I think there are alot of people that might be confussed as far as people thinking that the 2.4 ECOTECs have V-TEC or plainly just don't know what Variable Valve Timing is or does and what the difference is between Variable Valve Timing & V-TEC.
I know what it is but here is a better explination...
Variable Valve Timing itself
Quote:
Variable valve timing, or VVT, is a generic term for an automobile piston engine technology. VVT allows the lift or duration or timing (some or all) of the intake or exhaust valves (or both) to be changed while the engine is in operation. Two stroke engines use a Power valve system to get similar results to VVT.
Now V-TEC
Quote:
VTEC (standing for Variable valve Timing and lift Electronic Control) is a system developed by Honda Motor Co., Ltd. to improve the combustion efficiency of its internal combustion engines throughout the RPM range. This was the first system of its kind and eventually lead to different types of variable valve timing and lift control systems that were later designed by other manufacturers (ie. VVT-i from Toyota or VANOS from BMW).
Now the 2.4 ECOTEC Variable Valve Timing technology is mainly from Toyota, just like how the Toyota Celica GT-S, Toyota Matrix and Pontiac Vibe uses them. I want to say that the 2.4 VVT is more so like the Toyota VVT-i technology.
Toyota VVT-i
Quote:
VVT-i, or Variable Valve Timing with Intelligence, is an automobile variable valve timing technology developed by Toyota. The latest version of VVT-i varies the timing of the intake valves by adjusting the timing chain connecting the intake and exhaust camshafts. A pump applies hydraulic pressure to adjust the gear driving the timing chain.
Toyota recently started offering a new technology, VVTL-i, which can alter valve lift (and duration) as well as valve timing. This is accomplished differently than Honda's VTEC. Instead of switching between two different cam shafts, there are spacers that are slid between a single cam shaft and the valves. At higher RPM, controlled by the ECU, oil pressure is directed to push the spacers between the camshaft lobes and valves, effectively simulating a much "hotter cam" and creating increased valve lift. When the engine falls in RPM the spacers are pulled out of action and the engine operates more economically. This system is used in the Yamaha designed 1.8 liter 4 cylinder 2ZZ-GE which is used in the Toyota Celica GT-S, Toyota Matrix Toyota Corolla XRS, Pontiac Vibe GT and Lotus Elise 111R. This variable lift technology allows the engine to be quite fuel efficient at lower RPMs and, when called upon, able to produce much more power at the expense of fuel economy.
Now some of you might think to yourselves "How come the 2.4 has more torque than a V-TEC motor and they both have Variable Valve Timing?". That's simple....displacement, powerband & compression play a huge part of that. Example: The GSR Motor runs a 1.8L and 10:1 compression...a good amount of compression but small amount of displacement. Alot of the Honda motors also can Rev higher than the ECOTEC in stock form. They rely on high revs, short stroke and variable valve timing to make power. If you ever hear people say "Hondas make more horsepower to comphensate for torque"...that's kind of a BS thing to say.
Quote:
If torque is in lbf·ft and rotational speed in revolutions per minute, the above equation gives power in ft·lbf/min. The horsepower form of the equation is then derived by applying the conversion factor 33,000 ft·lbf/min per horsepower:
So with that said, torque is needed in most cases. Also, the CFM of a V-TEC cylinder head is bigger than a stock ECOTEC cylinder head for the purpose of supplying more airflow at higher RPMs. Honda motors rev higher, need more air....ECOTECs don't relatively rev that high so they use smaller ported cylinder heads. The use of smaller cylinder ports also helps with a more torquey powerband.
Also, examples of Honda Motors with V-TEC and compare it to the 2.4 VVT ECOTEC:
Acura RSX Type-S (uses i-VTEC btw) - 16 valve, DOHC, 2.0 liter, 200 HP @ 7400 RPM / 142 lbs/ft torque @ 6000 RPMs
Chevrolet Cobalt SS - 16 valve, DOHC, 2.4 liter, 171 HP, 163 lbs/ft torque @ 5000 RPMs
With everything I have explained, you will see why Honda motors have such different outcomes of power compared to the 2.4 VVT ECOTEC even though they share the same thing of Variable Valve Timing. In the end, it's not the comparison of VVT, but the Engines themselves and internal characteristics.
