In my earlier post I had mentioned that Octane rating of the regular gas in India is 91 Octane which is incorrect; what I actually meant is 91 RON which translates to 86-87 Octane; my apologies.
Quote:
Originally Posted by suhaas307 Strange.
As you've said, the Coyote V8 is designed to run on regular pump-gas (US jargon) i.e. 91/93 RON. If fuel of inferior octane is the diet chosen for the car, the ECU adjusts the timing in order to prevent engine knocking and consequently, power drops to 400 ish (as per several articles and forum discussions). So it comes as a surprise that Ford chose to de-tune the motor in the first place.
So, what if you chose to run it on 97 Octane? |
You’re right. The ECU would have detuned the engine however while detuning the engine at the factory itself Ford probably also changed/fine- tuned a number of other parameters in ECU/other affected sections of fuel system/valve train that could not be left to on the spot intervention by ECU. I think there might be other reasons for this detuning that I’m not aware of. If you use 97 RON/92-93 Octane you would not get any appreciable advantage by way of power delivery at the crank as the ECU has been programmed accordingly to run on 91 Ron/87 Octane, what you are assured of is very good quality gas that may help prevent other complications in the long term.
One thing I must caution all the folks driving the premium machines is that the regular gas in India (and in many other places around the world) has up to 10% Ethanol which is highly hygroscopic so if you’re driving an expansive car (especially from Europe) with a high displacement/highly strung/high power engine with or without forced induction, my suggestion would be to avoid regular gas (87 Octane/91 RON) if you can & use premium such as 95/97 RON.
Quote:
Originally Posted by akshay1234 The engine in my Mercedes has a very similar compression ratio, and it runs regular fuel just fine though I choose to fill her up with 97. And so will most of the owners of the Mustang. Hell, none of the Germans are detuning their engines even though they are running forced induction, why should Ford with a relatively simple NA engine.
Also since you were in the oil industry, over here don't they measure in RON rather than Octane?
|
I agree with your assumption that engines using forced induction are more susceptible to pinging. I don’t know which model of Mercedes Benz you’re driving so I cannot comment however consider this, all the premium German marques carry a recommendation in their owner’s manual to use premium unleaded (91 Octane/95-97 RON). If you drive your car on regular gas, of course there will not be a catastrophic failure however there will be drop in the power delivered that may or may not be noticeable in day to day driving. In addition there will be slight drop in fuel economy as the ECU will run a rich mixture to compensate.
I am sure you have noticed that there’s substantial price difference between regular gas & premium gas (95/97 RON) in India. The premium gas accounts for less than 1% of sales at these gas stations and is most likely to be free of any contamination. Bottom-line, if you’re keen to use gas that is free of contamination/adulteration use premium but don’t expect any power increase (a very popular misconception) especially for engines that are designed to run on regular gas. If your car/SUV requires premium gas, stick to premium.
Respectfully if I may mention what you refer to as a plain American engine is right up there with the Europeans. It is a dual overhead cam, 32 valve engine with variable valve timing, not an antiquated push rod engine (though personally I think there’s nothing wrong with those either). For the sake of comparison let’s take the MB’s M 278 engine which has been used in S, SL, CL & GL class. It is a 4.6 ltr V8 and also employs two turbo chargers. It is rated at 429 BHP at 5,250 rpm. The 5 ltr. V-8 employed by Ford produces 435 BHP without forced induction.
The reason that Ford decided not to use forced induction is because the proverbial American Muscle car in its iconic form (they do have forced induction engines on other variants) needs toque & loads of it. Forced induction engine are typically peaky in nature & most of the time what they lack is the bottom end torque though I must also add that variable vane geometry turbochargers have taken care of that problem to a large extent.
For American muscle, there’s no replacement for displacement.
As for fuel grading system used in India; 10 years ago when I left, the Octane rating system was very much in vogue, if it has changed over the years, I stand corrected.
Quote:
Originally Posted by Technocrat Small correction, regular pump gas is 87, 91 & 93 are premium which is what the V8 requires. |
RON is a European gas rating measurement while Octane is primarily American which is actually a mean of RON (Research Octane Number) & MON (Motor Octane number). 91 Ron is approx. equal to 87 Octane which is the regular gas. Premium would be 96 or 97 RON roughly equal to 91 Octane and other higher rated variants.
This Ford Mustang V8 is designed to run on 87 Octane/91 RON which is regular gas.