Re: DS mode
phil;323248 said:
Downshifting and using engine breaking wears out the engine? bwahahahah, funniest thing i have read all day. I really hope all those trucks dont use their exhaust brakes and downshift to slow down, engine spoil in no time.
Please lah, I SLAM my tranny into lower gears all the time to slow down, i hit corners to fast for the brakes to pull me up, must downshift one.
If got manual car, it is ok to downshift and engine wont spoil is it? Only on auto car cannot? hahahahahaha.
ITS a MACHINE, it doesnt care what you do, you wont hurt its feelings. The pistons are actually designed to go up and down, wether under acceleration or deccelaration.
sports mode rocks. Ive tried and tried to kill my diff and tranny, till this day i havent done it. Some solid stuff it must be made of. Wonder if it is steel
When I and you, Phil, learned to drive, engine braking was once NECESSARY because our brakes sucked. We had drums all round and crappy hydraulic fluid which boiled easily. Our cars were underbraked. So when going downhill for example, we were forced to engine brake, and even in street driving, that's what we did.
But today most cars have ample braking capacity on the street and even on downhills we will have sufficient reserves of braking power and the hydraulic fluid don't boil easy, especially for those who replaced with DOT5 stuff.
Whether on auto or manual cars, the disadvantages of engine braking are similar, except in that slushbox auto cars don't usually blip the throttle to rev match on downshift so that causes additional strain on the torque converter.
The issues are NOT normal wear and tear on the engine, as you said, engine pistons are supposed to go up and down and go on forever.
I summarize:
1) It's not necessary with today's big brakes
2) Your brakes lights don't come on, some people may just whack your bum
3) If no rev match done, it's called CLUTCH BRAKING or torque converter braking, and it wears the clutch or strains the torque converter a LOT for some moments.
4) Engine braking upsets the car if suddenly applied in the corners or in a slippery slope by causing the driving wheels to lose traction. Because engine braking is not managed by ABS, you WILL lose traction and there is a high probability of car spinning or being upset.
5) In engine braking you are transferring power to the drivetrain, including the engine, in an opposite direction from normal. Depending on how POWERFUL the engine braking effect is, and how low your gear is, the pressure required to open exhaust valves against compressed air in the cylinders is extremely high. In these instances the resulting load through the push tube back to the camshaft exceeds valve train loading capabilities. These excessively high pressures can quickly damage a valve train system.
All this being said, if you're coming down from Camerons or Genting, sure doesn't hurt to put your transmission on 3rd gear, and have the transmission control the descent. This is steady speed, without the detrimental effects of an `impulse' and you go on for a long time, and therefore more acceptable than engine braking on the street which involves many compression cycles.