Hopefully you guys under a bit better between the 2 and understand why Hondas and the 2.4 VVT share the same kind of technology but are still different.
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slap the noob sticker back on meh! cause this @!#$ was a lesson.
amazing right up!
Big Boi -Coloradojbody.org- wrote:slap the noob sticker back on meh! cause this @!#$ was a lesson.
amazing right up!
Thanks, glad you learned something from it.
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Daddy King, you renewed yourself. Great write up!!
98 Z24
RIP Specks
El Fuego ( the unstable ) wrote:Manta Z(JDM Approved by JoeDM) wrote:Big Boi -Coloradojbody.org- wrote:slap the noob sticker back on meh! cause this @!#$ was a lesson.
amazing right up!
X2.
x3
and its in the solstice too right
Ozzie(I Love Newbies) wrote:El Fuego ( the unstable ) wrote:Manta Z(JDM Approved by JoeDM) wrote:Big Boi -Coloradojbody.org- wrote:slap the noob sticker back on meh! cause this @!#$ was a lesson.
amazing right up!
X2.
x3
and its in the solstice too right
Yes but I wanted to give FWD examples.
www.kronosperformance.com / 732-742-8837
Great Post! Very well said.
-Aaron
www.TurboTechRacing.com
Performance Parts For Cavalier, Sunfire, Cobalts and More!!!
Ozzie(I Love Newbies) wrote:El Fuego ( the unstable ) wrote:Manta Z(JDM Approved by JoeDM) wrote:Big Boi -Coloradojbody.org- wrote:slap the noob sticker back on meh! cause this @!#$ was a lesson.
amazing right up!
X2.
x3
and its in the solstice too right
x4.... adam you sexy beast, thats a damn fine writeup.
_________________________________________________________________
this useless post brought to you by the alcoholic known as LUNDiS
Do you know if the gm 2.4 has the variable lift? You said you think it's VVT-i but compare it to the matrix and vibe which your explanation quote says has the VVTL-i. I'm just wondering if there's a way to find out which it has.
Eric Esler wrote:Do you know if the gm 2.4 has the variable lift? You said you think it's VVT-i but compare it to the matrix and vibe which your explanation quote says has the VVTL-i. I'm just wondering if there's a way to find out which it has.
I honestly couldn't find any information on which technology it's based off of. Trust me, I looked.
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V-Tak has to rev higher to make the HP that bigger GM motors get across the power band
I didnt see up there whether not VTEC was explained as far as what it does so here i go...
The way that a variable valve timing works is this. When at high rpms the motor begins to run out of air which is why on a non vtec once you hit a certain rpm you hp numbers drop until the motor hits its redline.
Now on a variable valve timing motor the vtec is tuned to kick in once the motor hits its peak hp on the "normal" lobes on the camshaft. Then the "wild" lobes on the camshaft are activated which cause the valves to open sooner and close later thus allowing more airflow. The result is a motor that builds hp almost the entire way to redline.
2007 GM Tuner Bash...HELL YEA
PA,MD,NJ,DE,NY and all states north caravan
Great info. But you forgot about Ford's, VVT program. The new Gen of ZTEC on the 2005+ Mustang GT's incorperates the use of VVT in the modular 4.6L SOHC engines. But the FoMoCo uses it to retard timing during decelaration. This saves gas and reduces Nx and CO. While it does kick in to help with heavy acceluration. It works more along the lines of Mitsubishi's MIVEC program in which horse power gain is marginal.
Tach Out Motorsports
Option D Inc.
Tach Out Motorsports wrote:Great info. But you forgot about Ford's, VVT program. The new Gen of ZTEC on the 2005+ Mustang GT's incorperates the use of VVT in the modular 4.6L SOHC engines. But the FoMoCo uses it to retard timing during decelaration. This saves gas and reduces Nx and CO. While it does kick in to help with heavy acceluration. It works more along the lines of Mitsubishi's MIVEC program in which horse power gain is marginal.
