vtec got so geng meh...

if u mean it works like a VVT then no, u r wrong..
read below

get to know what u r driving 1st.. thats the most important part..
ur engine is something called SOHC VTEC-E if i remember correctly and these kind of vtec does not have high lift lobe on the camshaft.. instead, it varies the valve being used in combustion.. for instant: at low speed, only 12V was used to maximise fuel efficiency while 16V was used to maximise power
i stand to be corrected

To Travies, about VTEC, I think I can, or most people will know it is the best N.A technology out there. Although some may argue Mivec but from much forum that I read, VTEC/i-VTEC>Mivec and all other N.A.

Yes.. the 12V on normal cruise I know, 16V only utilized when 4k rpm above, usually achieved in S mode, or 7 speed tip-tronic manually. In the city guide, it somehow says 4k is the VTEC power zone, it does have a louder sound but still ok la... It's not like the real VTEC out there, it just goes faster. In my notice, 1st gear can get to 65km/h if rev up to 5800rpm, which is the max HP level of my city. It's better than Vios and those 1.6 proton. And I heard that most people out there says that the ordinary VTEC kick in feelings is better than the i-VTEC?

Reference: http://asia.vtec.net/Reviews/VTECCityPrev/index.html
This shows some of my explanation, and much of yours correct points.

This post has been edited by ZeroSP: Oct 14 2008, 03:36 AM

so u look down on other car without vtec eh?
besides, ivtec again, works differently than the conventional vtec.. ivtec is more like cvvt, juz like newer version of mivecs.. juz pray u dont use ur vtec L15A to race satria mivec out there or u shat brix lol

AFAIK, i-Vtec can varies the lift infinitely instead of 2-stages as in Vtec by using solenoids to control the valve rather than lobes on cams. Because of this, you get better efficiency and power, but loose the 'feeling' of power surge when Vtec open.

i-DSI is more than just 2 spark plugs per cylinder- it's made for max fuel efficiency and minimal emissions, at the expense of all-out power, and has hi compression ratio (10.8:1?), minimal ignition timing advance, offset crankshaft position (so that the con rods are at a better angle to push down the crankshaft during the power/down strokes), swirl-inducing intake valve position for best air/fuel mixing, etc.

Very interesting design actually, but not really appreciated due to the low power output...

Hi Esky.I agree with you on the low output, but it's not as bad as most people thought with just 86BHPs.

Afterall,
The IDSI is tuned for maximised torque in town driving and modest horsepower for cruising on the highway. How do I know? my household has one.

When I drive it, it does accelerate (and it can smoke a typical Proton Wira 1.5 on green light, if accelerate more aggresively) briskly yet gentle.

Oh the highway, well, it wont pin a person to the seat. It will sail smoothly (its engine powerband, not handling) on the highway, though if you are the driver ferrying 4 people+luggage ,above 3000RPM and you will feel as though you are pushing the 8-valve unit abit, but the CVT tranny+ECU mask this very well.

FC on the otherwise,it averages from a steady 15-16Km/L. Almost can match with diesels. And furthermore it has been tested to run on 92RON safely (and gives better FC), through a trip from KL to Penang on 1 tank.

Emissions? Its really ULEV. Look at the tailpipe.Use your finger and swipe it. Not even 1 soot, carbon, anything on the tailpipe.

Theoritically, Nissan's new Selphy with it's 2.0L CVVT engine and CVT gearbox should give the best of both worlds. Power and fuel economy, but how economical...anyone got the figure?

This post has been edited by SleeplessEyes: Oct 14 2008, 08:41 AM

put cps also lar

Of course I don't race Mivec, I know the L15A power level. I am not looking down on non-VTEC cars either, because my brother Satria GTI 4g93 mod-ed high cam also that powerful that took down Mivec before. And I am just telling according to most of the automobile forum, thier discussion will most likely conclude VTEC is the best N.A. No offense ya... I am not a vehicle engineer, I just read through and try to understand what I can.

