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Engine Experts Pls Comment


Blackseal
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Its how the engineers want the car to sound like...

 

For a sports car, the exhaust need to sound sporty...eg the Lexus LFA is specially tuned to sound like a F1 car. But if a similar size engine Lexus passenger car, if it sounds like a F1 car, I think no towkay would want to buy.

 

A 2L sports car like Toyota MR-S sounds sporty while the 2.0L Camry sounds quiet.

 

Most of the time, its not the engine that create the sound...its the exhaust muffler that has a sporty or muffed note....depending on the construction. Semi flow exhaust will sound sportier than a restrictive exhaust.

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The main reason is torque vs power.

High rpm means power! Like the Vtec can go up to 8000rpm. But somehow car drivers dont like the 'delay' in getting the power.

Lower rpm mean more torque, just like those diesel engine at <4000rpm max.

 

In cars drivers prefer TORQUE as it gives them the sensation of power.

 

In motorcycle, there is more finer control of the power band to cater for precise cornering, etc. And guys like the high vibration inbetween their legs whent he engine is screeming at 15000rpm.

 

Of course there are big CC bikes whose RPM also like car below 6000rpm. Those are smooth cruiser type of bikes lah.

 

Its just a way of giving what the customers want. It not about why cannot this and that. Engine can be designed to any RPM vs power, just how the designer wants it to be thats all.

 

 

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wah lower max rpm means more torque meh? my legs only can move at 100rpm when i running at max speed leh.... my torque must be a gAZZillion Nm.

 

Diesels have higher torque because of the higher compression ratios required to combust the air/fuel mixture without the use of sparkplugs. Hence their piston stroke is longer than a petrol engine. A larger stroke means a larger diameter crankshaft which directly results in higher torque at the crankshaft. Because of higher compression ratios and longer stroke, moving parts of a diesel engine are engineered stronger and generally heavier, coupled with the combustion characteristics of diesel fuel, max RPMs are limited compared to a petrol engine.

 

btw, whats the max RPM on your new Bimmer? Is it FF, MF, FR or RR layout? max torque and max hp? Faster than citycab or not?

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oh and max "safe" engine rpm is dependant on the stroke and weight of the cylinders, crankshaft and rods coupled with fine balancing. Single piston bikes are rather "rough" and have low max engine rpms. However those 15000 rpm monster inline 4s are well balanced engines. Such bikes usually have shorter piston strokes and lighter moving components (compared to car engines).

 

i would think the difference in exhaust sound is due to the shorter distance btw the engine to the exhaust and the lack of damping from cat converters which are not standard for bikes, also perhaps the more frequent vibration pulses coming out of the exhaust gasses (imagine car 6000 rpm vs 15000 rpm) which gives it a different sound signature altogether.

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Neutral Newbie

so people just dont know what are say is true or not and jus shoot off.

 

i think zyro post are more reasonable.

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actually im no pro, just couldn't stand "Its just a way of giving what the customers want. It not about why cannot this and that. Engine can be designed to any RPM vs power, just how the designer wants it to be thats all."

 

may apply this concept to flashy designer handbags, but engineering design is another thing altogether!

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  On 4/7/2010 at 10:12 AM, Zyrofillica said:

wah lower max rpm means more torque meh? my legs only can move at 100rpm when i running at max speed leh.... my torque must be a gAZZillion Nm.

 

Diesels have higher torque because of the higher compression ratios required to combust the air/fuel mixture without the use of sparkplugs. Hence their piston stroke is longer than a petrol engine. A larger stroke means a larger diameter crankshaft which directly results in higher torque at the crankshaft. Because of higher compression ratios and longer stroke, moving parts of a diesel engine are engineered stronger and generally heavier, coupled with the combustion characteristics of diesel fuel, max RPMs are limited compared to a petrol engine.

 

btw, whats the max RPM on your new Bimmer? Is it FF, MF, FR or RR layout? max torque and max hp? Faster than citycab or not?

 

You mean his bimmer got smoked by a Citycab Crown? Sonata? [dizzy] [dizzy]

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  On 4/7/2010 at 8:22 AM, Ghostrider said:

Most of the time, its not the engine that create the sound...its the exhaust muffler that has a sporty or muffed note....depending on the construction. Semi flow exhaust will sound sportier than a restrictive exhaust.

 

not entirely true leh... free flow exhaust on a 4 pot jap wannabe sounds very different from one on a BMW or Merc V8 leh.. the 4 pot sounds terrible! like engine want to die like that...

 

if wat u say is true, how come those 4 pot jap wannabe don't fix a better sounding exhaust that sounds deep and creamy? they have no way of doing that, because their engine sounds terrible regardless what kind of high class exhaust they put on. The louder the exhaust, the more it amplifies what kind of pathetic 4 pot they have under the hood

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(edited)

Good question....bikes will be generally louder than cars...

