detach8
Well-Known Member
Hmm endless pursuit of more power. 
Everybody wants more low end power, who doesn't! :sneaky:
The new engines are already having full torque kick in at 1,250rpm. That's pretty much the start of the drivable RPM range. But people still want moreeeeeeee!
FYI some tunes I have seen for NA car is simply a high end sprint booster in disguise -- change the throttle curve, advance ignition timing a little, no fuelling change. You feel the car take off because now your first 20% of the throttle is so much more sensitive, but as you floor it everything is actually still the same because near the top end of the RPM range your car is pretty much making full power and most tuners don't dare to go mess around with ign timing and fueling in that territory. Granted in SG we have good quality fuel so maybe +2-3 degrees advance timing will make a few more hp. So that works out to maybe $200-300/hp gain. Sibey expensive, bro... you still won't win that Sonata taxi off the line. Just slap on some lightweight 17" rims and you should take off like a rocket and improve FC.
For TC engines, much easier job because some tunes will just boost the turbo pressure without altering fueling much. Hurray you get more power and better FC, but this will run your engine dangerously on the edge of lean without you knowing unless you continuously measure your exhaust with a wide band O2 sensor. Luckily in SG we have pretty high quality high octane fuel. If you are a frequent M'sia traveler - think not twice, but trice.
Think about it. You add more air (boost), you need to add more fuel. How does adding more fuel give better FC? Then in this case 328i should get better FC that 320i. This should be your first observation after tuning - more power, worse FC. If it's not the case, it should raise a red flag.
In real life it is not that simple. Your injectors have a finite limit to the amount of fuel it can give. Most engines have a safety cut off that if you run too lean it will simply STOP fueling so you won't have any combustion. At low throttle most should cope well, but at higher RPM ranges you will have two problems -- first the fueling (pressure) may be insufficient to keep up with the extra air, second the fueling and air metering may not be quick and accurate enough hence some cars tend to overfuel a bit to compensate and protect the engine.
Be very careful when tuning... unless you intend to sell your car next year. Long term reliability of the new N13/N20 engines is still unknown.
A lot of VW folks will know, MTM not enough... go for aftermarket ones give you crazy power. Luckily for VW the block is made largely of cast iron. BMW is magnesium. N46 and N52 bros will swear by the amount of leaks these magnesium blocks develop after 4-5 years or about 80,000 kms. You are threading a very thin line.
Everybody wants more low end power, who doesn't! :sneaky:
The new engines are already having full torque kick in at 1,250rpm. That's pretty much the start of the drivable RPM range. But people still want moreeeeeeee!
FYI some tunes I have seen for NA car is simply a high end sprint booster in disguise -- change the throttle curve, advance ignition timing a little, no fuelling change. You feel the car take off because now your first 20% of the throttle is so much more sensitive, but as you floor it everything is actually still the same because near the top end of the RPM range your car is pretty much making full power and most tuners don't dare to go mess around with ign timing and fueling in that territory. Granted in SG we have good quality fuel so maybe +2-3 degrees advance timing will make a few more hp. So that works out to maybe $200-300/hp gain. Sibey expensive, bro... you still won't win that Sonata taxi off the line. Just slap on some lightweight 17" rims and you should take off like a rocket and improve FC.
For TC engines, much easier job because some tunes will just boost the turbo pressure without altering fueling much. Hurray you get more power and better FC, but this will run your engine dangerously on the edge of lean without you knowing unless you continuously measure your exhaust with a wide band O2 sensor. Luckily in SG we have pretty high quality high octane fuel. If you are a frequent M'sia traveler - think not twice, but trice.
Think about it. You add more air (boost), you need to add more fuel. How does adding more fuel give better FC? Then in this case 328i should get better FC that 320i. This should be your first observation after tuning - more power, worse FC. If it's not the case, it should raise a red flag.
In real life it is not that simple. Your injectors have a finite limit to the amount of fuel it can give. Most engines have a safety cut off that if you run too lean it will simply STOP fueling so you won't have any combustion. At low throttle most should cope well, but at higher RPM ranges you will have two problems -- first the fueling (pressure) may be insufficient to keep up with the extra air, second the fueling and air metering may not be quick and accurate enough hence some cars tend to overfuel a bit to compensate and protect the engine.
Be very careful when tuning... unless you intend to sell your car next year. Long term reliability of the new N13/N20 engines is still unknown.
A lot of VW folks will know, MTM not enough... go for aftermarket ones give you crazy power. Luckily for VW the block is made largely of cast iron. BMW is magnesium. N46 and N52 bros will swear by the amount of leaks these magnesium blocks develop after 4-5 years or about 80,000 kms. You are threading a very thin line.
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