About Sylphy, apparently the figure is slightly less than i-DSI, which claim to be around 430km for a tank, but with a 2.0 engine, some say its because thier really new technology, and also low HP as a 2.0 if you compare the 2.0 to Honda or Toyota 1.8 or even 1.5... But can tell you from the test drive I got before, the Nissan CVT is not really that smooth as City one.

This post has been edited by ZeroSP: Oct 14 2008, 09:55 AM

Oh no. Varies lift infinitely, for Honda sake, is AVTEC.

VTEC is plain lifting along with fix set of phase timing setting per lift mode.

i-VTEC is lifting, with continuous phase timing - or in Toyota terms, you can say VVT-i with lifting (VVTL-i). Because of the continuous phasing, i-VTEC will be smoother (& more efficient) hence the non-existence illusion of boost.


Anyway, AFAIK (correct me pls), these are the group:
Continous lifting + continuous phasing: AVTEC (Honda) , Valvetronic (BMW), Valvematic (Toyota)
Lifting + continuous phasing: MIVEC (Mitsubishi), i-VTEC (Honda), VVTL-i (Toyota), Neo VVL (Nissan), VarioCam Plus (Porsche)
Lifting with variable lifting point: i-VTEC (L15A new Honda City)
Lifting + phasing: VTEC (Honda, on ~4krpm for example), CPS (Campro)
Lifting: CPS? (Campro) By logic, shouldn't have this since lifting already uses another cam lube, the lube itself should also have its phase differs.
Continuous phasing: (dual)VVT-i (Toyota), DVVT (Perodua), CVTC (Nissan), double-VANOS (BMW), (dual)AVCS (Subary), VarioCam (Porsche), CVVT (Hyundai)
Phasing (no idea which category of phasing): VANOS (BMW), VTC (Nissan)
Phasing with fix phasing point: (some say is) semi-VVT (Toyota, 4AGE 20v Silvertop on 4krpm)
Phasing with variable phasing point: VVT (Toyota of 4AGE 20v Blacktop)

Most the the above technology operate on intake cam only. However there are variants that functions on both intake and exhaust using the same name. And for continental lovers, you could add into the list.
Newer engines might employ camless valve timing technology, so no more DOHC vs SOHC . But might be entirely be replaced by eletric engines. Nobody knows....


p/s: I put Campro CPS on both category with a '?' because I'm unsure about it whether it came with just lifting only or, together with phasor system.

---

Added on October 14, 2008, 10:17 amThere are also another whole load of air intake technology, eg. IAFM, VIM... , that will also play an important role in the engine.

---

Added on October 14, 2008, 10:19 amAs for iDSI, to my understanding, it doesn't come with any valve timing technology, but rather it is the air intake technology (long & short runner) built into the engine with dual spark plug plus a leaner config that make it an illusion of 'efficient'.

---

Added on February 20, 2009, 10:30amAs for the L15A i-VTEC in the new City it doesn't have continuous phasing, unlike the K20 series i-VTEC. It is just the* lifting point* is variable instead of fixed on 4krpm.

There is also big different of "continuous lifting" vs "fix lifting height but infinite lifting point" vs "plain vanilla lifting" and also "phasing" vs "infinite phasing point" vs "continuous phasing". The more line I draw the more complicated it is.

This post has been edited by dstl1128: Nov 17 2009, 08:25 AM

L15A V-TEC system is different from those B16, where VTEC only switches between open/close one intake valve per cylinder and no exhaust valves are affected. So you can see how far it can go compared to 'big VTEC', isn't it? It just give you some added power at high RPM range for easier overtaking but definitely not a contender for their full power DOHC brothers B16s.
Honda has so many VTEC and i-VTEC variations. It is only fair to take apple-to-apple comparison. Same goes for MIVEC who also has MIVEC-MD.
Please correct if I get it wrong.