 

and yeah F1 engines go up to 17 to 18 thousand rpm

Edited by Ithunk
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  On 4/9/2010 at 6:54 AM, Viceroymenthol said:

not entirely true leh... free flow exhaust on a 4 pot jap wannabe sounds very different from one on a BMW or Merc V8 leh.. the 4 pot sounds terrible! like engine want to die like that...

 

if wat u say is true, how come those 4 pot jap wannabe don't fix a better sounding exhaust that sounds deep and creamy? they have no way of doing that, because their engine sounds terrible regardless what kind of high class exhaust they put on. The louder the exhaust, the more it amplifies what kind of pathetic 4 pot they have under the hood

 

Hmm...fact is each time one cylinder is added...eg to a four pot....the 5 pot will sound better than a four....the five pot added with another cylinder...the six pot will sound sweeter and etc etc [drivingcar]

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  On 4/9/2010 at 9:05 AM, Blackseal said:

Hmm...fact is each time one cylinder is added...eg to a four pot....the 5 pot will sound better than a four....the five pot added with another cylinder...the six pot will sound sweeter and etc etc [drivingcar]

 

High RPM can also make engine sounds nice though.

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Back to the topic

Not for show off but for knowledge base k

for me of family having a car (verna1.4a).. 6 bikes ( phatom200cc + rxs 115cc + st 1300cc, blackbird1100cc + super4 400cc+ frazer 1000cc)

i can feel how u feel.. the steroid sound of engive rev.

like some say motor bikes of different cc and class have different engine tech.. same as cars

here goes the almost same class of engines due to my expriences

Bikes vs cars

1cc - 200cc = 1cc - 1.3k cc

201cc - 401cc = 1.4k cc - 1.8k cc

401cc - 2000cc(gold wing )

touring bike = 1.8 and above ( usually mpv, suv, space wagon )

racing bike = Sports car

 

cause i did friendly race with my friend lambo and nsh drag when the place is clear and straight road

almost on par for speed and engine sound is almost the same even cc might half of it.

 

hope its help.. maybe u can listen and compare to the engines of bike and cars of the same standard

[laugh]

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  On 4/9/2010 at 10:12 AM, Introz said:

Back to the topic

Not for show off but for knowledge base k

for me of family having a car (verna1.4a).. 6 bikes ( phatom200cc + rxs 115cc + st 1300cc, blackbird1100cc + super4 400cc+ frazer 1000cc)

i can feel how u feel.. the steroid sound of engive rev.

like some say motor bikes of different cc and class have different engine tech.. same as cars

here goes the almost same class of engines due to my expriences

Bikes vs cars

1cc - 200cc = 1cc - 1.3k cc

201cc - 401cc = 1.4k cc - 1.8k cc

401cc - 2000cc(gold wing )

touring bike = 1.8 and above ( usually mpv, suv, space wagon )

racing bike = Sports car

 

cause i did friendly race with my friend lambo and nsh drag when the place is clear and straight road

almost on par for speed and engine sound is almost the same even cc might half of it.

 

hope its help.. maybe u can listen and compare to the engines of bike and cars of the same standard

 

Thanks for your imput....I'm sure you'll agree any bike with 400cc and above...their sound is very throaty [thumbsup]

[laugh]

 

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Valves and exhaust pressure

 

The four strokes are:

 

Intake: The piston travels down the cylinder while the intake valve is opened to allow a mixture of fuel and air to enter the combustion chamber.

 

Compression: The intake valve is closed and the piston travels back up the cylinder thereby compressing the gasses.

 

Combustion: The spark plug ignites the compressed gas causing it to explode, which forces the piston down.

 

Exhaust: The piston rises up the cylinder as the exhaust valve is opened, allowing the piston to clear the chamber to start the process over.

 

Each time the piston rises and falls it turns the crankshaft that is responsible for turning the wheels. This is how fuel is converted into forward motion.

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Neutral Newbie
  On 4/7/2010 at 5:27 AM, Danielgsx said:

lao uncle ar? should go geylang, not talk here :D

 

hey you eat kotex grow up one is it?

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Neutral Newbie
  On 4/9/2010 at 3:38 PM, Chiangauto said:

Valves and exhaust pressure

 

The four strokes are:

 

Intake: The piston travels down the cylinder while the intake valve is opened to allow a mixture of fuel and air to enter the combustion chamber.

 

Compression: The intake valve is closed and the piston travels back up the cylinder thereby compressing the gasses.

 

Combustion: The spark plug ignites the compressed gas causing it to explode, which forces the piston down.

 

Exhaust: The piston rises up the cylinder as the exhaust valve is opened, allowing the piston to clear the chamber to start the process over.

 

Each time the piston rises and falls it turns the crankshaft that is responsible for turning the wheels. This is how fuel is converted into forward motion.

 

aiya.

 

suck squeeze bang blow lor.

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