what is commonly called "detuning".

In case some foreign OEM is plannning to enter the Indian market. So how will they detune the Engine considering that RON 87 and RON 92 is avaliable in India.

Thanks

Amit

[Born2Slow]

Would like to know how some of the cars when brought to India are de-tuned. Like sx4 else where runs a compression ratio of 1:10 but in here it runs 1:9. How do they do it

1. Different pistons
2. Different combustion chamber or
3. Thicker head gaskets etc.

Do they also run different ecu,maps,cams.
Also i see new cars like ANHC running 10.5 compression for our fuel. whatever retarding of timing they do that kind of compression should result in a very out of optimum engine. I say this because my brothers Ritz (compression ratio 1:10 ) behaves way differently to high octane petrol than my sx4 (Hardly any noticble difference). Would like to know your opinion on this.
Thanks.