Well the old L15A is designed to have balanced FC as well as power. So it employ VTEC-E (or E-VTEC, damn I'm confuse with those name) with mixture of VTEC.

B16 uses more aggressive timing and... ... ... so both engine purpose is different. L15A looks more similar do D series engine than B.

L15A still lose to D15B by the way, L15A 110PS D15B 130PS and B16B 175PS. Let's see what's in AVTEC in the coming 3 years.

Definitely... B16 is another story than L15... And Campro and CPS, even the Lotus Manager will tell it is 10 years back technology when my dad went for Lotus Exige S. And my brother knew the engineer of Campro and CPS, Campro is fixed cam profiling which the engineer said nothing much, while CPS it's like they modified it into 2 set of fixed valve timing to provide better low end torque, no lifting for CPS and Campro. And that engineer says, "CPS and Campro are old tech la, but still Ok if it is on Manual Transmission"

This post has been edited by ZeroSP: Oct 14 2008, 10:31 AM

Sure or not? That means I have to change to:

This post has been edited by dstl1128: Oct 14 2008, 10:37 AM

CPS=Cam Profile Switching

这个CPS技术是由莲花(Lotus)公司为Porsche所开发的VarioCam Plus技术所简化来的...

很多人会把不同公司的引擎可变气门(Valve)技术搞混...什么VVT-i, MIVEC, VTEC, CVVT, CPS...其实这些并不是相同的气门技术。

基本上，可变气门技术可分为两大类：
1. Variable Valve Timing 可变气门正时
2. Variable Valve Lift 可变气门扬程


我们先来说说为何要使用可变气门技术把。

引擎在高转速时，其们开启的时间越来越短，吸入汽缸内的混合气体就会越来越少，这样就大大限制了引擎高转速时的功率提升。

如果一味的加大气门扬程(Lift)，或是气门的何时开启，时间长短（Timing/Duratin），虽然能够大幅增加引擎高转速时的功率，但是其中低转速时，废气就会过多的泻入进气岐管，吸气量反而会下降，气缸内气流也会紊乱，ECU也会难以对空燃比进行精确的控制，最终的效果是怠速不稳，低速扭矩偏低。

真的是两头不到岸...所以才会有可变气门技术的出现...

1. Variable Valve Timing 可变气门正时：
控制气门何时开启，在不同转速时增加/减少吸取空气的时间（开启次数，开启早晚）。
(Timing)

控制气门开启时间，在不同转速时增加/减少吸取空气的时间（增加/减少开启的时间）。 (Duration)

2. Variable Valve Lift 可变气门扬程
控制气门开启角度，在不同转速时增加/减少空气在同一个时间内的吸取量。

Well, you cant compare that way, altho L15A has less power than D15B but the L15A is design based upon today's strict emission control especially in european countries.

---

Added on October 14, 2008, 11:53 amOnce again bro, u made it all clear generally.

This post has been edited by Gouki: Oct 14 2008, 11:53 AM

If only I heard wrong from the engineer than I may be wrong... Lotus is an engineering company, they don't have their own engine but they have all the research and technology. Such as the Lotus Exige S, Elise... They are using Toyota 1.8 VVT-i engine for Elise, and for Exige S, they supercharge it. And the ultra light weight and super handling Lotus chassis. So that indeed Campro and CPS they say only Cam Profile Switching, no lifting. Believe it or not, Proton claims that Waja CPS 125PS, but yet on the road they still lose to 110PS L15A.

Paultan already dyno a CPS Gen.2 at got about 109whp in a hot afternoon.

This post has been edited by sphiroth: Oct 14 2008, 05:01 PM

Can give the link to that dyno? Sphiroth driving CPS Waja?

http://paultan.org/archives/2008/08/13/pro...ual-test-drive/

Yeah, I'm driving Waja CPS. Go to the 1 post in the CPS thread for some video.