closed for fail on everyones part
06-08-2011, 06:00 PM
#21
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I don't even remember who started this thread. I just found it slightly aggravating when someone trys to act like they know something, and starts spitting out stuff that doesn't make sense with such strong words. Just my opinion, but if you do own a honda and you don't know how vtec works and decide to ramble aimless words, you just need a brain check.
Switching Camshafts
When the computer decides to switch camshafts, it closes a valve that forces oil along passageways through the camshaft into the third rocker. It has little pistons which are forced outwards into the outer two rockers. All three rockers are then locked together and operate as one. The middle cam lobe has more lift than the outer two so it then controls the lift and duration of the set of valves. When switching back to the low speed cam the ECU just opens the valve, lets the oil out of the rockers, the pistons unlock the rockers and everything operates as before.
When to Switch Camshafts
The ECU is constantly comparing the torque curves of the low and high speed camshafts. It calculates the expected volumetric efficiency of the engine based on the current environmental conditions (air temperature and pressure) and the engine conditions (temperature, engine load, throttle position), and then derives the expected torque from the volumetric efficiency for each camshaft. Most of this has to be done anyhow in order to
determine how much fuel to inject.
When conditions are right (the revs are over about 4500-6000 rpm (depends on model), the engine is warm, there is enough oil pressure to activate the pistons and the car is moving) the ECU will switch from the low to high speed camshaft when the expected torque of the low speed camshaft equals the torque of the high speed camshaft. The ECU closes a solenoid valve that then forces engine oil, under pressure, along the camshafts to active the third rocker arm
06-08-2011, 06:05 PM
#22
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I'm not here to just insult people, if I offended you I'm sorry for that but just keep an open mind when people with knoledge come to the table. We are all here to help each other and give acurate and educated advice to others, opions are always greatly apreciated and should be brought with a certin leavle of task.
06-09-2011, 06:31 PM
#23
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Originally Posted by The-_-Asian' timestamp='1307570276' post='20663075
I don't even remember who started this thread. I just found it slightly aggravating when someone trys to act like they know something, and starts spitting out stuff that doesn't make sense with such strong words. Just my opinion, but if you do own a honda and you don't know how vtec works and decide to ramble aimless words, you just need a brain check.
Switching Camshafts
When the computer decides to switch camshafts, it closes a valve that forces oil along passageways through the camshaft into the third rocker. It has little pistons which are forced outwards into the outer two rockers. All three rockers are then locked together and operate as one. The middle cam lobe has more lift than the outer two so it then controls the lift and duration of the set of valves. When switching back to the low speed cam the ECU just opens the valve, lets the oil out of the rockers, the pistons unlock the rockers and everything operates as before.
When to Switch Camshafts
The ECU is constantly comparing the torque curves of the low and high speed camshafts. It calculates the expected volumetric efficiency of the engine based on the current environmental conditions (air temperature and pressure) and the engine conditions (temperature, engine load, throttle position), and then derives the expected torque from the volumetric efficiency for each camshaft. Most of this has to be done anyhow in order to
determine how much fuel to inject.
When conditions are right (the revs are over about 4500-6000 rpm (depends on model), the engine is warm, there is enough oil pressure to activate the pistons and the car is moving) the ECU will switch from the low to high speed camshaft when the expected torque of the low speed camshaft equals the torque of the high speed camshaft. The ECU closes a solenoid valve that then forces engine oil, under pressure, along the camshafts to active the third rocker arm
I have a feeling that you seriously didn't know how VTEC works and decided to WIKI. Where did you copy and paste this from? There's a few things there doesn't even make sense. VTEC doesn't switch "cams" just cam lobes buddy. That alone tells me you have no idea. Like I asked before, "Have you seen a VTEC head apart?"
06-09-2011, 11:11 PM
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Yes, I have. Many times. Did you even read the first sentence of that post? I have been working on cars for a very long time. My specialty is Lexus, but VVT-i is not much different from VTEC. I was a Technician for Lexus for 6 years and am still in the automotive industry.
06-13-2011, 02:30 PM
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Yes, I have. Many times. Did you even read the first sentence of that post? I have been working on cars for a very long time. My specialty is Lexus, but VVT-i is not much different from VTEC. I was a Technician for Lexus for 6 years and am still in the automotive industry.
VVT-I
[media]http://www.toyota-club.net/files/04-01-10/04-01-10_rem_eng_camry/vvt_i.gif[/media]
VTEC
[media]http://www.bellonsales.com/DeleteMe/v-tech.jpg[/media]
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