The only reason I didn't mention other VVT technologies out there is because Hondas V-tec is the most known and popular form of VVT to see or use and the 2.4 VVT is such new technology to us that people might confuse or compare it to V-tec.
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here's a pitiful and newbie question i'm dying to ask...
I know it sounds pitiful but I LOVE it when my buddie's GT-S Celica hits VVT-i and with his header/cat-back, I HEAR it kick in... kind of a waaaaaaaaa-AAAAAAAAAAAAA... per-se. I want to know, with a decent flowing exhaust, would one hear that changeover on the 2.4 VVT Ecotec?
I know, I know... pitiful, but I just love that sound... lol
Tim wrote:here's a pitiful and newbie question i'm dying to ask...
I know it sounds pitiful but I LOVE it when my buddie's GT-S Celica hits VVT-i and with his header/cat-back, I HEAR it kick in... kind of a waaaaaaaaa-AAAAAAAAAAAAA... per-se. I want to know, with a decent flowing exhaust, would one hear that changeover on the 2.4 VVT Ecotec?
I know, I know... pitiful, but I just love that sound... lol
LOL I personally have never been in one so I have no idea...
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Mitsubishi came up with a sort of Vtec called "Mivec".
[quote=Héctor]Mitsubishi came up with a sort of Vtec called "Mivec".
Vtec is a type of Variable Valve timing...Mivec has nothing to associate with Vtec, it's just another type of VVT.
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I think one thing that was not discussed yet in this thread was actually understanding the mechanics of each system
vtec- it is 4-valve per cylinder however each of the 2 cams has 3 lobes per cylinder. 2 are the primary lobes and 1 is the lobe that kicks in when the vtec hits. the 3rd lobe is usually taller and has more duration that the other 2. this 3rd lobe has its own separate lifter and the way it is actuated is when the engines rpm AND oil pressure reach a certain point a solenoid is activated and oil pressure is sent to that 3rd lifter thereby activating that higher cam lobe. making vtec more like an on-off switch. when you hear the whole waaaaaa-WAAAAAAAAA that is that 3rd larger lobe being activated. if you have vtec and what aftermarket cams you have to be weary of cheap replacements because at the moment the vtec kicks in there is a 50-100 rpm laps in airflow where power will drop considerably and it takes a buttload of research and r&d to produce a vtec cam that will transition smoothly from off to on
vvt- variable valve timing. this is where the camshaft can be either advanced or retarded depending on throttle, rpm, engine load, on any combination of. it is much less of an on-off switch and is infinitely adjustable withing its maximum(or minimum) parameters. valve lift is not increased or decreased and the duration is not effected however. with this you can make a low end motor run better top end or a top-end motor run better low end.
imo, with vtec you can make a street motor put out very good peak numbers, however, with a well thought out vvt system you could have a superior street motor and actually win more races
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I don't actually read your posts
I stare them down until they give me the information I require
I wasn't trying to get that in detail with it...this is just the newbies forum. I don't expect everyone to pickup every little detail of variable valve timing, just understand the basics lol
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Great post, learned a lot. I didn't know what any of it meant until i read it twice.
NJHK (King Of Newbies) wrote:I wasn't trying to get that in detail with it...this is just the newbies forum. I don't expect everyone to pickup every little detail of variable valve timing, just understand the basics lol
oh well, I figured I would put it out there for anyone who wants it
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I don't actually read your posts
I stare them down until they give me the information I require
NUTCASE . wrote:NJHK (King Of Newbies) wrote:I wasn't trying to get that in detail with it...this is just the newbies forum. I don't expect everyone to pickup every little detail of variable valve timing, just understand the basics lol
oh well, I figured I would put it out there for anyone who wants it
Not saying it wasn't good info though...thanks for the extra help.
www.kronosperformance.com / 732-742-8837
